Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

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STEP 4: POSTOPERATIVE CARE

The patient is returned to the intensive care unit. Fluid volume, hematocrit, acid-base status, liver function tests, and clotting factors are carefully monitored and replaced. Persistent acidosis is usually indicative of ongoing bleeding or bowel or hepatic ischemia.

Colonoscopy should be performed with care if colonic ischemia is suspected, because an intraluminal pressure greater than 30 mm Hg may further impair colonic blood flow. Prompt surgery is indicated if there is persistent acidosis, ongoing bleeding, or evidence of sepsis.

STEP 5: PEARLS AND PITFALLS

Early diagnosis and treatment of mesenteric ischemia is essential if the survival rate is to be improved.

A planned second-look operation to resect marginally viable segments of bowel is an integral part of the postoperative care of patients with mesenteric ischemia.

Ongoing bleeding may be due to increased fibrinolysis, especially in patients undergoing antegrade mesenteric bypass with prolonged hepatic ischemia. After other causes of bleeding have been excluded, blood should be drawn for plasminogen levels, and an infusion of small amounts of epsilon aminocaproic acid should be considered.

The choice of graft material is determined by the presence or absence of fecal contamination. Prosthetic grafts are preferred because they are less likely to kink. If there is gross contamination, an autogenous saphenous vein or superficial femoral vein graft should be used. These grafts should be carefully placed to avoid kinking and recurrent ischemia.

Patients undergoing surgery for mesenteric ischemia may require large volumes of fluid intraoperatively and postoperatively and are prone to developing abdominal compartment syndrome. If there is significant bowel edema, the abdomen should not be closed primarily. Temporary abdominal content containment with plastic bags (Bogota bag) or polyglactin mesh or application of a wound vacuum-assisted closure (VAC) device and delayed primary closure should be done once the visceral edema has resolved.

There is ongoing debate about the number of vessels to be revascularized. Patients with acute mesenteric ischemia are usually too critically ill to withstand total revascularization, and only the SMA should be revascularized. Revascularization of both the celiac artery and SMA should be considered in patients with chronic mesenteric ischemia.

SELECTED REFERENCES

1. Foley MI, Moneta GL, Abou-Zamzam AM, et al: Revascularization of the SMA alone for treatment of intestinal ischemia. J Vasc Surg 2000;32:37-47.

2. Morasch MD, Ebaugh JL, Chiou AG, et al: Mesenteric venous thrombosis: A changing clinical entity. J Vasc Surg 2001;34:680-684.

3. Wylie EJ, Stoney RJ, Ehrenfeld WK: Manual of Vascular Surgery. New York, Springer Verlag, 1980.

C H A P T E R 90

HEMODIALYSIS ACCESS PROCEDURES

Kenneth J. Woodside

STEP 1: SURGICAL ANATOMY

A comprehensive understanding of both the arterial inflow and venous outflow of the arm and forearm is critical to the successful placement and maintenance of hemodialysis access.

Figure 90-1 demonstrates typical target sites for arterial and venous anastomoses.

Figures 90-2 through 90-4 demonstrate key anatomic relationships underlying operative planning.

STEP 2: PREOPERATIVE CONSIDERATIONS

Placement of new access should be initiated several months before the anticipated need for hemodialysis to allow time for fistula maturation and troubleshooting, as well as to avoid catheter placement and the associated risk of central vein stenosis.

Physical examination for compressible veins in the forearm and arm should be performed, as well as Allen’s test for palmar arch patency. Any history of congestive heart failure, diabetes, intravenous drug use, or chemotherapy should be elicited.

In most patients, preoperative vein mapping should be obtained to maximize the creation of arteriovenous fistulae over graft placement. Target veins should have a diameter larger than 3 mm, although smaller distendable veins may be used.

Access creation should occur in the nondominant forearm first, starting at the most distal site possible. Strategic placement of access is important to maximize the number of sites available over the life of the patient.

In patients with more subcutaneous fat, consider vein transposition to make the vein closer to the skin surface and more accessible by the dialysis center.

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An end-to-side anastomosis is performed with 6-0 Prolene suture (Figure 90-7).

The clamps are removed, with the distal arterial clamp removed last. The cephalic vein is palpated for a thrill. Revision may be necessary if a thrill is not readily palpable. If the fistula is pulsatile without a thrill, a distal obstruction may be present. If the obstruction is not from inadequate vein mobilization, a venogram may need to be performed.

3. CLOSURE

The wound is closed in two layers with interrupted 3-0 Vicryl subcutaneous sutures and a running 4-0 Monocryl subcuticular layer.

Cephalic vein

Radial artery

FIGURE 90–7