NEJM：早期俯卧位通气可显著减少严重急性呼吸窘迫综合征患者死亡率

纳入急性呼吸窘迫综合征(ARDS)患者的既往研究并未显示出机械通气支持中采用俯卧位对结局有益。研究者评估了早期俯卧位通气对严重ARDS患者结局的效应。

这一多中心、前瞻性、随机对照试验中，研究者随机分配466例严重ARDS患者分别采用俯卧位通气至少16小时或左仰卧位通气。严重性ARDS定义为动脉氧分压与吸入氧气分率(Inspired oxygen fraction) (FiO2)少于150 mm Hg，FiO2至少为0.6，呼气末正压通气至少为5 cm水柱，潮气量接近6 ml每千克预测体重。主要终点为入组28天内任何原因死亡的患者比例。

结果显示，总共237例患者经随机分组分入俯卧位通气组，229例患者分入仰卧位通气组。俯卧位通气组28天死亡率为16.0%，仰卧位通气组死亡率则为32.8%(P<0.001)。俯卧位通气组和仰卧位通气组未校正90天死亡率分别为23.6%和41.0% (P<0.001)，危害比为0.44 (95% CI, 0.29 to 0.67)。并发症发生率两组间未见显著性差异，仰卧位通气组心跳停止发生率较高。

研究者由此得出结论，对于严重性ARDS患者人群，早期延长俯卧位通气可显著性减少患者28天和90天死亡率。

Prone Positioning in Severe Acute Respiratory Distress Syndrome
Background
Previous trials involving patients with the acute respiratory distress syndrome (ARDS) have failed to show a beneficial effect of prone positioning during mechanical ventilatory support on outcomes. We evaluated the effect of early application of prone positioning on outcomes in patients with severe ARDS.
Methods
In this multicenter, prospective, randomized, controlled trial, we randomly assigned 466 patients with severe ARDS to undergo prone-positioning sessions of at least 16 hours or to be left in the supine position. Severe ARDS was defined as a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (FiO2) of less than 150 mm Hg, with an FiO2 of at least 0.6, a positive end-expiratory pressure of at least 5 cm of water, and a tidal volume close to 6 ml per kilogram of predicted body weight. The primary outcome was the proportion of patients who died from any cause within 28 days after inclusion.
Results
A total of 237 patients were assigned to the prone group, and 229 patients were assigned to the supine group. The 28-day mortality was 16.0% in the prone group and 32.8% in the supine group (P<0.001). The hazard ratio for death with prone positioning was 0.39 (95% confidence interval [CI], 0.25 to 0.63). Unadjusted 90-day mortality was 23.6% in the prone group versus 41.0% in the supine group (P<0.001), with a hazard ratio of 0.44 (95% CI, 0.29 to 0.67). The incidence of complications did not differ significantly between the groups, except for the incidence of cardiac arrests, which was higher in the supine group.
Conclusions
In patients with severe ARDS, early application of prolonged prone-positioning sessions significantly decreased 28-day and 90-day mortality. (Funded by the Programme Hospitalier de Recherche Clinique National 2006 and 2010 of the French Ministry of Health; PROSEVA ClinicalTrials.gov number, NCT00527813.)