AUTOMATIC POSTOPERATIVE MONITORING OF INFRAINGUINAL BYPASS PROCEDURES

Objective: To evaluate the usefulness of a portable, computer-based, o scillometric, noninvasive blood pressure monitor for the automatic sur veillance of postoperative infrainguinal bypasses. Design: Prospective unblinded study. Setting: Regional tertiary care Veterans Affairs med ical center. Patients: A total of 60 limbs were examined in 3 groups ( n=20 in each group): normal, asymptomatic volunteers; older patients w ith symptomatic peripheral vascular disease; and patients who had unde rgone infrainguinal bypass procedures. Interventions: Noninvasive bloo d pressure monitor pressures, complete lower extremity arterial studie s with Doppler ankle-brachial index (ABI), segmental pressures, and pu lse volume recordings were performed in all groups. The patients who h ad undergone surgery also had hourly noninvasive blood pressure measur ements taken. Main Outcome Measures: Ankle-brachial indices obtained w ith the noninvasive blood pressure monitor were compared with simultan eous manual Doppler ABIs and pulse volume recordings. Results: There w as a significant overall correlation between the Doppler-derived ABIs and automatic oscillometric values (r=0.89, P<.001). Although there wa s a slight difference in absolute values (+/-SEM) (0.90+/-0.03 vs 0.84 +/-0.03, respectively), an excellent correlation was found between the 2 methods in the clinically relevant range of ABI values between 0.60 and 1.10. The oscillometric method, however, overestimated the ABI wh en it was less than 0.60 by the Doppler method (0.61+/-0.02 vs 0.44+/- 0.03, P<.001) and underestimated it when it was more than 1.10 (1.05+/ -0.02 vs 1.16+/-0.01, P<.001). (All values given as ?SEM.) Oscillometr ic overestimation correlated with depressed pulse volume recording wav eforms (P<.001) or diminished pulse volume recording amplitudes of les s than 10 mm (P<.001). Conclusion: The automatic oscillometric monitor provides a useful, accurate, objective, and quantitative method for p ostoperative bypass graft surveillance.