科研之友
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摘要
Purpose: To evaluate the efficacy of delivering a mixture of helium and oxygen gas (He-O(2)) in spontaneous ventilation. Three high oxygen flow reservoir masks were tested: the Heliox21, specifically designed for helium; the Hi-Ox(80) mask, with an inspiratory and an expiratory valve; and a standard high-concentration face mask. Methods: This prospective randomized crossover study was performed in six healthy volunteers in a laboratory setting. Volunteers breathed a mixture of 78% He/22% O(2) through each of the masks under two different breathing conditions (rest and hyperventilation: minute ventilation of 14.9 +/- 6.1 and 26.7 +/- 8.7 L min(-1), respectively) and four different He-O(2) flow rates (7, 10, 12, and 15 L min(-1)). Results: A nasopharyngeal catheter was used to estimate He pharyngeal concentration (Fp [He]) in the airways in order to determine the percentage of contamination with room air (% air cont) at end-expiration. Under all testing conditions, the Hi-Ox(80) mask presented a significantly lower % air cont. During resting breathing pattern, a Fp [He] higher than 50% was achieved in 54% of the tests performed with the Hi-Ox(80) mask compared to 29% for the Heliox21 mask and only 17% for the standard mask. At hyperventilation, a Fp [He] higher than 50% was achieved in 17% of the tests performed with the Hi-Ox mask compared to 4% for the other two masks. Conclusion: He-O(2) administration via the usual high-concentration reservoir masks results in significant dilution by room air. The Hi-Ox(80) mask minimized room air contamination and much more frequently achieved a pharyngeal He concentration higher than 50%.
- 出版日期2011-11
