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

Sixty patients, ASA I-III, presenting for elective colonic surgery wer e studied to assess the stability of blood pressure and heart rate dur ing anaesthesia with three equally potent anaesthetic techniques. Pati ents 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 i ntravenous propofol supplemented with nitrous oxide. Fentanyl and vecu ronium were used in all three groups. The depth of anaesthesia was jud ged 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 p ressure greater than or equal to 30%, or systolic blood pressure > 15 mmHg, above pre-operative value) were recorded when lasting > 5 min. A ny use of ephedrine or glycopyrrolate given to correct hypotension or bradycardia was documented: In group II, significantly more patients w ere given ephedrine (P<0.01) to treat hypotension. The drug was admini stered after intubation but before skin incision in the majority of ca ses (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 n umber of patients with 5 min episodes of hypotension, hypertension, ta chycardia or bradycardia. The intravenous techniques using propofol wi th or without nitrous oxide required more pharmacological intervention s before surgery than the regular isoflurane-based technique in order to maintain a stable blood pressure level and heart rate during this p eriod.