Comparison of A-Line Autoregressive Index and Observer Assessment of Alertness/Sedation Scale for Monitored Anesthesia Care With Target-controlled Infusion of Propofol in Patients Undergoing Percutaneous Vertebroplasty

Background Percutaneous vertebroplasty (PV) with monitored anesthesia care (MAC) is a growing trend. Without adequate sedation, patient movement can affect and even interrupt the procedure during MAC. The aim of this study was to compare the performance of the auditory-evoked potential (AEP) index and the Observer Assessment of Alertness/Sedation (OAA/S) scale as indicators of depth of sedation in patients undergoing PV. Methods Two hundred and twenty patients in ASA II to III, aged 43 to 92 years, undergoing elective PV with MAC, were randomly allocated to the AEP or the OAA/S group (n=110 each). Initially, all patients received 1 μg/kg of fentanyl and 0.02 mg/kg of midazolam intravenously and sedation with a target-controlled infusion (TCI) of propofol at a target concentration of 1.2 μg/mL. The concentration for the propofol TCI was adjusted in 0.2 μg/mL increments or decrements according to the A-Line autoregressive index (AAI) or the OAA/S scale. A blinded study nurse recorded the measured parameters. Results Some parameters were significantly different in the AEP group compared with the OAA/S group: lower AAI, lower OAA/S score, lower respiratory rates, and higher end-tidal carbon dioxide pressure were noted from local anesthetic infiltration to bone cement implantation, fewer patients whose movements affected the procedure (10 vs. 36, respectively, P<0.001), and more adjustments of TCI (twice vs. once, respectively, P<0.006). The surgeons' satisfaction was greater for the AEP group than for the OAA/S group. Conclusions TCI propofol with AEP monitoring can provide less patient movement, better sedation, and higher surgeon satisfaction in patients during prone-position PV procedures than can TCI propofol with OAA/S monitoring.