American Society of Anesthesiologists, 2006 Annual Meeting
A853
October 16, 2006
Room Hall E, Area C

Clinical Evaluation of the QED-100 Emergence Device
Robert R. Blocker, M.D., Derek J. Sakata, M.D., Nishant A. Gopalakrishnan, Ph.D., Joseph A. Orr, Ph.D., Dwayne R. Westenskow, Ph.D.

Introduction: To shorten emergence time after a procedure using volatile anesthesia many anesthesiologists use hyperventilation to rapidly clear the agent from the lungs. Hyperventilation has not been widely adapted into clinical practice because it also lowers the PaCO₂, which decreases cerebral blood flow and depresses respiratory drive. Adding dead space to the patient's airway may be a simple and safe method of maintaining a normal or slightly elevated PaCO₂ during hyperventilation. The device also incorporates activated charcoal to adsorb volatile agents from the rebreathed gas. We evaluated an emergence device (QED-100, Anecare Laboratories Inc, Salt Lake City, Utah) that allows simultaneous hyperventilation and hypercapnia during emergence.

Methods: After IRB approval, 16 ASA Class I and II patients scheduled for surgery were recruited for the study. Patients were randomly assigned to control and experimental groups. Anesthesia was maintained using 1 MAC of desflurane, 0.05-0.15 mcg/kg/min infusion of remifentanil and additional opioids as determined by the clinician. During anesthetic maintenance, patients were ventilated at 8 breaths per minute and the tidal volume was adjusted to maintain end-tidal CO₂ at 33 mmHg. Emergence was initiated when the adhesive wound closure strips were applied. The emergence protocol for the control group was to turn off the vaporizer and increase the fresh gas flow to 10 L/min. For the experimental group, emergence was initiated by turning off the vaporizer, activating the inline QED-100, doubling the minute ventilation and increasing the fresh gas flow to 10 L/min. Times to eye and mouth opening in response to command and time to extubation were recorded.

Results: The average time to opening eyes and extubation for the control group was 8.2±1.30 minutes and 8.5±1.53 minutes. For the experimental group the average time to opening eyes and extubation was 3.8±0.57 and 3.8±0.63 minutes respectively.

Discussion: The emergence device speeds emergence from desflurane anesthesia by 55%. Even though desflurane has a lower blood/gas solubility and already has a fast emergence profile, using the QED-100 to maintain hypercapnia with increased minute ventilation can still reduce emergence time. The results are possibly explained by decreased arterial partial pressure of agent due to hyperventilation and increased cerebral clearance of agent due to increased cerebral perfusion.