Vomiting, retching, headache and restlessness after halothane-, isoflurane- and enflurane-based anaesthesia. An analysis of pooled data following ear, nose, throat and eye surgery.

BACKGROUND: Isoflurane has exceeded halothane and enflurane in usage. A literature search, however, revealed no data comparing the effects on emesis, headache and restlessness of these three agents. METHODS: With hospital ethics committee approval and patient consent, a prospective, randomised, double-blind study of 556 patients undergoing ENT and eye surgery was undertaken to evaluate the effects of halothane, isoflurane and enflurane on vomiting, retching, headache and restlessness until 24 h after anaesthesia. Balanced general anaesthesia was administered comprising benzodiazepine premedication, induction with thiopentone-atracurium-morphine (ENT patients) or fentanyl (eye patients), controlled ventilation and maintenance with either halothane 0.4-0.6 vol% (n = 186), isoflurane 0.6-0.8 vol% (n = 184) or enflurane 0.8-1 vol% (n = 186) in nitrous oxide 67% and oxygen. RESULTS: The three study groups were comparable, and comprised comparable subgroups having ear, nose, throat, intraocular and non-intraocular surgery. During early recovery from anaesthesia, the respective requirements for halothane, isoflurane and enflurane for analgesia (7%, 9% and 10%), frequency of emesis (6%, 8% and 8%), antiemetic requirements (1%, 1% and 2%), restlessness-pain scores and time spent in the recovery ward (27 SD 10, 31 SD 12 and 26 SD 9 min) were similar. During the ensuing 24-h postoperative period, patients who had isoflurane experienced emesis less often than those who had halothane (36% vs 46%, P < 0.025) but did so with similar frequency to those who had enflurane (46% vs 41%). Antiemetic requirements were least in those given isoflurane (isoflurane 12%, halothane and enflurane 23% each, P < 0.005), but headache and analgesic requirements were similar. CONCLUSION: Isoflurane induces less postoperative emesis than halothane, but headache is similarly frequent after anaesthesia with any of these agents.

Choice of tracheal tube size for children: finger size or age-related formula?

A study was undertaken to compare the size of tracheal tube used for paediatric anaesthesia derived from either the diameter of the distal phalanx of the little or index finger, or from a standard formula (age in years/4 + 4.5 mm). The results showed that the diameter of the terminal phalanx was a poor predictor of the external diameter of the tube that provided the best fit. The mean (SD) diameters were 9.34 (1.02), 10.24 (1.23) and 7.56 (0.97) mm for the little finger, index finger and tracheal tube providing 'best fit', respectively. The formula provided a better correlation with the internal diameter of the chosen tracheal tube. The mean (SD) figures were 5.61 (0.75) and 5.70 (0.67) mm for the formula and the chosen tracheal tube, respectively. The use of the diameter of the terminal phalanx of either the little or the index finger is an unreliable measurement for the prediction of the tracheal tube size in paediatrics.