Vascular graft infections remain challenging clinical problems for the vascular surgeon, particularly when prosthetic material is involved. Traditional approaches, which before 1960s consisted of removal of all prosthetic grafts with extra-anatomic bypass or amputation, has given way to more conservative approaches in patients whom graft removal is not feasible. These approaches have significantly reduced mortality and improved limb salvage.
Contemporary management consists of an escalating algorithm of interventions that vary from retention from the graft with healing by secondary intention to graft replacement with muscle flap reconstruction of the defect. When definitive extra-anatomic bypass isn't feasible, in situ replacement of infected prosthetic grafts with cadaveric homografts or autogenous tissue is preferred. The decision to replace the graft is typically made by the vascular surgeon.
Salvage of an arterial graft may be considered in patients who have patency of the reconstruction, an intact anastomosis and localized infection. Systemic antibiotics should be administered preoperatively. Superficial infections that do not extend to the graft itself may be managed with debridement alone, then local wound care.
Flap reconstruction is the management of preference for deep infections that involve the graft. This is due to the its well-established utility in lowering bacterial counts, improving antibiotic delivery, filling dead space and providing tension-free soft tissue coverage. Patency of donor vessels to the intended flap must be assessed preoperatively using MRA or angiography.
The reconstructive surgeon must know the patency status from the graft before commencing the procedure. Staged debridements are usually necesary just before reconstruction. Wet-to-dry dressings, hydrogels, or closed suction drains can be utilized in the interim.
Probably the most commonly used flap in the groin is the sartorius. Harvest of the flap involves detaching in the anterior superior iliac spine, transposing it within the graft and suturing it towards the groin musculature and inguinal ligament. Care must be taken not to interrupt more than three perforating vessels to this flap, since its segmental circulation from the superficial femoral artery puts it in danger of necrosis.
An extended method of the gracilis can also be used successfully. It's approached with an overlying medial thigh incision. If your recent saphenectomy has been performed, this incision can be utilized. After medial reflection from the adductor longus, the gracilis is identified by the lack of nerves round the muscle, the lack of attachments deep and superficial towards the muscle, and tapering from the muscle as it dissection proceeds down the thigh.
The dominant pedicle is identified on the deep medial aspect of the muscle. The insertion from the gracilis towards the femur is split distally, and also the minor segmental pedicles are ligated, much like small vessels from the dominant pedicle that give you the overlying adductor longus. The origin from the gracilis at the pubic symphysis is then divided and also the muscle is tunneled beneath the adductor into the femoral triangle. Drains are put in the donor site and underneath the flap if possible.
The use of the rectus femoris is another option. This flap is reached through a midline thigh incision. The tendon is split 4 cm in the patella. The distal minor pedicle is ligated, and also the flap could be folded up to the wound. The rectus abdominis has additionally been used successfully in this setting. Finally, the ipsilateral or contralateral rectus muscle can be used for coverage of the groin when the profunda femoris vascular pedicle is compromised. Intraoperatively, blood circulation to the flap should be confirmed with a handheld Doppler, before it's elevated.
Intravenous antibiotics should be administered depending on intraoperative culture results. Some surgeons have suggested that therapy be continued for 6 weeks in the case of autogenous grafts or more to one year for prosthetic grafts. Lifelong suppressive doses of antibiotics taken orally should be considered in the latter group.
Although exposed dialysis grafts have traditionally been removed, the paucity of vascular access sites in long-term hemodialysis patients has led to several successful strategies to salvage them. Dialysis grafts are not acutely imperative alive or limb. As in arterial bypass grafts, hemorrhage or systemic infection mandates total graft excision. Since such grafts have a lifespan that averages 2-3 years, simple local flaps are typically used. Flaps such as the flexor carpi ulnaris and lateral arm flap allow coverage in the proximal forearm.
The radial artery island fasciocutaneous flap, meanwhile, may provide coverage towards the mid and distal forearm. Random pattern flaps should be used with caution, as they don't provide as reliable coverage. Vascular puncture can usually be continued during healing.
Patients with infected or exposed vascular grafts are in the highest risk group for subsequent wound complications. They have demonstrated wound healing problems using their initial surgery. Their vascularity and wound healing is compromised due to their underlying peripheral vascular disease. Many of these patients are also renal failure patients and malnourished.
In considering the coverage procedure, one should expect donor site complications in advance. The donor site should be distant from the graft site and away from important structures. For example, harvesting a sartorius flap for coverage of a groin bypass graft may not be wise if the donor site is in close proximity to the infected wound.
In regards towards the exposed graft, muscle coverage should be placed transversely on the longitudinal graft, so that when the coverage stops working, merely a small section of graft is going to be exposed. In addition, the graft should be covered in staggered layers by closing the muscle and skin layers separately without the skin incision lying directly over the muscle incision.
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Note: This article was sent to us by: Patricia Phillips at 02102011
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