Thach B T, Menon A P, Schefft G L
Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis Children's Hospital, Missouri 63110.
J Appl Physiol (1985). 1989 Apr;66(4):1599-605. doi: 10.1152/jappl.1989.66.4.1599.
Negative upper airway (UAW) pressure inhibits diaphragm inspiratory activity in animals, but there is no direct evidence of this reflex in humans. Also, little is known regarding reflex latency or effects of varying time of stimulation during the breathing cycle. We studied effects of UAW negative pressure on inspiratory airflow and respiratory timing in seven tracheostomized infants during quiet sleep with a face mask and syringe used to produce UAW suction without changing lower airway pressure. Suction trials lasted 2-3 s. During UAW suction, mean and peak inspiratory airflow as well as tidal volume was markedly reduced (16-68%) regardless of whether stimulation occurred in inspiration or expiration. Reflex latency was 42 +/- 3 ms. When suction was applied during inspiration or late expiration, the inspiration and the following expiration were shortened. In contrast, suction applied during midexpiration prolonged expiration and tended to prolong inspiration. The changes in flow, tidal volume, and timing indicate a marked inhibitory effect of UAW suction on thoracic inspiratory muscles. Such a reflex mechanism may function in preventing pharyngeal collapse by inspiratory suction pressure.
上气道（UAW）负压可抑制动物的膈肌吸气活动，但尚无直接证据表明人类存在这种反射。此外，对于该反射潜伏期或呼吸周期中不同刺激时间的影响知之甚少。我们使用面罩和注射器在7名气管切开的婴儿安静睡眠期间产生UAW负压，研究UAW负压对吸气气流和呼吸时间的影响，同时不改变下气道压力。抽吸试验持续2 - 3秒。在UAW抽吸期间，无论刺激发生在吸气还是呼气阶段，平均和峰值吸气气流以及潮气量均显著降低（16 - 68%）。反射潜伏期为42±3毫秒。当在吸气或呼气末期进行抽吸时，吸气和随后的呼气会缩短。相比之下，在呼气中期进行抽吸会延长呼气并倾向于延长吸气。气流、潮气量和时间的变化表明UAW抽吸对胸部吸气肌有显著的抑制作用。这种反射机制可能在通过吸气负压防止咽部塌陷方面发挥作用。
