Improved Postischemic Recovery After Peripheral Bypass Surgery Assessed by Near-Infrared Spectroscopy

Near-infrared spectroscopy has been established as a monitoring technique for assessment of cerebral oxygenation. With the sensor placed over the gastrocnemius muscle, we studied the vascular capacity before and after infrainguinal revascularization, as well as the temporal profile of muscle oxygenation in the first 24 postoperative hours. Twenty-three patients undergoing femorodistal bypass surgery for claudication (n=10) or critical ischemia (n=13) were examined. Vascular capacity was assessed in 10 patients and expressed as the time for 95% reoxygenation (reox-T 95) of calf muscles upon 4 minutes of tourniquet-induced ischemia. Five days postoperatively, reox-T95 was reduced from 128 (105 to 183) s to 85 (61 to 109) s (p<0.005) (median, interquartile range) compared with 56 (55 to 57) s for a group of seven young and 55 (36 to 56) s for a group of seven age-matched controls (p<0.05). Thirteen patients monitored for 24 hours postoperatively demonstrated postreconstructive hyperemia with a peak in skeletal muscle oxygenation (peak-SmO2) 3 h after surgery of 21 (4 to 33) units above the preoperative level (p < 0.01 ), declining to the preoperative level after 11 h. In conclusion, calf vascular capacity as expressed by postischemic recovery was improved markedly following peripheral bypass surgery, and near-infrared spectroscopy revealed marked hyperemia postreconstructively.