- Email: [email protected]
Improved hemodialysis access in children
Improved Hemodialysis Access in Children By Harry Applebaum, V. L. Shashikumar, Laurence A. Somers, H. Jorge Baluarte, Alan B. Gruskin, Michael Grossman, Mary Jo McGarvey, and William H. Weintraub Philadelphia, Pennsylvania 9 Vascular access for chronic hemodialysis in children is difficult because of problems that include obtaining vessels of sufficient size, the limited lifespan of external shunts, and the multiple painful punctures associated with internal fistulae. T w e n t y five expanded polytetraflouroethylene (PTFE) grafts of 6 - m m diameter w e r e inserted for dialysis access over a 2-yr period in 23 children. Grafts w e r e placed either in the upper arm or thigh. Each patient was successfully dialyzed from 60 to 3 7 0 times. Longterm patency of the PTFE grafts was 8 8 % , with a complication rate of 36%, mostly minor. The same ease of insertion and high flow characteristics w e r e noted in a series of 22 bovine carotid heterograft (BCH) fistulae inserted in the t w o years immediately preceeding this study. However, the patency rate was only 3 6 % and the complication rate was 6 9 % , mostly major. W e consider the PTFE graft fistula to be the preferred method for long-term hemodialysis access in children. INDEX W O R D S : Chronic renal failure; hemodialysis; polytetraflouroethylene (Gore-Tex) grafts; arteriovenous shunts; arteriorvenous fistulae.
ASCULAR access for chronic pediatric
hemodialysis is a surgical challenge. V Because peripheral blood vessels in children are small, the supply of vessels of adequate size to provide acceptable flow for dialysis is limited. A variety of external shunts is available, but they restrict the child's physical activity and they usually do not last long. Internal shunts may be poorly tolerated by the child because they require multiple, painful needle punctures. In an attempt to deal with these problems, we utilized large-caliber arteriovenous fistulas constructed of six millimeter diameter expanded polytetraflouroethylene (PTFE) (M. L. Gore From the Department o f Pediatric Surgery and the Section o f Nephrology, St. Christopher's Hospital for Children, Temple University School o f Medicine, Philadelphia, Penn. Presented before the l lth Annual Meeting o f the American Pediatric Surgical Association, Marco Island, Florida, May 7-10, 1980. Address reprint requests to V. L. Shashikumar, M.D., Suite 106, 1335 W. Tabor Road, Philadelphia, Penn. 19141. 9 1980 by Grune & Stratton, Inc. 00 2 2-3468/80/1506~9010501.00/0
764
and Associates, Inc., GORE-TEX, Flagstaff, Ariz.) grafts in 23 pediatric patients undergoing chronic hemodialysis. MATERIALS AND METHODS Daring the period September 1977 November 1979, 25 PTFE grafts were placed in 23 patients who required access for chronic hemodialysis. Two had a previously placed BCH fistula that was no longer functioning satisfactorily and 21 were new patients. The children were 4-18 yr old and most were growth-retarded because of chronic renal disease. Their weights ranged from 12 to 56 (Fig. 1A and B). At our institution peritoneal dialysis is preferred for children under 10 kilograms because of the multiple technical problems in the hemodialysis of these very small children. Peritoneal dialysis is also preferred in those children not living near a dialysis facility willing to treat them. PTFE grafts of 6-mm caliber were chosen because of previously demonstrated PTFE efficacy in adults, TM and because of superior patency rate in grafts whose diameter is 6 millimeters or greater. The first bovine grafts in the earlier series were placed in the thigh, usually because arm vessels had been used previously for external shunts, and in a few instances because of theoretically greater blood flow in the larger lower extremity. Subsequent initial grafts were placed in the arm in all but the smallest children as it became apparent that despite lower flow, the grafts in the upper extremity had no increased incidence of thrombosis. A major benefit of arm placement of the graft is greater personal privacy and patient mobility during dialysis.
Operative Technique Upper arm (brachial artery-brachial vein, brachial artery-axillary vein--(Fig. 2). Under general anesthesia a 2-cm transverse incision is made over the brachial artery just proximal to the antecubital crease. The artery is identified and mobilized to a superficial position. A second 2-cm transverse incision is made over the arterial pulse just distal to the axilla. At this point the two brachial veins usually have joined and lie anterior to the artery when the arm is abducted. If a suitably (at least 4 m m ) large vein is not found, a transverse incision is made below the lateral third of the clavicle. The pectoralis major muscle is spread in the direction of its fibers and the insertion of the pectoralis minor muscle to the coracoid process is divided. This maneuver gives good exposure of the axillary vein that can then be mobilized and used for the venous anastomosis. The brachial vein, however, is usually sufficient. A long, curved clamp is then used to make a subcutaneous tunnel in a gentle curve between the two incisions. The curve allows greater length for multiple needle punctures; extreme "looping" is avoided, however, because relatively straight grafts have a lower
Journal of Pediatric Surgery, Vol. 15, No. 6 (December),1980
HEMODIALYSIS ACCESS IN CHILDREN
765
Thigh (superficial femoral artery-femoral vein--(Fig. 3). A brachial artery less than 3 m m in diameter (in very
EPTFE GRAFTS WEIGHT DISTRIBUTION I09~q8'
~-
IJ.I 6-
4c~3"
A mo
2'0
3'0
mB m 4b
WEIGHT (kg.)
5'o
6~3
BCH GRAFTS WEIGHT DISTRIBUTION
7-
I--6Z 14j5-
3~2Z
B
Io
mmmW 2~3
30
4.o
5'o
m
small children) may be inadequate to provide an acceptable arteriovenous fistula. The superficial femoral artery is exposed through a transverse incision in the medial aspect of the lower part of the thigh, at the distal end of Hunter's canal. The femoral vein is exposed through a transverse incision in the groin. The subcutaneous tunnel and endto-side anastomoses are carried out as described above. Though some surgeons have used a loop configuration in the thigh, we have not done so. Chest (subclavian artery-subclavian vein). If the extremities are not suitable because of small size of vessels or because of previously failed vascular access, an arteriovenous fistual may be constructed between the subclavian artery and the subclavina vein, the graft lying in the anterior chest wall. The subclavian artery and vein are exposed through separate infraclavicular incisions, one on each side. The technique is the same as described previously for exposure of the axillary vein. The pectoralis minor muscle is detached from the
6'0
WEIGHT (kg.)
Fig. 1. (A) EPTFE g r a f t s - - w e i g h t distribution; (B) BCH g r a f t s - - w e i g h t distribution.
incidence of thrombosis. The tunnel is made as close as possible to the skin because subcutaneous tissue between the skin and the graft makes graft puncture more difficult. A tape or heavy suture is passed through the tunnel. While either vascular anastomosis may be done first, we prefer to start with the vein because its thin wall enhances susceptibility of inadvertant suturing of both incisional venous edges with the same stitch, and the graft may be freely manipulated from one side to the other only during the initial vascular anastomosis, to inspect for such inadvertant suturing. Fine bull dog clamps (or doubly looped sutures) are used to occlude the vein, and a 1 centimeter longitudinal slit is made in the vein. The venotomy is irrigated with heparinized saline solution. Using a heavy suture scissors, one end of the graft is obliquely transected with a single cut; no preclotting or irrigation of the graft is done. An end-to-side anastomosis is performed with a continuous 6-0 polyproplene (Prolene, Ethicon, Inc., Summerville, N.J.) suture. Since most graft thromboses are a result of inadequate venous outflow, care should be taken to make sure that the venous end of the anastomosis is adequate. The free end of the graft is attached to the tape or suture and drawn through the subcutaneous tunnel, taking care to avoid twisting. The free end of the graft is then flushed with heparinized saline and inspected for satisfactory filling at the venous end. Again, using a heavy suture scissors, the free end of the graft is transected obliquely with a single cut at the level of the planned arterial anastomosis, which is carried out in a similar end-to-side manner. No venting is necessary prior to tying the last suture, because collapse of the graft by the presence of surrounding tissue prevents air collection (and embolism). The vein is unclamped, followed by the artery.
Fig. 2. Graft insertion in arm. Brachial artery to brachial vein. If brachial vein inadequate, attachment of pectoralis minor to coracoid process is transected for use of axillary vein.
766
APPLEBAUM ET AL.
graft or by Doppler examination. After 48 hr, subcutaneous swelling usually has subsided so that a thrill is present. Small, noncircumferential dressings are applied following subcutaneous and skin closure. No systemic heparinization is necessary. Generally, the grafts are ready for use 7-10 days after surgery. (Simultaneous Scribner shunts are constructed when immediate dialysis is required.) Needle puncture of the graft is performed with a 16-gauge, over-needle catheter following antiseptic skin preparation. Many patients prefer needle insertion without local anesthesia. Only a single puncture is usually necessary to establish good flow. At the conclusion of each hemodialysis, the catheter is removed and gentle finger pressure is applied for 5-10 min over the catheter puncture hole, taking care not to occlude the graft. Circumferential dressings are avoided. Most patients are dialized 2-3 times/wk, and their puncture sites are rotated. If a graft clots, the patient is taken to the operating room as soon as possible. An incision is made over the tunnel near the venous end of the graft (avoiding the middle of the tunnel so as not to interfere with future needle punctures), and declotting is performed using a Fogarty catheter. If flow cannot be reestablished, or if the graft reelots, either a "jump" graft is performed to the axillary vein or a new shunt site is selected. RESULTS
Fig. 3. Graft insertion in thigh. Superficial femoral artery to femoral vein.
coracoid process to gain access to the axilla. The subclavian artery is mobilized on one side and the subclavian vein on the opposite side. The subcutaneous tunnel passes across the front of the chest.
Postoperative Care At the conclusion of the anastomoses, potency is best determined by palpation of a pulse at the venous end of the graft. A thrill usually is not palpable on the skin overlying the tunnel during the first 12-48 hr, during which time patency may be confirmed by an audible bruit over the
There were 25 P T F E grafts placed in 23 patients. Nine complications occurred, six of them minor (Table l). Transient numbness of the extremity thought to be due to limb ischemia occurred in 4 patients, 2 with grafts in the thigh and 2 with grafts in the arm. The numbness resolved within several weeks in all four patients. Two patients with g r a f t s in the thigh experienced minor wound hematomas, not associated with needle puncture sites; both resolved spontaTable 1. Complications i n 2 5 PTFE Grafts Thrombosis Infection Transient numbness Wound hematoma Total
2 1 4 2 9
HEMODIALYSlS ACCESS IN CHILDREN
767
neously. Two grafts thrombosed in the early postoperative period. Both probably represented errors of surgical judgment in not utilizing veins of sufficient caliber. Subsequent thigh grafts in these two patients were successful. A third graft required removal because of infection (draining sinus in the groin incision) 6 wk after placement in the thigh. This child had an infected BCH graft in the opposite thigh at the time of the PTFE graft insertion. Thus, the long-term patency rate for PTFE grafts was 88% with a complication rate of 36% (mostly minor). Each graft was successfully used for dialysis from 60 to 370 times. The 22 BCH grafts implanted in the 2 yr immediately prior to this study also provided adequate dialysis flows but resulted in a much higher complication rate (Table 2). There were 3 instances of graft infect:ion and 3 instances of mycotic pseudoaneurysm formation, necessitating graft removal in all 6 patients. Thrombosis occurred in nine grafts and few of these were salvagable for any appreciable length of time (though most occurred after successful kidney transplantation). Thus, the long term patency rate for BCH grafts was 31% with a complication rate of 69%, most involving loss of the graft. In both series shunt flows were satisfactory for dialysis. None of the patients in either series experienced high-output cardiac failure. The children were able to pursue all activities that their general condition permitted. No graftrelated deaths occurred. DISCUSSION
Access for hemodialysis poses problems in pediatric patients. Since institution of an endstay renal disease program at St. Christopher's Hospital for Children in 1969, we have transplanted over 100 kidneys and have acquired considerable experience with dialysis. The Scribner (external) shunt 5 and Brescia-Cimino (internal) arteriovenous fistula were the first dialysis accesses used frequently in children. Table 2. Complications in 22 BCH Grafts Infection Aneurysm Thrombosis Total
3 3 9 15
The small size of pediatric peripheral vessels predisposes Scribner shunts to thrombosis. Franzone6 reported that 50% of these shunts in children required at least one revision and 31% required multiple revisions. Idriss 7 reported an average shunt life of only 113 days in his pediatric series, with 40% requiring removal because of clotting or infection. Children often accept the Scribner shunt initially because of the ease of getting on dialysis(no needle sticks are necessary). Many children and their families eventually seek other types of hemodialysis access, however, because of occasional severe hemorrhage due to inadvertant separation of tubing, because of limited physical activity by bulky dressings required to protect the shunt, and because of frequent trips to the hospital for declotting. A unique advantage of the external shunt is t h a t dialysis can be performed immediately after the shunt is constructed; we now use such shunts only for emergency, short-term dialysis. Many modifications of the basic Scribner shunt have been described. The Thomas shunt 8 allows larger, more central vessels to be used because of its anastomosis to the vessels with an onlay patch, but problems associated with external cannulas are still present, and the use of more central vessels has been associated with distal ischemia. 9 The Brescia-Cimino arteriovenous fistula 1~(at the wrist) is entirely autogenous and internal. (Such fistulae, together with PTFE grafts, probably constitute the two most commonly used dialysis access procedures in adults today.) In the pediatric age group, larger adolescent patients are suitable candidates for such fistulae, but the small size of peripheral vessels in most pediatric renal patients makes construction of the fistula technically difficult and often the veins of the forearm d o not dilate to sufficient size for dialysis until months after construction, if at all. When these fistulae have been constructed in the antecubital fossa (to utilize large vessels), a high incidence of aneurysm formation ensues) ~ The fragility of pediatric veins also makes the fistula highly susceptible to hematoma formation, with temporary obscuring of sites for needle puncture and possible eventual loss of the A-V fistula. Modifications of this type of fistula utilizing either looped or autotransplanted saphenous vein have been tried, but
768
APPLEBAUM ET AL.
there is an appreciable incidence of unsuitable veins and aneurysm formation. ~2'~3 Even when successful, the Brescia-Cimino arteriovenous fistulae often require multiple puncture attempts with each dialysis, making it unpopular with children. In the mid 1970s, bovine heterografts came into use in children as a high-flow conduit that can be cannulated easily. The introduction of the single-needle technique for hemodialysis made it even easier for children to accept the BCH fistula. Unfortunately, the bovine heterograft also had an appreciable incidence of complications. These complications included a 54%-68% thrombosis rate at 1 yr, a 20% incidence of pseudoaneurysm formation (often with spontaneous hemorrhage), and a high infection rate. 4'~2 Infection surrounding the bovine heterograft necessitates graft removal because of the danger of pseudoaneurysm formation and hemorrhage. Pseudoaneurysm formation without infection may be amenable to excision and a vascular patch. High-output cardiac failure has been reported with use of large caliber diameter fistulae in adults with preexisting cardiac disease, 2 but this has not been a problem in our pediatric series. To avoid this high complication rate, in 1977 we changed to P T F E grafts, first introduction in 1975 for use in arterial bypass surgery. The material is a woven Teflon constructed as a composite of two structures: an inner tube, having longitudinal orientation and strength, and a peripheral layer, having circumferential orientation and strength. This construction is thought to be responsible for the low rate of aneurysm formation. Implanted grafts exhibit ingrowth of tissue, with complete neointima formation, in approximately 30 days, making for low thrombogenicity. 14 The material is pliable and easy to handle when performing anasto-
moses. Resistance to infection is unusually good when compared to other types of access material, and localized infections can be treated by systemic antibiotics, with or without local incision and drainage, so that the graft may not need to be removed, and dialysis can be continued following control of infection. The PTFE grafts thus have all of the advantages of the BCH grafts, including large size (easy target for puncture) and high flow, without most of the serious complications. We have also found the P T F E arteriovenous graft to be helpful for nondialysis vascular access in pediatric patients requiring long-term chemotherapy for tumors, long-term antibiotics (e.g., patients with cystic fibrosis), plasmapheresis, and intravenous nutrition. Robinson 15 has recently proposed P T F E grafts utilized as arterial-arterial fistulae in small children (from brachial artery in the axilla to brachial artery above the elbow). This type of fistula has the theoretical advantage of not increasing cardiac output and lessening the chance of steal syndrome. Ghantous 16 has reported arterial embolization distal to arterialarterial shunts, however, and high back-pressure predisposes to clotting. We have seen the steal syndrome in only one patient, who received a subclavian artery to contralateral subclavian vein fistula in the anterior chest wall, and who had prior ligation of the brachial artery for a Scribner shunt. CONCLUSION We now consider the P T F E graft fistula to be the preferred primary access method for longterm hemodialysis in children. The incidence of complications is low. Excellent patient acceptance has been achieved because the large caliber of the graft allows a single needle puncture for dialysis and the internal graft placement allows unrestricted physical activity.
REFERENCES 1. Baker LD Jr., Johnson JM, Goldfarb D: Expanded Polytetraflouroethylene (PTFE) subcutaneous arteriovenous conduit: An improved vascular access for chronic hemodialysis. Trans Am Soc Artif Intern Organs 22:382-386, 1976 2. Mohaideen AH, Avram MM, Mainzer RA: Polytetraflouroethylene grafts for arteriovenous fistulae. NY State J Med 76:2152-2155, 1976 3. Pasternack BM, Paruk S, Kogan S, et al: A synthetic vascular conduit (expanded PTFE) for hemodialysis ficcess--A preliminary report. Vasc Surg 11:99-102, 1977
4. Tellis VA, Kohlberg WI, Bhat D J, et al: Expanded polytetraflouroethylene graft fistula for chronic hemodialysis. Ann Surg 189:101-105, 1977 5. Quinton W, Dillard D, Scribner BH: Cannulation of blood vessels for prolonged hemodialysis. Trans Am Soc Artif Intern Organs 6:104-107, 1960 6. Frazone A J, Tucker BL, Brennan LP, et al: Hemodialysis in children: Experience with arteriovenous shunts. Arch Surg 102:592-593, 1971 7. Idriss FS, Nikaidoh H, King LR, et al: Arteriovenous
HEMODIALYSIS ACCESS IN CHILDREN
shunts for hemodialysis in infants and children. J Pediatr Surg 6:639-644, 1971 8. Thomas GI: Large vessel applique arteriovenous shunt for hemodialysis. Am J Surg 120:244-248, 1970 9. Buselmeier T J, Santiago EA, Simmons RL: Arteriovenous shunts for pediatric hemodialysis. Surgery 70:638-641, 1971 10. Brescia MJ, Cimino JE, Appel K, et al: Chronic hemodialysis using venipuncture and a surgically created arteriovenous fistula. N Engl J Med 16:297-300, 1966 11. Tellis VA, Veith F J, Soberman R J: Internal arteriovenous fistula for hemodialysis. Surg Gynecol Obstet 132:866-870, 1971 12. Mohaideen AH, Mendivil J, Avram MM, et al: Arte-
769
riovenous access utilizing modified bovine arterial grafts for hemodialysis. Ann Surg 186:643-646, 1977 13. Moy J, Tiller D, Johnson J, et al: Saphenous vein arteriovenous fistula in regular dialysis treatment. N Engl J Med 280:770-771, 1969 14. Shack RB, Wallace WN, Richie RE, et al: Expanded polytetraflouroethylene as dialysis access grafts: Serial study of histology and fibrinolytic activity. Am Surg 43:817-825, 1977 15. Robinson HB, Wenzle JE, Williams GR: Internal vascular access for hemodialysis in children weighing less than 15 kg. Surgery 85:525-529, 1979 16. Ghantous WN, Larson NE, Salkin MS, et al: Arteryto-artery polytetraflouroethylene (PTFE) shunt for hemodialysis. Trans Am Soc Artif Intern Organs 24:498-501,
ASCULAR access for chronic pediatric
hemodialysis is a surgical challenge. V Because peripheral blood vessels in children are small, the supply of vessels of adequate size to provide acceptable flow for dialysis is limited. A variety of external shunts is available, but they restrict the child's physical activity and they usually do not last long. Internal shunts may be poorly tolerated by the child because they require multiple, painful needle punctures. In an attempt to deal with these problems, we utilized large-caliber arteriovenous fistulas constructed of six millimeter diameter expanded polytetraflouroethylene (PTFE) (M. L. Gore From the Department o f Pediatric Surgery and the Section o f Nephrology, St. Christopher's Hospital for Children, Temple University School o f Medicine, Philadelphia, Penn. Presented before the l lth Annual Meeting o f the American Pediatric Surgical Association, Marco Island, Florida, May 7-10, 1980. Address reprint requests to V. L. Shashikumar, M.D., Suite 106, 1335 W. Tabor Road, Philadelphia, Penn. 19141. 9 1980 by Grune & Stratton, Inc. 00 2 2-3468/80/1506~9010501.00/0
764
and Associates, Inc., GORE-TEX, Flagstaff, Ariz.) grafts in 23 pediatric patients undergoing chronic hemodialysis. MATERIALS AND METHODS Daring the period September 1977 November 1979, 25 PTFE grafts were placed in 23 patients who required access for chronic hemodialysis. Two had a previously placed BCH fistula that was no longer functioning satisfactorily and 21 were new patients. The children were 4-18 yr old and most were growth-retarded because of chronic renal disease. Their weights ranged from 12 to 56 (Fig. 1A and B). At our institution peritoneal dialysis is preferred for children under 10 kilograms because of the multiple technical problems in the hemodialysis of these very small children. Peritoneal dialysis is also preferred in those children not living near a dialysis facility willing to treat them. PTFE grafts of 6-mm caliber were chosen because of previously demonstrated PTFE efficacy in adults, TM and because of superior patency rate in grafts whose diameter is 6 millimeters or greater. The first bovine grafts in the earlier series were placed in the thigh, usually because arm vessels had been used previously for external shunts, and in a few instances because of theoretically greater blood flow in the larger lower extremity. Subsequent initial grafts were placed in the arm in all but the smallest children as it became apparent that despite lower flow, the grafts in the upper extremity had no increased incidence of thrombosis. A major benefit of arm placement of the graft is greater personal privacy and patient mobility during dialysis.
Operative Technique Upper arm (brachial artery-brachial vein, brachial artery-axillary vein--(Fig. 2). Under general anesthesia a 2-cm transverse incision is made over the brachial artery just proximal to the antecubital crease. The artery is identified and mobilized to a superficial position. A second 2-cm transverse incision is made over the arterial pulse just distal to the axilla. At this point the two brachial veins usually have joined and lie anterior to the artery when the arm is abducted. If a suitably (at least 4 m m ) large vein is not found, a transverse incision is made below the lateral third of the clavicle. The pectoralis major muscle is spread in the direction of its fibers and the insertion of the pectoralis minor muscle to the coracoid process is divided. This maneuver gives good exposure of the axillary vein that can then be mobilized and used for the venous anastomosis. The brachial vein, however, is usually sufficient. A long, curved clamp is then used to make a subcutaneous tunnel in a gentle curve between the two incisions. The curve allows greater length for multiple needle punctures; extreme "looping" is avoided, however, because relatively straight grafts have a lower
Journal of Pediatric Surgery, Vol. 15, No. 6 (December),1980
HEMODIALYSIS ACCESS IN CHILDREN
765
Thigh (superficial femoral artery-femoral vein--(Fig. 3). A brachial artery less than 3 m m in diameter (in very
EPTFE GRAFTS WEIGHT DISTRIBUTION I09~q8'
~-
IJ.I 6-
4c~3"
A mo
2'0
3'0
mB m 4b
WEIGHT (kg.)
5'o
6~3
BCH GRAFTS WEIGHT DISTRIBUTION
7-
I--6Z 14j5-
3~2Z
B
Io
mmmW 2~3
30
4.o
5'o
m
small children) may be inadequate to provide an acceptable arteriovenous fistula. The superficial femoral artery is exposed through a transverse incision in the medial aspect of the lower part of the thigh, at the distal end of Hunter's canal. The femoral vein is exposed through a transverse incision in the groin. The subcutaneous tunnel and endto-side anastomoses are carried out as described above. Though some surgeons have used a loop configuration in the thigh, we have not done so. Chest (subclavian artery-subclavian vein). If the extremities are not suitable because of small size of vessels or because of previously failed vascular access, an arteriovenous fistual may be constructed between the subclavian artery and the subclavina vein, the graft lying in the anterior chest wall. The subclavian artery and vein are exposed through separate infraclavicular incisions, one on each side. The technique is the same as described previously for exposure of the axillary vein. The pectoralis minor muscle is detached from the
6'0
WEIGHT (kg.)
Fig. 1. (A) EPTFE g r a f t s - - w e i g h t distribution; (B) BCH g r a f t s - - w e i g h t distribution.
incidence of thrombosis. The tunnel is made as close as possible to the skin because subcutaneous tissue between the skin and the graft makes graft puncture more difficult. A tape or heavy suture is passed through the tunnel. While either vascular anastomosis may be done first, we prefer to start with the vein because its thin wall enhances susceptibility of inadvertant suturing of both incisional venous edges with the same stitch, and the graft may be freely manipulated from one side to the other only during the initial vascular anastomosis, to inspect for such inadvertant suturing. Fine bull dog clamps (or doubly looped sutures) are used to occlude the vein, and a 1 centimeter longitudinal slit is made in the vein. The venotomy is irrigated with heparinized saline solution. Using a heavy suture scissors, one end of the graft is obliquely transected with a single cut; no preclotting or irrigation of the graft is done. An end-to-side anastomosis is performed with a continuous 6-0 polyproplene (Prolene, Ethicon, Inc., Summerville, N.J.) suture. Since most graft thromboses are a result of inadequate venous outflow, care should be taken to make sure that the venous end of the anastomosis is adequate. The free end of the graft is attached to the tape or suture and drawn through the subcutaneous tunnel, taking care to avoid twisting. The free end of the graft is then flushed with heparinized saline and inspected for satisfactory filling at the venous end. Again, using a heavy suture scissors, the free end of the graft is transected obliquely with a single cut at the level of the planned arterial anastomosis, which is carried out in a similar end-to-side manner. No venting is necessary prior to tying the last suture, because collapse of the graft by the presence of surrounding tissue prevents air collection (and embolism). The vein is unclamped, followed by the artery.
Fig. 2. Graft insertion in arm. Brachial artery to brachial vein. If brachial vein inadequate, attachment of pectoralis minor to coracoid process is transected for use of axillary vein.
766
APPLEBAUM ET AL.
graft or by Doppler examination. After 48 hr, subcutaneous swelling usually has subsided so that a thrill is present. Small, noncircumferential dressings are applied following subcutaneous and skin closure. No systemic heparinization is necessary. Generally, the grafts are ready for use 7-10 days after surgery. (Simultaneous Scribner shunts are constructed when immediate dialysis is required.) Needle puncture of the graft is performed with a 16-gauge, over-needle catheter following antiseptic skin preparation. Many patients prefer needle insertion without local anesthesia. Only a single puncture is usually necessary to establish good flow. At the conclusion of each hemodialysis, the catheter is removed and gentle finger pressure is applied for 5-10 min over the catheter puncture hole, taking care not to occlude the graft. Circumferential dressings are avoided. Most patients are dialized 2-3 times/wk, and their puncture sites are rotated. If a graft clots, the patient is taken to the operating room as soon as possible. An incision is made over the tunnel near the venous end of the graft (avoiding the middle of the tunnel so as not to interfere with future needle punctures), and declotting is performed using a Fogarty catheter. If flow cannot be reestablished, or if the graft reelots, either a "jump" graft is performed to the axillary vein or a new shunt site is selected. RESULTS
Fig. 3. Graft insertion in thigh. Superficial femoral artery to femoral vein.
coracoid process to gain access to the axilla. The subclavian artery is mobilized on one side and the subclavian vein on the opposite side. The subcutaneous tunnel passes across the front of the chest.
Postoperative Care At the conclusion of the anastomoses, potency is best determined by palpation of a pulse at the venous end of the graft. A thrill usually is not palpable on the skin overlying the tunnel during the first 12-48 hr, during which time patency may be confirmed by an audible bruit over the
There were 25 P T F E grafts placed in 23 patients. Nine complications occurred, six of them minor (Table l). Transient numbness of the extremity thought to be due to limb ischemia occurred in 4 patients, 2 with grafts in the thigh and 2 with grafts in the arm. The numbness resolved within several weeks in all four patients. Two patients with g r a f t s in the thigh experienced minor wound hematomas, not associated with needle puncture sites; both resolved spontaTable 1. Complications i n 2 5 PTFE Grafts Thrombosis Infection Transient numbness Wound hematoma Total
2 1 4 2 9
HEMODIALYSlS ACCESS IN CHILDREN
767
neously. Two grafts thrombosed in the early postoperative period. Both probably represented errors of surgical judgment in not utilizing veins of sufficient caliber. Subsequent thigh grafts in these two patients were successful. A third graft required removal because of infection (draining sinus in the groin incision) 6 wk after placement in the thigh. This child had an infected BCH graft in the opposite thigh at the time of the PTFE graft insertion. Thus, the long-term patency rate for PTFE grafts was 88% with a complication rate of 36% (mostly minor). Each graft was successfully used for dialysis from 60 to 370 times. The 22 BCH grafts implanted in the 2 yr immediately prior to this study also provided adequate dialysis flows but resulted in a much higher complication rate (Table 2). There were 3 instances of graft infect:ion and 3 instances of mycotic pseudoaneurysm formation, necessitating graft removal in all 6 patients. Thrombosis occurred in nine grafts and few of these were salvagable for any appreciable length of time (though most occurred after successful kidney transplantation). Thus, the long term patency rate for BCH grafts was 31% with a complication rate of 69%, most involving loss of the graft. In both series shunt flows were satisfactory for dialysis. None of the patients in either series experienced high-output cardiac failure. The children were able to pursue all activities that their general condition permitted. No graftrelated deaths occurred. DISCUSSION
Access for hemodialysis poses problems in pediatric patients. Since institution of an endstay renal disease program at St. Christopher's Hospital for Children in 1969, we have transplanted over 100 kidneys and have acquired considerable experience with dialysis. The Scribner (external) shunt 5 and Brescia-Cimino (internal) arteriovenous fistula were the first dialysis accesses used frequently in children. Table 2. Complications in 22 BCH Grafts Infection Aneurysm Thrombosis Total
3 3 9 15
The small size of pediatric peripheral vessels predisposes Scribner shunts to thrombosis. Franzone6 reported that 50% of these shunts in children required at least one revision and 31% required multiple revisions. Idriss 7 reported an average shunt life of only 113 days in his pediatric series, with 40% requiring removal because of clotting or infection. Children often accept the Scribner shunt initially because of the ease of getting on dialysis(no needle sticks are necessary). Many children and their families eventually seek other types of hemodialysis access, however, because of occasional severe hemorrhage due to inadvertant separation of tubing, because of limited physical activity by bulky dressings required to protect the shunt, and because of frequent trips to the hospital for declotting. A unique advantage of the external shunt is t h a t dialysis can be performed immediately after the shunt is constructed; we now use such shunts only for emergency, short-term dialysis. Many modifications of the basic Scribner shunt have been described. The Thomas shunt 8 allows larger, more central vessels to be used because of its anastomosis to the vessels with an onlay patch, but problems associated with external cannulas are still present, and the use of more central vessels has been associated with distal ischemia. 9 The Brescia-Cimino arteriovenous fistula 1~(at the wrist) is entirely autogenous and internal. (Such fistulae, together with PTFE grafts, probably constitute the two most commonly used dialysis access procedures in adults today.) In the pediatric age group, larger adolescent patients are suitable candidates for such fistulae, but the small size of peripheral vessels in most pediatric renal patients makes construction of the fistula technically difficult and often the veins of the forearm d o not dilate to sufficient size for dialysis until months after construction, if at all. When these fistulae have been constructed in the antecubital fossa (to utilize large vessels), a high incidence of aneurysm formation ensues) ~ The fragility of pediatric veins also makes the fistula highly susceptible to hematoma formation, with temporary obscuring of sites for needle puncture and possible eventual loss of the A-V fistula. Modifications of this type of fistula utilizing either looped or autotransplanted saphenous vein have been tried, but
768
APPLEBAUM ET AL.
there is an appreciable incidence of unsuitable veins and aneurysm formation. ~2'~3 Even when successful, the Brescia-Cimino arteriovenous fistulae often require multiple puncture attempts with each dialysis, making it unpopular with children. In the mid 1970s, bovine heterografts came into use in children as a high-flow conduit that can be cannulated easily. The introduction of the single-needle technique for hemodialysis made it even easier for children to accept the BCH fistula. Unfortunately, the bovine heterograft also had an appreciable incidence of complications. These complications included a 54%-68% thrombosis rate at 1 yr, a 20% incidence of pseudoaneurysm formation (often with spontaneous hemorrhage), and a high infection rate. 4'~2 Infection surrounding the bovine heterograft necessitates graft removal because of the danger of pseudoaneurysm formation and hemorrhage. Pseudoaneurysm formation without infection may be amenable to excision and a vascular patch. High-output cardiac failure has been reported with use of large caliber diameter fistulae in adults with preexisting cardiac disease, 2 but this has not been a problem in our pediatric series. To avoid this high complication rate, in 1977 we changed to P T F E grafts, first introduction in 1975 for use in arterial bypass surgery. The material is a woven Teflon constructed as a composite of two structures: an inner tube, having longitudinal orientation and strength, and a peripheral layer, having circumferential orientation and strength. This construction is thought to be responsible for the low rate of aneurysm formation. Implanted grafts exhibit ingrowth of tissue, with complete neointima formation, in approximately 30 days, making for low thrombogenicity. 14 The material is pliable and easy to handle when performing anasto-
moses. Resistance to infection is unusually good when compared to other types of access material, and localized infections can be treated by systemic antibiotics, with or without local incision and drainage, so that the graft may not need to be removed, and dialysis can be continued following control of infection. The PTFE grafts thus have all of the advantages of the BCH grafts, including large size (easy target for puncture) and high flow, without most of the serious complications. We have also found the P T F E arteriovenous graft to be helpful for nondialysis vascular access in pediatric patients requiring long-term chemotherapy for tumors, long-term antibiotics (e.g., patients with cystic fibrosis), plasmapheresis, and intravenous nutrition. Robinson 15 has recently proposed P T F E grafts utilized as arterial-arterial fistulae in small children (from brachial artery in the axilla to brachial artery above the elbow). This type of fistula has the theoretical advantage of not increasing cardiac output and lessening the chance of steal syndrome. Ghantous 16 has reported arterial embolization distal to arterialarterial shunts, however, and high back-pressure predisposes to clotting. We have seen the steal syndrome in only one patient, who received a subclavian artery to contralateral subclavian vein fistula in the anterior chest wall, and who had prior ligation of the brachial artery for a Scribner shunt. CONCLUSION We now consider the P T F E graft fistula to be the preferred primary access method for longterm hemodialysis in children. The incidence of complications is low. Excellent patient acceptance has been achieved because the large caliber of the graft allows a single needle puncture for dialysis and the internal graft placement allows unrestricted physical activity.
REFERENCES 1. Baker LD Jr., Johnson JM, Goldfarb D: Expanded Polytetraflouroethylene (PTFE) subcutaneous arteriovenous conduit: An improved vascular access for chronic hemodialysis. Trans Am Soc Artif Intern Organs 22:382-386, 1976 2. Mohaideen AH, Avram MM, Mainzer RA: Polytetraflouroethylene grafts for arteriovenous fistulae. NY State J Med 76:2152-2155, 1976 3. Pasternack BM, Paruk S, Kogan S, et al: A synthetic vascular conduit (expanded PTFE) for hemodialysis ficcess--A preliminary report. Vasc Surg 11:99-102, 1977
4. Tellis VA, Kohlberg WI, Bhat D J, et al: Expanded polytetraflouroethylene graft fistula for chronic hemodialysis. Ann Surg 189:101-105, 1977 5. Quinton W, Dillard D, Scribner BH: Cannulation of blood vessels for prolonged hemodialysis. Trans Am Soc Artif Intern Organs 6:104-107, 1960 6. Frazone A J, Tucker BL, Brennan LP, et al: Hemodialysis in children: Experience with arteriovenous shunts. Arch Surg 102:592-593, 1971 7. Idriss FS, Nikaidoh H, King LR, et al: Arteriovenous
HEMODIALYSIS ACCESS IN CHILDREN
shunts for hemodialysis in infants and children. J Pediatr Surg 6:639-644, 1971 8. Thomas GI: Large vessel applique arteriovenous shunt for hemodialysis. Am J Surg 120:244-248, 1970 9. Buselmeier T J, Santiago EA, Simmons RL: Arteriovenous shunts for pediatric hemodialysis. Surgery 70:638-641, 1971 10. Brescia MJ, Cimino JE, Appel K, et al: Chronic hemodialysis using venipuncture and a surgically created arteriovenous fistula. N Engl J Med 16:297-300, 1966 11. Tellis VA, Veith F J, Soberman R J: Internal arteriovenous fistula for hemodialysis. Surg Gynecol Obstet 132:866-870, 1971 12. Mohaideen AH, Mendivil J, Avram MM, et al: Arte-
769
riovenous access utilizing modified bovine arterial grafts for hemodialysis. Ann Surg 186:643-646, 1977 13. Moy J, Tiller D, Johnson J, et al: Saphenous vein arteriovenous fistula in regular dialysis treatment. N Engl J Med 280:770-771, 1969 14. Shack RB, Wallace WN, Richie RE, et al: Expanded polytetraflouroethylene as dialysis access grafts: Serial study of histology and fibrinolytic activity. Am Surg 43:817-825, 1977 15. Robinson HB, Wenzle JE, Williams GR: Internal vascular access for hemodialysis in children weighing less than 15 kg. Surgery 85:525-529, 1979 16. Ghantous WN, Larson NE, Salkin MS, et al: Arteryto-artery polytetraflouroethylene (PTFE) shunt for hemodialysis. Trans Am Soc Artif Intern Organs 24:498-501,