急性呼吸窘迫综合征中的开放压力和萎陷伤。
Opening pressures and atelectrauma in acute respiratory distress syndrome.
机构信息
Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milan, Italy.
Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy.
出版信息
Intensive Care Med. 2017 May;43(5):603-611. doi: 10.1007/s00134-017-4754-8. Epub 2017 Mar 10.
PURPOSE
Open lung strategy during ARDS aims to decrease the ventilator-induced lung injury by minimizing the atelectrauma and stress/strain maldistribution. We aim to assess how much of the lung is opened and kept open within the limits of mechanical ventilation considered safe (i.e., plateau pressure 30 cmHO, PEEP 15 cmHO).
METHODS
Prospective study from two university hospitals. Thirty-three ARDS patients (5 mild, 10 moderate, 9 severe without extracorporeal support, ECMO, and 9 severe with it) underwent two low-dose end-expiratory CT scans at PEEP 5 and 15 cmHO and four end-inspiratory CT scans (from 19 to 40 cmHO). Recruitment was defined as the fraction of lung tissue which regained inflation. The atelectrauma was estimated as the difference between the intratidal tissue collapse at 5 and 15 cmHO PEEP. Lung ventilation inhomogeneities were estimated as the ratio of inflation between neighboring lung units.
RESULTS
The lung tissue which is opened between 30 and 45 cmHO (i.e., always closed at plateau 30 cmHO) was 10 ± 29, 54 ± 86, 162 ± 92, and 185 ± 134 g in mild, moderate, and severe ARDS without and with ECMO, respectively (p < 0.05 mild versus severe without or with ECMO). The intratidal collapses were similar at PEEP 5 and 15 cmHO (63 ± 26 vs 39 ± 32 g in mild ARDS, p = 0.23; 92 ± 53 vs 78 ± 142 g in moderate ARDS, p = 0.76; 110 ± 91 vs 89 ± 93, p = 0.57 in severe ARDS without ECMO; 135 ± 100 vs 104 ± 80, p = 0.32 in severe ARDS with ECMO). Increasing the applied airway pressure up to 45 cmHO decreased the lung inhomogeneity slightly (but significantly) in mild and moderate ARDS, but not in severe ARDS.
CONCLUSIONS
Data show that the prerequisites of the open lung strategy are not satisfied using PEEP up to 15 cmHO and plateau pressure up to 30 cmHO. For an effective open lung strategy, higher pressures are required. Therefore, risks of atelectrauma must be weighted versus risks of volutrauma.
TRIAL REGISTRATION
Clinicaltrials.gov identifier: NCT01670747 ( www.clinicaltrials.gov ).
目的
急性呼吸窘迫综合征（ARDS）期间的肺开放策略旨在通过最小化肺萎陷伤和压力/应变分布不均来减少呼吸机所致肺损伤。我们旨在评估在考虑安全的机械通气范围内（即平台压 30cmH₂O，PEEP 15cmH₂O）有多少肺被打开并保持开放。
方法
这是一项来自两家大学医院的前瞻性研究。33 名 ARDS 患者（轻度 5 例，中度 10 例，无体外膜肺氧合（ECMO）支持的重度 9 例，ECMO 支持的重度 9 例）分别在 PEEP 5cmH₂O 和 15cmH₂O 时进行两次低剂量呼气末 CT 扫描，在 19cmH₂O 至 40cmH₂O 时进行 4 次吸气末 CT 扫描。募集定义为恢复充气的肺组织分数。萎陷伤估计为 5cmH₂O 和 15cmH₂O PEEP 时的潮气量组织塌陷之间的差异。肺通气不均匀性估计为相邻肺单位之间的充气比。
结果
在 30 至 45cmH₂O 之间打开的肺组织（即在平台压 30cmH₂O 时始终关闭的肺组织）分别为轻度 ARDS（分别为 10±29、54±86、162±92 和 185±134g）、中度 ARDS（分别为 10±29、54±86、162±92 和 185±134g）、无 ECMO 支持的重度 ARDS（分别为 10±29、54±86、162±92 和 185±134g）和有 ECMO 支持的重度 ARDS（分别为 10±29、54±86、162±92 和 185±134g）（轻度 ARDS 与无或有 ECMO 支持的重度 ARDS 比较，p<0.05）。在 PEEP 5cmH₂O 和 15cmH₂O 时，潮气量塌陷相似（轻度 ARDS 分别为 63±26g 和 39±32g，p=0.23；中度 ARDS 分别为 92±53g 和 78±142g，p=0.76；无 ECMO 支持的重度 ARDS 分别为 110±91g 和 89±93g，p=0.57；有 ECMO 支持的重度 ARDS 分别为 135±100g 和 104±80g，p=0.32）。将应用的气道压力增加至 45cmH₂O 可使轻度和中度 ARDS 的肺不均匀性略有降低（但有统计学意义），但在重度 ARDS 中则没有。
结论
数据表明，在使用 PEEP 至 15cmH₂O 和平台压至 30cmH₂O 时，肺开放策略的前提条件得不到满足。为了实现有效的肺开放策略，需要更高的压力。因此，必须权衡萎陷伤的风险与容积伤的风险。
试验注册
Clinicaltrials.gov 标识符：NCT01670747（www.clinicaltrials.gov）。
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