A simple apparatus for accelerating recovery from inhaled volatile anesthetics

Hyperpnea increases anesthetic elimination but is difficult to implement with current anesthetic circuits without decreasing arterial PCO2. To circumvent this, we modified a standard resuscitation bag to maintain isocapnia during hyperpnea without rebreathing by passively matching inspired PCO2 to minute ventilation. We evaluated the feasibility of using this apparatus to accelerate recovery from anesthesia in a pilot study in four isoflurane-anesthetized dogs. The apparatus was easy to use, and all dogs tolerated being ventilated with it. Under our experimental conditions, isocapnic hyperpnea reduced the time to extubation by 62%, from an average of 17.5 to 6.6 min (P = 0.012), but not time from extubation to standing unaided. This apparatus may provide a practical means of applying isocapnic hyperpnea to shorten recovery time from volatile anesthetics.

A simple modification to a standard resuscitation bag allows one to increase ventilation without decreasing blood carbon dioxide levels. In dogs, we confirmed that this circuit can be used to accelerate the elimination of and recovery from volatile anesthetics.