From the Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy (G.B., A.G., S.S., S.G., G.F.) Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy (G.B., A.G., S.S., S.G., G.F.) Departments of Critical Care Medicine and Anesthesia, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada (B.P.K.) Department of Anesthesia, Critical Care and Emergency Medicine, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy (A.P.).
Anesthesiology. 2019 Sep;131(3):594-604. doi: 10.1097/ALN.0000000000002846.
Higher driving pressure during controlled mechanical ventilation is known to be associated with increased mortality in patients with acute respiratory distress syndrome.Whereas patients with acute respiratory distress syndrome are initially managed with controlled mechanical ventilation, as they improve, they are transitioned to assisted ventilation. Whether higher driving pressure assessed during pressure support (assisted) ventilation can be reliably assessed and whether higher driving pressure is associated with worse outcomes in patients with acute respiratory distress syndrome has not been well studied.
This study shows that in the majority of adult patients with acute respiratory distress syndrome, both driving pressure and respiratory system compliance can be reliably measured during pressure support (assisted) ventilation.Higher driving pressure measured during pressure support (assisted) ventilation significantly associates with increased intensive care unit mortality, whereas peak inspiratory pressure does not.Lower respiratory system compliance also significantly associates with increased intensive care unit mortality.
Driving pressure, the difference between plateau pressure and positive end-expiratory pressure (PEEP), is closely associated with increased mortality in patients with acute respiratory distress syndrome (ARDS). Although this relationship has been demonstrated during controlled mechanical ventilation, plateau pressure is often not measured during spontaneous breathing because of concerns about validity. The objective of the present study is to verify whether driving pressure and respiratory system compliance are independently associated with increased mortality during assisted ventilation (i.e., pressure support ventilation).
This is a retrospective cohort study conducted on 154 patients with ARDS in whom plateau pressure during the first three days of assisted ventilation was available. Associations between driving pressure, respiratory system compliance, and survival were assessed by univariable and multivariable analysis. In patients who underwent a computed tomography scan (n = 23) during the stage of assisted ventilation, the quantity of aerated lung was compared with respiratory system compliance measured on the same date.
In contrast to controlled mechanical ventilation, plateau pressure during assisted ventilation was higher than the sum of PEEP and pressure support (peak pressure). Driving pressure was higher (11 [9-14] vs. 10 [8-11] cm H2O; P = 0.004); compliance was lower (40 [30-50] vs. 51 [42-61] ml · cm H2O; P < 0.001); and peak pressure was similar, in nonsurvivors versus survivors. Lower respiratory system compliance (odds ratio, 0.92 [0.88-0.96]) and higher driving pressure (odds ratio, 1.34 [1.12-1.61]) were each independently associated with increased risk of death. Respiratory system compliance was correlated with the aerated lung volume (n = 23, r = 0.69, P < 0.0001).
In patients with ARDS, plateau pressure, driving pressure, and respiratory system compliance can be measured during assisted ventilation, and both higher driving pressure and lower compliance are associated with increased mortality.
在急性呼吸窘迫综合征患者中，控制性机械通气时较高的驱动压与死亡率增加相关。虽然急性呼吸窘迫综合征患者最初采用控制性机械通气进行治疗，但随着病情的改善，会逐渐过渡到辅助通气。在压力支持（辅助）通气期间评估的较高驱动压是否可以可靠地评估，以及在急性呼吸窘迫综合征患者中较高的驱动压是否与较差的预后相关，尚未得到很好的研究。
本研究表明，在大多数急性呼吸窘迫综合征成年患者中，在压力支持（辅助）通气期间，驱动压和呼吸系统顺应性均可可靠测量。在压力支持（辅助）通气期间测量的较高驱动压与重症监护病房死亡率增加显著相关，而峰压则没有。较低的呼吸系统顺应性也与重症监护病房死亡率增加显著相关。
在急性呼吸窘迫综合征（ARDS）患者中，驱动压（平台压与呼气末正压（PEEP）之间的差值）与死亡率增加密切相关。尽管这一关系在控制性机械通气中已经得到了证实，但由于对有效性的担忧，在自主呼吸期间通常不会测量平台压。本研究的目的是验证在辅助通气（即压力支持通气）期间，驱动压和呼吸系统顺应性是否与死亡率增加独立相关。
这是一项对 154 例接受 ARDS 辅助通气的患者进行的回顾性队列研究，在这些患者中，在辅助通气的前三天内获得了平台压数据。通过单变量和多变量分析评估驱动压、呼吸系统顺应性和生存率之间的关系。在接受计算机断层扫描（n = 23）的患者中，比较了通气期间测量的呼吸系统顺应性与同一日期的充气肺量。
与控制性机械通气不同，辅助通气时的平台压高于 PEEP 和压力支持之和（峰压）。驱动压更高（11 [9-14] vs. 10 [8-11] cm H2O；P = 0.004）；顺应性更低（40 [30-50] vs. 51 [42-61] ml · cm H2O；P < 0.001）；峰压相似，在幸存者与非幸存者之间。较低的呼吸系统顺应性（比值比，0.92 [0.88-0.96]）和较高的驱动压（比值比，1.34 [1.12-1.61]）均与死亡风险增加独立相关。呼吸系统顺应性与充气肺量相关（n = 23，r = 0.69，P < 0.0001）。
在 ARDS 患者中，在辅助通气期间可以测量平台压、驱动压和呼吸系统顺应性，较高的驱动压和较低的顺应性均与死亡率增加相关。
