REBREATHING ABSORBER TO SPEED EMERGENCE FROM ANESTHESIA

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DESCRIPTION (provided by applicant): When general anesthesia is administered, anesthetics in the form of vapors are delivered to a patient in 1% to 5% concentrations. Once the surgical procedure has been completed and anesthesia is no longer administered, blood carries the inhaled anesthetic from the brain to the lungs where it is exhaled from the body. The higher the brain blood flow and the ventilation rate, the quicker the effects of the general anesthetic are reversed and the faster the patient wakes up. Axon Medical has developed a simple device to shorten the wake up time. The device's rebreathing hose indirectly increases the patient's arterial CO2 concentration thereby increasing brain blood flow and increasing the rate at which blood carries anesthetic agents from the brain to the lungs. The device contains activated charcoal that rapidly absorbs anesthetic vapor as it leaves the lungs to prevent it from being rebreathed. We evaluated the device in a study with nine pigs. It shortened wake up times by an average of 14.5 minutes when isoflurane was used and 10.5 minutes when sevoflurane was used. In a clinical study with 12 patients anesthetized with isoflurane, the device shortened emergence times by 9.8 minutes. The Phase I proposal includes an engineering task to optimize the device's design, a human factors test of device usability and a clinical study where half the patients will use the rebreathing absorber. We will measure differences in wake up times with and without the device by asking an anesthesiologist to review video tapes (blinded to the presence of the device) and mark the time to return of spontaneous breathing, spontaneous eye opening, mouth opening to verbal command, and removal of the endotracheal tube. It is expected that the rebreathing absorber will shorten the wake up time by at least eight minutes. We will use the clinical data to develop a computer model of the physiologic processes involved during wake up. We will use the model to determine what should be included in the device's instructions so that clinicians will use the device most effectively. Use of the rebreathing/absorber device to shorten wake up time after inhaled anesthesia could potentially reduce the overall cost of surgery in each of the 20 million general anesthetic procedures performed in the United States each year. Shorter wake up times might decrease the overall time needed for surgery and improve the efficiency of the operating room staff and the use of hospital facilities.