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Surgery for renal replacement therapy
TRANSPLANTATION
as they are complicated by stenosis in 40e50% of patients;1 this precludes future AVF formation in that arm due to the risk of venous hypertension. If the internal jugular veins are not suitable for use, the femoral vein should be used as an alternative. For short-term haemodialysis while an in-patient non-cuffed, non-tunnelled catheters are acceptable. However, for long-term use these catheters have unacceptably high rates of catheterassociated bacteraemia. Therefore, they should be exchanged for a cuffed, tunnelled catheter. These were traditionally inserted by surgeons in theatre using an open cutdown method: the internal jugular vein is easily accessed through a transverse incision centred over the lower third of sternocleidomastoid. Latterly these have increasingly been inserted by nephrologists or radiologists using a percutaneous Seldinger technique. The use of ultrasound guidance in this situation increases first-time cannulation rates, decreases inadvertent puncture of the carotid artery and is recommended by NICE. Whichever technique is used, the catheter position should be checked radiologically to ensure its tip lies in the SVC. The long-term use of vascular access catheters should be avoided, as the risk of thrombosis is high. However, in some patients, particularly those who have been on haemodialysis for many years, all potential options for vascular or peritoneal access have been exhausted and this is the only option available.
Surgery for renal replacement therapy Adam D Barlow
Abstract Surgical intervention is required for long-term access for both haemodialysis and peritoneal dialysis. As the number and complexity of patients on dialysis increases, this presents an increasing challenge. Successful renal access surgery requires both careful planning and technical skill. This article describes the evaluation of patients for surgery, explores the surgical options for dialysis modalities and discusses the common complications of these.
Keywords Access; arteriovenous fistula; haemodialysis; peritoneal dialysis
Introduction The two forms of dialysis available to patients with end-stage renal failure (ESRF) are haemodialysis and peritoneal dialysis. Access for both modalities requires surgical intervention. Traditionally this workload has fallen under the remit of the transplant surgery team, but in recent years vascular surgeons and interventional radiologists have become increasingly involved.
Complications of vascular access catheters: as mentioned above, the principal complication of vascular access catheters is thrombosis. This occurs in around 15% of patients2 and accounts for most catheter dysfunction. Treatment in the first instance involves infusion of a thrombolytic, such as urokinase, through the catheter. If this fails the catheter may need to be replaced, which can be done by exchange over a guidewire placed through the non-functioning catheter. In patients with recurrent catheter dysfunction, long-term anticoagulation with warfarin may be of benefit. Other causes of catheter dysfunction include initial malposition or kinking of the tip, fibrin sheath formation around the catheter or central venous thrombosis. If in doubt injection of radio-opaque dye through the catheter under X-ray screening may help differentiate between these causes. Catheter-related infection also results in failure of a significant number of vascular access catheters, with rates around 2 per 1000 catheter days for tunnelled lines.2 Infection occurs most commonly by migration of skin organisms from the exit along the catheter track or via the lumen from contamination during handling of the catheter. Preventative measures include strict personal hygiene and handling of the catheter only by trained dialysis nurses. In most cases, exit site infections settle with oral antibiotics. Intravenous antibiotics should be instigated if there is evidence of systemic sepsis or bacteraemia on blood cultures. If the infection fails to resolve, catheter removal is necessary.
Access for haemodialysis The gold standard access for haemodialysis is an autogenous arteriovenous fistula (AVF). However, patients may present acutely with ESRF requiring haemodialysis before an AVF has been formed. Additionally, as patients requiring vascular access become progressively older with more comorbidities and atherosclerosis, establishing an AVF becomes increasingly challenging. In these situations other approaches are necessary. Temporary vascular access catheters About 40% of patients with ESRF present acutely and require temporary vascular access for haemodialysis. This is achieved by percutaneous insertion of a double lumen large bore venous catheter. Other indications for the use of vascular access catheters are as follows: while waiting for maturation of autogenous AVF until an arteriovenous graft or peritoneal catheter is ready to use while waiting for planned living donor renal transplantation after previous failed vascular access or peritoneal dialysis permanent access once all other options exhausted. The vein of choice for vascular access catheters is the right internal jugular vein. This provides the most direct route to the superior vena cava and right atrium and has greater patency rates than other sites.1 Subclavian venous catheters should be avoided
Arteriovenous fistulae and grafts An autogenous arteriovenous fistula, where a peripheral vein is anastomosed directly to an artery, is the vascular access of choice for long-term haemodialysis. The ideal AVF for haemodialysis has the following characteristics: blood flow greater than or equal to 300 mL/min sufficient length of vein to allow two needles to be inserted
Adam D Barlow MD FRCS is a Clinical Lecturer in Transplant Surgery at the University of Cambridge and Honorary Specialist Registrar at Addenbrooke’s Hospital, UK. Conflicts of interest: none declared.
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Ó 2014 Elsevier Ltd. All rights reserved.
TRANSPLANTATION
large diameter for easy venepuncture good long-term patency. If it is to be successful, vascular access surgery needs careful planning and to proceed in a step-wise fashion. There are some general rules which should be adhered to: use the most distal suitable vein first use the non-dominant arm first arm vessels should be used in preference to leg vessels prosthetic grafts should only be used if no autogenous veins are suitable All vascular access surgery adheres to the basic principles of vascular anastomosis. The anastomosis is performed using a continuous, monofilament, non-absorbable suture. The edges of the vessels should be everted to exclude thrombogenic adventitia, there must be no tension and all layers of the vessel wall should be included in the suture to prevent subintimal flap formation. The success of surgery is indicated by the presence of a palpable thrill and audible bruit in the venous limb of the AVF. The venous limb of an autogenous AVF matures and becomes arterialized over several weeks. This involves venous dilatation and thickening of the vessel wall. It is common to leave all AVFs for 6 weeks prior to needling, as early puncture can result in haematoma and early thrombosis. Preoperative assessment: when deciding on the site of AVF formation the above general rules should be adhered to. In addition, an AVF is only going to be successful if the following requirements are satisfied: satisfactory arterial inflow patent superficial vein of adequate diameter no outflow obstruction (patent axillary, subclavian and central veins) The arterial inflow is assessed clinically, with an easily palpable pulse usually being sufficient. Overt atherosclerosis can also be detected, although this does not necessarily preclude AVF formation at this site. Allen’s test should be performed prior to radiocephalic AVF formation to confirm a patent ulnar artery. The suitability of veins can be assessed either clinically or radiologically. A sound knowledge of the venous anatomy of the arm is paramount (Figure 1). Clinical assessment is performed by inspection and palpation following tourniquet placement around the upper arm. The patency of the cephalic vein in the forearm can be assessed by light percussion at the wrist, while feeling for a transmitted wave in the vein at the elbow. Ultrasound mapping may identify suitable veins not detected clinically, particularly in obese patients. The other option if no suitable arm veins are palpable is venography, where contrast is injected into a superficial vein in the hand or wrist and the venous anatomy of the arm demonstrated. Assessment of the patency of the venous drainage of the arm can also be performed by venography or duplex ultrasound. Clinical signs suggesting central venous occlusion include prominent collateral veins around the shoulder, chest or neck with associated arm or neck swelling. Presence of these features necessitates assessment of the central veins.
Figure 1
under local anaesthetic as a day case. It was first described by Brescia et al. in 1966 as a side-to-side anastomosis.3 Many surgeons now prefer an end of vein-to-side of artery anastomosis as there is a lower incidence of venous hypertension in the hand. However, this can be avoided by ligating the redundant distal venous limb of a side-to-side anastomosis. Radiocephalic AVFs have a primary patency rate (without intervention) of around 63% at 1 year.4
Radiocephalic arteriovenous fistula: this is the first choice of AVF and involves anastomosis between the radial artery and cephalic vein at the wrist (Figure 2), which can be performed
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Figure 2 A mature radiocephalic arteriovenous fistula with long-term use.
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Arteriovenous grafts for vascular access: this technique involves tunnelling a graft subcutaneously between a suitable artery and vein and anastomosing one end of the graft to the side of the vein and the other end to the side of the artery. Various graft materials are available. In principle, the autogenous saphenous vein should be a sound choice. However, this vein is of variable quality and the extensive dissection required necessitates not only a general anaesthetic, but also several days in hospital to recuperate. Nevertheless, forearm loop graft patency rates of 90% at 1 year have been reported.7 The most used graft material for vascular access is expanded PTFE. Advantages of PTFE are easy handling and the wide range of sizes available. Disadvantages are the expense and higher complication rates than autogenous AVF. In addition, it is necessary to wait 6 weeks following surgery before a PTFE graft can be needled. PTFE is not self-sealing and needling before perigraft fibrosis has developed can result in significant bleeding. Primary patency rates for upper limb grafts are around 50% at 1 year.8 Arteriovenous grafts have been used in a number of anatomical sites for vascular access. One of the most common is between the brachial artery at the elbow and the axillary vein. This is often the next step once brachiobasilic AVFs have failed or if the basilic veins are unsuitable for use. The vessels are exposed through small incisions at the elbow and axilla, and the graft tunnelled between. This technique is effective if attempts at autogenous AVF formation have failed. An alternative option if the brachial artery is either small or diseased is a loop graft anastomosed to the axillary artery and vein. Forearm grafts are particularly popular in the United States, where many surgeons favour the use of prosthetic material for primary or secondary vascular access procedures. These grafts can use either the brachial or radial artery as their inflow, and any of the elbow veins as the outflow. One of the most common configurations is a loop graft between the brachial artery and basilic vein. In patients with exhausted arm and axillary veins, options include loop grafts to the common femoral vessels at the groin or superficial femoral vessels in the mid-thigh, straight brachiojugular grafts and so-called ‘necklace’ grafts between opposite axillary or subclavian vessels.
Brachiocephalic arteriovenous fistula: in patients with either failed wrist fistulae in both arms or unsuitable forearm veins, the next step should be a brachiocephalic AVF. This involves an anastomosis between the brachial artery and cephalic vein at the elbow. It can also be performed under local anaesthetic as a day case. The disadvantage of a brachiocephalic AVF is the relatively short length of vein suitable for needling. The anastomosis is most commonly performed as an end of vein-to-side of artery. Several variations are possible depending on the vascular anatomy at the elbow, which is variable. The median cubital vein, if present, may be anastomosed directly to the brachial artery. This has the advantage of arterializing both the cephalic and basilic venous systems. The brachial artery has higher blood flow than the radial artery. As such, haemodynamic complications such as steal syndrome and high output cardiac failure are more common with brachiocephalic than radiocephalic AVFs. This can be limited by restricting the brachial arteriotomy to a maximum of 75% of the diameter of the artery. The long-term results of brachiocephalic AVFs are good with secondary patency rates (with intervention) of up to 80% at 3 years.5 Brachiobasilic arteriovenous fistula: this procedure is reserved for patients in whom radiocephalic or brachiocephalic AVFs are either not feasible or have failed in both arms. It is imperative that the basilic vein is imaged preoperatively either by duplex ultrasound or venography to confirm its suitability, as it is not possible to assess this clinically. The basilic vein only lies superficially at the elbow. The majority of the vein lies deep to the deep fascia of the upper arm. As such, it is not amenable to venepuncture or cannulation and is usually preserved even if the cephalic vein is unsuitable for AVF formation. However, if an AVF is formed with the vein in this deep position, only a short portion is available for needling. Therefore, the basilic vein is dissected from its bed, all branches ligated and the vein transposed to a subcutaneous pocket or tunnel down the middle of the upper arm. The end of the vein is then anastomosed to the side of the brachial artery at the elbow. This operation is best performed under general anaesthetic due to the length of the incision, which runs along the medial aspect of the arm from antecubital fossa to axilla. The secondary patency rates of brachiobasilic AVFs are around 72% at 1 year.6 Drawbacks include the extensive incision and dissection required, which is both painful and prone to infection. Alternatively, brachiobasilic AVF formation may be performed as a two-stage procedure. In the initial procedure, performed under local anaesthetic, the basilic vein is anastomosed end-to-side to the brachial artery through an incision over the medial aspect of the elbow. Once the basilic vein has matured the second-stage procedure to transpose the basilic vein to a more superficial position is performed. This approach is particularly applicable if there are concerns over the quality of the basilic vein and avoids the morbidity of a general anaesthetic and long arm incision if the vein fails to mature. A first-stage brachiobasilic AVF can also be formed as an alternative to a planned brachiocephalic AVF if the cephalic vein is found to be unsuitable at the time of surgery.
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Complications of arteriovenous fistulae and grafts: the main complications of arteriovenous fistulae and grafts are as follows: haemorrhage thrombosis infection aneurysm formation steal syndrome Haemorrhage e early haemorrhage after vascular access surgery is usually related to technical error or disruption of the anastomosis. Late bleeding can occur when the same puncture site is repeatedly used, or is related to aneurysm formation. If significant haemorrhage occurs, pressure over the bleeding point usually provides temporary control, but surgical exploration is usually required. Thrombosis e thrombosis occurring in the first 24 hours is usually related to technical error or poor vessel quality. If the vessel quality was deemed adequate at the time of surgery, immediate re-exploration is indicated as it may be possible to
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salvage the AVF by thrombectomy and refashioning of the anastomosis. In the long-term, thrombosis is the most common cause of failure of AV fistulae and grafts. This is usually related to an underlying stenosis, although may also result from inadvertent compression, post-dialysis hypotension or dehydration. Once an AVF has thrombosed, the only chance of salvage is to perform an immediate thrombectomy before the thrombus becomes organized. Unfortunately, by the time the patient presents the opportunity has often been missed. Once the thrombus has been cleared any underlying stenosis can be identified by fistulography and treated by percutaneous trans-luminal fistuloplasty. The ideal is to identify stenotic lesions before thrombosis occurs. Clues to suggest a failing fistula include increasing venous pressures and poor flow on dialysis, reduced palpable thrill or audible bruit and increases in urea recirculation. These changes should prompt investigation in the form of duplex ultrasound or fistulography. Aneurysm formation e AV fistulae and grafts may be complicated by both false and true aneurysms. False aneurysms tend to occur at sites of repeated venepuncture and are more common in prosthetic grafts than autogenous AVFs. These should be treated as the risk of haemorrhage is high if they are left. True aneurysmal dilatation of autogenous AVFs is very common. Intervention is only required if the overlying skin becomes threatened or there is rapid expansion. Surgical intervention for both types of aneurysm involves resection of the affected segment and restoration of the AVF by either end-to-end anastomosis or, occasionally, a short PTFE interposition graft. Plication of true aneurysms can be performed, but recurrence is almost inevitable. Steal syndrome e this occurs when ischaemic changes develop in a limb distal to an AV fistula or graft. It is most common with procedures employing the brachial artery and in patients with atherosclerosis or diabetes. Investigation of the complete arterial system of the affected limb is mandatory in patients presenting with steal syndrome as treatment of either a proximal or distal arterial stenosis may resolve the symptoms. Mild steal syndromes occurring soon after surgery often resolve spontaneously over weeks, but in more severe cases intervention is necessary to limit the flow in the fistula. This can be achieved by a plication suture in the vein or graft just above the anastomosis. In more severe or recurrent cases, a DRIL (distal revascularization-interval ligation) procedure can be performed. This involves ligation of the artery just distal to the AVF anastomosis, with bypass from the proximal artery to a point distal to the ligature using saphenous vein or PTFE graft (Figure 3).9
DRIL (distal revascularization − interval ligation) procedure for steal syndrome AVF Brachial artery
Graft AVF, arteriovenous fistula Figure 3
While the majority of patients are suitable for PD, there are some contraindications. Absolute contraindications include previous sclerosing peritonitis, inflammatory bowel disease and documented severe peritoneal adhesions. Relative contraindications include morbid obesity, inoperable abdominal hernias, stomas and chronic obstructive airways disease. In patients who have undergone previous surgery, initial laparoscopy may be used to assess the severity of adhesions and, as appropriate, perform adhesiolysis prior to PD catheter insertion. Catheter insertion The three options for catheter insertion are peritoneoscopic, laparoscopic and open. The peritoneoscopic approach can be performed under local anaesthetic with sedation. A trocar is passed through the abdominal wall and a low pressure pneumoperitoneum established. A 2.2 mm laparoscope is used to confirm the trocar is within the peritoneal cavity. The laparoscope is then removed, a dilator passed and the catheter inserted. Following removal of the trocar the catheter is tunnelled laterally. The main disadvantage of this method is that the catheter is passed blindly into the pelvis and a satisfactory position is not confirmed. The laparoscopic approach is very similar to the peritoneoscopic approach, but uses a separate 5e10 mm port, usually in the left or right upper quadrant. This allows the catheter position to be visualized and a further 5 mm port can be used to manipulate the tube into the pelvis. The tube tip should be placed in the rectovesical pouch in men and the rectovaginal pouch of Douglas in women (Figure 4). In the open technique, a small vertical infra-umbilical incision is made. The rectus sheath is opened, a small incision made in the peritoneum and the tube inserted into the pelvis. The peritoneum is closed around the cuff with an absorbable suture to create a watertight closure. The rectus sheath is then closed over the cuff using a non-absorbable suture and the catheter tunnelled subcutaneously.
Access for peritoneal dialysis
Complications of peritoneal dialysis Peritoneal dialysis peritonitis: this is the most significant complication of PD with 0.5e1.5 episodes per patient per year.10 It is also the most common cause of technique failure. Clinical features include abdominal pain and tenderness with a cloudy effluent containing >100 106/L white blood cells. The most common causative organisms are Gram-positive cocci with Staphylococcus aureus, S. epidermidis and Streptococcus spp. accounting for over a third of cases.11
Approximately half of UK dialysis patients are on peritoneal dialysis (PD). This utilizes the selectively permeable characteristics of the peritoneum, with a surface area over 2 m2. Instillation of a hypertonic dialysate fluid into the peritoneal cavity results in ultrafiltration of solutes and electrolytes from the bloodstream into the fluid, which is then drained. This requires an indwelling peritoneal dialysis catheter, the most popular being a cuffed Tenckhoff catheter with a curled intraperitoneal end.
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Distal ligation of artery
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Catheter obstruction: this is most commonly due to omental wrapping. Other causes include intra-abdominal adhesions and extrinsic compression from bladder distension or faeces in the sigmoid colon. In the early postoperative period a blood clot may block the catheter; this usually responds to an infusion of urokinase via the catheter. Catheter tip migration out of the pelvis can also cause catheter blockage or incomplete drainage. Patients presenting with catheter obstruction should have a plain abdominal radiograph performed to assess catheter position and faecal loading. If faecal loading is present, aperients often resolve the problem. In the absence of faecal loading, or if the catheter tip is not in the pelvis, laparoscopic repositioning or freeing of the omental wrap can be performed. Leak: early postoperative leak may result with any condition that predisposes to poor wound healing, such as diabetes or steroid use. Alternatively, it may result from poor surgical technique. Treatment involves stopping PD for 2e4 weeks and then restarting. Ongoing leaks usually necessitate catheter exchange, as do late onset leaks. Encapsulating sclerosing peritonitis is a rare but potentially fatal complication of PD, with mortality rates between 40% and 75%.13,14 It is a result of recurrent PD peritonitis with replacement of the mesothelial layer of the peritoneum with an encapsulating fibrin and hyaline layer. Patients present with abdominal pain, ascites, blood-stained effluent or bowel obstruction. CT or ultrasound examination may show loculated fluid collections, bowel wall and peritoneal thickening or peritoneal calcification. Medical treatment options include tamoxifen and steroids, although the benefit of these is questionable. Surgical treatment to remove the thickened peritoneum carries a very high risk and should probably be reserved for patients presenting with generalized peritonitis or bowel obstruction. A
Figure 4
Initial management includes sending dialysate samples for microbiological examination and commencement of intraperitoneal antibiotics. These can be supplemented with intravenous antibiotics in more severe cases. Indications for surgical intervention include failure to improve after 5 days of medical management, generalized peritonitis, fungal peritonitis and Psuedomonas peritonitis. Surgical treatment involves thorough peritoneal lavage and removal of the PD catheter. This can be performed either laparoscopically or through a midline laparotomy. The laparoscopic approach appears to have advantages in terms of postoperative pain and a quicker return of bowel function.12
REFERENCES 1 Cimochowski GE, Worley E, Rutherford WE, Sartain J, Blondin J, Harter H. Superiority of the internal jugular over the subclavian access for temporary dialysis. Nephron 1990; 54: 154e61. 2 Thomson P, Stirling C, Traynor J, Morris S, Mactier R. A prospective observational study of catheter-related bacteraemia and thrombosis in a haemodialysis cohort: univariate and multivariate analyses of risk association. Nephrol Dial Transplant 2010; 25: 1596e604. 3 Brescia MJ, Cimino JE, Appel K, Hurwich BJ. Chronic hemodialysis using venipuncture and a surgically created arteriovenous fistula. N Engl J Med 1966; 275: 1089e92. 4 Rooijens PP, Tordoir JH, Stijnen T, Burgmans JP, Smet de AA, Yo TI. Radiocephalic wrist arteriovenous fistula for hemodialysis: metaanalysis indicates a high primary failure rate. Eur J Vasc Endovasc Surg 2004; 28: 583e9. 5 Bender MH, Bruyninckx CM, Gerlag PG. The Gracz arteriovenous fistula evaluated. Results of the brachiocephalic elbow fistula in haemodialysis angio-access. Eur J Vasc Endovasc Surg 1995; 10: 294e7. 6 Glass C, Porter J, Singh M, Gillespie D, Young K, Illig K. A large-scale study of the upper arm basilic transposition for hemodialysis. Ann Vasc Surg 2010; 24: 85e91.
Exit site and tunnel infections are common and generally not significant, although approximately 10% will lead on to PD peritonitis. A positive culture from the exit site alone should not be treated; however, if two or more cultures are positive treatment should be instigated. Erythema alone with no discharge may be treated with topical agents. In cases with purulent discharge from the exit site ultrasound may be used to diagnose tunnel infection, which usually necessitates catheter removal. Catheter removal is also indicated in fungal, Psuedomonas and persistent gram-negative exit site infections. Hernias: as the increased intra-abdominal pressure from the dialysate can enlarge pre-existing hernias, these are best repaired before or at the time of catheter insertion. However, de novo hernias can also develop. Ideally repair of these should avoid breaching the peritoneum, as this risks a postoperative fluid leak. Patients with a patent processus vaginalis can also present with scrotal or labial oedema following exchanges. This requires surgical ligation. Some surgeons withhold PD for a number of weeks following hernia repair to reduce the risk of a leak or recurrence. Others use a low-volume, high-frequency exchange regimen, which removes the need for temporary haemodialysis.
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7 Bhandari S, Wilkinson A, Sellars L. Saphenous vein forearm grafts and gortex thigh grafts as alternative forms of vascular access. Clin Nephrol 1995; 44: 325e8. 8 Ko PJ, Liu YH, Hung YN, Hsieh HC. Patency rates of cuffed and noncuffed extended polytetrafluoroethylene grafts in dialysis access: a prospective, randomized study. World J Surg 2009; 33: 846e51. 9 Berman SS, Gentile AT, Glickman MH, et al. Distal revascularizationinterval ligation for limb salvage and maintenance of dialysis access in ischemic steal syndrome. J Vasc Surg 1997; 26: 393e402. discussion 402e4. 10 Brook NR, White SA, Waller JR, Nicholson ML. The surgical management of peritoneal dialysis catheters. Ann R Coll Surg Engl 2004; 86: 190e5.
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11 Golper TA, Hartstein AI. Analysis of the causative pathogens in uncomplicated CAPD-associated peritonitis: duration of therapy, relapses, and prognosis. Am J Kidney Dis 1986; 7: 141e5. 12 Barlow AD, Yates PJ, Hosgood SA, Nicholson ML. Case-control comparison of laparoscopic and open washout for peritoneal dialysisassociated peritonitis. Br J Surg 2008; 95: 1416e9. 13 Nomoto Y, Kawaguchi Y, Kubo H, Hirano H, Sakai S, Kurokawa K. Sclerosing encapsulating peritonitis in patients undergoing continuous ambulatory peritoneal dialysis: a report of the Japanese sclerosing encapsulating peritonitis study group. Am J Kidney Dis 1996; 28: 420e7. 14 Brown MC, Simpson K, Kerssens JJ, Mactier RA, Scottish Renal Registry. Encapsulating peritoneal sclerosis in the new millennium: a national cohort study. Clin J Am Soc Nephrol 2009; 4: 1222e9.
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as they are complicated by stenosis in 40e50% of patients;1 this precludes future AVF formation in that arm due to the risk of venous hypertension. If the internal jugular veins are not suitable for use, the femoral vein should be used as an alternative. For short-term haemodialysis while an in-patient non-cuffed, non-tunnelled catheters are acceptable. However, for long-term use these catheters have unacceptably high rates of catheterassociated bacteraemia. Therefore, they should be exchanged for a cuffed, tunnelled catheter. These were traditionally inserted by surgeons in theatre using an open cutdown method: the internal jugular vein is easily accessed through a transverse incision centred over the lower third of sternocleidomastoid. Latterly these have increasingly been inserted by nephrologists or radiologists using a percutaneous Seldinger technique. The use of ultrasound guidance in this situation increases first-time cannulation rates, decreases inadvertent puncture of the carotid artery and is recommended by NICE. Whichever technique is used, the catheter position should be checked radiologically to ensure its tip lies in the SVC. The long-term use of vascular access catheters should be avoided, as the risk of thrombosis is high. However, in some patients, particularly those who have been on haemodialysis for many years, all potential options for vascular or peritoneal access have been exhausted and this is the only option available.
Surgery for renal replacement therapy Adam D Barlow
Abstract Surgical intervention is required for long-term access for both haemodialysis and peritoneal dialysis. As the number and complexity of patients on dialysis increases, this presents an increasing challenge. Successful renal access surgery requires both careful planning and technical skill. This article describes the evaluation of patients for surgery, explores the surgical options for dialysis modalities and discusses the common complications of these.
Keywords Access; arteriovenous fistula; haemodialysis; peritoneal dialysis
Introduction The two forms of dialysis available to patients with end-stage renal failure (ESRF) are haemodialysis and peritoneal dialysis. Access for both modalities requires surgical intervention. Traditionally this workload has fallen under the remit of the transplant surgery team, but in recent years vascular surgeons and interventional radiologists have become increasingly involved.
Complications of vascular access catheters: as mentioned above, the principal complication of vascular access catheters is thrombosis. This occurs in around 15% of patients2 and accounts for most catheter dysfunction. Treatment in the first instance involves infusion of a thrombolytic, such as urokinase, through the catheter. If this fails the catheter may need to be replaced, which can be done by exchange over a guidewire placed through the non-functioning catheter. In patients with recurrent catheter dysfunction, long-term anticoagulation with warfarin may be of benefit. Other causes of catheter dysfunction include initial malposition or kinking of the tip, fibrin sheath formation around the catheter or central venous thrombosis. If in doubt injection of radio-opaque dye through the catheter under X-ray screening may help differentiate between these causes. Catheter-related infection also results in failure of a significant number of vascular access catheters, with rates around 2 per 1000 catheter days for tunnelled lines.2 Infection occurs most commonly by migration of skin organisms from the exit along the catheter track or via the lumen from contamination during handling of the catheter. Preventative measures include strict personal hygiene and handling of the catheter only by trained dialysis nurses. In most cases, exit site infections settle with oral antibiotics. Intravenous antibiotics should be instigated if there is evidence of systemic sepsis or bacteraemia on blood cultures. If the infection fails to resolve, catheter removal is necessary.
Access for haemodialysis The gold standard access for haemodialysis is an autogenous arteriovenous fistula (AVF). However, patients may present acutely with ESRF requiring haemodialysis before an AVF has been formed. Additionally, as patients requiring vascular access become progressively older with more comorbidities and atherosclerosis, establishing an AVF becomes increasingly challenging. In these situations other approaches are necessary. Temporary vascular access catheters About 40% of patients with ESRF present acutely and require temporary vascular access for haemodialysis. This is achieved by percutaneous insertion of a double lumen large bore venous catheter. Other indications for the use of vascular access catheters are as follows: while waiting for maturation of autogenous AVF until an arteriovenous graft or peritoneal catheter is ready to use while waiting for planned living donor renal transplantation after previous failed vascular access or peritoneal dialysis permanent access once all other options exhausted. The vein of choice for vascular access catheters is the right internal jugular vein. This provides the most direct route to the superior vena cava and right atrium and has greater patency rates than other sites.1 Subclavian venous catheters should be avoided
Arteriovenous fistulae and grafts An autogenous arteriovenous fistula, where a peripheral vein is anastomosed directly to an artery, is the vascular access of choice for long-term haemodialysis. The ideal AVF for haemodialysis has the following characteristics: blood flow greater than or equal to 300 mL/min sufficient length of vein to allow two needles to be inserted
Adam D Barlow MD FRCS is a Clinical Lecturer in Transplant Surgery at the University of Cambridge and Honorary Specialist Registrar at Addenbrooke’s Hospital, UK. Conflicts of interest: none declared.
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large diameter for easy venepuncture good long-term patency. If it is to be successful, vascular access surgery needs careful planning and to proceed in a step-wise fashion. There are some general rules which should be adhered to: use the most distal suitable vein first use the non-dominant arm first arm vessels should be used in preference to leg vessels prosthetic grafts should only be used if no autogenous veins are suitable All vascular access surgery adheres to the basic principles of vascular anastomosis. The anastomosis is performed using a continuous, monofilament, non-absorbable suture. The edges of the vessels should be everted to exclude thrombogenic adventitia, there must be no tension and all layers of the vessel wall should be included in the suture to prevent subintimal flap formation. The success of surgery is indicated by the presence of a palpable thrill and audible bruit in the venous limb of the AVF. The venous limb of an autogenous AVF matures and becomes arterialized over several weeks. This involves venous dilatation and thickening of the vessel wall. It is common to leave all AVFs for 6 weeks prior to needling, as early puncture can result in haematoma and early thrombosis. Preoperative assessment: when deciding on the site of AVF formation the above general rules should be adhered to. In addition, an AVF is only going to be successful if the following requirements are satisfied: satisfactory arterial inflow patent superficial vein of adequate diameter no outflow obstruction (patent axillary, subclavian and central veins) The arterial inflow is assessed clinically, with an easily palpable pulse usually being sufficient. Overt atherosclerosis can also be detected, although this does not necessarily preclude AVF formation at this site. Allen’s test should be performed prior to radiocephalic AVF formation to confirm a patent ulnar artery. The suitability of veins can be assessed either clinically or radiologically. A sound knowledge of the venous anatomy of the arm is paramount (Figure 1). Clinical assessment is performed by inspection and palpation following tourniquet placement around the upper arm. The patency of the cephalic vein in the forearm can be assessed by light percussion at the wrist, while feeling for a transmitted wave in the vein at the elbow. Ultrasound mapping may identify suitable veins not detected clinically, particularly in obese patients. The other option if no suitable arm veins are palpable is venography, where contrast is injected into a superficial vein in the hand or wrist and the venous anatomy of the arm demonstrated. Assessment of the patency of the venous drainage of the arm can also be performed by venography or duplex ultrasound. Clinical signs suggesting central venous occlusion include prominent collateral veins around the shoulder, chest or neck with associated arm or neck swelling. Presence of these features necessitates assessment of the central veins.
Figure 1
under local anaesthetic as a day case. It was first described by Brescia et al. in 1966 as a side-to-side anastomosis.3 Many surgeons now prefer an end of vein-to-side of artery anastomosis as there is a lower incidence of venous hypertension in the hand. However, this can be avoided by ligating the redundant distal venous limb of a side-to-side anastomosis. Radiocephalic AVFs have a primary patency rate (without intervention) of around 63% at 1 year.4
Radiocephalic arteriovenous fistula: this is the first choice of AVF and involves anastomosis between the radial artery and cephalic vein at the wrist (Figure 2), which can be performed
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Figure 2 A mature radiocephalic arteriovenous fistula with long-term use.
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Arteriovenous grafts for vascular access: this technique involves tunnelling a graft subcutaneously between a suitable artery and vein and anastomosing one end of the graft to the side of the vein and the other end to the side of the artery. Various graft materials are available. In principle, the autogenous saphenous vein should be a sound choice. However, this vein is of variable quality and the extensive dissection required necessitates not only a general anaesthetic, but also several days in hospital to recuperate. Nevertheless, forearm loop graft patency rates of 90% at 1 year have been reported.7 The most used graft material for vascular access is expanded PTFE. Advantages of PTFE are easy handling and the wide range of sizes available. Disadvantages are the expense and higher complication rates than autogenous AVF. In addition, it is necessary to wait 6 weeks following surgery before a PTFE graft can be needled. PTFE is not self-sealing and needling before perigraft fibrosis has developed can result in significant bleeding. Primary patency rates for upper limb grafts are around 50% at 1 year.8 Arteriovenous grafts have been used in a number of anatomical sites for vascular access. One of the most common is between the brachial artery at the elbow and the axillary vein. This is often the next step once brachiobasilic AVFs have failed or if the basilic veins are unsuitable for use. The vessels are exposed through small incisions at the elbow and axilla, and the graft tunnelled between. This technique is effective if attempts at autogenous AVF formation have failed. An alternative option if the brachial artery is either small or diseased is a loop graft anastomosed to the axillary artery and vein. Forearm grafts are particularly popular in the United States, where many surgeons favour the use of prosthetic material for primary or secondary vascular access procedures. These grafts can use either the brachial or radial artery as their inflow, and any of the elbow veins as the outflow. One of the most common configurations is a loop graft between the brachial artery and basilic vein. In patients with exhausted arm and axillary veins, options include loop grafts to the common femoral vessels at the groin or superficial femoral vessels in the mid-thigh, straight brachiojugular grafts and so-called ‘necklace’ grafts between opposite axillary or subclavian vessels.
Brachiocephalic arteriovenous fistula: in patients with either failed wrist fistulae in both arms or unsuitable forearm veins, the next step should be a brachiocephalic AVF. This involves an anastomosis between the brachial artery and cephalic vein at the elbow. It can also be performed under local anaesthetic as a day case. The disadvantage of a brachiocephalic AVF is the relatively short length of vein suitable for needling. The anastomosis is most commonly performed as an end of vein-to-side of artery. Several variations are possible depending on the vascular anatomy at the elbow, which is variable. The median cubital vein, if present, may be anastomosed directly to the brachial artery. This has the advantage of arterializing both the cephalic and basilic venous systems. The brachial artery has higher blood flow than the radial artery. As such, haemodynamic complications such as steal syndrome and high output cardiac failure are more common with brachiocephalic than radiocephalic AVFs. This can be limited by restricting the brachial arteriotomy to a maximum of 75% of the diameter of the artery. The long-term results of brachiocephalic AVFs are good with secondary patency rates (with intervention) of up to 80% at 3 years.5 Brachiobasilic arteriovenous fistula: this procedure is reserved for patients in whom radiocephalic or brachiocephalic AVFs are either not feasible or have failed in both arms. It is imperative that the basilic vein is imaged preoperatively either by duplex ultrasound or venography to confirm its suitability, as it is not possible to assess this clinically. The basilic vein only lies superficially at the elbow. The majority of the vein lies deep to the deep fascia of the upper arm. As such, it is not amenable to venepuncture or cannulation and is usually preserved even if the cephalic vein is unsuitable for AVF formation. However, if an AVF is formed with the vein in this deep position, only a short portion is available for needling. Therefore, the basilic vein is dissected from its bed, all branches ligated and the vein transposed to a subcutaneous pocket or tunnel down the middle of the upper arm. The end of the vein is then anastomosed to the side of the brachial artery at the elbow. This operation is best performed under general anaesthetic due to the length of the incision, which runs along the medial aspect of the arm from antecubital fossa to axilla. The secondary patency rates of brachiobasilic AVFs are around 72% at 1 year.6 Drawbacks include the extensive incision and dissection required, which is both painful and prone to infection. Alternatively, brachiobasilic AVF formation may be performed as a two-stage procedure. In the initial procedure, performed under local anaesthetic, the basilic vein is anastomosed end-to-side to the brachial artery through an incision over the medial aspect of the elbow. Once the basilic vein has matured the second-stage procedure to transpose the basilic vein to a more superficial position is performed. This approach is particularly applicable if there are concerns over the quality of the basilic vein and avoids the morbidity of a general anaesthetic and long arm incision if the vein fails to mature. A first-stage brachiobasilic AVF can also be formed as an alternative to a planned brachiocephalic AVF if the cephalic vein is found to be unsuitable at the time of surgery.
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Complications of arteriovenous fistulae and grafts: the main complications of arteriovenous fistulae and grafts are as follows: haemorrhage thrombosis infection aneurysm formation steal syndrome Haemorrhage e early haemorrhage after vascular access surgery is usually related to technical error or disruption of the anastomosis. Late bleeding can occur when the same puncture site is repeatedly used, or is related to aneurysm formation. If significant haemorrhage occurs, pressure over the bleeding point usually provides temporary control, but surgical exploration is usually required. Thrombosis e thrombosis occurring in the first 24 hours is usually related to technical error or poor vessel quality. If the vessel quality was deemed adequate at the time of surgery, immediate re-exploration is indicated as it may be possible to
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salvage the AVF by thrombectomy and refashioning of the anastomosis. In the long-term, thrombosis is the most common cause of failure of AV fistulae and grafts. This is usually related to an underlying stenosis, although may also result from inadvertent compression, post-dialysis hypotension or dehydration. Once an AVF has thrombosed, the only chance of salvage is to perform an immediate thrombectomy before the thrombus becomes organized. Unfortunately, by the time the patient presents the opportunity has often been missed. Once the thrombus has been cleared any underlying stenosis can be identified by fistulography and treated by percutaneous trans-luminal fistuloplasty. The ideal is to identify stenotic lesions before thrombosis occurs. Clues to suggest a failing fistula include increasing venous pressures and poor flow on dialysis, reduced palpable thrill or audible bruit and increases in urea recirculation. These changes should prompt investigation in the form of duplex ultrasound or fistulography. Aneurysm formation e AV fistulae and grafts may be complicated by both false and true aneurysms. False aneurysms tend to occur at sites of repeated venepuncture and are more common in prosthetic grafts than autogenous AVFs. These should be treated as the risk of haemorrhage is high if they are left. True aneurysmal dilatation of autogenous AVFs is very common. Intervention is only required if the overlying skin becomes threatened or there is rapid expansion. Surgical intervention for both types of aneurysm involves resection of the affected segment and restoration of the AVF by either end-to-end anastomosis or, occasionally, a short PTFE interposition graft. Plication of true aneurysms can be performed, but recurrence is almost inevitable. Steal syndrome e this occurs when ischaemic changes develop in a limb distal to an AV fistula or graft. It is most common with procedures employing the brachial artery and in patients with atherosclerosis or diabetes. Investigation of the complete arterial system of the affected limb is mandatory in patients presenting with steal syndrome as treatment of either a proximal or distal arterial stenosis may resolve the symptoms. Mild steal syndromes occurring soon after surgery often resolve spontaneously over weeks, but in more severe cases intervention is necessary to limit the flow in the fistula. This can be achieved by a plication suture in the vein or graft just above the anastomosis. In more severe or recurrent cases, a DRIL (distal revascularization-interval ligation) procedure can be performed. This involves ligation of the artery just distal to the AVF anastomosis, with bypass from the proximal artery to a point distal to the ligature using saphenous vein or PTFE graft (Figure 3).9
DRIL (distal revascularization − interval ligation) procedure for steal syndrome AVF Brachial artery
Graft AVF, arteriovenous fistula Figure 3
While the majority of patients are suitable for PD, there are some contraindications. Absolute contraindications include previous sclerosing peritonitis, inflammatory bowel disease and documented severe peritoneal adhesions. Relative contraindications include morbid obesity, inoperable abdominal hernias, stomas and chronic obstructive airways disease. In patients who have undergone previous surgery, initial laparoscopy may be used to assess the severity of adhesions and, as appropriate, perform adhesiolysis prior to PD catheter insertion. Catheter insertion The three options for catheter insertion are peritoneoscopic, laparoscopic and open. The peritoneoscopic approach can be performed under local anaesthetic with sedation. A trocar is passed through the abdominal wall and a low pressure pneumoperitoneum established. A 2.2 mm laparoscope is used to confirm the trocar is within the peritoneal cavity. The laparoscope is then removed, a dilator passed and the catheter inserted. Following removal of the trocar the catheter is tunnelled laterally. The main disadvantage of this method is that the catheter is passed blindly into the pelvis and a satisfactory position is not confirmed. The laparoscopic approach is very similar to the peritoneoscopic approach, but uses a separate 5e10 mm port, usually in the left or right upper quadrant. This allows the catheter position to be visualized and a further 5 mm port can be used to manipulate the tube into the pelvis. The tube tip should be placed in the rectovesical pouch in men and the rectovaginal pouch of Douglas in women (Figure 4). In the open technique, a small vertical infra-umbilical incision is made. The rectus sheath is opened, a small incision made in the peritoneum and the tube inserted into the pelvis. The peritoneum is closed around the cuff with an absorbable suture to create a watertight closure. The rectus sheath is then closed over the cuff using a non-absorbable suture and the catheter tunnelled subcutaneously.
Access for peritoneal dialysis
Complications of peritoneal dialysis Peritoneal dialysis peritonitis: this is the most significant complication of PD with 0.5e1.5 episodes per patient per year.10 It is also the most common cause of technique failure. Clinical features include abdominal pain and tenderness with a cloudy effluent containing >100 106/L white blood cells. The most common causative organisms are Gram-positive cocci with Staphylococcus aureus, S. epidermidis and Streptococcus spp. accounting for over a third of cases.11
Approximately half of UK dialysis patients are on peritoneal dialysis (PD). This utilizes the selectively permeable characteristics of the peritoneum, with a surface area over 2 m2. Instillation of a hypertonic dialysate fluid into the peritoneal cavity results in ultrafiltration of solutes and electrolytes from the bloodstream into the fluid, which is then drained. This requires an indwelling peritoneal dialysis catheter, the most popular being a cuffed Tenckhoff catheter with a curled intraperitoneal end.
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Distal ligation of artery
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Catheter obstruction: this is most commonly due to omental wrapping. Other causes include intra-abdominal adhesions and extrinsic compression from bladder distension or faeces in the sigmoid colon. In the early postoperative period a blood clot may block the catheter; this usually responds to an infusion of urokinase via the catheter. Catheter tip migration out of the pelvis can also cause catheter blockage or incomplete drainage. Patients presenting with catheter obstruction should have a plain abdominal radiograph performed to assess catheter position and faecal loading. If faecal loading is present, aperients often resolve the problem. In the absence of faecal loading, or if the catheter tip is not in the pelvis, laparoscopic repositioning or freeing of the omental wrap can be performed. Leak: early postoperative leak may result with any condition that predisposes to poor wound healing, such as diabetes or steroid use. Alternatively, it may result from poor surgical technique. Treatment involves stopping PD for 2e4 weeks and then restarting. Ongoing leaks usually necessitate catheter exchange, as do late onset leaks. Encapsulating sclerosing peritonitis is a rare but potentially fatal complication of PD, with mortality rates between 40% and 75%.13,14 It is a result of recurrent PD peritonitis with replacement of the mesothelial layer of the peritoneum with an encapsulating fibrin and hyaline layer. Patients present with abdominal pain, ascites, blood-stained effluent or bowel obstruction. CT or ultrasound examination may show loculated fluid collections, bowel wall and peritoneal thickening or peritoneal calcification. Medical treatment options include tamoxifen and steroids, although the benefit of these is questionable. Surgical treatment to remove the thickened peritoneum carries a very high risk and should probably be reserved for patients presenting with generalized peritonitis or bowel obstruction. A
Figure 4
Initial management includes sending dialysate samples for microbiological examination and commencement of intraperitoneal antibiotics. These can be supplemented with intravenous antibiotics in more severe cases. Indications for surgical intervention include failure to improve after 5 days of medical management, generalized peritonitis, fungal peritonitis and Psuedomonas peritonitis. Surgical treatment involves thorough peritoneal lavage and removal of the PD catheter. This can be performed either laparoscopically or through a midline laparotomy. The laparoscopic approach appears to have advantages in terms of postoperative pain and a quicker return of bowel function.12
REFERENCES 1 Cimochowski GE, Worley E, Rutherford WE, Sartain J, Blondin J, Harter H. Superiority of the internal jugular over the subclavian access for temporary dialysis. Nephron 1990; 54: 154e61. 2 Thomson P, Stirling C, Traynor J, Morris S, Mactier R. A prospective observational study of catheter-related bacteraemia and thrombosis in a haemodialysis cohort: univariate and multivariate analyses of risk association. Nephrol Dial Transplant 2010; 25: 1596e604. 3 Brescia MJ, Cimino JE, Appel K, Hurwich BJ. Chronic hemodialysis using venipuncture and a surgically created arteriovenous fistula. N Engl J Med 1966; 275: 1089e92. 4 Rooijens PP, Tordoir JH, Stijnen T, Burgmans JP, Smet de AA, Yo TI. Radiocephalic wrist arteriovenous fistula for hemodialysis: metaanalysis indicates a high primary failure rate. Eur J Vasc Endovasc Surg 2004; 28: 583e9. 5 Bender MH, Bruyninckx CM, Gerlag PG. The Gracz arteriovenous fistula evaluated. Results of the brachiocephalic elbow fistula in haemodialysis angio-access. Eur J Vasc Endovasc Surg 1995; 10: 294e7. 6 Glass C, Porter J, Singh M, Gillespie D, Young K, Illig K. A large-scale study of the upper arm basilic transposition for hemodialysis. Ann Vasc Surg 2010; 24: 85e91.
Exit site and tunnel infections are common and generally not significant, although approximately 10% will lead on to PD peritonitis. A positive culture from the exit site alone should not be treated; however, if two or more cultures are positive treatment should be instigated. Erythema alone with no discharge may be treated with topical agents. In cases with purulent discharge from the exit site ultrasound may be used to diagnose tunnel infection, which usually necessitates catheter removal. Catheter removal is also indicated in fungal, Psuedomonas and persistent gram-negative exit site infections. Hernias: as the increased intra-abdominal pressure from the dialysate can enlarge pre-existing hernias, these are best repaired before or at the time of catheter insertion. However, de novo hernias can also develop. Ideally repair of these should avoid breaching the peritoneum, as this risks a postoperative fluid leak. Patients with a patent processus vaginalis can also present with scrotal or labial oedema following exchanges. This requires surgical ligation. Some surgeons withhold PD for a number of weeks following hernia repair to reduce the risk of a leak or recurrence. Others use a low-volume, high-frequency exchange regimen, which removes the need for temporary haemodialysis.
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7 Bhandari S, Wilkinson A, Sellars L. Saphenous vein forearm grafts and gortex thigh grafts as alternative forms of vascular access. Clin Nephrol 1995; 44: 325e8. 8 Ko PJ, Liu YH, Hung YN, Hsieh HC. Patency rates of cuffed and noncuffed extended polytetrafluoroethylene grafts in dialysis access: a prospective, randomized study. World J Surg 2009; 33: 846e51. 9 Berman SS, Gentile AT, Glickman MH, et al. Distal revascularizationinterval ligation for limb salvage and maintenance of dialysis access in ischemic steal syndrome. J Vasc Surg 1997; 26: 393e402. discussion 402e4. 10 Brook NR, White SA, Waller JR, Nicholson ML. The surgical management of peritoneal dialysis catheters. Ann R Coll Surg Engl 2004; 86: 190e5.
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11 Golper TA, Hartstein AI. Analysis of the causative pathogens in uncomplicated CAPD-associated peritonitis: duration of therapy, relapses, and prognosis. Am J Kidney Dis 1986; 7: 141e5. 12 Barlow AD, Yates PJ, Hosgood SA, Nicholson ML. Case-control comparison of laparoscopic and open washout for peritoneal dialysisassociated peritonitis. Br J Surg 2008; 95: 1416e9. 13 Nomoto Y, Kawaguchi Y, Kubo H, Hirano H, Sakai S, Kurokawa K. Sclerosing encapsulating peritonitis in patients undergoing continuous ambulatory peritoneal dialysis: a report of the Japanese sclerosing encapsulating peritonitis study group. Am J Kidney Dis 1996; 28: 420e7. 14 Brown MC, Simpson K, Kerssens JJ, Mactier RA, Scottish Renal Registry. Encapsulating peritoneal sclerosis in the new millennium: a national cohort study. Clin J Am Soc Nephrol 2009; 4: 1222e9.
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