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A189
October 17, 2009 10:00 AM - 11:30 AM Room Room 356 |
| Hypercapnic Hyperpnoea during Emergence with the QED-100 Reduces PONV |
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* Dwayne Westenskow, Ph.D., Noah Syroid, M.S., Cameron Jacobson, B.S., Joseph Orr, Ph.D., Derek Sakata, M.D. Anesthesiology, University of Utah, Salt Lake City, Utah |
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Introduction:
Return of responsiveness after inhaled anesthesia occurs sooner with hypercapnia and increased minute ventilation.[1-4] Hyperventilation increases the rate of elimination of volatile anesthetics from the lungs. Hypercapnia increases cerebral blood flow and the rate of elimination from the brain tissue. The benefits of hypercapnia may continue during the post anesthesia care period with lower sub-anesthetic concentrations and enhanced respiratory drive.[5]
Methods: We studied 22 patients who received desflurane during eye surgery. The QED-100 (Anecare Inc, Salt Lake City, Utah) was used during emergence for 11 of the patients. These patients in the experimental group were hypercapnic and were ventilated with twice the minute ventilation during emergence. The study nurse that received the patients in the PACU was unaware as to whether the patients were in the experimental or control group. Every ten minutes the study nurse asked the patients to rate their level of nausea and administered rescue antiemetics (ondansetron, promethazine or droperidol) as needed. Results: When the QED-100 was used to provide hypercapnic hyperpnoea during emergence the P et CO 2 was elevated to an average of 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 vs. 6.5 ± 2.3 min (P = 0.009). The time until the patients 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 vs. 18.2 + 9.7 (P = 0.039). Figure 1 shows the results when the study nurse asked the patients if they were experiencing mild, moderate or severe nausea. Their responses are plotted with light gray showing mild nausea and dark gray showing moderate nausea. The patients in each group were rank ordered from left to right by the severity of their nausea. Six control and three experimental patients reported nausea. Vomiting occurred in one control patient. Five patients in the control group and one in the experimental group were given rescue antiemetics. A Wilcoxon-Mann-Whitney test reports that the distribution of the PACU antiemetics dosing was statistically different (P < 0.05) and the point estimate of shift in median values is one dose different.[figure1] Conclusions: When hypercapnic hyperpnoea was used during emergence there was a reduction in the utilization of rescue antiemetics. Eye muscle surgery patients may receive particular benefit as they are more susceptible to nausea because of the altered eye-muscle coordination. Hypercapnic hyperpnoea statistically decrease time for cognitive recovery. A more awake and oriented PACU patient may be at lower risk for airway obstruction and respiratory depression. References: 1. Anesth Analg 2001;93:1188-91. 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. From Proceedings of the 2009 Annual Meeting of the American Society Anesthesiologists. |
Figure 1
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