Parreira V F, Delguste P, Jounieaux V, Aubert G, Dury M, Rodenstein D O
Pneumology Unit, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium.
Chest. 1997 Nov 5;112(5):1267-77. doi: 10.1378/chest.112.5.1267.
The purpose of the present study was to compare in awake and asleep healthy subjects, under nasal intermittent positive pressure ventilation (nIPPV) with a two-level intermittent positive pressure device (two-level nIPPV), the efficacy of the controlled and spontaneous modes, and of different ventilator settings in increasing effective minute ventilation (VE).
Eight healthy subjects were studied.
In the controlled mode, inspiratory positive airway pressure (IPAP) was kept at 15 cm H2O, expiratory positive airway pressure (EPAP) at 4 cm H2O, and the inspiratory/expiratory (I/E) time ratio at 1. The respirator frequencies were 17 and 25/min. In the spontaneous mode experiment, IPAP was started at 10 cm H2O and progressively increased to 15 and 20 cm H2O; EPAP was kept at 4 cm H2O.
We measured breath by breath the effective tidal volume (VT with respiratory inductive plethysmography), actual respiratory frequency (f), and effective VE. Using the controlled mode, effective VE was significantly higher on nIPPV than during spontaneous unassisted breathing, except in stage 2 nonrapid eye movement sleep at 17/min of frequency; increases in f from 17 to 25/min led to a significant decrease in VT reaching the lungs, during wakefulness and sleep; effective VE was higher at 25 than at 17/min of frequency only during sleep; periodic breathing was scarce and apneas were never observed. Using the spontaneous mode, with respect to awake spontaneous unassisted breathing, two-level nIPPV at 10 and 15 cm H2O of IPAP did not result in any significant increase in effective VE either in wakefulness or in sleep; only IPAP levels of 20 cm H2O resulted in a significant increase in effective VE; during sleep, effective VE was significantly lower than during wakefulness; respiratory rhythm instability (ie, periodic breathing and central apneas) were exceedingly common, and in some subjects extremely frequent, leading to surprisingly large falls in arterial oxygen saturation.
It appears that two-level nIPPV should be used in the controlled mode rather than in the spontaneous mode, since it seems easier to increase effective VE with a lower IPAP at a high frequency than at a high pressure using the spontaneous mode. We suggest that the initial respirator settings in the controlled mode should be an f around 20/min, an I/E ratio of 1, 15 cm H2O of IPAP, and EPAP as low as possible.
本研究旨在比较在清醒和睡眠状态的健康受试者中，使用两级间歇正压通气设备进行鼻间歇正压通气（nIPPV）时，控制模式和自主模式以及不同呼吸机设置在增加有效分钟通气量（VE）方面的效果。
对8名健康受试者进行了研究。
在控制模式下，吸气气道正压（IPAP）保持在15 cm H₂O，呼气气道正压（EPAP）保持在4 cm H₂O，吸呼比（I/E）为1。呼吸频率分别为17次/分钟和25次/分钟。在自主模式实验中，IPAP从10 cm H₂O开始，逐渐增加到15 cm H₂O和20 cm H₂O；EPAP保持在4 cm H₂O。
我们逐次测量了有效潮气量（通过呼吸感应体积描记法测量VT）、实际呼吸频率（f）和有效VE。使用控制模式时，除了在非快速眼动睡眠2期频率为17次/分钟时，nIPPV时的有效VE显著高于自主非辅助呼吸时；清醒和睡眠期间，频率从17次/分钟增加到25次/分钟导致到达肺部的VT显著减少；仅在睡眠期间，频率为25次/分钟时的有效VE高于17次/分钟时；周期性呼吸很少见，从未观察到呼吸暂停。使用自主模式时，与清醒自主非辅助呼吸相比，IPAP为10 cm H₂O和15 cm H₂O的两级nIPPV在清醒和睡眠状态下均未使有效VE有任何显著增加；仅IPAP水平为20 cm H₂O时有效VE显著增加；睡眠期间，有效VE显著低于清醒时；呼吸节律不稳定（即周期性呼吸和中枢性呼吸暂停）非常常见，在一些受试者中极其频繁，导致动脉血氧饱和度惊人地大幅下降。
似乎两级nIPPV应使用控制模式而非自主模式，因为在高频下使用较低的IPAP比在自主模式下使用高压似乎更容易增加有效VE。我们建议控制模式下初始呼吸机设置应为频率约20次/分钟、I/E比为1、IPAP为15 cm H₂O且EPAP尽可能低。
