Direct anastomotic assessment for postoperative microvascular monitoring.

An experimental comparison of two techniques for direct monitoring of anastomoses postoperatively is presented. Arterial differential temperature measurements indicated arterial occlusion (n = 24) in island flaps by mean temperature decreases in the affected artery of 0.5 degrees = C, but temperature changes in cases of venous occlusion (n = 17) were small (mean, 0.2 degrees C), inconsistent, and not of predictive value. The technique did not distinguish success (n = 4) from failure (n = 2) in experimental free flaps, and occlusion of deep arteries produced little or no change in the arterial wall temperature. In contrast, an implanted ultrasound Doppler probe reliably indicated arterial and venous occlusion in island flaps (n = 10), because in both circumstances the mean arterial Doppler signal invariably decreased to 0. The two could be distinguished between by changes in Doppler sound and instantaneous signal. In experimental free flaps, success (n = 10) was clearly distinguished from failure (n = 3) by characteristic patterns of Doppler sound and signal. Arterial differential thermometry had serious limitations, but implanted ultrasound Doppler showed great potential as a postoperative monitor applicable to all microvascular procedures.