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Comparative Study of Use of Diastat versus Standard Wall PTFE Grafts in Upper Arm Hemodialysis Access
Original Articles
Comparative Study of Use of Diastat versus Standard Wall PTFE Grafts in Upper Arm Hemodialysis Access P. Jimenez Almonacid, MD, E. Criado Pallares, PhD, A. Quintans Rodriguez, PhD, J. Sanabria Valdes, PhD, J.A. Rueda Orgaz, MD, and J.R. Polo, PhD, Madrid, Spain
The objective of this study was to review our experience with using brachioaxillary Diastat vascular grafts (Diastat) compared to standard wall brachioaxillary PTFE grafts (sPTFE) in two similar groups of hemodialysis patients. We conducted a retrospective study comparing complications and graft survival in two similar groups (in terms of age, diabetes mellitus, surgical technique, and previous vascular access) of hemodialysis patients during the period 1994-1997 who had received Diastat姞 (n = 40) or (sPTFE) (n = 40) grafts. We found that the Diastat graft for upper arm hemodialysis access has lower patency and higher complication rates than sPTFE grafts. (Ann Vasc Surg 2000;14:659-662.) DOI: 10.1007/s100169910117
INTRODUCTION In many patients with end-stage renal disease, immediate vascular access is required. In this situation, temporary central venous catheters are commonly used. The use of central lines is associated with a significant rate of acute and chronic complications, including bleeding, hematoma, infection, pneumotorax and vein stenosis, and thrombosis.1-4 Central vein stenosis and thrombosis hinder the construction of an arteriovenous shunt in the affected extremity because of the risk of venous hypertension. The ideal permanent vascular access for hemodialysis should be usable immediately after surgery and have a low complication rate. With this combination in mind, a new graft for early cannulation, the Diastat威 graft, was developed. The advantages
From the Fundacion Hospital Alcorcon, (P.J.A., E.C.P., A.Q.R.), and Hospital General Universitario Gregorio Maran˜on (J.S.V., J.A.R.O., J.R.P.M.), Madrid, Spain. Correspondence to: J.R. Polo, PhD, Vascular Access Unit, Hospital General Universitario Gregorio Maran˜ón, Dr Esquerdo, 46, E-28007, Madrid, Spain.
of this graft are that it allows immediate cannulation, and is associated with a decrease in bleeding after removal of the cannulation needles and less incidence of pseudoaneurysms. Several early reports have shown promising results.5-7 To assess the potential benefits of the Diastat graft, we reviewed our experience using this new graft over a 3-year period and compared the graft survival and complication rates with those for a similar group of patients who underwent access with standard wall polytetrafluoroethyle (sPTFE) grafts.
MATERIALS AND METHODS Clinical and surgical procedures to construct or maintain vascular access for hemodialysis were prospectively included in a computer database. Followup of patients was regularly obtained from 15 dialysis units (about 1000 dialysis patients) associated with nine hospitals located in Madrid and other surrounding cities, for which the Hospital General Universitario Gregorio Maran˜on is the reference center for hemodialysis access. All primary procedures, graft revisions, and treatment of complications were done at the same hospital. 659
660
Almonacid et al.
All procedures were performed under local anesthesia (0.25% alkalinized bupivacaine) on an ambulatory basis. Two grams of intravenous Cefazolin were given preoperatively. Both groups received upper arm shunts between the brachial artery and the axillary vein, in which either a 6-mm diameter PTFE (W.I. Gore & Associates, Flagstaff, AZ) or 6-mm-diameter Diastat (W.L. Gore & Associates) vascular access graft was used. The Diastat vascular access graft is a sPTFE graft at the ends, with a thicker-walled cannulation segment in the middle of the graft covered with several layers of PTFE fibers and an outer layer of a thin, fenestrated extended PTFE (ePTFE). The ends are designed in such a way so as to enable standard arterial and venous anastomoses and the cannulation segment is designed to decrease bleeding after removal of the cannulation needles. Vascular access revision was surgical in all cases. Fistulography was conducted in cases of graft dysfunction or after simple thrombectomy if there was no evidence of anatomical disturbance. Graft dysfunction was considered when any of the following situations were detected: dialysis flow <300 mL/ min; venous pressure >200 mmHg (in the drip chamber, with flow of 300 mL/min using 15 French needles), or recirculation rates >20% or Kt/V <0.8. Venous stenoses were treated with a PTFE bypass to a patent proximal vein in both groups of patients. Graft thromboses were treated with thrombectomy alone or with a proximal vein bypass when venous stenosis was observed during the procedure. If a temporal dialysis catheter was needed, the femoral veins were used when possible to avoid complications from central thoracic vein line placement. We retrospectively reviewed our results with Diastat grafts and compared them with those for a group of patients who underwent sPTFE vascular access and were similar to the Diastat group with regard to comorbid conditions, age, number of previous access, and surgical technique. Patients in the sPTFE group were randomly selected from our database of brachioaxillary shunts performed during the same period using sPTFE. A complication was defined as any event that produced graft dysfunction, thrombosis, or failure or that required graft revision or removal. The late complication rate was defined as the number of complication episodes per patient per year of follow-up. Primary patency was defined as normal graft function from the date of shunt construction to the occurrence of the first complication requiring revision. Secondary patency was defined as normal graft function from the date of placement to graft failure, when revisions were required, or complications treated during the inter-
Annals of Vascular Surgery
Table I. Comparison of Diastat and sPTFE groups
Patients Mean age (years) Females Upper arm graft Diabetes Previous access
Diastat
sPTFE
40 66.475 55% (22) 100% 15% (6) 45% (18)
40 63.925 85% (34) 100% 17.5% (7) 50% (20)
p
NS <0.01 NS NS
NS, not significant.
val. Patency curves were obtained using the lifetable method (Kaplan-Meier). Comparisons of patency between groups were obtained by the Mantel Haenzsel method (log-rank). A software statistical package (RSigma Babel, Madrid, Horus Hardware, 1991) was used for analysis.
RESULTS Forty Diastat grafts were implanted in 40 patients during the study period. This constituted 20% of all brachioaxillary shunts constructed during this period. The indication for the use of diastat grafts in this group of patients was the greater urgency for dialysis in these patients. A sPTFE control group (n = 40; matched for age associated diabetes mellitus, previous vascular access) was selected from our database. There were no significant differences between both groups in terms of age, incidence of diabetes mellitus, and percentage of previous permanent vascular access. There was only a significant difference (p < 0.01) in the percentage of females (Diastat group, 55%; sPTFE group, 85%) (Table I). Median follow-up was 11.4 months in the Diastat group and 13.4 months in the sPTFE group (p > 0.05). There were no perioperative complications. The overall complication rate was 1.2/patient/year in the Diastat group and 0.39/patient/year in the sPTFE group (p < 0.001). The thrombosis rate was 0.99/patient/year for the Diastat group and 0.26 for the sPTFE group (p < 0.001). Thrombosis and dysfunction during dialysis were the most frequent complications in both groups. There were no statistical differences in bleeding and the infection rate (Table II). No steal phenomena or pseudoaneurysm formation were observed. Primary patency was 79, 50, and 24% in the Diastat group and 89, 81, and 72% in the sPTFE group at 6, 12, and 18 months (p < 0.001) (Fig. 1). Secondary patency was 87, 73, and 55% in the Diastat group and 97, 93, and 88% in the sPTFE group
Vol. 14, No. 6, 2000
Use of Diastat versus standard wall PTFE grafts 661
Table II. Complications in Diastat and ePTFE groups
Dysfunction Thrombosis Infection Hemorrhage Total (patient/year) Follow-up, months (median)
Diastat
ePTFE
6 38 2 0 46 (1.2) 456 (11.4)
5 12 0 1 18 (0.39) 545 (13.4)
p
<0.001
<0.001
Fig. 1. Primary patency rates of Diastat and PTFE grafts in the brachioaxillary position.
Fig. 2. Secondary patency rates of Diastat and PTFE grafts in the brachioaxillary position.
at 6, 12, and 18 months (p < 0.001) (Fig. 2). Only 40% of the Diastat grafts were cannulated within 2 weeks after placement; edema and pain were the reasons for delay of the first cannulation in all patients. All sPTFE grafts were cannulated after 2 weeks of surgery.
DISCUSSION Standard wall PTFE grafts need at least 2 weeks for maturation before first cannulation is performed to decrease the risk of bleeding or perioprosthetic hematoma. In this situation, if the patient needs he-
662
Almonacid et al.
modialysis, temporary central vein catheters are used. In recent years new grafts have become available that allow cannulation immediately after implantation, avoiding acute and chronic complications of central vein cannulation, with promising early results.5-8 Our experience with one of these grafts (Diastat) differs from that of these earlier studies but is similar to that in later reports.9,10 In our series, the thrombosis and overall complication rates were higher in the Diastat group with statistical significance. Our primary and secondary patency rates were better in both the Diastat and sPTFE groups compared with those from other published series.5-10 This could be explained by our use of a large vein (the axillary vein) for the shunt’s outflow in all patients. The worse results with the Diastat graft may be secondary to the structure and design of the graft itself since the clinical conditions and vascular risk factors were similar in both groups. Early cannulation in the Diastat group was impossible in 60% of the patients because of severe inflammatory reaction in the arm. Our 40% early cannulation rate is worse than that of 70% in Lohr et al.’s study.10 The surgical revisions of the Diastat grafts (thrombectomies, new bypass, or removal of the grafts) were technically more complex because the heterogeneous structure of the cannulation segment makes surgical dissection and anastomosis more difficult. Other problems associated with the use of the Diastat graft were technical difficulties with implantation secondary to the standard length of the cannulation segment. In summary, the advantage of early cannulation
Annals of Vascular Surgery
with the Diastat graft occurs only in a small percentage of patients. Furthermore, because of its lower patency and higher complication rate, compared with the sPTFE graft, the Diastat graft is far from the ideal upper arm hemodialysis access. REFERENCES 1. Vanherweghem JL, Yassine T, Goldman L, et al. Subclavian vein thrombosis: a frecuent complication of subclavian vein cannulation for hemodialysis. Clin Nephrol 1986;26:235238. 2. Schwab SJ, Quarles LD, Middleton JP, et al. Hemodialysisassociated subclavian vein stenosis. Kidney Int 1988;33: 1156-1159. 3. Allmiral J, Gonza´lez J, Rello J, et al. Infection in long termjugular hemodialysis catheters: incidence and mechanisms. Am J Nephrol 1989;9:454-459. 4. Kahn D, Pontin AR, Jacobson JE, et al. Arteriovenous fistula in the presence of subclavian vein stenosis: a serious complication. Br J Surg 1990;77:682. 5. Barlett ST, Schweitzer EJ, Roberts JE, et al. Early experience with a new ePTFE vascular prosthesis for hemodialysis. Am J Surg 1995;170:118-122. 6. Gelbfish GA. The Diastat vascular acces graft: technical issues and preliminary results. In: Vascular Access for Hemodialysis V. Chicago: Precept Press, 1997, pp 11-23. 7. Park TC. The Diastat vascular dialysis graft and the stretch graft: a 12 month comparative study. In: Vascular Access for Hemodialysis V. Chicago: Precept Press, 1997, pp 77-85. 8. Glickman MH. Early experience with the Perma-seal graft for hemodialysis. In: Vascular Access for Hemodialysis V. Precept Press, 1997, pp 112-118. 9. Coyne DW, Lowell JA, Windus DW, et al. Comparison of survival of an expanded politetrafluoroethylene graft designed for early cannulation to standard wall politetrafluoroethylene grafts. J Am Coll Surg 1996;183:401-405. 10. Lohr JM, James KV, Hearn AT, et al. Lessons learned from the Diastat vascular access graft. Am J Surg 1996;172:205209.
Comparative Study of Use of Diastat versus Standard Wall PTFE Grafts in Upper Arm Hemodialysis Access P. Jimenez Almonacid, MD, E. Criado Pallares, PhD, A. Quintans Rodriguez, PhD, J. Sanabria Valdes, PhD, J.A. Rueda Orgaz, MD, and J.R. Polo, PhD, Madrid, Spain
The objective of this study was to review our experience with using brachioaxillary Diastat vascular grafts (Diastat) compared to standard wall brachioaxillary PTFE grafts (sPTFE) in two similar groups of hemodialysis patients. We conducted a retrospective study comparing complications and graft survival in two similar groups (in terms of age, diabetes mellitus, surgical technique, and previous vascular access) of hemodialysis patients during the period 1994-1997 who had received Diastat姞 (n = 40) or (sPTFE) (n = 40) grafts. We found that the Diastat graft for upper arm hemodialysis access has lower patency and higher complication rates than sPTFE grafts. (Ann Vasc Surg 2000;14:659-662.) DOI: 10.1007/s100169910117
INTRODUCTION In many patients with end-stage renal disease, immediate vascular access is required. In this situation, temporary central venous catheters are commonly used. The use of central lines is associated with a significant rate of acute and chronic complications, including bleeding, hematoma, infection, pneumotorax and vein stenosis, and thrombosis.1-4 Central vein stenosis and thrombosis hinder the construction of an arteriovenous shunt in the affected extremity because of the risk of venous hypertension. The ideal permanent vascular access for hemodialysis should be usable immediately after surgery and have a low complication rate. With this combination in mind, a new graft for early cannulation, the Diastat威 graft, was developed. The advantages
From the Fundacion Hospital Alcorcon, (P.J.A., E.C.P., A.Q.R.), and Hospital General Universitario Gregorio Maran˜on (J.S.V., J.A.R.O., J.R.P.M.), Madrid, Spain. Correspondence to: J.R. Polo, PhD, Vascular Access Unit, Hospital General Universitario Gregorio Maran˜ón, Dr Esquerdo, 46, E-28007, Madrid, Spain.
of this graft are that it allows immediate cannulation, and is associated with a decrease in bleeding after removal of the cannulation needles and less incidence of pseudoaneurysms. Several early reports have shown promising results.5-7 To assess the potential benefits of the Diastat graft, we reviewed our experience using this new graft over a 3-year period and compared the graft survival and complication rates with those for a similar group of patients who underwent access with standard wall polytetrafluoroethyle (sPTFE) grafts.
MATERIALS AND METHODS Clinical and surgical procedures to construct or maintain vascular access for hemodialysis were prospectively included in a computer database. Followup of patients was regularly obtained from 15 dialysis units (about 1000 dialysis patients) associated with nine hospitals located in Madrid and other surrounding cities, for which the Hospital General Universitario Gregorio Maran˜on is the reference center for hemodialysis access. All primary procedures, graft revisions, and treatment of complications were done at the same hospital. 659
660
Almonacid et al.
All procedures were performed under local anesthesia (0.25% alkalinized bupivacaine) on an ambulatory basis. Two grams of intravenous Cefazolin were given preoperatively. Both groups received upper arm shunts between the brachial artery and the axillary vein, in which either a 6-mm diameter PTFE (W.I. Gore & Associates, Flagstaff, AZ) or 6-mm-diameter Diastat (W.L. Gore & Associates) vascular access graft was used. The Diastat vascular access graft is a sPTFE graft at the ends, with a thicker-walled cannulation segment in the middle of the graft covered with several layers of PTFE fibers and an outer layer of a thin, fenestrated extended PTFE (ePTFE). The ends are designed in such a way so as to enable standard arterial and venous anastomoses and the cannulation segment is designed to decrease bleeding after removal of the cannulation needles. Vascular access revision was surgical in all cases. Fistulography was conducted in cases of graft dysfunction or after simple thrombectomy if there was no evidence of anatomical disturbance. Graft dysfunction was considered when any of the following situations were detected: dialysis flow <300 mL/ min; venous pressure >200 mmHg (in the drip chamber, with flow of 300 mL/min using 15 French needles), or recirculation rates >20% or Kt/V <0.8. Venous stenoses were treated with a PTFE bypass to a patent proximal vein in both groups of patients. Graft thromboses were treated with thrombectomy alone or with a proximal vein bypass when venous stenosis was observed during the procedure. If a temporal dialysis catheter was needed, the femoral veins were used when possible to avoid complications from central thoracic vein line placement. We retrospectively reviewed our results with Diastat grafts and compared them with those for a group of patients who underwent sPTFE vascular access and were similar to the Diastat group with regard to comorbid conditions, age, number of previous access, and surgical technique. Patients in the sPTFE group were randomly selected from our database of brachioaxillary shunts performed during the same period using sPTFE. A complication was defined as any event that produced graft dysfunction, thrombosis, or failure or that required graft revision or removal. The late complication rate was defined as the number of complication episodes per patient per year of follow-up. Primary patency was defined as normal graft function from the date of shunt construction to the occurrence of the first complication requiring revision. Secondary patency was defined as normal graft function from the date of placement to graft failure, when revisions were required, or complications treated during the inter-
Annals of Vascular Surgery
Table I. Comparison of Diastat and sPTFE groups
Patients Mean age (years) Females Upper arm graft Diabetes Previous access
Diastat
sPTFE
40 66.475 55% (22) 100% 15% (6) 45% (18)
40 63.925 85% (34) 100% 17.5% (7) 50% (20)
p
NS <0.01 NS NS
NS, not significant.
val. Patency curves were obtained using the lifetable method (Kaplan-Meier). Comparisons of patency between groups were obtained by the Mantel Haenzsel method (log-rank). A software statistical package (RSigma Babel, Madrid, Horus Hardware, 1991) was used for analysis.
RESULTS Forty Diastat grafts were implanted in 40 patients during the study period. This constituted 20% of all brachioaxillary shunts constructed during this period. The indication for the use of diastat grafts in this group of patients was the greater urgency for dialysis in these patients. A sPTFE control group (n = 40; matched for age associated diabetes mellitus, previous vascular access) was selected from our database. There were no significant differences between both groups in terms of age, incidence of diabetes mellitus, and percentage of previous permanent vascular access. There was only a significant difference (p < 0.01) in the percentage of females (Diastat group, 55%; sPTFE group, 85%) (Table I). Median follow-up was 11.4 months in the Diastat group and 13.4 months in the sPTFE group (p > 0.05). There were no perioperative complications. The overall complication rate was 1.2/patient/year in the Diastat group and 0.39/patient/year in the sPTFE group (p < 0.001). The thrombosis rate was 0.99/patient/year for the Diastat group and 0.26 for the sPTFE group (p < 0.001). Thrombosis and dysfunction during dialysis were the most frequent complications in both groups. There were no statistical differences in bleeding and the infection rate (Table II). No steal phenomena or pseudoaneurysm formation were observed. Primary patency was 79, 50, and 24% in the Diastat group and 89, 81, and 72% in the sPTFE group at 6, 12, and 18 months (p < 0.001) (Fig. 1). Secondary patency was 87, 73, and 55% in the Diastat group and 97, 93, and 88% in the sPTFE group
Vol. 14, No. 6, 2000
Use of Diastat versus standard wall PTFE grafts 661
Table II. Complications in Diastat and ePTFE groups
Dysfunction Thrombosis Infection Hemorrhage Total (patient/year) Follow-up, months (median)
Diastat
ePTFE
6 38 2 0 46 (1.2) 456 (11.4)
5 12 0 1 18 (0.39) 545 (13.4)
p
<0.001
<0.001
Fig. 1. Primary patency rates of Diastat and PTFE grafts in the brachioaxillary position.
Fig. 2. Secondary patency rates of Diastat and PTFE grafts in the brachioaxillary position.
at 6, 12, and 18 months (p < 0.001) (Fig. 2). Only 40% of the Diastat grafts were cannulated within 2 weeks after placement; edema and pain were the reasons for delay of the first cannulation in all patients. All sPTFE grafts were cannulated after 2 weeks of surgery.
DISCUSSION Standard wall PTFE grafts need at least 2 weeks for maturation before first cannulation is performed to decrease the risk of bleeding or perioprosthetic hematoma. In this situation, if the patient needs he-
662
Almonacid et al.
modialysis, temporary central vein catheters are used. In recent years new grafts have become available that allow cannulation immediately after implantation, avoiding acute and chronic complications of central vein cannulation, with promising early results.5-8 Our experience with one of these grafts (Diastat) differs from that of these earlier studies but is similar to that in later reports.9,10 In our series, the thrombosis and overall complication rates were higher in the Diastat group with statistical significance. Our primary and secondary patency rates were better in both the Diastat and sPTFE groups compared with those from other published series.5-10 This could be explained by our use of a large vein (the axillary vein) for the shunt’s outflow in all patients. The worse results with the Diastat graft may be secondary to the structure and design of the graft itself since the clinical conditions and vascular risk factors were similar in both groups. Early cannulation in the Diastat group was impossible in 60% of the patients because of severe inflammatory reaction in the arm. Our 40% early cannulation rate is worse than that of 70% in Lohr et al.’s study.10 The surgical revisions of the Diastat grafts (thrombectomies, new bypass, or removal of the grafts) were technically more complex because the heterogeneous structure of the cannulation segment makes surgical dissection and anastomosis more difficult. Other problems associated with the use of the Diastat graft were technical difficulties with implantation secondary to the standard length of the cannulation segment. In summary, the advantage of early cannulation
Annals of Vascular Surgery
with the Diastat graft occurs only in a small percentage of patients. Furthermore, because of its lower patency and higher complication rate, compared with the sPTFE graft, the Diastat graft is far from the ideal upper arm hemodialysis access. REFERENCES 1. Vanherweghem JL, Yassine T, Goldman L, et al. Subclavian vein thrombosis: a frecuent complication of subclavian vein cannulation for hemodialysis. Clin Nephrol 1986;26:235238. 2. Schwab SJ, Quarles LD, Middleton JP, et al. Hemodialysisassociated subclavian vein stenosis. Kidney Int 1988;33: 1156-1159. 3. Allmiral J, Gonza´lez J, Rello J, et al. Infection in long termjugular hemodialysis catheters: incidence and mechanisms. Am J Nephrol 1989;9:454-459. 4. Kahn D, Pontin AR, Jacobson JE, et al. Arteriovenous fistula in the presence of subclavian vein stenosis: a serious complication. Br J Surg 1990;77:682. 5. Barlett ST, Schweitzer EJ, Roberts JE, et al. Early experience with a new ePTFE vascular prosthesis for hemodialysis. Am J Surg 1995;170:118-122. 6. Gelbfish GA. The Diastat vascular acces graft: technical issues and preliminary results. In: Vascular Access for Hemodialysis V. Chicago: Precept Press, 1997, pp 11-23. 7. Park TC. The Diastat vascular dialysis graft and the stretch graft: a 12 month comparative study. In: Vascular Access for Hemodialysis V. Chicago: Precept Press, 1997, pp 77-85. 8. Glickman MH. Early experience with the Perma-seal graft for hemodialysis. In: Vascular Access for Hemodialysis V. Precept Press, 1997, pp 112-118. 9. Coyne DW, Lowell JA, Windus DW, et al. Comparison of survival of an expanded politetrafluoroethylene graft designed for early cannulation to standard wall politetrafluoroethylene grafts. J Am Coll Surg 1996;183:401-405. 10. Lohr JM, James KV, Hearn AT, et al. Lessons learned from the Diastat vascular access graft. Am J Surg 1996;172:205209.