Pulmonary Division, Heart Institute (InCor), University of São Paulo School of Medicine, São Paulo, Brazil.
J Appl Physiol (1985). 2011 Nov;111(5):1315-22. doi: 10.1152/japplphysiol.00508.2011. Epub 2011 Aug 18.
The critical closing pressure (Pcrit) is the airway pressure at which the airway collapses and reflects the anatomical contribution to the genesis of obstructive sleep apnea. Pcrit is usually determined during non-rapid eye movement sleep at night, but has been determined under midazolam sedation during the day in the absence of sleep stage monitoring. Indeed, little is known about the effects of midazolam on sleep architecture. Moreover, deeper sedation with midazolam can decrease upper airway muscle activity and increase collapsibility compared with natural sleep. Pcrit under sedation has not been systematically compared with the usual method performed during natural sleep. Therefore, this study aimed to test the hypothesis that Pcrit following low doses of midazolam during the day would be comparable to Pcrit measured during natural sleep in the same patient. Fifteen men (age 54 ± 10 yr, body mass index 30 ± 4 kg/m(2)) with obstructive sleep apnea underwent a baseline standard overnight polysomnogram (apnea-hypopnea index 38 ± 22 events/h, range: 8-66 events/h), and Pcrit was determined during natural sleep and following midazolam. Sleep induction was obtained with low doses of midazolam (2.4 mg, range 2.0-4.4 mg), and sleep architecture was comparable to natural sleep. Natural sleep and induced sleep Pcrit were similar (-0.82 ± -3.44 and -0.97 ± 3.21 cmH(2)O, P = 0.663) and closely associated (intraclass correlation coefficient = 0.92; 95% confidence interval, 0.78-0.97, P < 0.001). Natural and midazolam-induced Pcrit correlated with obstructive sleep apnea severity, indicating that both Pcrit measures provided meaningful physiological information. Pcrit determined during the day with sleep induction is similar to natural overnight sleep and is a valid alternative approach in which to determine Pcrit.
临界闭合压力（Pcrit）是气道塌陷时的气道压力，反映了阻塞性睡眠呼吸暂停的解剖学贡献。Pcrit 通常在夜间非快速眼动睡眠期间确定，但在没有睡眠阶段监测的情况下，在白天咪达唑仑镇静下也可以确定。实际上，人们对咪达唑仑对睡眠结构的影响知之甚少。此外，与自然睡眠相比，咪达唑仑的更深镇静可降低上气道肌肉活动并增加塌陷性。镇静下的 Pcrit 尚未与自然睡眠期间通常进行的方法进行系统比较。因此，本研究旨在检验以下假设：白天给予低剂量咪达唑仑后，Pcrit 与同一患者自然睡眠期间测量的 Pcrit 相比是可比的。15 名男性（年龄 54 ± 10 岁，体重指数 30 ± 4 kg/m²）患有阻塞性睡眠呼吸暂停，进行了基线标准过夜多导睡眠图（呼吸暂停低通气指数 38 ± 22 次/小时，范围：8-66 次/小时），并在自然睡眠和咪达唑仑后测量了 Pcrit。使用低剂量咪达唑仑（2.4 mg，范围 2.0-4.4 mg）进行睡眠诱导，并且睡眠结构与自然睡眠相似。自然睡眠和诱导睡眠的 Pcrit 相似（-0.82 ± -3.44 和-0.97 ± 3.21 cmH2O，P = 0.663），并且密切相关（组内相关系数= 0.92；95%置信区间，0.78-0.97，P < 0.001）。自然和咪达唑仑诱导的 Pcrit 与阻塞性睡眠呼吸暂停的严重程度相关，表明两种 Pcrit 测量均提供了有意义的生理信息。白天通过睡眠诱导确定的 Pcrit 与夜间自然睡眠相似，是确定 Pcrit 的有效替代方法。
