Long-term experience with the Thomas shunt, the forgotten permanent vascular access for haemodialysis
Francisco Coronel1,,
José A. Herrero1,
Pablo Mateos1,
María L. Illescas1,
Jaime Torrente1 and
María J. del Valle2
1 Department of Nephrology, Hospital Clínico San Carlos, and
2 Hemodialysis Unit ICN-Moncloa, Madrid, Spain
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Abstract
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Background. Vascular access complications are the main cause of hospitalization in dialysis patients. The difficulty in creating and maintaining vascular access after several years on haemodialysis (HD) remains the primary problem in these patients. The femorofemoral Thomas shunt is a permanent vascular access that was used in the 1970s and is all but forgotten at present. We analysed our experience with the Thomas shunt since 1979 in patients with no other possibility of regular vascular access.
Methods. We retrospectively studied 27 Thomas shunts implanted in 10 patients, aged 2775 years at the time of first shunt implantation. Prior to implantation of the Thomas shunt, these patients had experienced 80 failed vascular accesses (plus four patients on CAPD), with an average of 8.6 accesses per patient. All Thomas shunts were implanted in femoral vessels. Clinical data were extracted from hospital and dialysis unit records and were analysed for efficacy, complications, and duration of patency.
Results. Total follow-up was 1176 months, with an average shunt duration of 43.7 months (range 3151 months). One-, 2-, 3- and 6-year survival rates were 85, 57, 49 and 25% respectively. Five patients spent more than 10 years on HD using the Thomas shunt, and one patient had the same unit for 12.5 years. A high blood flow (450 ml/min) was obtained, without recirculation, due to the characteristics of this shunt. Efficacy, measured as percentage urea reduction (PRU), was high (on average 77.8±1.5%). The infection incidence was one episode every 37.5 patient-months, Staphylococcus species being the most commonly isolated. There were no shunt removals because of infection. The most important cause of shunt withdrawal was thrombosis, with an incidence of one episode every 7 patient-months. Percutaneous angioplasty was successful in the majority of stenosis episodes.
Conclusions. This study indicates that the Thomas shunt provides a good permanent vascular access for HD patients who have no other possibility of a regular vascular access. This shunt offers high dialysis efficacy without recirculation and an access duration comparable to AV fistulae. For these reasons the Thomas shunt should continue to be used as a vascular access in HD.
Keywords: arteriovenous shunt; dialysis efficacy; femorofemoral shunt; haemodialysis; permanent access; vascular access
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Introduction
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The increasing survival of patients with chronic renal failure treated with dialysis, including a large percentage of older patients and diabetics, points to the importance of creating and maintaining a vascular access for haemodialysis (HD). Vascular access complications are the most frequent cause of hospital admissions in dialysis patients [1,2]. Native arteriovenous (AV) fistulae and vascular grafts with polytetrafluoroethylene (PTFE) offer the best results in terms of duration and efficacy. When a permanent vascular access is not feasible, the most frequent alternatives are a central venous catheter or transfer to peritoneal dialysis, if technically possible.
In the 1960s and 1970s, the AV QuintonScribner shunt [3] was the first choice for immediate vascular access and provided a bridge to a matured AV fistula. This shunt consisted of two silastic cannulae surgically implanted in an artery and vein of the forearm or leg, connected by a Teflon junction after subcutaneous tunnelling. These shunts had a limited duration. The Thomas shunt (TS) was designed for longer survival, and when no other possibility of permanent vascular access was available [4,5]. Nowadays the TS is no longer mentioned in most nephrology textbooks, even as a historical note, and most young nephrologists have never heard of it.
In the Hospital Clínico San Carlos we use the TS as a last-resort vascular access for HD when the creation of an AV fistula or a PTFE graft is not possible, and when the vascular map has been exhausted on the upper limbs. We have patients who have had long-term HD using this permanent access. The purpose of this study is to communicate our long experience with the TS and to remind the nephrological community that it remains a valuable option in HD.
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Subjects and methods
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We retrospectively evaluated all the TS implanted at the Hospital Clínico San Carlos since 1979 into patients from both the Nephrology Department and one of its HD satellite units. Of the 35 TS, eight were excluded from the study because these patients had left our HD unit within the first 3 months after vascular access implantation (four patients were transferred to their HD facilities after the post-surgery period, two patients were transplanted, and two patients died from causes unrelated to vascular access). Each of these eight patients had a functioning TS. We followed a total of 27 TS implanted in 10 patients (none was diabetic), having a mean age of 55.5±16.7 years (range 2757 years). Clinical data were extracted from hospital and dialysis unit records. TS implantation was always used as a last resort when there was no possibility of creating regular vascular access on the upper limbs. In fact, all patients had received several vascular accesses before TS implantation. A total of 80 vascular accesses (plus four patients on CAPD), with a mean of 7.8±6.5 per patient, were performed in the 10 patients previously to TS implantation (35 Scribner shunts, 21 endogenous AV fistulae, 13 PTFE grafts, and 11 central venous catheters). The TS is used in 7% of our patients, 79% are dialysed by AV fistula, 11% by PTFE graft, and 3% by central catheters.
The TS were surgically implanted in femoral vessels with an adult type device (Fuji Systems). The shunt is composed of two silastic cannulae positioned in the femoral artery and the femoral vein, which are attached to the walls of the femoral vessels with a Dacron patch to prevent vessel occlusion by the cannula (Figure 1
). The two catheters are tunnelled subcutaneously in the thigh and emerge through two skin exit sites on the anterointernal surface. The length of the subcutaneous loop is 1214 cm and the distance from the exit site to the connector 1617 cm. The two external cannula tips are joined with a Teflon connector to form a closed circuit, which is opened when the patient is to be connected for dialysis (Figures 1
and 2
).
The TS is used 2448 h after implantation and antibiotic coverage is usually employed in the first 48 h. Preventive use of anticoagulants or antiaggregants is always advised. Connection and disconnection to dialysis must always be performed under sterile conditions and nurses must wear gloves during the process. Survival of TS was assessed using KaplanMeier techniques. Comparisons were made with data from existing studies.
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Results
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Our cumulative experience with the 27 TS was 1176 months. The number of TS per patient varied from one to nine (three patients with one shunt, five with two shunts, one with five shunts, and one patient with nine TS). The mean duration of the TS was 43.7 months (range 3151 months). Seven of the 10 patients were still on HD and using a TS as vascular access at the time of this publication. Five of the patients had been on dialysis using TS for more than 10 years (one for 17.3 years with nine TS, one for 16.5 years with two TS, one for 14.7 years with five TS, one for 15 years with two TS, and one for 12.5 years with one TS still functioning until renal transplantation, shortly before this paper was written). The KaplanMeier curve of TS (Figure 3
) shows 85, 57, 49, and 25% survival respectively at 1, 2, 3 and 6 years.
Efficacy
Blood flows obtained with TS were always higher than 400 ml/min, and normal values were approximately 450 ml/min. Because of the TS design, there is no recirculation, and the mean value of PRU (percentage reduction of urea), as a method of measuring the efficacy of dialysis, was 77.8±1.5% in the seven patients still on HD.
Main complications
There were 30 infectious episodes, with an incidence of one episode every 37.5 patient-months. Staphylococcus aureus was the most commonly isolated organism. Nine infectious episodes were produced by S. aureus and five by Staphylococcus epidermidis. Streptococcus and Pseudomonas were detected on three and two occasions respectively. There were no shunt infection-related deaths, and in all cases cure was effected with antibiotic treatment. No TS had to be removed because of infection.
The most common cause of TS failure was malfunction (thrombosis, or stenosis causing thrombosis). The location of thrombosis was usually at the junction of the venous limb of the TS with the femoral vein. There were 160 thrombosis episodes, with an incidence of one episode every 7 patient-months. Thrombosis of venous cannulae was the most frequent cause, in spite of antiaggregant treatment. Malfunctioning caused by thrombosis, associated or not with vascular stenosis, was the most important cause of shunt withdrawal in our experience. Radiologically demonstrated vascular stenosis was observed on 42 occasions, with an incidence of one episode every 26.8 patient-months. In all cases percutaneous angioplasty was performed, with favourable results [6]. In cases of thrombosis, in situ declotting techniques were successfully applied by our nephrologists in 50% of the episodes during first attempts in the HD room, and using heparin or urokinase. When this approach failed, a vascular radiologist performed embolectomy using balloon catheters [6,7] on 33% of occasions, while surgery was necessary in 13% of cases.
Other complications
There were post-surgery problems, including two cases of local infection, four haematomas in the implantation area, and one subcutaneous tunnel haemorrhage. Associated complications such as oedema occurred in nine cases, phlebitis in three, and ischaemia in one case. Accidental complications such as disconnections occurred in three patients. Post-surgery complications were unusual and typically involved local haematoma. Oedema of the affected leg was the most common associated complication. One case involved an accidental disconnection that resulted in the death of the patient. However, the circumstances of this case indicated that death was by suicide.
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Discussion
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The advanced age of patients now being offered HD, the longer survival on this treatment, and the growing number of diabetic patients being accepted make it increasingly difficult to perform and maintain good vascular access. In this report we analyse 20 years experience with the TS, and show that it is a viable solution in some cases where creating a regular vascular access is difficult. No diabetic patients were included in our study, and this type of vascular access would probably not be the most appropriate for these patients. An advantage of the TS is that, like central venous catheters, they can be used from the moment of implantation. The efficacy of the device has been proven and it obtains excellent flows without recirculation. It has a high PRU, comparing favourably with tunnelled catheters [8], endogenous fistulae, and PTFE prostheses [9]. In recent years the implantation of PTFE grafts in the thigh has been frequently described as an alternative vascular access [1013]. Experience with this type of vascular access shows that it could be a good option, with the same indications as the TS [10,12], but with a greater tendency to complications. A long follow-up of PTFE thigh grafts will determine whether they can obtain as good a survival as we have achieved with the TS. Our experience with thigh grafts has been limited (three patients), and the results were unsatisfactory.
In our experience, infection has not been a frequent problem, with an incidence of one episode every 37 patient-months. This is approximately one-third of the infection incidence described for permanent silicon central venous catheters [14]. In our patients, it was not necessary to remove any TS because of infection, and all episodes resolved favourably with antibiotics. Currier et al. [15] described the complete removal of an infected TS using ligation of the femoral vessels. These infections, which usually reach the Dacronarterial anastomosis, are more frequent in TS implanted in iliac vessels, and the management of the infection is hazardous [16]. The primary cause of TS removal in our patients was thrombosis, especially when it was associated with stenosis. However, in recent years percutaneous transluminal angioplasty corrected stenosis in 100% of cases [6]. The thrombosis rate was high, but many incidents were partial and were solved in situ by nephrology staff. In a recent report [17], thrombosis in TS was also the most frequent cause of shunt failure. This was the reason for the systematic use of anticoagulants in our patients. Therefore, in the last few years we have regularly administered daily doses of 250 mg of ticlopidine for anticoagulation. Most thrombosis episodes were associated with high ultrafiltration rates in patients with low blood pressure.
There was a low incidence of associated complications, and only one case of death directly related to TS, produced by disconnection of the union site of the two branches of the device. Accidental disconnection deserves comment because of the potential fatal consequences. Although our patient had announced her intention to disconnect the TS, efforts were made to prevent this (the nurses secured the attachment of both branches after each HD session and applied surgical tape around the cannula tips and Teflon connector as extra protection). In two patients, rupture of the outer section of the cannulae was due to repeated application of metallic surgical forceps to the same point on the Silastic cannulae during connection and disconnection manoeuvres. Therefore the use of plastic forceps is mandatory, as is changing the position of clamps for each dialysis.
The mean survival of TS was 43.7 months, and KaplanMeier analysis show a survival of 85 and 50% at 1 and 3 years respectively. This compares favourably with recently reported survival data for central venous catheters and vascular grafts [11,13,18]. The mean survival rate was the same as that of native AV fistulae [18]. In the 1980s, certain reports described the TS as a good long-term access [16], but since then, few data on TS survival have been reported. In 1992, Freedman et al. [17] reported a median shunt survival of 28 months, with a maximum duration of 132 months. In this regard, one of our patients received HD with a succession of nine TS for 18 years. Moreover, of the five patients still on HD with TS for more than 10 years, one has exceeded 12 years using one TS only.
In conclusion, the present study demonstrates that the Thomas shunt represents a good option in HD patients when permanent vascular access is not possible. The TS has the same indications as thigh grafts but with better efficacy. The more aggressive TS implant surgery is balanced by greater efficacy and better survival than other vascular accesses for HD. Thus, this forgotten vascular access should again be included among the last resort therapeutic tools used by nephrologists.
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Editor's note
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Please see also Editorial notes by Bommer pp. 17611762 and Krönung pp. 17621763.
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Notes
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Correspondence and offprint requests to: Dr Francisco Coronel MD PhD, Department of Nephrology, Hospital Clínico San Carlos, C/ Dr Martín Lagos s/n, E-28040 Madrid, Spain. 
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References
|
---|
-
Lazarus JM. Complications in hemodialysis: an overview. Kidney Int1980; 18: 783786[ISI][Medline]
-
Feldman HI, Held PJ, Hutchinson JT, Stoiber E, Hartigan MF, Berlin JA. Hemodialysis vascular access morbidity in the United States. Kidney Int1993; 43: 10911096[ISI][Medline]
-
Quinton WE, Dillard DH, Scribner BH. Cannulation of blood vessels for prolonged hemodialysis. Trans Am Soc Artif Intern Organs1960; 6: 104[ISI][Medline]
-
Thomas GI. A large-vessel applique A-V shunt for hemodialysis. Trans Am Soc Artif Intern Organs1969; 15: 288292[ISI][Medline]
-
Thomas GI. Large vessel applique arteriovenous shunt for hemodialysis. A new concept. Am J Surg1970; 120: 244248[ISI][Medline]
-
Gallego Beuter JJ, Hernandez Lezana A, Herrero Calvo J, Moreno Carriles R. Early detection and treatment of hemodialysis access dysfunction. Cardiovasc Intervent Radiol2000; 23: 4048[ISI][Medline]
-
Mandel SR, Jaques PF. Salvage procedure of Thomas femoral shunts by balloon angioplasty. Surg Gynecol Obstet1980; 151: 673674[ISI][Medline]
-
Perini S, LaBerge JM, Pearl JM et al. Tesio catheter: radiologically guided placement, mechanical performance and adequacy of delivered dialysis. Radiology2000; 215: 129137[Abstract/Free Full Text]
-
Ifudu O, Mayers JD, Matthew JJ, Fowler A, Friedman EA. Haemodialysis dose is independent of type of surgically created vascular access. Nephrol Dial Transplant1998; 13: 23112316[Abstract]
-
Bhandari S, Wilkinson A, Sellars L. Saphenous vein forearm grafts and Gore-Tex thigh grafts as alternative forms of vascular access. Clin Nephrol1995; 44: 325328[ISI][Medline]
-
Wang SS, Chu SH. Clinical use of omniflow vascular graft as arteriovenous bridging graft for hemodialysis. Artif Organs1996; 20: 12781281[ISI][Medline]
-
Khadra MH, Dwyer AJ, Thompson JF. Advantages of polytetrafluoroethylene arteriovenous loops in the thigh for hemodialysis access. Am J Surg1997; 173: 280283[ISI][Medline]
-
Chia KH, Ong HS, Teoh MK, Lim TT, Tan SG. Chronic haemodialysis with PTFE arterio-venous grafts. Singapore Med J1999; 40: 685690[Medline]
-
Canaud B. Haemodialysis catheter-related infection: time for action. Nephrol Dial Transplant1999; 14: 22882290[Free Full Text]
-
Currier CB Jr, Montalbert C, Dholakia SV, Diaz MH, Helfrich GB, Sulkin MD. Surgical management of infected Thomas shunt. Surgery1981; 89: 375377[ISI][Medline]
-
Meech PR, Hardie IR, Hartley LC, Woodruff PW, Strong RW, Clunie GJ. Long-term experience of Thomas shunts on the iliac vessels. Aust NZ J Surg1981; 51: 161165[ISI][Medline]
-
Freedman BI, Anderson RL, Tuttle AB, Canzanello VJ. The Thomas shunt revisited. Am J Kidney Dis1992; 19: 4548[ISI][Medline]
-
Rodriguez JA, Lopez J, Cleries M, Vela E, and Renal Registry Committee. Vascular access for hemodialysisAn epidemiological study of the Catalan Renal Registry. Nephrol Dial Transplant1999; 14: 16511657[Abstract]
Received for publication: 29. 6.00
Accepted in revised form: 21. 3.01