CONTINUOUS PULSE AMPLITUDE MONITORING OF INFRAINGUINAL BYPASS GRAFTS IN THE FIRST 24 POSTOPERATIVE HOURS

To evaluate continuous pulse amplitude monitoring (CPAM) as a method f or early postoperative graft surveillance following infrainguinal bypa ss surgery, a prospective observational study was carried out in 34 co nsecutive infrainguinal bypass grafts. CPAM tracings were compared wit h pre- and postoperative pulse palpation, ankle/brachial index (ABI) m easurements, and pulse volume recordings (PVR). The utility of each me thod was defined by its ability to demonstrate graft patency in the fi rst 24 hours. Pulse palpation was considered a useful monitoring tool if a postoperative pedal pulse was found in the absence of palpable pr eoperative pulses. The ABI qualified in this respect if a postoperativ e 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 w as established by an increase of at least 5 mm compared to the preoper ative values. There were no early graft failures. We were therefore un able to calculate the ability of the studies to predict graft failure. The percentages (95% confidence limits) for which pulse palpation, AB I, and PVR were found capable of demonstrating graft patency were 50% (range 34% to 65%), 53% (range 36% to 70%), and 71% (range 54% to 83%) , respectively. CPAM appeared to be far superior to these three method s with a utility of 94% (range 81% to 98%; p <0.05). Patient and opera tor acceptability of CPAM was high. Skin pressure problems are a poten tial 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 infrai nguinal vascular reconstructions. Apart from being inexpensive, contin uous, objective, and simple, CPAM is noninvasive and painless. It is a dvisable to remove the probe 24 hours after surgery, when the most cru cial period for graft monitoring has passed.