• Alison B Froese.
• Department of Anesthesiology & Perioperative Medicine, Queen's University, Victory 2, Kingston General Hospital, 76 Stuart Street, Kingston, ON, K7L 2V7, Canada, froesea@kgh.kari.net.
• Can J Anaesth. 2014 Apr 1;61(4):379-82.

PurposeIn 1978, Drs. R Knill and A. Gelb published the results of a study to measure the effect of subanesthetic levels of halothane on the ability of fit volunteers to respond to sustained hypoxia, and to determine how long potentially hazardous levels of halothane persist after a brief non-complex surgical procedure in healthy patients. The purpose of this commentary is to highlight the historical context of their findings and the impact of their work on our modern day practice of anesthesia.Principal FindingsIn six fit male volunteers, steady states of halothane reduced the ventilatory response to normocapnic hypoxemia (PETO2 40 mmHg) by ~ 50% at 0.05 MAC and by 70% at 0.10 MAC without affecting resting levels of ventilation. Subjects remained easily rousable and coherent with full memory of events. Symptoms of hypoxemia were markedly reduced or totally absent during hypoxic periods. In five patients recovering from dental procedures (mean duration 59 min), 0.10 MAC halothane levels persisted in the recovery room for approximately one hour.ConclusionsPatients emerging from a brief (about one hour) halothane anesthetic, although appearing conscious, may have a hazardous degree of depression of the usually protective ventilatory response to hypoxemia for about one hour in the recovery room. Both the symptoms and signs of hypoxemia will be substantially reduced during this emergence phase, enhancing the risk that severe hypoxic episodes may go unrecognized.AuthorsGelb AW, Knill RL.CitationSubanaesthetic halothane: Its effect on regulation of ventilation and relevance to the recovery room. Can Anaesth Soc J 1978; 25: 488-94.

18 keywords...

hide…