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Current Status of Vascular Access Techniques
Symposium on Selected Problems in Venous and Arterial Disease
Current Status of Vascular Access Techniques
Samuel E. Wilson, M.D.,* Bruce E. Stabile, M.D.,f Russell A. Williams, M.B., B.S.,+ and Milton L. Owens, M.D.§
Obtaining long-term access to the vascular system may be the critical skill required in establishing successful parenteral nutrition or providing trouble-free years for patients on chronic hemodialysis. In this article we have distilled the practical aspects of the vascular access techniques that have proved most useful to us.
VASCULAR ACCESS FOR TOTAL PARENTERAL NUTRITION Total parenteral nutrition (TPN) solutions may be infused peripherally or, more commonly; into the central venous system. For administration of peripheral venous TPN, no specialized techniques for vascular access are required. On the other hand, institution of central venous TPN necessitates the placement of some type of indwelling catheter whose tip lies in the superior vena cava or the right atrium of the heart. A number of catheter insertion techniques are currently available, and familiarity with these is essential for the optimal and safe utilization of modern nutritional therapy.
Peripheral Venous Total Parenteral Nutrition TPN solutions provide nonprotein calories as glucose or fat, or both. The currently available lipid emulsions contain either soybean or safHower oil at 10 or 20 per cent solutions. Since they are isotonic, these lipid emulsions may be infused into any available peripheral vein. Standard intravenous needles and cannulas are used, and no special techniques of insertion are required. However, particular attention should be given to antimicrobial skin preparation, aseptic cannulation technique, and daily sterile dressing changes. The lipid emulsion cannot be mixed with *Professor of Surgery, UCLA School of Medicine; Chief, Vascular Surgery, Veterans Administration Wadsworth Medical Center, Los Angeles, California tAssistant Professor of Surgery, UCLA School of Medicine, Los Angeles, California :j:Assistant Professor of Surgery, UCLA School of Medicine, Los Angeles, California §Assistant Professor of Surgery, UCLA School of Medicine; Chief, Transplantation Section, Veterans Administration Wadsworth Medical Center, Los Angeles, California
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WILSON, STABILE, WILLIAMS, AND OWENS
amino acids or with any other component of the TPN system but may be infused through the same peripheral vein by means of a Y connector just proximal to the cannula. Unfortunately, the average peripheral infusion site will remain functional for only one to three days. The availability of adequate peripheral veins, therefore, becomes the factor that limits the duration of peripheral TPN therapy. If additional TPN is required, a central venous catheter must be placed.
Central Venous Total Parenteral Nutrition Access to the central venous system is always required for the infusion of TPN solutions containing hypertonic glucose as the primary caloric source. Peripheral veins promptly develop phlebitis and thrombosis when subjected to hypertonic infusions. Over the past dozen years a variety of catheters and catheterization techniques have been used for the delivery of central venous TPN. Dudrick and his colleagues were the first to successfully administer hypertonic TPN solutions when they adopted the technique of percutaneous infraclavicular subclavian catheterization 11 that was originally developed by the French military surgeon Aubaniac." This method of central venous access remains the most commonly used approach for TPN today. Other less popular percutaneous techniques include the supraclavicular approach to the subclavian vein and internal jugular vein catheterization. Both polyethylene and silicone rubber catheters are currently available for percutaneous insertion. The former is stiff, more likely to perforate the venous system, and more prone to thrombosis, the latter is more flexible and more disposed to kinking and misplacement. In recent years the concept of the TPN system as an "artificial gut" capable of supplying total nutrition needs for very long periods has led to the development of the specialized large-bore Broviac and Hickman catheters.v> These catheters are made of radiopaque soft silicone rubber, measure 90 ern in length, and have a small dacron felt cuff 30 em from the Luer-Lok external end. The Broviac catheter has an internal diameter of 1 mm, and the Hickman modification differs only in that it has an internal diameter of 1. 6 mm. A pediatric-sized Broviac catheter is also available. Since these catheters are inserted via direct venous cutdown into the cephalic or jugular veins, the risks related to "blind" percutaneous catheterization are eliminated. In addition, the silicone elastomer is less thrombogenic and less tissue reactive than is polyethylene. Placement of the Broviac or Hickman catheter entails tunneling the catheter through the subcutanous tissue in order to separate the skin exit site from the venotomy. Fibrous ingrowth into the dacron cuff located in the tunnel presents an effective barrier to the migration of microorganisms from the skin into the venous system along the outer surface of the catheter. As a consequence, the sepsis rate with these catheters is low. 22 ,25 Because of its proven durability and safety, the Broviac or Hickman type of catheter is preferred in any patient at high risk for percutaneous catheterization (such as one with emphysema, previous pneumonectomy, or massive obesity), in any patient who is anticipated to require more than two or three weeks of central venous TPN in the hospital, and in all home hyperalimentation patients. The placement of any central venous TPN catheter is always considered to be an elective, sterile operative procedure. "Thus, the patient should have hypovolemia and electrolyte abnormalities corrected prior to catheterization. Adequate lighting, instruments, nursing assistance, and strict aseptic techniques are absolute prerequisites for safe insertion of the TPN catheter. A thorough knowledge of the venous
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anatomy of the upper body and adequate experience or supervision are likewise mandatory. Infraclavicular Subclavian Catheterization. The patient is placed in the Trendelenburg position with hands at sides and head rotated away from the side to be catheterized. A·~rolled towel is placed under the upper thoracic spine to allow the shoulders to fall backward. The shoulder and upper chest are shaved, washed with soap and water, and the skin is defatted with 10 per cent acetone. Povidone-iodine is used to prepare the skin, and a sterile field to include the clavicular area and the lower neck is draped. The site for insertion is located 1 em below the curve at the midportion of the clavicle. A skin wheal is raised at the site using 1 per cent lidocaine local anesthesia. The muscles below and deep to the clavicle are also infiltrated. A 14-gauge needle attached to a 2- or 5-ml syringe is advanced in a horizontal direction through the skin, subcutaneous fat, and muscle, then deep to the clavicle but superficial to the first rib while the operator aims for the suprasternal notch (Fig. 1). It is critically important to maintain the horizontal plane parallel to the anterior chest wall in order to gain entrance into the subclavian vein as it passes over the first rib and underneath the medial third of the clavicle. Failure to advance the needle in this plane greatly increases the risk of penetrating the more posterior structures, such as the apex of the lung, subclavian artery, or brachial plexus. Constant negative pressure is maintained on the syringe so that successful venipuncture will be immediately indicated by a Hushback of dark venous blood. When this occurs, the
Figure 1. The technique of percutaneous infraclavicular subclavian vein catheterization is shown.
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WILSON, STABILE, WILLIAMS, AND OWENS
patient is instructed to stop breathing, and the bevel of the needle tip is turned downward toward the feet to facilitate passage of the catheter centrally into the superior vena cava. With the needle held stationary, the syringe is removed and the 8-inch long, 16-gauge catheter is quickly advanced its entire length until the catheter end fits tightly into the needle hub. Once the vein is entered, the operator's gloved finger should always be placed over the open end of the needle hub to protect against air embolization. If catheter advancement is met with resistance, the needle and catheter should be withdrawn as a unit, since shearing off and embolization of the catheter tip may occur if the catheter is pulled back against the stationary needle. As soon as the catheter is successfully inserted, an intravenous tubing is quickly connected and isotonic saline infusion is begun. The intravenous bottle is then momentarily lowered below the patient's heart. Back bleeding or venous blood flowing into the intravenous tubing confirms the intraluminal position of the catheter tip. The needle is then withdrawn out of the skin, the plastic needle guard is snapped on, and the guard is sutured to the skin with 3-0 nylon. Povidone-iodine ointment is applied to the skin exit site and a sterile occlusive dressing is placed. A gentle loop of intravenous tubing is taped to the dressing to prevent catheter dislodgement should traction be applied to the tubing. Chest auscultation and a chest x-ray film are always immediately carried out to check for pneumothorax and to confirm the proper position of the catheter tip in the superior vena cava. Other Percutaneous Catheterization Techniques. The supraclavicular approach to the subclavian vein has the advantage of a shorter distance from skin surface to vein but the disadvantages of greater movement at the dressing site above the clavicle and greater risk of thoracic duct injury when the left side is used. Because of the left-sided location of the thoracic duct and the straighter course of the right innominate vein into the superior vena cava, the right side is preferred for the supraclavicular technique. Following proper positioning, the skin is prepared and draped as for infraclavicular catheterization, and 1 per cent lidocaine is infiltrated into the skin at a point 1 to 1. 5 em above the angle created by the lateral margin of the sternomastoid muscle and the superior surface of the clavicle. The 14-gauge needle is introduced at this point and advanced deep to the clavicle in a direction bisecting the angle formed by sternomastoid and clavicle, the operator aiming for the midpoint of the sternomanubrial junction. After entry of the needle into the subclavian vein (at a point just lateral to its confluence with the internal jugular vein), the catheter is inserted, fixed, and dressed as described for the infraclavicular technique. Several techniques have been advocated for percutaneous internal jugular vein catheterization. All have the advantage of fewer injuries to the pleura and subclavian artery but the disadvantages of difficult dressing maintenance secondary to neck movement. Again, the right side is preferred because of venous and lymphatic anatomic considerations. After preparation, draping, and instillation of local anesthesia, with the patient in the Trendelenburg position the 14-gauge needle is inserted at the medial border of the sternomastoid muscle at the level of the thyroid cartilage. While the index finger of the operator's free hand palpates the common carotid artery, the needle is advanced under the muscle toward the thoracic inlet at a 30degree downward angle, with the operator aiming toward the internal jugular vein as it passes deep to the sternal end of the clavicle. An alternative approach utilizes insertion of the needle at the lateral border of the sternomastoid 3 em above the clavicle, with advancement under the muscle, aiming toward the sternal notch.
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A chest x-ray film is mandatory after every successful or unsuccessful attempt at percutaneous central venous catheterization using any of the foregoing techniques. Furthermore, after failure to catheterize the subclavian vein on one side, an attempt should never be made on the opposite side without first obtaining a chest x-ray film to rule out occult pneumothorax. Fatal bilateral pneumothorax has occurred when this admonition has been ignored. Safe percutaneous TPN catheterization always requires adherence to the following essential points: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Knowledge of anatomy, insertion techniques, and complications and their treatments. Adequate experience or supervision. Appropriate patient instruction and sedation, if warranted. Prior repletion of fluid volume deficits. Proper positioning, skin preparation, and sterile draping. Adequate local anesthesia. Precise needle advancement with constant negative pressure on syringe. Flashback of dark venous blood to confirm venipuncture. Swift removal of syringe and catheter advancement. Prevention of air embolization through open needle or catheter. Secure suture fixation of catheter or needle guard to skin. Confirmation of intraluminal catheter tip position by backbleeding. Meticulous sterile dressing technique. X-ray film confirmation of correct catheter tip position prior to hypertonic fluid infusion.
Although pneumothorax remains the most frequently encountered serious complication, numerous others have been reported in the literature, including the following: 6,17,23 Thoracic Pneumothorax Hemothorax Hydrothorax Hemomediastinum Chylothorax Venous Laceration Air embolism Catheter em holism Thrombosis Arterial Laceration or perforation Pseudoaneurysm Arteriovenous fistula Lymphatic Thoracic duct fistula
Cardiac Arrhythmia Perforation and tamponade Coronary sinus thrombosis Neurologic Injury Brachial plexus Phrenic nerve Vagus nerve Recurrent laryngeal nerve Septic Catheter sepsis Septic thrombosis Suppurative thrombophlebitis Catheter Failure Misplacement Occlusion Breakage or kinking
Placement of Broviac or Hickman Catheter by Cutdown. Since the Broviac or Hickman catheter is inserted by direct venous cutdown, all the risks inherent in "blind" percutaneous catheterization are eliminated. In theory, the Broviac or Hickman catheter may be placed into any vein accessible by cutdown, but in practice, the cephalic vein in the deltopectoral groove and the external jugular vein in the neck are the preferred sites. If these are unavailable, the internal jugular, the common facial, the large pectoral radical, the thoracoacromial, and the great saphenous veins are alternatives. In patients receiving TPN who have had numerous previous catheters, preoperative venography is often required to verify patency of the superior vena cava or the subclavian veins or their tributaries. In most hospitals the Broviac or Hickman catheter is inserted in the controlled environment of the operating room where x-ray or fluoroscopy is available to confirm
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WILSON, STABILE, WILLIAMS, AND OWENS
the proper position of the catheter tip prior to skin closure. After selection of the cutdown site, proper positioning and standard surgical preparation and draping, 1 per cent lidocaine local anesthesia is instilled. For the cephalic vein cutdown, a 2- to 3-cm oblique skin incision is made just inferior to the coracoid process in the area of the deltopectoral groove. For the jugular vein approach, a 1- to 2-cm transverse midcervical incision is made over the vein. Mter dissection verifies·patency and adequate size of the vein, a subcutaneous tunnel is made with a long alligator forceps from the cutdown to the cutaneous exit site of the catheter medial to the breast (Fig. 2). A small stab wound is made at this site, and the catheter is brought up through
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Figure 2. Preferred cutdown sites and the technique for creating a subcutaneous tunnel for a Broviac or Hickman catheter are shown.
537
CURRENT STATUS OF VASCULAR ACCESS TECHNIQUES
the tunnel so that the dacron felt cuff resides 2 to 4 em inside the tunnel. The catheter is then shortened so that the tip will just reach the right atrium. The catheter is filled with heparinized' saline by syringe. The vein is ligated distally and the catheter is introduced through a small venotomy and advanced its full length. A proximal ligature placed around the vein secures the catheter in position (Fig. 3). If the internal jugular vein is used, the catheter may be introduced through a lateral venotomy and fixed with a purse string of fine vascular suture. After the catheter is fully advanced, it is aspirated with the attached syringe. If dark venous blood does not return, the catheter is either kinked or misplaced, and it should be withdrawn and advanced again. Radiographic verification of proper catheter tip position in the right atrium is always obtained before the wound is closed. The catheter is fixed to the skin at the exit site with a nylon suture, and this is removed one to two weeks later after fibrous ingrowth into the dacron cuff has occurred. Povidone-iodine ointment and a sterile dressing are applied to the exit site, and a loop of redundant catheter is taped to the chest wall. The catheter may be either heparin locked using the Luer-Lok cap provided or immediately connected to an intravenous infusion set. An atraumatic clamp is always kept immediately available at the bedside for emergency use should disconnection or breakage of the catheter threaten air embolism or back bleeding. The patient, as well as the nursing staff, should be thoroughly familiar with the indications for use of the clamp.
CUTDOWN SITE
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Figure 3. A Broviac or Hickman catheter is inserted into the left cephalic vein with correct positioning of the dacron cuff in a subcutaneous tunnel and the catheter tip in the right atrium.
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WILSON, STABILE, WILLIAMS, AND OWENS
VASCULAR ACCESS SITES FOR DIALYSIS With the number of Americans requiring maintenance hemodialysis approaching 55,000 and increasing at the rate of almost 5000 patients per year, vascular access surgery has emerged as a special area of competence for the vascular surgeon. 29 Implementation of the Medicare end-stage renal disease program in 1973 increased the number of aged and diabetics undergoing dialysis: currently 53 per cent of dialysis patients are 50 years of age or older, and 12 per cent are diabetic. 14 The increasing life expectancy of these patients, who often have poor vasculature, can tax the ingenuity of the surgeon in maintaining a route for vascular access.
Emergency Vascular Access Although partially exteriorized arteriovenous shunts were widely used for chronic 'dialysis access in both adult and pediatric patients prior to 1966, they have been largely replaced through improvements in the use of internal fistulas, peritoneal dialysis catheters, and femoral and subclavian venipuncture techniques. 2,7,9,10,27 Nevertheless, they are still widely used in the management of acute renal failure and have occasional, although diminishing, applications in the treatment of chronic renal failure. In 1960, Quinton, Dillard, and Scribner described the Teflon-Silastic arteriovenous shunt." This used a loop of Silastic tubing lying on the volar aspect of the forearm to connect Teflon catheters placed in both the radial artery and a nearby wrist vein. The Scribner shunt was quickly and widely adopted, as it was the most durable current means of providing vascular access for dialysis treatment of patients with end-stage renal disease. The disadvantages of this external shunt are threefold: (1) infection is highly likely to enter from the skin along the Teflon catheter tissue tracks, (2) clotting of the blood is apt to occur as it courses through the Silastic and Teflon conduits, and (3) patients do not readily accept the external appliance since the extra care necessary to prevent its dislodgement and its appearance tax their already heavily burdened tolerance. When an external shunt is needed, the radial or posterior tibial vessels are satisfactory sites; we use rigid Teflon vessel tips and a straight Silastic connector with wings (Ramirez winged shunt) for the procedure. The Scribner or Ramirez winged shunt, which can be readily constructed using local anesthesia, may be advantageous for treatment of acutely ill patients in whom an urgent but short course of dialysis or plasmapheresis is anticipated. The radial artery and cephalic vein in the arm are most often used, but other vessels may be chosen, and it is occasionally necessary to use the saphenous vein and posterior tibial artery in the lower leg. Variably sized Teflon tips are chosen to fit into the particular artery or vein. The tips are connected to standardized Silastic tubing, which is tunneled for some distance before exiting through the skin. Externally, the arterial and venous ends of the Silastic tubing may be disconnected for attachment to the dialysis machine. Depending on how thoroughly the surgeon anchors these shunts internally, removal may be effected simply by pulling them out, or it may require another minor operation. Advantages include ease of placement and availability for immediate use. Thrombosis and infection usually prevent longterm use. In comparison to the Allen-Brown and Thomas shunts, the stiff in-dwelling tip in the Teflon-Silastic shunt is more likely to cause vessel damage from movement
CURRENT STATUS OF VASCULAR ACCESS TECHNIQUES
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and is also somewhat more difficult to declot successfully with the balloon-tipped catheter. Allen-Brown and Thomas Shunts. The Allen-Brown and Thomas shunts 12 , 16 ,26 have dacron cuffs attached to Silastic tubing a'hd must be sewn to the chosen artery and vein." This is more difficult and time consuming than the simple cannulations required for the Teflon-Silastic shunts but may have some advantages when large vessels are used or the shunt must be placed near a flexion crease or in the lower leg. In these sites movement causes the shunt to slide back and forth. In these circumstances the in-dwelling Teflon tip of the Teflon-Silastic shunt may rapidly erode the vessels in which it is placed. Removal of the Allen-Brown and Thomas shunts requires reoperation. Our experience indicates that dialysis should be delayed 24, and preferably 48, hours after placement of the Allen-Brown or Thomas shunts in order to prevent bleeding through the dacron cuffs. Venipuncture Techniques. Currently, percutaneous cannulation of the femoral or subclavian veins is increasingly displacing the Scribner shunt for provision of temporary vascular access. 13 The treated blood is returned to the patient via a peripheral vein (or via the same cannulated vein along the second lumen of a double lumened catheter). Most importantly, the vessels are preserved at the very sites that are best suited to construction of a subcutaneous arteriovenous fistula. With this technique, short term dialysis needs are met through the transcutaneous introduction of stiff-walled catheters with external diameters of approximately 2.5 mm. These catheters are generally introduced over a guide wire and may be left in place for several days.v Depending on the situation, either single catheter dialysis with pulsatile flow or double catheter dialysis with continuous flow may be chosen. The latter is usually elected when urgent and aggressive dialysis is necessary, as for poisoning or fluid overload. Thrombosis is usually prevented by continuous low dose heparin infusion. These catheters are most useful in the following situations: (1) acute renal failure in which it is anticipated that only a few dialyses will be necessary, (2) chronic renal failure during the immediate postoperative period after placement of an internal fistula, (3) in patients with transplantations who have thrombosed arteriovenous fistulas, (4) in patients needing urgent transfer from peritoneal dialysis, and (5) for the treatment of poisoning. The main advantage of venipuncture techniques is that vessels that may be needed for the later construction of internal fistulas are not wasted. Disadvantages include patient discomfort, a greater amount of time spent by the physician per dialysis, and a relatively greater number of traumatic, septic, and thrombotic complications than would occur over the same time period if the Teflon-Silastic external arteriovenous shunt were used.
Arteriovenous Fistula The autogenous arteriovenous fistula, usually made by joining the end of the cephalic vein to the side of the radial artery at the wrist, still remains by far the longest lasting and most dependable site for vascular access. When successful, this fistula has a long-term patency rate of approximately 75 per cent between two and three years. Further, it is frequently possible to revise a failing fistula by excising an aneurysm or re-anastomosing a major vein higher on the radial artery. An autogenous fistula may be unsatisfactory in diabetic patients with advanced arteriosclerotic changes extending into the radial artery; in patients with a thick layer of subcutaneous fat; or if the veins are too small, fragile, and thin walled to mature sufficiently for repeated needle puncture. Complications are unusual, but venous hypertension of
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WILSON, STABILE, WILLIAMS, AND OWENS
the hand and carpal tunnel compression symptoms have been noted with side-toside anstomoses. Brescia-Cimino Fistula. The subcutaneous arteriovenous fistula was described by Brescia, Cimino, Appel, and Hurwich in 1966. 7 Being constructed of the patient's own vessels, the Brescia-Cimino fistula in great part overcomes the disadvantages of the Scribner shunt. Following formation of the fistula, arterial pressure is transmitted directly into the contiguous veins, which dilate and develop a hypertrophied muscular wall. This arterialization may take up to six weeks before sufficiently sized and thick-walled vessels have developed that are suitable for repeated venipuncture. Treatment, if necessary, may be secured for this period using subclavian or femoral vein cannulation, a Scribner shunt, or peritoneal dialysis. Before operation, the veins, preferably in the nondominant hand, are distended and examined utilizing a sphygmomanometer with cuff applied to the upper arm and inflated below the systolic pressure level to produce venous engorgement. All suitably sized veins are marked with an indelible pen (Codman surgical marker). Should the fistula of choice fail following construction at operation, these markings aid the surgeon in choosing another site. Suitable subcutaneous veins may not be evident in patients with fat arms, and in others the veins may simply be too small to be useful. In patients who have had repeated phlebotomies, phlebitis may have obliterated the majority of superficial veins so that even if a fistula were constructed, the paucity of venous channels would restrict the runoff of blood and blood flow through the fistula, increasing the chances of its clotting. The ulnar and radial artery pulses are palpated. In the diabetic patient, especially one with severe atherosclerosis, these vessels may be too narrowed to sustain flow through a fistula. Determine beforehand that the ulnar artery can support the circulation to the hand (should the radial artery be divided or subsequently clot). Digital compression, occluding both arteries at the wrist, is followed by pallor of the elevated hand. Release of the ulnar artery returns a normal appearance to the hand if the blood supply is sufficient. The fistula may be constructed with local infiltration, brachial nerve block, or general anesthesia of the operation site. A successful result is more likely with meticulous vascular surgical technique in the operating room using fine instruments and suture material. The arm is surgically cleaned, abducted at a right angle from the body, placed on an arm board or table, and draped, leaving the operation site exposed. Operative technique is facilitated if the surgeon and assistant are comfortably seated. An oblique or longitudinal skin incision is made over the radial artery, proximal to the wrist skin fold. A 7- to 10-cm length of cephalic vein is dissected free of surrounding subcutaneous tissue and adventitia. Its tributaries are ligated, freeing it further so that it lies adjacent to the radial artery without kinking or twisting. A comparable length of the radial artery, here found under the deep fascia of the forearm, is isolated and cleaned. The artery and vein may be anastomosed as follows (Fig. 4): 1. Side-to-side, with a fistula opening approximately 1 em in length. Technically, this is the easiest anastomosis to construct and has the highest fistula blood flow. It is the most likely fistula to be associated with venous hypertension and swelling in the hand. These complications are moderated by the presence of valves that prevent reversal of venous blood flow in the hand, at least in the early months.
CURRENT STATUS OF VASCULAR ACCESS TECHNIQUES
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Figure 4. Four commonly used anastomoses between the radial artery and the cephalic vein are (A) side-to-side, (B) side of artery to end of vein, (C) end of artery to side of vein, and (D) end-to-end. (From Fernando, O.N.: Arteriovenous fistulas by direct anastomosis. In Wilson, S.E., and Owens, M.L. (eds.): Vascular Access Surgery, with permission. Copyright © 1980 by Year Book Medical Publishers, Inc., Chicago.)
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2. Arterial end to vein side eliminates the distal "steal" of blood but has a lower fistula blood flow. Care is required during construction to avoid twisting of the artery. 3. Vein end to arterial side minimizes distal venous blood flow, although it is technically more difficult to construct than a side-to-side anastomosis. 4. End-to-end anastomosis produces the least "steal" of blood and venous hypertension but has the lowest fistula flow.
Proximal and distal control of the two vessels is achieved by application of small bulldog clamps or a fine Silastic sling. The vessels are anastomosed with a 6-0 polypropylene suture, with the knots placed outside of the lumen. Before the anastomosis is finally closed, a check is made by passage of a coronary artery or biliary dilator to detect any stenosis. Any bleeding from the anastomosis is first controlled
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WILSON, STABILE, WILLIAMS, AND OWENS
by simple pressure with a gauze swab for several minutes. Too hasty a resort to suture repair is liable to produce further bleeding sites and narrowing of the anastomosis. Upon conclusion, the artery and vein lie beside each other without twists or kinks. A thrill should be easily felt over the fistula and propagated for a moderate distance along the contiguous venous channels. A transmitted pulse without a thrill suggests that there is an outflow obstruction or a clotted fistula. The proximal vein may be probed and irrigated with a Fogarty catheter (avoiding intimal damage by not inflating the balloon during manipulation of the catheter) or dilated with bougies. If these maneuvers do not produce a strong thrill and the fistula is technically satisfactory, consider construction of a fistula at another site. On occasion in such a case, a bruit appears as the veins dilate and blood flow increases, especially when there was no outflow obstruction shown by the preceding technique. Following the operation, the arm is elevated by the patient's side for 24 hours. Any swelling usually resolves over subsequent weeks. Prevent constriction of the venous outflow of the fistula-bearing arm, especially by using dressings, sphygmomanometer cuffs, and clothing. Several weeks should elapse before the veins are used for phlebotomy. Puncturing the vessels before they are arterialized is often associated with hematoma formation, as early on the dilated veins are particularly thin walled. Exercise of the forearm by squeezing a rubber ball increases the fistula flow, which aids maturation of the arterialized veins.
Bridge Fistula When the Cimino fistula fails or cannot be constructed, one must use a conduit to form a bridge arteriovenous fistula. Descriptions are to be found of bridge fistulas constructed between almost any of the suitably sized superficial arteries and veins of the body. For vascular access these are a second choice to the Cimino-Brescia subcutaneous fistula. However, when placed, these easily palpable conduits can be readily punctured by needle. If possible, this should be avoided for some weeks until there is incorporation of the prosthetic material into the patients' tissues. Premature attempts at use are associated with a high complication rate, especially the leak of blood at the puncture site forming a perigraft hematoma. In current practice, the ends of the graft are anastomosed to the side of the artery or vein. If the two anastomoses are near each other, the conduit takes on a V -configuration; if they are separated by some distance, it may lie straight or in a curve. Grafts with a diameter of 6 mm permit a good fistula blood flow in the 'arm and there is little likelihood of producing distal limb ischemia. In the groin, a graft with an 8 mm diameter is similarly satisfactory. In the arm, fistulas are satisfactorily made between the radial artery and a cubital fossa vein, the brachial artery (in the cubital fossa before its division) and the adjacent cephalic vein (V-configuration), and the brachial artery and the axillary vein. Construction of an arm fistula is more demanding technically and its long-term patency rate is not as high as that of a thigh fistula. In the arm, however, the risk of infection and distal limb ischemia is less. Patients with claudication or an ankle arterial pressure less than 80 per cent of that at the wrist are not suitable for thigh fistulas because the proximal steal of blood through the fistula is likely to increase ischemia in the leg. In the thigh, the arterial anastomosis should, in the first instance, be to the superficial femoral artery, either immediately proximal to the adductor canal or to
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its more cephalad part. If the superficial femoral artery is occluded, the common femoral artery may be used, with the understanding that if it becomes infected and ligation is subsequently required, leg ischemia may ensue. At times, patency of a short segment, including the origin of the superficial femoral artery, can be reestablished and used for anastomosis. The venous anastomosis is made to the proximal saphenous, common, or superficial femoral vein. The site we prefer to use first is from the distal radial artery to the cephalic or basilic vein in the antecubital fossa (Fig. 5). The graft should be anastomosed endto-side to the radial artery, tunneled along the lateral aspect of the forearm, then anastomosed end-to-side to the largest vein in the antecubital fossa. In positioning the graft it is most important to insure that the patient's arm will rest comfortably while on dialysis. The advantages of the radiocephalic location are as follows: by using a small peripheral artery for the arterial origin, postoperative complications are unlikely to result in serious ischemic changes; the procedure can be done under local anesthesia; ease in preparation of the forearm results in a low infection rate; and the seated position of the surgeon facilitates use of magnifying glasses and microinstruments. The one disadvantage is an earlier occlusion because of the lower flow from the small radial artery. Secondary vascular access sites include (1) brachiocephalic loop fistula in the forearm (Fig. 6A), (2) brachioaxillary fistula in the upper arm (Fig. 6B), and (3) femorosaphenous fistula in the thigh (Fig. 6C). The loop graft placed in the forearm allows a good length of graft for dialysis; the upper arm graft curving over the lateral
RADIOBASILIC BRIDGE FISTULA
Figure 5. A radiobasilic conduit in the forearm, when technically feasible, is our first choice of bridge fistula for hemodialysis.
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WILSON, STABILE, WILLIAMS, AND OWENS
BRACHIOAXILLARY
BRACHIOBASILIC LOOP FISTULA
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FEMOROSAPHENOU9 BRIDGE FISTULA
Figure 6. Satisfactory secondary vascular access sites are (A) the brachiocephalic loop fistula in the forearm, (B) the brachioaxillary fistula, and (C) the femorosaphenous fistula.
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aspect of the brachium allows a slightly shorter needle puncture area. Both of these upper extremity procedures can be done with the patient under local anesthesia and both have a low incidence of infection. Of the two, the brachioaxillary graft has the higher How rate and would be expected to remain open for the longest period of time. The femorosaphenous shunt is usually done with the patient under a spinal or general anesthetic, although in cooperative patients a local infiltration technique can be used. We prefer to place the arterial origin of the graft proximal to the adductor canal so that should a vascular complication cause occlusion of the superficial femoral artery, adequate collateral channels provide filling of the popliteal segment. The femorosaphenous graft is curved over the lateral aspect of the thigh and anastomosed to the proximal saphenous vein (see Fig. 6C). The disadvantages of this technique are the somewhat higher infection rate, due to inability to thoroughly prepare the groin, and a vascular steal phenomenon with reversal of How in the distal femoral artery. Accordingly, one should make sure of an ankle-wrist systolic pressure ratio of at least 0.80 prior to constructing this access." Fortunately, most patients with steal are not symptomatic, since the activity of the dialysis patient is so limited. A less useful access site is the loop arteriovenous fistula placed in the groin from the common femoral artery to the femoral vein. Complications rendering the femorofemoral site less favorable are the high How (greater than 700 ml per minute) leading to increased cardiac output, the possibility of limb loss should complications at the common femoral artery anastomosis develop, and the risk of infection. Venous hypertension in the leg has not been a problem. High fistula blood flow rates increase cardiac output and have led to cardiac failure in some elderly patients. Choose a graft with a 6 to 8 mm diameter if this problem is anticipated. Should it develop, the diameter of the graft may be reduced by a "banding procedure." When the foregoing sites are already expended, the surgeon is forced to choose a more central location, such as a graft placed between the axillary artery and the axillary vein on the anterior chest wall. Always bear in mind that as one moves centrally, complications at the access site are not only more likely to occur but more serious when they do. Technical points that have proved helpful include the following: 1. Use of a 5-0 or 6-0 polypropylene suture for the anastomoses. 2. 5000 units of heparin intravenously is usually sufficient anticoagulant for the patient on dialysis. 3. A graft with a diameter of 6 mm is usually the largest that can be utilized in the forearm, but in the lower extremity an 8 mm graft is quite easily placed. 4. Avoid direct arteriovenous fistulas placed at the level of the antecubital fossa, since these have been accompanied with an unacceptably high rate of distal ischemia. 5. A thrill but not pulsation on completion of a graft procedure portends success.
Should infection develop in these grafts, removal is required for its control. A further bridge fistula is formed only after removal of the infected graft to minimize the chance of blood-borne seeding of the second graft. If the infection involves the anastomosis, removal of the graft may require ligation of the adjacent artery or vein. This can produce distal ischemia, especially if it is the brachial or common femoral artery that is ligated. The initial choice of an artery is always tempered by the knowledge of this possibility. Materials for Bridge Fistulas. The autogenous saphenous vein was the first conduit used in construction of the bridge arteriovenous fistulas. Its chief appeal is
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safety from contiguous infection, but on the balance, such disadvantages as an unpredictably small size, the separate incision for removal, and early sclerosis on repeated puncture outweigh this factor. In Sydney, a large experience with 71 autogenous saphenous vein conduits resulted in a 66 per cent patency rate at two years, decreasing to 40 per cent at three years.!" Only a 20 per cent patency rate at 2 years, however, was reported from the United States, reflecting the accelerated loss due to fibrosis that occurs after two years of continuous puncture and accounts for its relatively infrequent use." With an accumulated clinical experience of almost 10 years, the bovine heterograft has well-recognized complications, including development of aneurysms, rapid deterioration in the presence of infection, and late thrombosis due to stenosis of the venous anastomosis. The two-year patency rate for bovine carotid artery grafts has been reported as 45 per cent and as 52 per cent. 1,5 .., Expanded polytetrafluoroethylene or Teflon (Goretex and Impra) is the only synthetic prosthesis widely used for vascular access. Sample two-year patency rates from experienced centers are 67, 68, and 73 per cent.1.5,15 Some polytetrafluoroethylene grafts manufactured prior to 1977 were subject to stretch resulting in dilatation. Increasing the wall thickness or wrapping the graft with an exterior layer appears to have eliminated true dilatation, although pseudoaneurysms may still occur (Fig. 7). Venous runoff stenosis develops as early as three months and is a common reason for late thrombosis. When increasing pressure in the venous return line is detected during dialysis, an angiogram will define the area of stenosis, and anastomotic revision (patch angioplasty or percutaneous transluminal dilatation) may be instituted prior to complete occlusion. By the time thrombosis of the graft occurs, the shrunken and fibrotic segment of vein may extend too far to be amenable to local revision. Persistent collections of semi-solid proteinaceous material or seromas, reported in 33 patients with polytetrafluoroethylene grafts, are thought to develop if wetting of the graft occurs prior to implantation." Experimental studies show that a plasma-like fluid may weep through the polytetrafluoroethylene graft, especially when the hematocrit is less than 30 per cent. The human umbilical cord vein (Bioflow) is the newest graft for vascular access; its advantages are low thrombogenicity and absence of immunologic reaction. Early clinical trials show promise, with a one-year patency rate of 65 per cent. I B,20 Lastly, all grafts have common drawbacks. Local infection at a needle puncture site may develop at any interval as a result of less than aseptic technique. Postcannulation bleeding and hematoma can occur in the first three weeks after implantation (Fig. 8). Often the credit for long-lasting graft function is due to the dialysis nurses, technicians, and patients who are responsible for the day-to-day technical management and care of the access site.' On review it is still apparent that every effort should be made to construct and preserve a functioning Cimino fistula as the site of choice for maintenance hemodialysis.
VASCULAR ACCESS FOR CANCER CHEMOTHERAPY AND CHRONIC INTRAVENOUS MEDICATION A course of treatment with antineoplastic drugs usually requires multiple intravenous injections administered over a long period. Many of these drugs induce chemical thrombophlebitis, and within a short time few suitable veins remain through
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Figure 7. Multiple small pseudoaneurysms are shown at needle puncture sites in an expanded polytetrafluoroethylene vascular access conduit.
which the drug can be given. Repeated blood samples are also needed for analysis so that vascular access becomes a critical problem. When the decision is made to treat malignant disease with chemotherapy, definite considerations should also be given to the patient's likely future needs for vascular access. Construction of a vascular access at this time could avoid future anguish. A subcutaneous arteriovenous fistula is least likely to develop complications and most convenient, from the patient' s view, as an access site. Delay until sites for injection are unfortunately limited makes the surgical construction of a subcutaneous arteriovenous fistula likely to fail because of restriction of the venous outflow. Faced with such patients, bridge fistulas have been successful using bovine heterografts or synthetic Teflon grafts. These patients often have a low platelet count and may bleed excessively at operation. They are also prone to infection and delayed wound healing. The synthetic material in a bridge fistula is more likely than a Brescia-Cimino fistula to become infected, and the surgical construction of such a fistula is a serious undertaking that
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Figure 8. Too early use of a vascular access conduit can result in perigraft extravasation. The graft is usually sufficiently incorporated for safe use after three weeks.
may be complicated by hematoma formation in the subcutaneous graft tunnel. A poor outcome may also be due to delayed wound healing. Hickman and Broviac catheters are now often used for long-term chemotherapy vascular access sites. The Hickman catheter has an internal diameter of 1.6 mm compared with 1 mm for the Broviac catheter and permits easier withdrawal of the many required blood samples. Careful catheter care is required, as in patients receiving TPN. Patients needing long-term medication who have diseases such as hemophilia, Christmas disease, and von Willebrand's disease now have the prospect of a relatively normal life style because of the availability of purified extracts of factors VIII and IX. Some brittle diabetic patients require frequent intravenous therapy for treatment of repeated episodes of hypoglycemia or hyperglycemia, and other patients with chronic anemias, such as sickle cell disease, may need frequent transfusions. Vascular access often becomes a difficult, limiting problem during these patients' lives. A subcutaneous fistula is the most desirable access. The best time for its construction is early while suitable veins are available. It can be predicted that patients with hereditary clotting disorders will need frequent intravenous therapy.
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Those in whom a subcutaneous arteriovenous fistula has been made are able to treat bleeding episodes themselves, early and at home, using prepacked factors VIII or IX. Prompt control of bleeding under these conditions results in use of smaller quantities of plasma concentrates, many fewer hospitalizations, and less loss of work time. A fistula-in the nondominant arm is easiest for self-cannulation. It is often possible to predict that a patient will have the need for long-term vascular access. A subcutaneous arteriovenous fistula made while still technically feasible will avoid future frustration.
PLASMAPHERESIS Plasmapheresis is the technique for removal of plasma from a donor without reduction of circulating red blood cell mass. It became relatively safe with the advent of integrally interconnected plastic collection bags that permit centrifugation and manipulation of the blood without contamination. The continuous flow centrifuge has decreased the time necessary for completing a course of treatment. Therapeutically, plasmapheresis is used for removal of specific materials, such as toxins, proteins, or a type of cell that are responsible for an illness. Blood banks use the technique to obtain plasma and protein fractions or cells from a small pool of donors. This decreases the risk of transmitting hepatitis and increases the quality of the product.
*
c.
D.
SALINE INTO PATENT
Figure 9. A simplified schematic representation of plasmapheresis. (From Williams, R.A.: Vascular access for cancer chemotherapy, chronic intravenous medication and plasmapheresis. In Wilson, S.E., and Owens, M.L. (eds.): Vascular Access Surgery, with permission. Copyright © 1980 by Year Book Medical Publishers, Inc., Chicago.)
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A simple method for plasmapheresis is to remove 300 to 500 ml of whole blood into a plastic bag containing an anticoagulant (acid-citrate-dextrose) and to layer the blood into its various components by centrifugation at a specific speed (Fig. 9). The desired component is eluted, via the integrated. tubing, into another bag and the red cells returned to the patient with 300 to 500 ml of saline. "Double plasmapheresis" is a repetition of this sequence. Continuous flow centrifuges similarly perform the plasmapheresis as a continuum and can totally exchange 5 liters of patient plasma in about three hours. A decision as to the future needs for vascular access should be made early in the course of plasmapheresis treatment for a disease. It will be based on the response to initial plasma exchanges, the frequency with which these need to be done, and the time before any adjunct therapy will control the disease. In an illness expected to be short-lasting, such as Beye's syndrome or Goodpasture's syndrome, emergency vascular access may be provided by a Scribner shunt or subclavian or femoral vein cannulation. In a patient with long-term needs for plasmapheresis, a subcutaneous arteriovenous fistula is the best method for provision of vascular access. Construction of a bridge fistula is the alternative if a BresciaCimino fistula is not feasible. While these fistulas are maturing or being incorporated, the treatment may be carried out using the veins of the other arm or one of the other routes for emergency vascular access.
REFERENCES 1. Anderson, C.B., Sicard, G.A., and Etheredge, E.F.: Bovine carotid artery and expanded poly tetrafluoroethylene grafts for hemodialysis vascular access. J. Surg. Res., 29:184, 1980. 2. Arana, V.A., Menno, A.D., Hodson, J., et al.: Methods to gain access to the blood stream for hemodialysis. Nebr. Med. J., 59:18--20, 1974. 3. Aubaniac, R.: L'infection intraveineuse sousclavicularie: Avantages et technique. Presse Med., 60:1456 1952. 4. Bolton, W., and Cannon, J. A.: Seroma formation associated with PTFE vascular grafts used as arteriovenous fistulae. Dial. Transpl., 10:60, 1981. 5. Bore, G. E., and Pomaizl, M.J.: Prospective comparison of polytetrafluoroethylene and bovine grafts for hemodialysis. J. Surg. Res., 29:223, 1980. 6. Borja, A. R.: Current status of infraclavicular subclavian vein catheterization: Review of the English literature. Ann. Thorac, Surg., 13:615, 1972. 7. Brescia, M.J., Cimino, J.E., Appel, K., et al.: Chronic hemodialysis using venipuncture and a surgically created arteriovenous fistula. N. Engl. J. Med., 275:1089-1092, 1966. 8. Broviac, J.W., Cole, J.J., and Scribner, B.H.: A silicone rubber atrial catheter for prolonged parenteral alimentation. Surg. Gynecol. Obstet., 136:602, 1973. 9. Butt, K.M.H., Kountz, S.L., and Friedman, E.A.: Angioaccess for hemodialysis: Which, when, why. Clin, Nephrol., 3:207-210, 1975. 10. Cerilli, J., and Limbert, J. G.: Technique and results of the construction of arteriovenous fistulas for hemodialysis. Surg. Gynecol. Obstet., 137:922-924, 1973. 11. Dudrick, S.J., Wilmore, D.W., Vars, H.M., et al.: Long-term total parenteral nutrition with growth, development and positive nitrogen balance. Surgery, 64:134, 1968. 12. Gelber, R. L., and Sadler, J. H. : The use of the Allen -Brown shunt on major blood vessels for hemodialysis. Abstracts of 23rd Meeting of American Society for Artificial Intemal Organs, 6:25, 1977. 13. Grodstein, J., and Kraut, J.: Emergency vascular access for hemodialysis. In Wilson, S.E., and Owens, M.L. (eds.): Vascular Access Surgery. Chicago, Year Book Medical Publishers, 1980. 14. Gutman, R.H., Stead, W.W., and Robinson, R.R.: Physical activity and employment status of patients on maintenance dialysis. N. Engl. J. Med., 304:309, 1981. 15. Haimov, M., Burrows, L., Schanzer, H., et al.: Experience with arterial substitutes in the construction of vascular access for hemodialysis. J. Cardiovasc. Surg., 21:149, 1980. 16. Hepps, S.A., Gentile, D.E., Miller, R.B., et al.: Preservation of the arterial circulation in children requiring hemodialysis by use of an end-to-side dacron-Silastic shunt. Proc. Clin. Dial. Transplant Forum, 4:108--111, 1974. 17. Herbst, C.A.: Indications, management and complications of percutaneous subclavian catheters: An audit. Arch. Surg., 113:1421, 1978.
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18. Hussey, J.L.: Experience with 30 human umbilical cord grafts as conduits for hemodialysis. Dial. Transpl., 9:341, 1980. 19. May, J., Harris; J't and Fletcher, J.: Long term results of saphenous vein graft arteriovenous fistulas. Am. J. Surg., 140:387, 1980. 20. Mindich, B.: Experimental and clinical experience with umbilical cord for vascular replacement: Continued follow-up. Helv. Chir. Acta, 47:191, 1980. 21. Quinton, W., Dillard, D., and Scribner, B. H.: Cannulation of blood vessels for prolonged hemodialysis. Trans. Am. Soc. Artif. Intern. Organs, 6:1043, 1960. 22. Riella, M.C., and Scribner, B.H.: Five year's experience with a right atrial catheter for prolonged parenteral nutrition at home. Surg. Gynecol. Obstet. t 143:205, 1976. 23. Ryan, J. A., Abel, R. M., Abbot, W. M., et al.: Catheter complications in total parenteral nutrition: A prospective study of 200 consecutive patients. N. Engl. J. Med., 290:757, 1974. 24. Scribner, B.H., Cole, J.J., Christopher, T.G., et al.: Long-term total parenteral nutrition: The concept of an artificial gut. J .A. M.A., 212:457, 1970. 25. Strobel, C.T., Byrne, W.J., Fonkalsrud, E.W., et al.: Home parenteral nutrition: Results in 34 pediatric patients. Ann. Surg., 188:394, 1978. 26. Thomas, G.I.: Large vessel applique arteriovenous shunt for hemodialysis. Am. J. Surg., 120:244-248, 1970. 27. Uldall, P.R., Dyek, R.F., Woods, F., et al.: A subclavian cannula for temporary vascular access for hemodialysis or plasmapheresis. Dial. Transpl., 8:963--968, 1979. 28. Wilson, S.E., Hillman, M., and Owens, M.L.: Hemodynamic effects of bovine femorosaphenous fistula. Dial. Transpl., 6:84, 1977. 29. Wilson, S.E., and Owens, M.L.: Vascular Access Surgery. Chicago, Year Book Medical Publishers, 1980.
Chief, Vascular Surgery (691/112K) Veterans Administration Wadsworth Medical Center Los Angeles, California 90073
Current Status of Vascular Access Techniques
Samuel E. Wilson, M.D.,* Bruce E. Stabile, M.D.,f Russell A. Williams, M.B., B.S.,+ and Milton L. Owens, M.D.§
Obtaining long-term access to the vascular system may be the critical skill required in establishing successful parenteral nutrition or providing trouble-free years for patients on chronic hemodialysis. In this article we have distilled the practical aspects of the vascular access techniques that have proved most useful to us.
VASCULAR ACCESS FOR TOTAL PARENTERAL NUTRITION Total parenteral nutrition (TPN) solutions may be infused peripherally or, more commonly; into the central venous system. For administration of peripheral venous TPN, no specialized techniques for vascular access are required. On the other hand, institution of central venous TPN necessitates the placement of some type of indwelling catheter whose tip lies in the superior vena cava or the right atrium of the heart. A number of catheter insertion techniques are currently available, and familiarity with these is essential for the optimal and safe utilization of modern nutritional therapy.
Peripheral Venous Total Parenteral Nutrition TPN solutions provide nonprotein calories as glucose or fat, or both. The currently available lipid emulsions contain either soybean or safHower oil at 10 or 20 per cent solutions. Since they are isotonic, these lipid emulsions may be infused into any available peripheral vein. Standard intravenous needles and cannulas are used, and no special techniques of insertion are required. However, particular attention should be given to antimicrobial skin preparation, aseptic cannulation technique, and daily sterile dressing changes. The lipid emulsion cannot be mixed with *Professor of Surgery, UCLA School of Medicine; Chief, Vascular Surgery, Veterans Administration Wadsworth Medical Center, Los Angeles, California tAssistant Professor of Surgery, UCLA School of Medicine, Los Angeles, California :j:Assistant Professor of Surgery, UCLA School of Medicine, Los Angeles, California §Assistant Professor of Surgery, UCLA School of Medicine; Chief, Transplantation Section, Veterans Administration Wadsworth Medical Center, Los Angeles, California
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amino acids or with any other component of the TPN system but may be infused through the same peripheral vein by means of a Y connector just proximal to the cannula. Unfortunately, the average peripheral infusion site will remain functional for only one to three days. The availability of adequate peripheral veins, therefore, becomes the factor that limits the duration of peripheral TPN therapy. If additional TPN is required, a central venous catheter must be placed.
Central Venous Total Parenteral Nutrition Access to the central venous system is always required for the infusion of TPN solutions containing hypertonic glucose as the primary caloric source. Peripheral veins promptly develop phlebitis and thrombosis when subjected to hypertonic infusions. Over the past dozen years a variety of catheters and catheterization techniques have been used for the delivery of central venous TPN. Dudrick and his colleagues were the first to successfully administer hypertonic TPN solutions when they adopted the technique of percutaneous infraclavicular subclavian catheterization 11 that was originally developed by the French military surgeon Aubaniac." This method of central venous access remains the most commonly used approach for TPN today. Other less popular percutaneous techniques include the supraclavicular approach to the subclavian vein and internal jugular vein catheterization. Both polyethylene and silicone rubber catheters are currently available for percutaneous insertion. The former is stiff, more likely to perforate the venous system, and more prone to thrombosis, the latter is more flexible and more disposed to kinking and misplacement. In recent years the concept of the TPN system as an "artificial gut" capable of supplying total nutrition needs for very long periods has led to the development of the specialized large-bore Broviac and Hickman catheters.v> These catheters are made of radiopaque soft silicone rubber, measure 90 ern in length, and have a small dacron felt cuff 30 em from the Luer-Lok external end. The Broviac catheter has an internal diameter of 1 mm, and the Hickman modification differs only in that it has an internal diameter of 1. 6 mm. A pediatric-sized Broviac catheter is also available. Since these catheters are inserted via direct venous cutdown into the cephalic or jugular veins, the risks related to "blind" percutaneous catheterization are eliminated. In addition, the silicone elastomer is less thrombogenic and less tissue reactive than is polyethylene. Placement of the Broviac or Hickman catheter entails tunneling the catheter through the subcutanous tissue in order to separate the skin exit site from the venotomy. Fibrous ingrowth into the dacron cuff located in the tunnel presents an effective barrier to the migration of microorganisms from the skin into the venous system along the outer surface of the catheter. As a consequence, the sepsis rate with these catheters is low. 22 ,25 Because of its proven durability and safety, the Broviac or Hickman type of catheter is preferred in any patient at high risk for percutaneous catheterization (such as one with emphysema, previous pneumonectomy, or massive obesity), in any patient who is anticipated to require more than two or three weeks of central venous TPN in the hospital, and in all home hyperalimentation patients. The placement of any central venous TPN catheter is always considered to be an elective, sterile operative procedure. "Thus, the patient should have hypovolemia and electrolyte abnormalities corrected prior to catheterization. Adequate lighting, instruments, nursing assistance, and strict aseptic techniques are absolute prerequisites for safe insertion of the TPN catheter. A thorough knowledge of the venous
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anatomy of the upper body and adequate experience or supervision are likewise mandatory. Infraclavicular Subclavian Catheterization. The patient is placed in the Trendelenburg position with hands at sides and head rotated away from the side to be catheterized. A·~rolled towel is placed under the upper thoracic spine to allow the shoulders to fall backward. The shoulder and upper chest are shaved, washed with soap and water, and the skin is defatted with 10 per cent acetone. Povidone-iodine is used to prepare the skin, and a sterile field to include the clavicular area and the lower neck is draped. The site for insertion is located 1 em below the curve at the midportion of the clavicle. A skin wheal is raised at the site using 1 per cent lidocaine local anesthesia. The muscles below and deep to the clavicle are also infiltrated. A 14-gauge needle attached to a 2- or 5-ml syringe is advanced in a horizontal direction through the skin, subcutaneous fat, and muscle, then deep to the clavicle but superficial to the first rib while the operator aims for the suprasternal notch (Fig. 1). It is critically important to maintain the horizontal plane parallel to the anterior chest wall in order to gain entrance into the subclavian vein as it passes over the first rib and underneath the medial third of the clavicle. Failure to advance the needle in this plane greatly increases the risk of penetrating the more posterior structures, such as the apex of the lung, subclavian artery, or brachial plexus. Constant negative pressure is maintained on the syringe so that successful venipuncture will be immediately indicated by a Hushback of dark venous blood. When this occurs, the
Figure 1. The technique of percutaneous infraclavicular subclavian vein catheterization is shown.
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WILSON, STABILE, WILLIAMS, AND OWENS
patient is instructed to stop breathing, and the bevel of the needle tip is turned downward toward the feet to facilitate passage of the catheter centrally into the superior vena cava. With the needle held stationary, the syringe is removed and the 8-inch long, 16-gauge catheter is quickly advanced its entire length until the catheter end fits tightly into the needle hub. Once the vein is entered, the operator's gloved finger should always be placed over the open end of the needle hub to protect against air embolization. If catheter advancement is met with resistance, the needle and catheter should be withdrawn as a unit, since shearing off and embolization of the catheter tip may occur if the catheter is pulled back against the stationary needle. As soon as the catheter is successfully inserted, an intravenous tubing is quickly connected and isotonic saline infusion is begun. The intravenous bottle is then momentarily lowered below the patient's heart. Back bleeding or venous blood flowing into the intravenous tubing confirms the intraluminal position of the catheter tip. The needle is then withdrawn out of the skin, the plastic needle guard is snapped on, and the guard is sutured to the skin with 3-0 nylon. Povidone-iodine ointment is applied to the skin exit site and a sterile occlusive dressing is placed. A gentle loop of intravenous tubing is taped to the dressing to prevent catheter dislodgement should traction be applied to the tubing. Chest auscultation and a chest x-ray film are always immediately carried out to check for pneumothorax and to confirm the proper position of the catheter tip in the superior vena cava. Other Percutaneous Catheterization Techniques. The supraclavicular approach to the subclavian vein has the advantage of a shorter distance from skin surface to vein but the disadvantages of greater movement at the dressing site above the clavicle and greater risk of thoracic duct injury when the left side is used. Because of the left-sided location of the thoracic duct and the straighter course of the right innominate vein into the superior vena cava, the right side is preferred for the supraclavicular technique. Following proper positioning, the skin is prepared and draped as for infraclavicular catheterization, and 1 per cent lidocaine is infiltrated into the skin at a point 1 to 1. 5 em above the angle created by the lateral margin of the sternomastoid muscle and the superior surface of the clavicle. The 14-gauge needle is introduced at this point and advanced deep to the clavicle in a direction bisecting the angle formed by sternomastoid and clavicle, the operator aiming for the midpoint of the sternomanubrial junction. After entry of the needle into the subclavian vein (at a point just lateral to its confluence with the internal jugular vein), the catheter is inserted, fixed, and dressed as described for the infraclavicular technique. Several techniques have been advocated for percutaneous internal jugular vein catheterization. All have the advantage of fewer injuries to the pleura and subclavian artery but the disadvantages of difficult dressing maintenance secondary to neck movement. Again, the right side is preferred because of venous and lymphatic anatomic considerations. After preparation, draping, and instillation of local anesthesia, with the patient in the Trendelenburg position the 14-gauge needle is inserted at the medial border of the sternomastoid muscle at the level of the thyroid cartilage. While the index finger of the operator's free hand palpates the common carotid artery, the needle is advanced under the muscle toward the thoracic inlet at a 30degree downward angle, with the operator aiming toward the internal jugular vein as it passes deep to the sternal end of the clavicle. An alternative approach utilizes insertion of the needle at the lateral border of the sternomastoid 3 em above the clavicle, with advancement under the muscle, aiming toward the sternal notch.
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A chest x-ray film is mandatory after every successful or unsuccessful attempt at percutaneous central venous catheterization using any of the foregoing techniques. Furthermore, after failure to catheterize the subclavian vein on one side, an attempt should never be made on the opposite side without first obtaining a chest x-ray film to rule out occult pneumothorax. Fatal bilateral pneumothorax has occurred when this admonition has been ignored. Safe percutaneous TPN catheterization always requires adherence to the following essential points: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Knowledge of anatomy, insertion techniques, and complications and their treatments. Adequate experience or supervision. Appropriate patient instruction and sedation, if warranted. Prior repletion of fluid volume deficits. Proper positioning, skin preparation, and sterile draping. Adequate local anesthesia. Precise needle advancement with constant negative pressure on syringe. Flashback of dark venous blood to confirm venipuncture. Swift removal of syringe and catheter advancement. Prevention of air embolization through open needle or catheter. Secure suture fixation of catheter or needle guard to skin. Confirmation of intraluminal catheter tip position by backbleeding. Meticulous sterile dressing technique. X-ray film confirmation of correct catheter tip position prior to hypertonic fluid infusion.
Although pneumothorax remains the most frequently encountered serious complication, numerous others have been reported in the literature, including the following: 6,17,23 Thoracic Pneumothorax Hemothorax Hydrothorax Hemomediastinum Chylothorax Venous Laceration Air embolism Catheter em holism Thrombosis Arterial Laceration or perforation Pseudoaneurysm Arteriovenous fistula Lymphatic Thoracic duct fistula
Cardiac Arrhythmia Perforation and tamponade Coronary sinus thrombosis Neurologic Injury Brachial plexus Phrenic nerve Vagus nerve Recurrent laryngeal nerve Septic Catheter sepsis Septic thrombosis Suppurative thrombophlebitis Catheter Failure Misplacement Occlusion Breakage or kinking
Placement of Broviac or Hickman Catheter by Cutdown. Since the Broviac or Hickman catheter is inserted by direct venous cutdown, all the risks inherent in "blind" percutaneous catheterization are eliminated. In theory, the Broviac or Hickman catheter may be placed into any vein accessible by cutdown, but in practice, the cephalic vein in the deltopectoral groove and the external jugular vein in the neck are the preferred sites. If these are unavailable, the internal jugular, the common facial, the large pectoral radical, the thoracoacromial, and the great saphenous veins are alternatives. In patients receiving TPN who have had numerous previous catheters, preoperative venography is often required to verify patency of the superior vena cava or the subclavian veins or their tributaries. In most hospitals the Broviac or Hickman catheter is inserted in the controlled environment of the operating room where x-ray or fluoroscopy is available to confirm
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the proper position of the catheter tip prior to skin closure. After selection of the cutdown site, proper positioning and standard surgical preparation and draping, 1 per cent lidocaine local anesthesia is instilled. For the cephalic vein cutdown, a 2- to 3-cm oblique skin incision is made just inferior to the coracoid process in the area of the deltopectoral groove. For the jugular vein approach, a 1- to 2-cm transverse midcervical incision is made over the vein. Mter dissection verifies·patency and adequate size of the vein, a subcutaneous tunnel is made with a long alligator forceps from the cutdown to the cutaneous exit site of the catheter medial to the breast (Fig. 2). A small stab wound is made at this site, and the catheter is brought up through
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Figure 2. Preferred cutdown sites and the technique for creating a subcutaneous tunnel for a Broviac or Hickman catheter are shown.
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CURRENT STATUS OF VASCULAR ACCESS TECHNIQUES
the tunnel so that the dacron felt cuff resides 2 to 4 em inside the tunnel. The catheter is then shortened so that the tip will just reach the right atrium. The catheter is filled with heparinized' saline by syringe. The vein is ligated distally and the catheter is introduced through a small venotomy and advanced its full length. A proximal ligature placed around the vein secures the catheter in position (Fig. 3). If the internal jugular vein is used, the catheter may be introduced through a lateral venotomy and fixed with a purse string of fine vascular suture. After the catheter is fully advanced, it is aspirated with the attached syringe. If dark venous blood does not return, the catheter is either kinked or misplaced, and it should be withdrawn and advanced again. Radiographic verification of proper catheter tip position in the right atrium is always obtained before the wound is closed. The catheter is fixed to the skin at the exit site with a nylon suture, and this is removed one to two weeks later after fibrous ingrowth into the dacron cuff has occurred. Povidone-iodine ointment and a sterile dressing are applied to the exit site, and a loop of redundant catheter is taped to the chest wall. The catheter may be either heparin locked using the Luer-Lok cap provided or immediately connected to an intravenous infusion set. An atraumatic clamp is always kept immediately available at the bedside for emergency use should disconnection or breakage of the catheter threaten air embolism or back bleeding. The patient, as well as the nursing staff, should be thoroughly familiar with the indications for use of the clamp.
CUTDOWN SITE
DACRON FELT CUFF IN TUNNEL
,..-----+---01--- EXIT
51 TE
LUER LOCK END
Figure 3. A Broviac or Hickman catheter is inserted into the left cephalic vein with correct positioning of the dacron cuff in a subcutaneous tunnel and the catheter tip in the right atrium.
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VASCULAR ACCESS SITES FOR DIALYSIS With the number of Americans requiring maintenance hemodialysis approaching 55,000 and increasing at the rate of almost 5000 patients per year, vascular access surgery has emerged as a special area of competence for the vascular surgeon. 29 Implementation of the Medicare end-stage renal disease program in 1973 increased the number of aged and diabetics undergoing dialysis: currently 53 per cent of dialysis patients are 50 years of age or older, and 12 per cent are diabetic. 14 The increasing life expectancy of these patients, who often have poor vasculature, can tax the ingenuity of the surgeon in maintaining a route for vascular access.
Emergency Vascular Access Although partially exteriorized arteriovenous shunts were widely used for chronic 'dialysis access in both adult and pediatric patients prior to 1966, they have been largely replaced through improvements in the use of internal fistulas, peritoneal dialysis catheters, and femoral and subclavian venipuncture techniques. 2,7,9,10,27 Nevertheless, they are still widely used in the management of acute renal failure and have occasional, although diminishing, applications in the treatment of chronic renal failure. In 1960, Quinton, Dillard, and Scribner described the Teflon-Silastic arteriovenous shunt." This used a loop of Silastic tubing lying on the volar aspect of the forearm to connect Teflon catheters placed in both the radial artery and a nearby wrist vein. The Scribner shunt was quickly and widely adopted, as it was the most durable current means of providing vascular access for dialysis treatment of patients with end-stage renal disease. The disadvantages of this external shunt are threefold: (1) infection is highly likely to enter from the skin along the Teflon catheter tissue tracks, (2) clotting of the blood is apt to occur as it courses through the Silastic and Teflon conduits, and (3) patients do not readily accept the external appliance since the extra care necessary to prevent its dislodgement and its appearance tax their already heavily burdened tolerance. When an external shunt is needed, the radial or posterior tibial vessels are satisfactory sites; we use rigid Teflon vessel tips and a straight Silastic connector with wings (Ramirez winged shunt) for the procedure. The Scribner or Ramirez winged shunt, which can be readily constructed using local anesthesia, may be advantageous for treatment of acutely ill patients in whom an urgent but short course of dialysis or plasmapheresis is anticipated. The radial artery and cephalic vein in the arm are most often used, but other vessels may be chosen, and it is occasionally necessary to use the saphenous vein and posterior tibial artery in the lower leg. Variably sized Teflon tips are chosen to fit into the particular artery or vein. The tips are connected to standardized Silastic tubing, which is tunneled for some distance before exiting through the skin. Externally, the arterial and venous ends of the Silastic tubing may be disconnected for attachment to the dialysis machine. Depending on how thoroughly the surgeon anchors these shunts internally, removal may be effected simply by pulling them out, or it may require another minor operation. Advantages include ease of placement and availability for immediate use. Thrombosis and infection usually prevent longterm use. In comparison to the Allen-Brown and Thomas shunts, the stiff in-dwelling tip in the Teflon-Silastic shunt is more likely to cause vessel damage from movement
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and is also somewhat more difficult to declot successfully with the balloon-tipped catheter. Allen-Brown and Thomas Shunts. The Allen-Brown and Thomas shunts 12 , 16 ,26 have dacron cuffs attached to Silastic tubing a'hd must be sewn to the chosen artery and vein." This is more difficult and time consuming than the simple cannulations required for the Teflon-Silastic shunts but may have some advantages when large vessels are used or the shunt must be placed near a flexion crease or in the lower leg. In these sites movement causes the shunt to slide back and forth. In these circumstances the in-dwelling Teflon tip of the Teflon-Silastic shunt may rapidly erode the vessels in which it is placed. Removal of the Allen-Brown and Thomas shunts requires reoperation. Our experience indicates that dialysis should be delayed 24, and preferably 48, hours after placement of the Allen-Brown or Thomas shunts in order to prevent bleeding through the dacron cuffs. Venipuncture Techniques. Currently, percutaneous cannulation of the femoral or subclavian veins is increasingly displacing the Scribner shunt for provision of temporary vascular access. 13 The treated blood is returned to the patient via a peripheral vein (or via the same cannulated vein along the second lumen of a double lumened catheter). Most importantly, the vessels are preserved at the very sites that are best suited to construction of a subcutaneous arteriovenous fistula. With this technique, short term dialysis needs are met through the transcutaneous introduction of stiff-walled catheters with external diameters of approximately 2.5 mm. These catheters are generally introduced over a guide wire and may be left in place for several days.v Depending on the situation, either single catheter dialysis with pulsatile flow or double catheter dialysis with continuous flow may be chosen. The latter is usually elected when urgent and aggressive dialysis is necessary, as for poisoning or fluid overload. Thrombosis is usually prevented by continuous low dose heparin infusion. These catheters are most useful in the following situations: (1) acute renal failure in which it is anticipated that only a few dialyses will be necessary, (2) chronic renal failure during the immediate postoperative period after placement of an internal fistula, (3) in patients with transplantations who have thrombosed arteriovenous fistulas, (4) in patients needing urgent transfer from peritoneal dialysis, and (5) for the treatment of poisoning. The main advantage of venipuncture techniques is that vessels that may be needed for the later construction of internal fistulas are not wasted. Disadvantages include patient discomfort, a greater amount of time spent by the physician per dialysis, and a relatively greater number of traumatic, septic, and thrombotic complications than would occur over the same time period if the Teflon-Silastic external arteriovenous shunt were used.
Arteriovenous Fistula The autogenous arteriovenous fistula, usually made by joining the end of the cephalic vein to the side of the radial artery at the wrist, still remains by far the longest lasting and most dependable site for vascular access. When successful, this fistula has a long-term patency rate of approximately 75 per cent between two and three years. Further, it is frequently possible to revise a failing fistula by excising an aneurysm or re-anastomosing a major vein higher on the radial artery. An autogenous fistula may be unsatisfactory in diabetic patients with advanced arteriosclerotic changes extending into the radial artery; in patients with a thick layer of subcutaneous fat; or if the veins are too small, fragile, and thin walled to mature sufficiently for repeated needle puncture. Complications are unusual, but venous hypertension of
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the hand and carpal tunnel compression symptoms have been noted with side-toside anstomoses. Brescia-Cimino Fistula. The subcutaneous arteriovenous fistula was described by Brescia, Cimino, Appel, and Hurwich in 1966. 7 Being constructed of the patient's own vessels, the Brescia-Cimino fistula in great part overcomes the disadvantages of the Scribner shunt. Following formation of the fistula, arterial pressure is transmitted directly into the contiguous veins, which dilate and develop a hypertrophied muscular wall. This arterialization may take up to six weeks before sufficiently sized and thick-walled vessels have developed that are suitable for repeated venipuncture. Treatment, if necessary, may be secured for this period using subclavian or femoral vein cannulation, a Scribner shunt, or peritoneal dialysis. Before operation, the veins, preferably in the nondominant hand, are distended and examined utilizing a sphygmomanometer with cuff applied to the upper arm and inflated below the systolic pressure level to produce venous engorgement. All suitably sized veins are marked with an indelible pen (Codman surgical marker). Should the fistula of choice fail following construction at operation, these markings aid the surgeon in choosing another site. Suitable subcutaneous veins may not be evident in patients with fat arms, and in others the veins may simply be too small to be useful. In patients who have had repeated phlebotomies, phlebitis may have obliterated the majority of superficial veins so that even if a fistula were constructed, the paucity of venous channels would restrict the runoff of blood and blood flow through the fistula, increasing the chances of its clotting. The ulnar and radial artery pulses are palpated. In the diabetic patient, especially one with severe atherosclerosis, these vessels may be too narrowed to sustain flow through a fistula. Determine beforehand that the ulnar artery can support the circulation to the hand (should the radial artery be divided or subsequently clot). Digital compression, occluding both arteries at the wrist, is followed by pallor of the elevated hand. Release of the ulnar artery returns a normal appearance to the hand if the blood supply is sufficient. The fistula may be constructed with local infiltration, brachial nerve block, or general anesthesia of the operation site. A successful result is more likely with meticulous vascular surgical technique in the operating room using fine instruments and suture material. The arm is surgically cleaned, abducted at a right angle from the body, placed on an arm board or table, and draped, leaving the operation site exposed. Operative technique is facilitated if the surgeon and assistant are comfortably seated. An oblique or longitudinal skin incision is made over the radial artery, proximal to the wrist skin fold. A 7- to 10-cm length of cephalic vein is dissected free of surrounding subcutaneous tissue and adventitia. Its tributaries are ligated, freeing it further so that it lies adjacent to the radial artery without kinking or twisting. A comparable length of the radial artery, here found under the deep fascia of the forearm, is isolated and cleaned. The artery and vein may be anastomosed as follows (Fig. 4): 1. Side-to-side, with a fistula opening approximately 1 em in length. Technically, this is the easiest anastomosis to construct and has the highest fistula blood flow. It is the most likely fistula to be associated with venous hypertension and swelling in the hand. These complications are moderated by the presence of valves that prevent reversal of venous blood flow in the hand, at least in the early months.
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Figure 4. Four commonly used anastomoses between the radial artery and the cephalic vein are (A) side-to-side, (B) side of artery to end of vein, (C) end of artery to side of vein, and (D) end-to-end. (From Fernando, O.N.: Arteriovenous fistulas by direct anastomosis. In Wilson, S.E., and Owens, M.L. (eds.): Vascular Access Surgery, with permission. Copyright © 1980 by Year Book Medical Publishers, Inc., Chicago.)
t
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..
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-----.,.--
. '.' 'Jf .. ,"~..
C
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2. Arterial end to vein side eliminates the distal "steal" of blood but has a lower fistula blood flow. Care is required during construction to avoid twisting of the artery. 3. Vein end to arterial side minimizes distal venous blood flow, although it is technically more difficult to construct than a side-to-side anastomosis. 4. End-to-end anastomosis produces the least "steal" of blood and venous hypertension but has the lowest fistula flow.
Proximal and distal control of the two vessels is achieved by application of small bulldog clamps or a fine Silastic sling. The vessels are anastomosed with a 6-0 polypropylene suture, with the knots placed outside of the lumen. Before the anastomosis is finally closed, a check is made by passage of a coronary artery or biliary dilator to detect any stenosis. Any bleeding from the anastomosis is first controlled
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by simple pressure with a gauze swab for several minutes. Too hasty a resort to suture repair is liable to produce further bleeding sites and narrowing of the anastomosis. Upon conclusion, the artery and vein lie beside each other without twists or kinks. A thrill should be easily felt over the fistula and propagated for a moderate distance along the contiguous venous channels. A transmitted pulse without a thrill suggests that there is an outflow obstruction or a clotted fistula. The proximal vein may be probed and irrigated with a Fogarty catheter (avoiding intimal damage by not inflating the balloon during manipulation of the catheter) or dilated with bougies. If these maneuvers do not produce a strong thrill and the fistula is technically satisfactory, consider construction of a fistula at another site. On occasion in such a case, a bruit appears as the veins dilate and blood flow increases, especially when there was no outflow obstruction shown by the preceding technique. Following the operation, the arm is elevated by the patient's side for 24 hours. Any swelling usually resolves over subsequent weeks. Prevent constriction of the venous outflow of the fistula-bearing arm, especially by using dressings, sphygmomanometer cuffs, and clothing. Several weeks should elapse before the veins are used for phlebotomy. Puncturing the vessels before they are arterialized is often associated with hematoma formation, as early on the dilated veins are particularly thin walled. Exercise of the forearm by squeezing a rubber ball increases the fistula flow, which aids maturation of the arterialized veins.
Bridge Fistula When the Cimino fistula fails or cannot be constructed, one must use a conduit to form a bridge arteriovenous fistula. Descriptions are to be found of bridge fistulas constructed between almost any of the suitably sized superficial arteries and veins of the body. For vascular access these are a second choice to the Cimino-Brescia subcutaneous fistula. However, when placed, these easily palpable conduits can be readily punctured by needle. If possible, this should be avoided for some weeks until there is incorporation of the prosthetic material into the patients' tissues. Premature attempts at use are associated with a high complication rate, especially the leak of blood at the puncture site forming a perigraft hematoma. In current practice, the ends of the graft are anastomosed to the side of the artery or vein. If the two anastomoses are near each other, the conduit takes on a V -configuration; if they are separated by some distance, it may lie straight or in a curve. Grafts with a diameter of 6 mm permit a good fistula blood flow in the 'arm and there is little likelihood of producing distal limb ischemia. In the groin, a graft with an 8 mm diameter is similarly satisfactory. In the arm, fistulas are satisfactorily made between the radial artery and a cubital fossa vein, the brachial artery (in the cubital fossa before its division) and the adjacent cephalic vein (V-configuration), and the brachial artery and the axillary vein. Construction of an arm fistula is more demanding technically and its long-term patency rate is not as high as that of a thigh fistula. In the arm, however, the risk of infection and distal limb ischemia is less. Patients with claudication or an ankle arterial pressure less than 80 per cent of that at the wrist are not suitable for thigh fistulas because the proximal steal of blood through the fistula is likely to increase ischemia in the leg. In the thigh, the arterial anastomosis should, in the first instance, be to the superficial femoral artery, either immediately proximal to the adductor canal or to
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its more cephalad part. If the superficial femoral artery is occluded, the common femoral artery may be used, with the understanding that if it becomes infected and ligation is subsequently required, leg ischemia may ensue. At times, patency of a short segment, including the origin of the superficial femoral artery, can be reestablished and used for anastomosis. The venous anastomosis is made to the proximal saphenous, common, or superficial femoral vein. The site we prefer to use first is from the distal radial artery to the cephalic or basilic vein in the antecubital fossa (Fig. 5). The graft should be anastomosed endto-side to the radial artery, tunneled along the lateral aspect of the forearm, then anastomosed end-to-side to the largest vein in the antecubital fossa. In positioning the graft it is most important to insure that the patient's arm will rest comfortably while on dialysis. The advantages of the radiocephalic location are as follows: by using a small peripheral artery for the arterial origin, postoperative complications are unlikely to result in serious ischemic changes; the procedure can be done under local anesthesia; ease in preparation of the forearm results in a low infection rate; and the seated position of the surgeon facilitates use of magnifying glasses and microinstruments. The one disadvantage is an earlier occlusion because of the lower flow from the small radial artery. Secondary vascular access sites include (1) brachiocephalic loop fistula in the forearm (Fig. 6A), (2) brachioaxillary fistula in the upper arm (Fig. 6B), and (3) femorosaphenous fistula in the thigh (Fig. 6C). The loop graft placed in the forearm allows a good length of graft for dialysis; the upper arm graft curving over the lateral
RADIOBASILIC BRIDGE FISTULA
Figure 5. A radiobasilic conduit in the forearm, when technically feasible, is our first choice of bridge fistula for hemodialysis.
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WILSON, STABILE, WILLIAMS, AND OWENS
BRACHIOAXILLARY
BRACHIOBASILIC LOOP FISTULA
FISTULA
B
A
FEMOROSAPHENOU9 BRIDGE FISTULA
Figure 6. Satisfactory secondary vascular access sites are (A) the brachiocephalic loop fistula in the forearm, (B) the brachioaxillary fistula, and (C) the femorosaphenous fistula.
c
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aspect of the brachium allows a slightly shorter needle puncture area. Both of these upper extremity procedures can be done with the patient under local anesthesia and both have a low incidence of infection. Of the two, the brachioaxillary graft has the higher How rate and would be expected to remain open for the longest period of time. The femorosaphenous shunt is usually done with the patient under a spinal or general anesthetic, although in cooperative patients a local infiltration technique can be used. We prefer to place the arterial origin of the graft proximal to the adductor canal so that should a vascular complication cause occlusion of the superficial femoral artery, adequate collateral channels provide filling of the popliteal segment. The femorosaphenous graft is curved over the lateral aspect of the thigh and anastomosed to the proximal saphenous vein (see Fig. 6C). The disadvantages of this technique are the somewhat higher infection rate, due to inability to thoroughly prepare the groin, and a vascular steal phenomenon with reversal of How in the distal femoral artery. Accordingly, one should make sure of an ankle-wrist systolic pressure ratio of at least 0.80 prior to constructing this access." Fortunately, most patients with steal are not symptomatic, since the activity of the dialysis patient is so limited. A less useful access site is the loop arteriovenous fistula placed in the groin from the common femoral artery to the femoral vein. Complications rendering the femorofemoral site less favorable are the high How (greater than 700 ml per minute) leading to increased cardiac output, the possibility of limb loss should complications at the common femoral artery anastomosis develop, and the risk of infection. Venous hypertension in the leg has not been a problem. High fistula blood flow rates increase cardiac output and have led to cardiac failure in some elderly patients. Choose a graft with a 6 to 8 mm diameter if this problem is anticipated. Should it develop, the diameter of the graft may be reduced by a "banding procedure." When the foregoing sites are already expended, the surgeon is forced to choose a more central location, such as a graft placed between the axillary artery and the axillary vein on the anterior chest wall. Always bear in mind that as one moves centrally, complications at the access site are not only more likely to occur but more serious when they do. Technical points that have proved helpful include the following: 1. Use of a 5-0 or 6-0 polypropylene suture for the anastomoses. 2. 5000 units of heparin intravenously is usually sufficient anticoagulant for the patient on dialysis. 3. A graft with a diameter of 6 mm is usually the largest that can be utilized in the forearm, but in the lower extremity an 8 mm graft is quite easily placed. 4. Avoid direct arteriovenous fistulas placed at the level of the antecubital fossa, since these have been accompanied with an unacceptably high rate of distal ischemia. 5. A thrill but not pulsation on completion of a graft procedure portends success.
Should infection develop in these grafts, removal is required for its control. A further bridge fistula is formed only after removal of the infected graft to minimize the chance of blood-borne seeding of the second graft. If the infection involves the anastomosis, removal of the graft may require ligation of the adjacent artery or vein. This can produce distal ischemia, especially if it is the brachial or common femoral artery that is ligated. The initial choice of an artery is always tempered by the knowledge of this possibility. Materials for Bridge Fistulas. The autogenous saphenous vein was the first conduit used in construction of the bridge arteriovenous fistulas. Its chief appeal is
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safety from contiguous infection, but on the balance, such disadvantages as an unpredictably small size, the separate incision for removal, and early sclerosis on repeated puncture outweigh this factor. In Sydney, a large experience with 71 autogenous saphenous vein conduits resulted in a 66 per cent patency rate at two years, decreasing to 40 per cent at three years.!" Only a 20 per cent patency rate at 2 years, however, was reported from the United States, reflecting the accelerated loss due to fibrosis that occurs after two years of continuous puncture and accounts for its relatively infrequent use." With an accumulated clinical experience of almost 10 years, the bovine heterograft has well-recognized complications, including development of aneurysms, rapid deterioration in the presence of infection, and late thrombosis due to stenosis of the venous anastomosis. The two-year patency rate for bovine carotid artery grafts has been reported as 45 per cent and as 52 per cent. 1,5 .., Expanded polytetrafluoroethylene or Teflon (Goretex and Impra) is the only synthetic prosthesis widely used for vascular access. Sample two-year patency rates from experienced centers are 67, 68, and 73 per cent.1.5,15 Some polytetrafluoroethylene grafts manufactured prior to 1977 were subject to stretch resulting in dilatation. Increasing the wall thickness or wrapping the graft with an exterior layer appears to have eliminated true dilatation, although pseudoaneurysms may still occur (Fig. 7). Venous runoff stenosis develops as early as three months and is a common reason for late thrombosis. When increasing pressure in the venous return line is detected during dialysis, an angiogram will define the area of stenosis, and anastomotic revision (patch angioplasty or percutaneous transluminal dilatation) may be instituted prior to complete occlusion. By the time thrombosis of the graft occurs, the shrunken and fibrotic segment of vein may extend too far to be amenable to local revision. Persistent collections of semi-solid proteinaceous material or seromas, reported in 33 patients with polytetrafluoroethylene grafts, are thought to develop if wetting of the graft occurs prior to implantation." Experimental studies show that a plasma-like fluid may weep through the polytetrafluoroethylene graft, especially when the hematocrit is less than 30 per cent. The human umbilical cord vein (Bioflow) is the newest graft for vascular access; its advantages are low thrombogenicity and absence of immunologic reaction. Early clinical trials show promise, with a one-year patency rate of 65 per cent. I B,20 Lastly, all grafts have common drawbacks. Local infection at a needle puncture site may develop at any interval as a result of less than aseptic technique. Postcannulation bleeding and hematoma can occur in the first three weeks after implantation (Fig. 8). Often the credit for long-lasting graft function is due to the dialysis nurses, technicians, and patients who are responsible for the day-to-day technical management and care of the access site.' On review it is still apparent that every effort should be made to construct and preserve a functioning Cimino fistula as the site of choice for maintenance hemodialysis.
VASCULAR ACCESS FOR CANCER CHEMOTHERAPY AND CHRONIC INTRAVENOUS MEDICATION A course of treatment with antineoplastic drugs usually requires multiple intravenous injections administered over a long period. Many of these drugs induce chemical thrombophlebitis, and within a short time few suitable veins remain through
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Figure 7. Multiple small pseudoaneurysms are shown at needle puncture sites in an expanded polytetrafluoroethylene vascular access conduit.
which the drug can be given. Repeated blood samples are also needed for analysis so that vascular access becomes a critical problem. When the decision is made to treat malignant disease with chemotherapy, definite considerations should also be given to the patient's likely future needs for vascular access. Construction of a vascular access at this time could avoid future anguish. A subcutaneous arteriovenous fistula is least likely to develop complications and most convenient, from the patient' s view, as an access site. Delay until sites for injection are unfortunately limited makes the surgical construction of a subcutaneous arteriovenous fistula likely to fail because of restriction of the venous outflow. Faced with such patients, bridge fistulas have been successful using bovine heterografts or synthetic Teflon grafts. These patients often have a low platelet count and may bleed excessively at operation. They are also prone to infection and delayed wound healing. The synthetic material in a bridge fistula is more likely than a Brescia-Cimino fistula to become infected, and the surgical construction of such a fistula is a serious undertaking that
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Figure 8. Too early use of a vascular access conduit can result in perigraft extravasation. The graft is usually sufficiently incorporated for safe use after three weeks.
may be complicated by hematoma formation in the subcutaneous graft tunnel. A poor outcome may also be due to delayed wound healing. Hickman and Broviac catheters are now often used for long-term chemotherapy vascular access sites. The Hickman catheter has an internal diameter of 1.6 mm compared with 1 mm for the Broviac catheter and permits easier withdrawal of the many required blood samples. Careful catheter care is required, as in patients receiving TPN. Patients needing long-term medication who have diseases such as hemophilia, Christmas disease, and von Willebrand's disease now have the prospect of a relatively normal life style because of the availability of purified extracts of factors VIII and IX. Some brittle diabetic patients require frequent intravenous therapy for treatment of repeated episodes of hypoglycemia or hyperglycemia, and other patients with chronic anemias, such as sickle cell disease, may need frequent transfusions. Vascular access often becomes a difficult, limiting problem during these patients' lives. A subcutaneous fistula is the most desirable access. The best time for its construction is early while suitable veins are available. It can be predicted that patients with hereditary clotting disorders will need frequent intravenous therapy.
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Those in whom a subcutaneous arteriovenous fistula has been made are able to treat bleeding episodes themselves, early and at home, using prepacked factors VIII or IX. Prompt control of bleeding under these conditions results in use of smaller quantities of plasma concentrates, many fewer hospitalizations, and less loss of work time. A fistula-in the nondominant arm is easiest for self-cannulation. It is often possible to predict that a patient will have the need for long-term vascular access. A subcutaneous arteriovenous fistula made while still technically feasible will avoid future frustration.
PLASMAPHERESIS Plasmapheresis is the technique for removal of plasma from a donor without reduction of circulating red blood cell mass. It became relatively safe with the advent of integrally interconnected plastic collection bags that permit centrifugation and manipulation of the blood without contamination. The continuous flow centrifuge has decreased the time necessary for completing a course of treatment. Therapeutically, plasmapheresis is used for removal of specific materials, such as toxins, proteins, or a type of cell that are responsible for an illness. Blood banks use the technique to obtain plasma and protein fractions or cells from a small pool of donors. This decreases the risk of transmitting hepatitis and increases the quality of the product.
*
c.
D.
SALINE INTO PATENT
Figure 9. A simplified schematic representation of plasmapheresis. (From Williams, R.A.: Vascular access for cancer chemotherapy, chronic intravenous medication and plasmapheresis. In Wilson, S.E., and Owens, M.L. (eds.): Vascular Access Surgery, with permission. Copyright © 1980 by Year Book Medical Publishers, Inc., Chicago.)
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A simple method for plasmapheresis is to remove 300 to 500 ml of whole blood into a plastic bag containing an anticoagulant (acid-citrate-dextrose) and to layer the blood into its various components by centrifugation at a specific speed (Fig. 9). The desired component is eluted, via the integrated. tubing, into another bag and the red cells returned to the patient with 300 to 500 ml of saline. "Double plasmapheresis" is a repetition of this sequence. Continuous flow centrifuges similarly perform the plasmapheresis as a continuum and can totally exchange 5 liters of patient plasma in about three hours. A decision as to the future needs for vascular access should be made early in the course of plasmapheresis treatment for a disease. It will be based on the response to initial plasma exchanges, the frequency with which these need to be done, and the time before any adjunct therapy will control the disease. In an illness expected to be short-lasting, such as Beye's syndrome or Goodpasture's syndrome, emergency vascular access may be provided by a Scribner shunt or subclavian or femoral vein cannulation. In a patient with long-term needs for plasmapheresis, a subcutaneous arteriovenous fistula is the best method for provision of vascular access. Construction of a bridge fistula is the alternative if a BresciaCimino fistula is not feasible. While these fistulas are maturing or being incorporated, the treatment may be carried out using the veins of the other arm or one of the other routes for emergency vascular access.
REFERENCES 1. Anderson, C.B., Sicard, G.A., and Etheredge, E.F.: Bovine carotid artery and expanded poly tetrafluoroethylene grafts for hemodialysis vascular access. J. Surg. Res., 29:184, 1980. 2. Arana, V.A., Menno, A.D., Hodson, J., et al.: Methods to gain access to the blood stream for hemodialysis. Nebr. Med. J., 59:18--20, 1974. 3. Aubaniac, R.: L'infection intraveineuse sousclavicularie: Avantages et technique. Presse Med., 60:1456 1952. 4. Bolton, W., and Cannon, J. A.: Seroma formation associated with PTFE vascular grafts used as arteriovenous fistulae. Dial. Transpl., 10:60, 1981. 5. Bore, G. E., and Pomaizl, M.J.: Prospective comparison of polytetrafluoroethylene and bovine grafts for hemodialysis. J. Surg. Res., 29:223, 1980. 6. Borja, A. R.: Current status of infraclavicular subclavian vein catheterization: Review of the English literature. Ann. Thorac, Surg., 13:615, 1972. 7. Brescia, M.J., Cimino, J.E., Appel, K., et al.: Chronic hemodialysis using venipuncture and a surgically created arteriovenous fistula. N. Engl. J. Med., 275:1089-1092, 1966. 8. Broviac, J.W., Cole, J.J., and Scribner, B.H.: A silicone rubber atrial catheter for prolonged parenteral alimentation. Surg. Gynecol. Obstet., 136:602, 1973. 9. Butt, K.M.H., Kountz, S.L., and Friedman, E.A.: Angioaccess for hemodialysis: Which, when, why. Clin, Nephrol., 3:207-210, 1975. 10. Cerilli, J., and Limbert, J. G.: Technique and results of the construction of arteriovenous fistulas for hemodialysis. Surg. Gynecol. Obstet., 137:922-924, 1973. 11. Dudrick, S.J., Wilmore, D.W., Vars, H.M., et al.: Long-term total parenteral nutrition with growth, development and positive nitrogen balance. Surgery, 64:134, 1968. 12. Gelber, R. L., and Sadler, J. H. : The use of the Allen -Brown shunt on major blood vessels for hemodialysis. Abstracts of 23rd Meeting of American Society for Artificial Intemal Organs, 6:25, 1977. 13. Grodstein, J., and Kraut, J.: Emergency vascular access for hemodialysis. In Wilson, S.E., and Owens, M.L. (eds.): Vascular Access Surgery. Chicago, Year Book Medical Publishers, 1980. 14. Gutman, R.H., Stead, W.W., and Robinson, R.R.: Physical activity and employment status of patients on maintenance dialysis. N. Engl. J. Med., 304:309, 1981. 15. Haimov, M., Burrows, L., Schanzer, H., et al.: Experience with arterial substitutes in the construction of vascular access for hemodialysis. J. Cardiovasc. Surg., 21:149, 1980. 16. Hepps, S.A., Gentile, D.E., Miller, R.B., et al.: Preservation of the arterial circulation in children requiring hemodialysis by use of an end-to-side dacron-Silastic shunt. Proc. Clin. Dial. Transplant Forum, 4:108--111, 1974. 17. Herbst, C.A.: Indications, management and complications of percutaneous subclavian catheters: An audit. Arch. Surg., 113:1421, 1978.
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Chief, Vascular Surgery (691/112K) Veterans Administration Wadsworth Medical Center Los Angeles, California 90073