Algera Anna Geke, Pisani Luigi, Chaves Renato Carneiro de Freitas, Amorim Thiago Chaves, Cherpanath Thomas, Determann Rogier, Dongelmans Dave A, Paulus Frederique, Tuinman Pieter Roel, Pelosi Paolo, Gama de Abreu Marcelo, Schultz Marcus J, Serpa Neto Ary
Department of Intensive Care, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Department of Critical Care Medicine, Hospital Israelita Albert Einstein, São Paulo, Brazil.
Ann Transl Med. 2018 Jan;6(2):25. doi: 10.21037/atm.2017.12.05.
It is well-known that positive end-expiratory pressure (PEEP) can prevent ventilator-induced lung injury (VILI) and improve pulmonary physiology in animals with injured lungs. It's uncertain whether PEEP has similar effects in animals with uninjured lungs. A systematic review of randomized controlled trials (RCTs) comparing different PEEP levels in animals with uninjured lungs was performed. Trials in animals with injured lungs were excluded, as were trials that compared ventilation strategies that also differed with respect to other ventilation settings, e.g., tidal volume size. The search identified ten eligible trials in 284 animals, including rodents and small as well as large mammals. Duration of ventilation was highly variable, from 1 to 6 hours and tidal volume size varied from 7 to 60 mL/kg. PEEP ranged from 3 to 20 cmHO, and from 0 to 5 cmHO, in the 'high PEEP' or 'PEEP' arms, and in the 'low PEEP' or 'no PEEP' arms, respectively. Definitions used for lung injury were quite diverse, as were other outcome measures. The effects of PEEP, at any level, on lung injury was not straightforward, with some trials showing less injury with 'high PEEP' or 'PEEP' and other trials showing no benefit. In most trials, 'high PEEP' or 'PEEP' was associated with improved respiratory system compliance, and better oxygen parameters. However, 'high PEEP' or 'PEEP' was also associated with occurrence of hypotension, a reduction in cardiac output, or development of hyperlactatemia. There were no differences in mortality. The number of trials comparing 'high PEEP' or 'PEEP' with 'low PEEP' or 'no PEEP' in animals with uninjured lungs is limited, and results are difficult to compare. Based on findings of this systematic review it's uncertain whether PEEP, at any level, truly prevents lung injury, while most trials suggest potential harmful effects on the systemic circulation.
众所周知，呼气末正压（PEEP）可预防呼吸机诱导的肺损伤（VILI），并改善肺损伤动物的肺生理功能。尚不确定PEEP在未受伤的动物中是否有类似作用。我们对比较未受伤动物不同PEEP水平的随机对照试验（RCT）进行了系统评价。排除了肺损伤动物的试验，以及比较在其他通气设置（如潮气量大小）方面也不同的通气策略的试验。检索发现了涉及284只动物（包括啮齿动物以及小型和大型哺乳动物）的10项合格试验。通气时间差异很大，从1至6小时不等，潮气量大小从7至60 mL/kg不等。在“高PEEP”或“PEEP”组以及“低PEEP”或“无PEEP”组中，PEEP分别为3至20 cmH₂O和0至5 cmH₂O。用于定义肺损伤的标准以及其他结局指标差异很大。任何水平的PEEP对肺损伤的影响都不直接，一些试验显示“高PEEP”或“PEEP”组的损伤较少，而其他试验则显示无益处。在大多数试验中，“高PEEP”或“PEEP”与呼吸系统顺应性改善以及更好的氧参数相关。然而，“高PEEP”或“PEEP”也与低血压的发生、心输出量减少或高乳酸血症的发展相关。死亡率没有差异。比较未受伤动物中“高PEEP”或“PEEP ”与 “低PEEP” 或 “无PEEP” 的试验数量有限，结果难以比较。基于该系统评价的结果，尚不确定任何水平的PEEP是否真的能预防肺损伤，而大多数试验表明其对体循环可能有有害影响。
