Canadian Journal of Anesthesia, Vol 25, 488-494, Copyright © 1978 by Canadian Anesthesiologists' Society

Subanaesthetic Halothane: Its Effect on Regulation of Ventilation and Relevance to the Recovery Room

¹ Department of Anaesthesia, University of Toronto
² Department of Anaesthesia, University Hospital, University of Western Ontario, London, Canada

Address reprint requests to Dr. R.L. Knill, Department of Anaesthesia, P.O. Box 5339, Postal Station "A", London, Ontario, N6A 5A5.

Ventilation and the ventilatory response to a steady-state of isocapnic hypoxaemia were measured in six healthy volunteers, both awake and while sedated with low doses of halothane (0.05 and 0.1 MAC). Halothane sedation markedly reduced ventilatory responses to sustained hypoxaemia, in a dose-related fashion.

We estimated the length of time after anaesthesia that halothane 0.1 MAC would be present in patients in the recovery room. In five healthy patients who had halothane anaesthesia with a mean duration of one hour, halothane 0.1 MAC or more persisted for approximately one hour.

We conclude that, during emergence from halothane anaesthesia, patients may have a significant impairment of the ventilatory response to hypoxaemia, which persists for some time even after regaining consciousness.

Note:

A portion of this paper was presented in the Resident's Competition of the Canadian Anaesthetists' Society Annual Meeting in Saskatoon, Saskatchewan in June. 1977.