Evaluation of two anestheltic techniques for mainernance of anesthesia during open heart surgery

ABSTRACT

Previous studies have highlighted the disadvantages of high-dose opioid anesthesia during cardiac surgery. On the other hand, the pharmacokinetic profile of propofol may constitute another advantage when used for maintenance of anesthesia by continuous infusion in open-heart surgery. This study investigated the use of an infusion of either propofol or fentanyl, for maintenance of anesthesia, in twenty adult patients undergoing elective open-heart surgery for valve replacement. After induction, anesthesia was maintained with either 4-10 mg/kg/hr propofol [P group], or 0.2 micro g/kg/min fentanyl supplemented with 0 - 1% isoflurane [F group]. In ICU, sedation was provided with an infusion of either propofol [in PG] or midazolam [in FG]; together with morphine infusion for analgesia. Heart rate [HR] and mean arterial pressure [MAP] were registered prior to induction of anesthesia [baseline], after intubation and sternotomy, before and 15 min after CPB, and at the end of operation. Other hemodynamic variables were also recorded before induction, before 15 min after CPB, and at the end of operation. In ICU, timing of extubation and adverse events were recorded. There was no significant hemodynamic response to tracheal intubation or sternotomy in both groups. Compared to the baseline values, significant increase in HR, and decreases in MAP and SVRI were observed 15 minutes after CPB [p<0.05]. Also, fifteen minutes of CPB resulted in significant increases in CO and CI, which were further increased at the end of surgery [p<0.05]. This increase was more in PG than in FG [p<0.05]. The changes in CVP and PCWP were insignificant over the observation period. There were no significant differences between groups in terms of CPB time, duration of anesthesia or hemodynamic changes [except CO and CI]. Patients in PG were extubated earlier [p<0.05] than those in FG [mean times were 354 +/- 65 min and 745 +/- 117 min; respectively]. No patient had recall of intraoperative events and there were no perioperative complications. We conclude that the use of propofol infusion, for maintenance of anesthesia during open-heart surgery and for sedation in ICU, is a safe technique as it produces cardiovascular stability similar to that associated with fentanyl, facilitates early extubation and reduces the possibility of intraoperative awareness that may occur with the use of high-dose opioid anesthesia