EMERGENCE AND RECOVERY FROM BIS-GUIDED ADMINISTRATION OF ANESTHESIA

S499 INTRODUCTION: Remifentanil, a short-acting opioid has been shown to reduce the amount of co-administered hypnotic required. [1] Bispectral index (BIS), a processed EEG variable, correlates with the level of hypnosis during anesthesia. [2,3] BIS levels under 60 are required to obtain adequate hypnosis during surgical procedures. [4,5] This study compares emergence and recovery from BIS-guided anesthesia with remifentanil with either isoflurane or propofol. METHODS: After HIC approval, 76 consenting patients were randomized to two groups, one receiving remifentanil and isoflurane (ISO), the other remifentanil and propofol (PRO). In both groups, anesthesia was induced with propofol and remifentanil. Hemodynamic responses were used to titrate remifentanil infusion rates, maintaining MAP and heart rate within a 20% range compared with awake baseline. BIS was used to titrate ISO/PRO, maintaining BIS between 45 and 60. Thirty minutes before end of surgery 0.15 mg/kg morphine was administered for postoperative pain control. 15 min. before end of surgery anesthetics were reduced to keep BIS between 60 and 75. At the end of surgery, remifentanil and anesthetic agents were discontinued. Patients were observed for return of spontaneous and adequate respiration, return of consciousness and extubation. Postanesthetic assessment was performed using a modified Aldrete-score (0-10). [6] A score of 9 was needed for discharge. Statistical analysis was performed using Chi square and repeated t-testing (Bonferoni-Holms adjusted). RESULTS: Demographic data showed no significant differences between the groups (Table 1). Surgical duration was significantly shorter with isoflurane (94 +/- 40 min) than with propofol (121 +/- 53 min).Table 1: Demographic dataRecovery data were calculated from end of drugs' administration to return of spontaneous respiration (spont resp), adequate respiration (adeq resp), consciousness (ROC), extubation (EXT) and and full recovery (REC). (Table 2)Table 2: Recovery times (min)Mean remifentanil infusion rate was significantly lower (p<0.001) with ISO (0.18 +/- 0.06 [micro sign]g/kg/min) than with PRO (0.31 +/- 0.20 [micro sign]g/kg/min). Average isoflurane endtidal concentration was 0.66 +/- 0.13 %, propofol infusion rate 123 +/- 48 [micro sign]g/kg/min. CONCLUSIONS: BIS-guided anesthesia with remifentanil in combination with both isoflurane or propofol has comparably short recovery times. At comparable hypnotic levels, controlled by BIS, hemodynamic control requires higher doses of remifentanil with propofol, than with isoflurane.