Fallibility of postoperative Doppler ankle pressures in determining the adequacy of proximal arterial...

Twenty-three consecutive patients with limb-threatening ischemia underwent proximal arterial revascularization. In all patients Doppler ankle pressure was measured hourly in the postoperative period. In 16 limbs with patent superficial femoral arteries, the pressure index increased from 0.55 +/- 0.06 to 0.78 +/- 0.06 within the 1st hour postoperatively. Twenty limbs with occluded superficial femoral arteries, did not demonstrate a significant increase until 3 hours postoperatively (from 0.41 +/- 0.06 to 0.62 +/- 0.05). Immediate improvement in the Doppler pressure index is to be expected in patients with isolated aortoiliac disease who undergo successful arterial reconstruction. Failure to demonstrate such improvement is diagnostic of an intraoperative accident. Lack of immediate improvement in patients with combined aortoiliac and femoropopliteal disease should not be construed as evidence of intraoperative failure. With 3 to 4 hours, however, the ankle/arm pressure ratio should exceed the preoperative value. The failure to do so within that interval is strongly suggestive of inadequate revascularization, and in most cases immediate operative revision or the later addition of a distal bypass procedure will be necessary.