Krishnan B S, Clemens R E, Zintel T A, Stockwell M J, Gallagher C G
Division of Respiratory Medicine, Department of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 0W8.
J Appl Physiol (1985). 1997 Jul;83(1):82-8. doi: 10.1152/jappl.1997.83.1.82.
The substitution of a normoxic helium mixture (HeO2) for room air (Air) during exercise results in a sustained hyperventilation, which is present even in the first breath. We hypothesized that this response is dependent on intact airway afferents; if so, airway anesthesia (Anesthesia) should affect this response. Anesthesia was administered to the upper airways by topical application and to lower central airways by aerosol inhalation and was confirmed to be effective for over 15 min. Subjects performed constant work-rate exercise (CWE) at 69 +/- 2 (SE) % maximal work rate on a cycle ergometer on three separate days: twice after saline inhalation (days 1 and 3) and once after Anesthesia (day 2). CWE commenced after a brief warm-up, with subjects breathing Air for the first 5 min (Air-1), HeO2 for the next 3 min, and Air again until the end of CWE (Air-2). The resistance of the breathing circuit was matched for Air and HeO2. Breathing HeO2 resulted in a small but significant increase in minute ventilation (VI) and decrease in alveolar PCO2 in both the Saline (average of 2 saline tests; not significant) and Anesthesia tests. Although Anesthesia had no effect on the sustained hyperventilatory response to HeO2 breathing, the VI transients within the first six breaths of HeO2 were significantly attenuated with Anesthesia. We conclude that the VI response to HeO2 is not simply due to a reduction in external tubing resistance and that, in humans, airway afferents mediate the transient but not the sustained hyperventilatory response to HeO2 breathing during exercise.
运动期间用常氧氦混合气（HeO2）替代室内空气（Air）会导致持续的通气过度，即使在第一口气时就已出现。我们推测这种反应依赖于完整的气道传入神经；如果是这样，气道麻醉（Anesthesia）应该会影响这种反应。通过局部应用对上部气道进行麻醉，并通过气溶胶吸入对下部中央气道进行麻醉，且证实其有效性超过15分钟。受试者在三天内分别在自行车测力计上以69±2（标准误）%的最大工作率进行恒定工作率运动（CWE）：两次在吸入盐水后（第1天和第3天），一次在麻醉后（第2天）。CWE在短暂热身之后开始，受试者在前5分钟呼吸Air（Air-1），接下来3分钟呼吸HeO2，然后再次呼吸Air直至CWE结束（Air-2）。呼吸回路对Air和HeO2的阻力进行了匹配。在盐水组（两次盐水测试的平均值；无显著差异）和麻醉组测试中，呼吸HeO2均导致分钟通气量（VI）小幅但显著增加以及肺泡PCO2降低。尽管麻醉对HeO2呼吸引起的持续通气过度反应没有影响，但HeO2呼吸开始的前六次呼吸内的VI瞬变在麻醉后显著减弱。我们得出结论，对HeO2的VI反应并非仅仅由于外部管道阻力降低所致，而且在人类中，气道传入神经介导了运动期间对HeO2呼吸的瞬态而非持续通气过度反应。
