Outcome prediction in patients with acute respiratory distress syndrome (ARDS) greatly improves when patients are reclassified based on predefined arterial oxygen partial pressure to fractional inspired oxygen ratios (PaO2/FiO2) and positive end–expiratory pressure (PEEP) cutoffs 24 h after the initial ARDS diagnosis. The aim of this study was to test whether outcome prediction improves when patients are reclassified based on predefined PaO2/FiO2 and PEEP cutoffs 24 h after development of mild hypoxemia while not having ARDS. Post hoc analysis of a large prospective, multicenter, observational study that ran in the ICUs of two academic hospitals in the Netherlands between January 2011 and December 2013. Patients were classified into four groups using predefined cutoffs for PaO2/FiO2 (250 mmHg) and PEEP (5 cm H2O), both at onset of hypoxemia and after 24 h: PaO2/FiO2 ≥ 250 mmHg and PEEP < 6 cm H2O (group I), PaO2/FiO2 ≥ 250 mmHg and PEEP ≥ 6 cm H2O (group II), PaO2/FiO2 < 250 mmHg and PEEP < 6 cm H2O (group III), and PaO2/FiO2 < 250 mmHg and PEEP ≥ 6 cm H2O (group IV), to look for trend association with all-cause in-hospital mortality, the primary outcome. Secondary outcome were ICU- and 90-day mortality, and the number of ventilator-free days or ICU-free days and alive at day 28. The analysis included 689 consecutive patients. All-cause in-hospital mortality was 35%. There was minimal variation in mortality between the four groups at onset of hypoxemia (33, 36, 38, and 34% in groups I to IV, respectively; P = 0.65). Reclassification after 24 h resulted in a strong trend with increasing mortality from group I to group IV (31, 31, 37, and 48% in groups I to IV, respectively; P < 0.01). Similar trends were found for the secondary endpoints. Reclassification using PaO2/FiO2 and PEEP cutoffs after 24 h improved classification for outcome in invasively ventilated ICU patients with hypoxemia not explained by ARDS, compared to classification at onset of hypoxemia. ClinicalTrials.gov identifier: NCT01905033. Registered on July 11, 2013. Retrospectively registered.

中文翻译：

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基于 P/F 和 PEEP 的低氧血症有创通气 ICU 患者的预后分类——来自 MARS 研究的见解

根据预定义的动脉氧分压与吸入氧分数比 (PaO2/FiO2) 和呼气末正压 (PEEP) 截断值在初始治疗 24 小时后重新分类，急性呼吸窘迫综合征 (ARDS) 患者的预后预测大大提高ARDS 诊断。本研究的目的是测试在未患有 ARDS 的情况下发生轻度低氧血症后 24 小时根据预定义的 PaO2/FiO2 和 PEEP 临界值对患者进行重新分类时，结果预测是否有所改善。对 2011 年 1 月至 2013 年 12 月在荷兰两家学术医院的 ICU 进行的大型前瞻性、多中心、观察性研究的事后分析。使用预先定义的 PaO2/FiO2 (250 mmHg) 和 PEEP 临界值将患者分为四组(5 厘米 H2O), 低氧血症开始时和 24 小时后：PaO2/FiO2 ≥ 250 mmHg 且 PEEP < 6 cm H2O（I 组），PaO2/FiO2 ≥ 250 mmHg 且 PEEP ≥ 6 cm H2O（II 组），PaO2/FiO2 < 250 mmHg PEEP < 6 cm H2O（III 组）、PaO2/FiO2 < 250 mmHg 和 PEEP ≥ 6 cm H2O（IV 组），以寻找与全因院内死亡率（主要结果）的趋势关联。次要结果是 ICU 和 90 天死亡率，以及第 28 天的无呼吸机天数或无 ICU 天数且存活。分析包括 689 名连续患者。全因住院死亡率为 35%。在低氧血症开始时，四组之间的死亡率差异很小（I 至 IV 组分别为 33%、36%、38% 和 34%；P = 0.65）。24 小时后重新分类导致死亡率从 I 组增加到 IV 组（31、31、37、I至IV组分别为48%；P < 0.01)。次要终点也发现了类似的趋势。与低氧血症发生时的分类相比，24 小时后使用 PaO2/FiO2 和 PEEP 截断值重新分类改善了有创通气 ICU 低氧血症患者的预后分类，而不是由 ARDS 解释。ClinicalTrials.gov 标识符：NCT01905033。2013年7月11日登记，追溯登记。