"Islands of ischemia": transcutaneous PtcO2 documentation of pedal malperfusion following lower limb...

Doppler, pulse volume recording (PVR) and transcutaneous oxygen (PtcO2) mapping was performed in eleven patients (group I) before and after uniform revascularization of ischemic limbs. Group I results were compared to three patients (group II) whose ischemic ulcers healed poorly following successful bypass. Inhaled oxygen was used to magnify oxygen gradients comparing foot, below-the-knee, and chest values. Significant postoperative increases in Doppler index from 0.42 to 0.89 and decreases in PVR class from 3.1 to 1.2 (P less than 0.001) were found in groups I and II. Revascularization increased the below-the-knee PtcO2 from 48 to 57 mm Hg (P less than 0.05) and foot PtcO2 from 30 to 57 mm Hg (P less than 0.01). Inhaled oxygen delineated limitation of limb oxygen transfer and demonstrated the completeness of revascularization. Despite comparable revascularization in groups I and II, PtcO2 values of less than 20 mm Hg were measured adjacent to areas of persistent ulceration. Transcutaneous oxygen monitoring clearly delineates successive revascularization. Nonhealing foot ulcers following revascularization are "islands of ischemia" due to multiple causes.