原创： Alpha Jun 阿尔法医学英语 4天前
医学的进步是先辈们筚路蓝缕，一点一滴开拓出来，从青霉素到HPV疫苗，从肿瘤化疗到CART细胞治疗。而现代医学的基石是一个个里程碑式的临床试验 （landmark trial）。我们的教科书的根本也是基于这些landmark trials。
让我们来一起阅读医学史上的经典。阅读，不仅仅是学习医学英语最好的方式，也能更好地理解现代医学的精髓。
Proseva——治疗ARDS的正确姿势
50年前，Ashbaugh 对12例感染或创伤后出现呼吸急促、难治性低氧血症以及胸片显示弥漫性阴影的患者进行了阐述。在7例死亡患者中，发现6例患者的肺泡腔内被覆盖明显的透明膜，在此之前，肺泡腔内透明膜被认为是新生儿呼吸窘综合征的特异体征。因此，Ashbaugh提出了成人（Adult, 后改为急性acute）呼吸窘迫综合征（ARDS）一词。
ARDS治疗除了肺保护性通气预防呼吸机相关损伤（低潮气量通气）之外，另一个重要的研究进展是对于重症ARDS患者的姿势调整。
Chest x-ray of person with severe ARDS
widespread "ground-glass" appearing opacities in both lungs
Picture From Wikipedia
这篇发表于2013年新格兰医学杂志（NEJM）的经典文献如下：
主要结论
- ICU patients with severe Acute Respiratory Distress Syndrome (ARDS) who underwent prone positioning had lower 28-day and 90-day mortality rates than those who remained supine.
- This mortality benefit appears to stem from superior oxygenation and a decrease in ventilator lung strain that has been shown in prior studies.
试验背景
Previous trials involving patients with 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.
试验结果
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.
Prone Postion
Supine Position
vs
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
LINK: Comparison of AECC to Berlin Deifinition of ARDS
Proseva Trial set the including criteria according to AECC
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.
It was concluded that in patients with severe ARDS, early application of prolonged prone-positioning sessions significantly decreased 28-day and 90-day mortality.
深度解析与批评
Prior studies have shown that prone positioning of ventilated patients allows for more homogenous oxygenation and reduced lung strain than supine positioning. However, no studies had shown a clear mortality benefit to this practice. The Proseva trial found that placing ICU patients with severe acute respiratory distress syndrome (ARDS) in prone position early in the clinical course significantly increased survival rates.
The study was performed at centers that already employed prone-positioning in their ICUs and were therefore well-versed in the practice. Therefore, the results of the trial might not be generalizable to centers without prior experience.
Additionally, the protocol used by Proseva involved returning patients to supine position. It is possible the observed mortality benefit may stem from the act of turning the patients between prone and supine position and not from being in the prone position itself.
Summary of the respiratory and circulatory effects of the prone position
Figure From Kenny J-E. Predicting the Haemodynamic Response to Prone Positioning: A Novel and Simultaneous Analysis of the Guyton and Rahn Diagrams. Critical Care Horizons 2017:1-7.
Key Word:
- Acute Respiratory Distress Syndrome (ARDS)
- 急性呼吸窘迫综合症
- prone [prəʊn]
- adj.俯卧的，趴着的
- supine [ˈsuː.paɪn]
- adj. 仰卧的
- ventilatory [ˈven.tɪ.leɪ.təry]
- adj. 人工呼吸机的
- ventilator [ˈven.tɪ.leɪ.tər]
- n. 人工呼吸机
- tidal volume [ˈtaɪ.dəl ˈvɒl.juːm]
- n. 潮气量
Supine position is not for me
回复Proseva获得文献原文哦:D
阅读医学经典系列
慢性肝病之MELD评分
Child-Pugh Score的诞生之路
发了两次NEJM的地中海饮食研究PREDIMED
UKPDS—糖尿病治疗的基石研究
ADVANCE—糖尿病治疗的基石研究
CAST—终结心梗后抗心律失常药物的研究
AFFIRM——房颤的心率控制VS节律控制
点击“阅读原文”一览往期更多经典
AlphaMedEnglish
gif from giphy.com
edited by zyr
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