Continuous pulse amplitude monitoring of infrainguinal bypass grafts in the first 24 postoperative hours.

To evaluate continuous pulse amplitude monitoring (CPAM) as a method for early postoperative graft surveillance following infrainguinal bypass surgery, a prospective observational study was carried out in 34 consecutive infrainguinal bypass grafts. CPAM tracings were compared with pre- and postoperative pulse palpation, ankle/brachial index (ABI) measurements, and pulse volume recordings (PVR). The utility of each method was defined by its ability to demonstrate graft patency in the first 24 hours. Pulse palpation was considered a useful monitoring tool if a postoperative pedal pulse was found in the absence of palpable preoperative pulses. The ABI qualified in this respect if a postoperative increase of at least 0.25 could be demonstrated; for PVR tracings an increase of at least one category was required. The utility of CPAM was established by an increase of at least 5 mm compared to the preoperative values. There were no early graft failures. We were therefore unable to calculate the ability of the studies to predict graft failure. The percentages (95% confidence limits) for which pulse palpation, ABI, and PVR were found capable of demonstrating graft patency were 50% (range 34% to 66%), 53% (range 36% to 70%), and 71% (range 54% to 83%), respectively. CPAM appeared to be far superior to these three methods with a utility of 94% (range 81% to 98%; p < 0.05). Patient and operator acceptability of CPAM was high. Skin pressure problems are a potential risk if the CPAM probe is left attached to the skin for more than 24 hours. CPAM was a valuable and reliable means of monitoring infrainguinal vascular reconstructions. Apart from being inexpensive, continuous, objective, and simple, CPAM is noninvasive and painless. It is advisable to remove the probe 24 hours after surgery, when the most crucial period for graft monitoring has passed.