From the Department of Anesthesia and Intensive Care (E.Ö., L.E.) the Department of Radiology (A.T.), Västerås and Köping Hospital, Västerås, Sweden Center for Clinical Research, Västerås, Sweden (M.E.) Department of Surgical Sciences, Anesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden (H.Z.) Department of Medical Sciences, Clinical Physiology, Uppsala University, Uppsala, Sweden (G.H.).
Anesthesiology. 2018 Jun;128(6):1117-1124. doi: 10.1097/ALN.0000000000002134.
Various methods for protective ventilation are increasingly being recommended for patients undergoing general anesthesia. However, the importance of each individual component is still unclear. In particular, the perioperative use of positive end-expiratory pressure (PEEP) remains controversial. The authors tested the hypothesis that PEEP alone would be sufficient to limit atelectasis formation during nonabdominal surgery.
This was a randomized controlled evaluator-blinded study. Twenty-four healthy patients undergoing general anesthesia were randomized to receive either mechanical ventilation with PEEP 7 or 9 cm H2O depending on body mass index (n = 12) or zero PEEP (n = 12). No recruitment maneuvers were used. The primary outcome was atelectasis area as studied by computed tomography in a transverse scan near the diaphragm, at the end of surgery, before emergence. Oxygenation was evaluated by measuring blood gases and calculating the ratio of arterial oxygen partial pressure to inspired oxygen fraction (PaO2/FIO2 ratio).
At the end of surgery, the median (range) atelectasis area, expressed as percentage of the total lung area, was 1.8 (0.3 to 9.9) in the PEEP group and 4.6 (1.0 to 10.2) in the zero PEEP group. The difference in medians was 2.8% (95% CI, 1.7 to 5.7%; P = 0.002). Oxygenation and carbon dioxide elimination were maintained in the PEEP group, but both deteriorated in the zero PEEP group.
During nonabdominal surgery, adequate PEEP is sufficient to minimize atelectasis in healthy lungs and thereby maintain oxygenation. Thus, routine recruitment maneuvers seem unnecessary, and the authors suggest that they should only be utilized when clearly indicated.
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各种保护性通气方法越来越多地被推荐用于接受全身麻醉的患者。然而，每个单独组件的重要性仍不清楚。特别是，围手术期使用呼气末正压通气（PEEP）仍然存在争议。作者检验了这样一个假设，即单独使用 PEEP 就足以限制非腹部手术期间的肺不张形成。
这是一项随机对照评估者盲法研究。24 名接受全身麻醉的健康患者随机分为两组，根据体重指数接受 PEEP 7 或 9 cm H2O 的机械通气（n = 12）或零 PEEP（n = 12）。未使用复张手法。主要结局是通过膈肌附近的横断层 CT 扫描研究术中结束时的肺不张面积。在苏醒前评估氧合作用，通过测量血气并计算动脉氧分压与吸入氧分数比（PaO2/FIO2 比值）来评估。
在手术结束时，PEEP 组的肺不张面积中位数（范围）表示为全肺面积的百分比为 1.8（0.3 至 9.9），零 PEEP 组为 4.6（1.0 至 10.2）。中位数差异为 2.8%（95%CI，1.7 至 5.7%；P = 0.002）。PEEP 组的氧合和二氧化碳排出得到维持，但零 PEEP 组的氧合和二氧化碳排出均恶化。
在非腹部手术中，足够的 PEEP 足以最大限度地减少健康肺的肺不张，从而维持氧合作用。因此，常规复张手法似乎没有必要，作者建议仅在明确需要时使用。
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