Valta P, Corbeil C, Chassé M, Braidy J, Milic-Emili J
Respiratory Division, Hôpital Saint-Luc, Université de Montréal, Quebec, Canada.
Am J Respir Crit Care Med. 1996 Jun;153(6 Pt 1):1825-30. doi: 10.1164/ajrccm.153.6.8665041.
Mean airway pressure (Pao) has been advocated as a useful index for monitoring hemodynamic performance and risk for barotrauma during mechanical ventilation. This is based on the assumption that Pao closely reflects mean alveolar pressure (Palv). In the present study we have compared Pao with Palv in 12 sedated, paralyzed, mechanically ventilated patients. External PEEP ranged from 0.3 to 8.9 cm H2O. Palv was estimated by measuring Pao after rapid flow interruptions made at different points in time of the breathing cycle, using a modification of the method of Fuhrman and coworkers (4). All subjects exhibited intrinsic PEEP (PEEPi), which ranged from 0.5 to 9.4 cm H2O. A significant negative correlation (p < 0.001) was found between Pao/Palv and PEEPi. On average, at PEEPi of 10 cm H2O, Pao underestimated Palv by about 50%. We conclude that Pao cannot be taken as an index of Palv in patients who exhibit dynamic hyperinflation and PEEPi caused by expiratory flow limitation.
平均气道压（Pao）一直被认为是机械通气期间监测血流动力学表现和气压伤风险的有用指标。这是基于Pao能密切反映平均肺泡压（Palv）这一假设。在本研究中，我们比较了12例接受镇静、肌松和机械通气患者的Pao与Palv。外部呼气末正压（PEEP）范围为0.3至8.9 cmH₂O。采用对Fuhrman及其同事（4）方法的改良，通过在呼吸周期不同时间点进行快速气流中断后测量Pao来估算Palv。所有受试者均表现出内源性呼气末正压（PEEPi），范围为0.5至9.4 cmH₂O。发现Pao/Palv与PEEPi之间存在显著负相关（p < 0.001）。平均而言，在PEEPi为10 cmH₂O时，Pao低估Palv约50%。我们得出结论，对于表现出由呼气气流受限导致的动态肺过度充气和PEEPi的患者，Pao不能被视为Palv的指标。
