Hypercapnic Hyperpnoea during Emergence with the QED-100 Shortens the
Time to Awake in the OR and Oriented in the PACU
Copyright 2009 International Anesthesia Research Society

D. Sakata¹, D. Westenskow², N. Syroid², D. Tyler², J. White², C. Jacobson²;
Anesthesiology, University of Utah, Salt Lake City, UT ¹, University of Utah, Salt Lake City, UT²

INTRODUCTION: A more rapid return of responsiveness occurs after inhaled anesthesia when hypercapnia and hyperpnoea are used during emergence^1-4. The benefits extend into the post anesthesia care unit⁵. This study measured the decrease in time to meet recovery criteria in the PACU when hypercapnic hyperpnoea was used during emergence in the operating room.

METHODS: Written informed consent was obtained from 22 adult ASA class I-III patients scheduled to undergo eye surgery. Anesthesia was provided with 6% desflurane and a remifentanil infusion. At the end of surgery patients were randomly assigned to one of the two treatment groups. In the experimental group a QED-100 (Anecare Inc., Salt Lake City, UT) was placed between the endotracheal tube and the anesthesia breathing circuit and the respiratory rate was doubled.

RESULTS: When the QED-100 was used to provide hypercapnic hyperpnoea during emergence (respiratory rate was doubled and the EtCO2 was elevated to 48 mmHg, rather than 35 mmHg) the time from the end of surgery to when patients opened their eyes to command was 4.1 + 1.4 min whereas the time for the control group was 6.5 + 2.3 min (P = 0.009). The time from the end of surgery until the patient became oriented and could correctly state their full name, date, month and year of birth and the current year was 10.9 + 5.1 min for the hypercapnic group and 18.2 + 9.7 for the control group (P = 0.039).

Figure 1: Time to reach each stage of recovery after surgery. The dark gray bars are times for the QED-100 hypercapnic hyperpnoea group. The light gray bars are for the control group. *P<0.05

DISCUSSION: When the QED-100 provided hypercapnic hyperpnoea during emergence patients wake up 2.4 min faster. The benefits of hypercapnic hyperpnoea extend into the PACU where the patients were oriented sooner (could correctly state their name and birthday). An awake and oriented PACU patient may be at lower risk for airway obstruction and respiratory depression⁶. Better predictability of recovery times can allow for better planning of recovery room care and discharge.

References:
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2. Clinical Implications of Inhaled Anesthetic. Lippincott Williams & Wilkins: Philadelphia Penn 2002.
3. Anesth Analg 2007;104:815-21.
4. Br J Anaesth 2003;91:787.
5. Can J Anesth 2006 Jun; 53:26357.
6. Anesth Analg 2008;107:1543-63.