Laboratório de Pneumologia, Laboratório de Investigação Médica 09, Disciplina de Pneumologia, Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
Instituto de Ensino e Pesquisa, Hospital Sírio-Libanes, São Paulo, São Paulo, Brazil.
Am J Respir Crit Care Med. 2021 Aug 1;204(3):303-311. doi: 10.1164/rccm.202009-3467OC.
Mortality in acute respiratory distress syndrome (ARDS) has decreased after the adoption of lung-protective strategies. Lower Vt, lower driving pressure (ΔP), lower respiratory rates (RR), and higher end-expiratory pressure have all been suggested as key components of lung protection strategies. A unifying theoretical explanation has been proposed that attributes lung injury to the energy transfer rate (mechanical power) from the ventilator to the patient, calculated from a combination of several ventilator variables. To assess the impact of mechanical power on mortality in patients with ARDS as compared with that of primary ventilator variables such as the ΔP, Vt, and RR. We obtained data on ventilatory variables and mechanical power from a pooled database of patients with ARDS who had participated in six randomized clinical trials of protective mechanical ventilation and one large observational cohort of patients with ARDS. The primary outcome was mortality at 28 days or 60 days. We included 4,549 patients (38% women; mean age, 55 ± 23 yr). The average mechanical power was 0.32 ± 0.14 J · min · kg of predicted body weight, the ΔP was 15.0 ± 5.8 cm HO, and the RR was 25.7 ± 7.4 breaths/min. The driving pressure, RR, and mechanical power were significant predictors of mortality in adjusted analyses. The impact of the ΔP on mortality was four times as large as that of the RR. Mechanical power was associated with mortality during controlled mechanical ventilation in ARDS, but a simpler model using only the ΔP and RR was equivalent.
急性呼吸窘迫综合征（ARDS）采用肺保护性策略后死亡率降低。更低的潮气量（Vt）、更低的驱动压（ΔP）、更低的呼吸频率（RR）和更高的呼气末正压（PEEP）都被认为是肺保护性策略的关键组成部分。一种统一的理论解释认为，呼吸机向患者传递的能量转移率（机械功率）导致了肺损伤，该理论是通过几个呼吸机变量的组合来计算的。评估机械功率对 ARDS 患者死亡率的影响，与 ΔP、Vt 和 RR 等主要呼吸机变量相比。我们从参与保护性机械通气的 6 项随机临床试验和一项大型 ARDS 患者观察队列的汇总数据库中获取了通气变量和机械功率的数据。主要结局是 28 天或 60 天的死亡率。我们纳入了 4549 名患者（38%为女性；平均年龄 55±23 岁）。平均机械功率为 0.32±0.14 J·min·kg 预测体重，ΔP 为 15.0±5.8 cm H2O，RR 为 25.7±7.4 次/分钟。调整后的分析显示，驱动压、RR 和机械功率是死亡率的显著预测因素。ΔP 对死亡率的影响是 RR 的四倍。在 ARDS 的控制机械通气中，机械功率与死亡率相关，但使用 ΔP 和 RR 的更简单模型同样有效。
