关于COVID-19相关呼吸衰竭时程肺部呼吸力学和气体交换的数据有限。本研究旨在探索呼吸力学和气体交换,在机械通气的时间过程中,肺部可招募性和过度扩张的风险。
这是一项前瞻性观察性研究,在谢切诺夫大学重症监护病房收治的危重机械通气患者(n=116)中接受了COVID-19。主要终点是:在最低驱动压力和最高SpO2之间平衡的“最佳”呼气末正压(PEEP)水平以及机械通气第1天和第7天的可招募肺患者人数。我们在预设潮气量的不同PEEP水平(14、12、10和8cmH2O)下测量了驱动压力,并且在预设的PEEP水平下,随着潮气量增加100毫升和200毫升,并计算出静态呼吸系统顺应性(CRS),第1、3、5、7、10、14和21天的PaO2/FiO2、肺泡死腔和通气比。
第1天的“最佳”PEEP水平为11.0(10.0-12.8)cmH2O和第7天的10.0(9.0-12.0)cmH2O。在第1天观察到27.6%的患者对募集的阳性反应,在第7天观察到9.2%的患者对募集的阳性反应。PEEP从10增加到14cmH2O和VT增加100和200ml导致CRS从第1天到第14天显著降低(p<0.05)。在第1天,非幸存者和1.9(1.6-2.6)幸存者的通气比率为2.2(1.7-2,7),仅在第7天幸存者中降低(p<0.01)。第1天非幸存者的PaO2/FiO2为105.5(76.2-141.7)mmHg,幸存者为136.6(106.7-160.8)(p=0.002)。在幸存者中,PaO2/FiO2在第3天上升(p=0.008),然后在第7和10天之间上升(p=0.046)。
COVID-19的肺部招募能力较低,并且在疾病过程中有所下降,但肺过度扩张发生在“中间”PEEP和VT水平。在第7天错配CRS后的幸存者气体交换改善。
ClinicalTrials.gov,NCT04445961。注册2020年6月24日-追溯注册。
Data on the lung respiratory mechanics and gas exchange in the time course of COVID-19-associated respiratory failure is limited. This study aimed to explore respiratory mechanics and gas exchange, the lung recruitability and risk of overdistension during the time course of mechanical ventilation.
This was a prospective observational study in critically ill mechanically ventilated patients (n = 116) with COVID-19 admitted into Intensive Care Units of Sechenov University. The primary endpoints were: «optimum» positive end-expiratory pressure (PEEP) level balanced between the lowest driving pressure and the highest SpO2 and number of patients with recruitable lung on Days 1 and 7 of mechanical ventilation. We measured driving pressure at different levels of PEEP (14, 12, 10 and 8 cmH2O) with preset tidal volume, and with the increase of tidal volume by 100 ml and 200 ml at preset PEEP level, and calculated static respiratory system compliance (CRS), PaO2/FiO2, alveolar dead space and ventilatory ratio on Days 1, 3, 5, 7, 10, 14 and 21.
The «optimum» PEEP levels on Day 1 were 11.0 (10.0-12.8) cmH2O and 10.0 (9.0-12.0) cmH2O on Day 7. Positive response to recruitment was observed on Day 1 in 27.6% and on Day 7 in 9.2% of patients. PEEP increase from 10 to 14 cmH2O and VT increase by 100 and 200 ml led to a significant decrease in CRS from Day 1 to Day 14 (p < 0.05). Ventilatory ratio was 2.2 (1.7-2,7) in non-survivors and in 1.9 (1.6-2.6) survivors on Day 1 and decreased on Day 7 in survivors only (p < 0.01). PaO2/FiO2 was 105.5 (76.2-141.7) mmHg in non-survivors on Day 1 and 136.6 (106.7-160.8) in survivors (p = 0.002). In survivors, PaO2/FiO2 rose on Day 3 (p = 0.008) and then between Days 7 and 10 (p = 0.046).
Lung recruitability was low in COVID-19 and decreased during the course of the disease, but lung overdistension occurred at «intermediate» PEEP and VT levels. In survivors gas exchange improvements after Day 7 mismatched CRS.
ClinicalTrials.gov, NCT04445961 . Registered 24 June 2020-Retrospectively registered.