MODERN OPERATIVE TECHNICS
A Salvage Technic for Extruded Arteriovenous
Shunts
Kenneth A. Marshall, MD, Charlottesville, Virginia Keith Shearlock, MD, Charlottesville, Virginia Richard F. Edlich, MD, PhD, Charlottesville, Virginia Milton 1. Edgerton, MD, FACS, Charlottesville, Virginia
The establishment and maintenance of the arteriovenous shunt or fistula for hemodialysis is a critical element in the care of patients with endstage renal disease. Some dialysis patients are not suitable for transplantation and those who are potential allograft recipients have lengthy waits due to the shortage of suitable donor kidneys. This, along with the expanding dialysis population and consequently expanding recipient pool, promises to lengthen the dialysis period of most patients. Prolonged vascular access for hemodialysis is thus becoming more important. The life expectancy of a Silastic@ QuintonScribner arteriovenous shunt averages ten to twelve months [I]. Typically, they fail due to thrombosis, stenosis, or perforation of the vessel by the stiff cannula with or without concomitant infection. However, occasionally there is erosion of the cannula through thin overlying skin, most commonly through scar. In the past, even in the absence of infection, shunt extrusion has required relocation of the cannula with abandonment of even a functional vessel. As shunts are lost successively, each attempt to reestablish a shunt has led to further scarring of regional skin, making subsequent shunt erosion more likely. Because only a limited number of suitable sites exist, efforts directed toward increasing the life of each vascular site seem well spent. To avoid technical complications, alternative methods of constructing shunts or fistulas with autogenous saphenous vein grafts as well as with various other synthetic materials have been proposed and reviewed by a number of authors [2,3]. To date, however, Silastic cannulas have proved most convenient and efficient. In an effort to preserve From the Departments of Plastic Surgery, and Internal Medicine, The University Of Virginia Medical Center, Charlottesville, Virginia. Reprint requests shoultj be addressed to Kenneth A. Marshall. MD. Division of Plastic Surgery. Harvard University, Cambridge Hospital, Cambridge, Massachusetts 02138.
noninfected extruded arteriovenous shunts or fistulas with satisfactory vessels and function, skin flaps have been designed to avoid vessel sacrifice. The results of this technic constitute the basis for this report. Technic
If a sizable flap or any complimentary skin graft is required systemic anticoagulation is reversed and appropriate tubings are attached to each cannula of the arteriovenous shunt or fistulas to allow intermittent irrigation. This minimizes the possibility of bleeding and subsequent formation of hematoma from a fresh surgical wound while it maintains the patency of the vessel. Five ml of a solution of sodium-heparin diluted in 0.9 per cent sodium chloride (14 units of heparin per ml) are injected rapidly either manually or by an automatic injection syringe into the arterial and venous cannulas every 30 minutes. This irrigation is initiated preoperatively and continued during surgery until 48 hours after operation. Systemic anticoagulation with either warfarin or heparin is then resumed. After cleansing the entire arm and external cannulas with Betadine@ antiseptic solution, the surgical salvage technic is planned. A bipedicle flap can be designed to transfer healthy, unscarred adjacent forearm tissue over the eroded arterial or venous cannula. (Figure 1.) After local anesthesia (1 per cent lidocaine) a bipedicle flap is raised. Care is taken to secure the cannula subcutaneously with 4-O clear monofilament nylon suture to immobilize it and to avoid any major deviation in either its direction or entrance into its major vessel. The cannula is always fixed with adequate soft tissue coverage and away from lines of incision. All bleeding is controlled by electrocoagulation to avoid hematoma formation. The flap based on its two pedicles is then transposed and seated over
The American Journal ef Surgery
Arteriovenous
the buried cannula and sutured into place. The external element of the cannula is allowed to penetrate skin wherever necessary to avoid kinking of the tubing, even if the cannula must penetrate the base of the flap. After instillation of local anesthesia, a split thickness skin graft is harvested from the inner aspect of the upper arm and applied to the area of the forearm from which the bipedicle flap has been raised. Alternatively, a fusiform-shaped, thin full thickness graft can be taken transversely from the antecubital space and the donor site closed primarily. The graft is then applied and sutured in place using 5-O monofilament nylon interrupted sutures. Alternatively, in some patients with excess regional skin a local rotation advancement flap can be designed to cover the cannula. This may be done safely with minimal dissection and without reversal of systemic anticoagulation. With more difficult and larger coverage problems, reversal of systemic anticoagulation has been mandatory for satisfactory hemostasis. Results In seven of eight patients, we have successfully salvaged the eroded cannula using a flap coverage technic without sacrificing the vascular site. I&nor modifications and adjustments of flap design were required in each patient to avoid transfer of scar tissue. The seven patients with successful salvages of their cannulas suffered no complications and have retained their shunts from six to twelve months. Six of seven shunts remain functional; one patient has undergone renal transplantation and no longer has need for a shunt. Comments Erosion of an implanted foreign body through the thin inadequate skin of scar tissue is predictable because the tensile strength of scar tissue is less than that of unwounded skin [4]. As in other fields of surgery, the location and technic of installing a nonbiologic implant is critical [5]. With a “cushion” of subcutaneous tissue and healthy skin over the cannula and with avoidance of overlying incisions, erosions can be minimized. When erosion of implanted cannulas through scar occurs, salvage can be accomplished by coverage of the implant with a pedicle flap of unwounded skin.
VMums 131. yuch 1976
Shunts
Comtalimentorv skin g& behind fiap
Flgure 7. Bipedkle f/ap coverage of eroded cannda.
Coverage of the extruded arteriovenous cannulas with pedicle flaps has salvaged shunts in seven patients. The success of this salvage technic warrants its use in the management of the extruded arteriovenous shunt. Sumniary In view of the often prolonged periods of pretransplantation and chronic dialysis, every effort should be made to maintain existing arteriovenous shunts or fistulas and to salvage eroded ones when possible. The transposition of unwounded bipedicle flaps or small regional rotation advancement flaps over exposed cannulas is a surgical technic that can salvage eroded shunts and prevent their extrusion and removal. References 1. Quinton WE, Dilloid D, Scribner BH: Cannulation of blood vessels for prolonged hemodialysis. Trans Am Sot Artif Intern Organs 6: 104. 1960. 2. May J, Tiller D, Johnson J, Sheil AGR: Saphenous vein arteriovenous fistula in regular hemodialysis treatment. N Engl J A&d 260: 770, 1969. 3. Morgan A. Lazarus M: Vascular access for dialysis. Technics and results with newer methods. Am J Surg 129: 432, 1975. 4. Lichtenstein IL, Herzikoff S, Shore JM, et al: The dynamics of wound healing. Surg Gynecol Obstet 130: 685, 1970, 5. Edgerton MT, Sacchetta CA: Principles in the use and salvage of implants in ear reconstruction, p 58. Symposium on Recohstruction of the Auricle, Vol 10 (Tanzer RC, Edgerton MT, ed). St. Louis, CV Mosby, 1974.
387
A Salvage Technic for Extruded Arteriovenous
Shunts
Kenneth A. Marshall, MD, Charlottesville, Virginia Keith Shearlock, MD, Charlottesville, Virginia Richard F. Edlich, MD, PhD, Charlottesville, Virginia Milton 1. Edgerton, MD, FACS, Charlottesville, Virginia
The establishment and maintenance of the arteriovenous shunt or fistula for hemodialysis is a critical element in the care of patients with endstage renal disease. Some dialysis patients are not suitable for transplantation and those who are potential allograft recipients have lengthy waits due to the shortage of suitable donor kidneys. This, along with the expanding dialysis population and consequently expanding recipient pool, promises to lengthen the dialysis period of most patients. Prolonged vascular access for hemodialysis is thus becoming more important. The life expectancy of a Silastic@ QuintonScribner arteriovenous shunt averages ten to twelve months [I]. Typically, they fail due to thrombosis, stenosis, or perforation of the vessel by the stiff cannula with or without concomitant infection. However, occasionally there is erosion of the cannula through thin overlying skin, most commonly through scar. In the past, even in the absence of infection, shunt extrusion has required relocation of the cannula with abandonment of even a functional vessel. As shunts are lost successively, each attempt to reestablish a shunt has led to further scarring of regional skin, making subsequent shunt erosion more likely. Because only a limited number of suitable sites exist, efforts directed toward increasing the life of each vascular site seem well spent. To avoid technical complications, alternative methods of constructing shunts or fistulas with autogenous saphenous vein grafts as well as with various other synthetic materials have been proposed and reviewed by a number of authors [2,3]. To date, however, Silastic cannulas have proved most convenient and efficient. In an effort to preserve From the Departments of Plastic Surgery, and Internal Medicine, The University Of Virginia Medical Center, Charlottesville, Virginia. Reprint requests shoultj be addressed to Kenneth A. Marshall. MD. Division of Plastic Surgery. Harvard University, Cambridge Hospital, Cambridge, Massachusetts 02138.
noninfected extruded arteriovenous shunts or fistulas with satisfactory vessels and function, skin flaps have been designed to avoid vessel sacrifice. The results of this technic constitute the basis for this report. Technic
If a sizable flap or any complimentary skin graft is required systemic anticoagulation is reversed and appropriate tubings are attached to each cannula of the arteriovenous shunt or fistulas to allow intermittent irrigation. This minimizes the possibility of bleeding and subsequent formation of hematoma from a fresh surgical wound while it maintains the patency of the vessel. Five ml of a solution of sodium-heparin diluted in 0.9 per cent sodium chloride (14 units of heparin per ml) are injected rapidly either manually or by an automatic injection syringe into the arterial and venous cannulas every 30 minutes. This irrigation is initiated preoperatively and continued during surgery until 48 hours after operation. Systemic anticoagulation with either warfarin or heparin is then resumed. After cleansing the entire arm and external cannulas with Betadine@ antiseptic solution, the surgical salvage technic is planned. A bipedicle flap can be designed to transfer healthy, unscarred adjacent forearm tissue over the eroded arterial or venous cannula. (Figure 1.) After local anesthesia (1 per cent lidocaine) a bipedicle flap is raised. Care is taken to secure the cannula subcutaneously with 4-O clear monofilament nylon suture to immobilize it and to avoid any major deviation in either its direction or entrance into its major vessel. The cannula is always fixed with adequate soft tissue coverage and away from lines of incision. All bleeding is controlled by electrocoagulation to avoid hematoma formation. The flap based on its two pedicles is then transposed and seated over
The American Journal ef Surgery
Arteriovenous
the buried cannula and sutured into place. The external element of the cannula is allowed to penetrate skin wherever necessary to avoid kinking of the tubing, even if the cannula must penetrate the base of the flap. After instillation of local anesthesia, a split thickness skin graft is harvested from the inner aspect of the upper arm and applied to the area of the forearm from which the bipedicle flap has been raised. Alternatively, a fusiform-shaped, thin full thickness graft can be taken transversely from the antecubital space and the donor site closed primarily. The graft is then applied and sutured in place using 5-O monofilament nylon interrupted sutures. Alternatively, in some patients with excess regional skin a local rotation advancement flap can be designed to cover the cannula. This may be done safely with minimal dissection and without reversal of systemic anticoagulation. With more difficult and larger coverage problems, reversal of systemic anticoagulation has been mandatory for satisfactory hemostasis. Results In seven of eight patients, we have successfully salvaged the eroded cannula using a flap coverage technic without sacrificing the vascular site. I&nor modifications and adjustments of flap design were required in each patient to avoid transfer of scar tissue. The seven patients with successful salvages of their cannulas suffered no complications and have retained their shunts from six to twelve months. Six of seven shunts remain functional; one patient has undergone renal transplantation and no longer has need for a shunt. Comments Erosion of an implanted foreign body through the thin inadequate skin of scar tissue is predictable because the tensile strength of scar tissue is less than that of unwounded skin [4]. As in other fields of surgery, the location and technic of installing a nonbiologic implant is critical [5]. With a “cushion” of subcutaneous tissue and healthy skin over the cannula and with avoidance of overlying incisions, erosions can be minimized. When erosion of implanted cannulas through scar occurs, salvage can be accomplished by coverage of the implant with a pedicle flap of unwounded skin.
VMums 131. yuch 1976
Shunts
Comtalimentorv skin g& behind fiap
Flgure 7. Bipedkle f/ap coverage of eroded cannda.
Coverage of the extruded arteriovenous cannulas with pedicle flaps has salvaged shunts in seven patients. The success of this salvage technic warrants its use in the management of the extruded arteriovenous shunt. Sumniary In view of the often prolonged periods of pretransplantation and chronic dialysis, every effort should be made to maintain existing arteriovenous shunts or fistulas and to salvage eroded ones when possible. The transposition of unwounded bipedicle flaps or small regional rotation advancement flaps over exposed cannulas is a surgical technic that can salvage eroded shunts and prevent their extrusion and removal. References 1. Quinton WE, Dilloid D, Scribner BH: Cannulation of blood vessels for prolonged hemodialysis. Trans Am Sot Artif Intern Organs 6: 104. 1960. 2. May J, Tiller D, Johnson J, Sheil AGR: Saphenous vein arteriovenous fistula in regular hemodialysis treatment. N Engl J A&d 260: 770, 1969. 3. Morgan A. Lazarus M: Vascular access for dialysis. Technics and results with newer methods. Am J Surg 129: 432, 1975. 4. Lichtenstein IL, Herzikoff S, Shore JM, et al: The dynamics of wound healing. Surg Gynecol Obstet 130: 685, 1970, 5. Edgerton MT, Sacchetta CA: Principles in the use and salvage of implants in ear reconstruction, p 58. Symposium on Recohstruction of the Auricle, Vol 10 (Tanzer RC, Edgerton MT, ed). St. Louis, CV Mosby, 1974.
387
