Revascularized diabetic limbs: positional changes in regional perfusion index

We measured pre- and postoperative ankle:brachial index (ABI), regional perfusion index (RPI = foot/chest transcutaneous oxygen tension [TcpO2]), and variation in RPI with limb elevation in 22 ischemic lower extremities of 20 patients to compare ABI and RPI measurements for quantifying limb perfusion and analyze perioperative positional changes in RPI. Measurements were compared, using t tests, with all limbs grouped according to severity of clinical ischemia and, again, according to presence or absence of diabetes. Preoperative mean and mean post-revascularization increases in ABI values ranged from 0.27 to 0.48 and 0.40 to 0.54, respectively; corresponding RPI values ranged from 0.18 to 0.45 and 0.48 to 0.60, respectively. Pre- and postoperative decreases in RPI with elevation ranged from 0.07 to 0.11 and 0.11 to 0.23, respectively. ABI and RPI values were equally effective in assessing clinical ischemia preoperatively and increased perfusion postoperatively, regardless of degree of ischemia or diabetes. Upon elevation, all limbs exhibited larger decrements in blood flow to the skin postoperatively compared to preoperatively, as estimated by RPI. However, postoperative positional decrease in RPI was greater in diabetics compared with nondiabetics (0.23 +/- 0.12 vs 0.12 +/- 0.06; P < 0.05), suggesting postoperative elevation of diabetic limbs with ischemic skin lesions may be unadvisable.