A COMPARISON OF PROPOFOL AND ISOFLURANE ANESTHESIA - THE NEED FOR EPHEDRINE AND GLYCOPYRROLATE

Sixty patients, ASA I-III, presenting for elective colonic surgery were studied to assess the stability of blood pressure and heart rate during anaesthesia with three equally potent anaesthetic techniques. Patients in group I (n=20) received thiopentone induction, isoflurane and nitrous oxide; patients in group II (n=20) received total intravenous anaesthesia with propofol; and patients in group III (n=20) received intravenous propofol supplemented with nitrous oxide. Fentanyl and vecuronium were used in all three groups. The depth of anaesthesia was judged on clinical signs of adequate anaesthesia. Episodes of bradycardia (heart rate <50 beats min(-1)), tachycardia (heart rate >90 beats min(-1)), hypotension (mean arterial pressure greater than or equal to 30% below pre-operative blood pressure) or hypertension (mean arterial pressure greater than or equal to 30%, or systolic blood pressure > 15 mmHg, above pre-operative value) were recorded when lasting > 5 min. Any use of ephedrine or glycopyrrolate given to correct hypotension or bradycardia was documented: In group II, significantly more patients were given ephedrine (P<0.01) to treat hypotension. The drug was administered after intubation but before skin incision in the majority of cases (9/11). Glycopyrrolate was given to significantly more patients in group III (P<0.025) to treat bradycardia, and in 21 of a total of 34 patients given glycopyrrolate it was administered before surgery. With the use of these additional drugs, there were no differences in the number of patients with 5 min episodes of hypotension, hypertension, tachycardia or bradycardia. The intravenous techniques using propofol with or without nitrous oxide required more pharmacological interventions before surgery than the regular isoflurane-based technique in order to maintain a stable blood pressure level and heart rate during this period.