A 2017 guideline strongly recommends the use of prone ventilation for 12+ hours daily in individuals with severe ARDS (1). A JAMA article gave similar recommendations for critically ill patients with COVID-19 (2).
The recommendations are often based on a NEJM 2013 randomized-controlled study involving 466 patients with severe ARDS (3). While previous research had demonstrated improved oxygenation in the prone position (4), this study demonstrated a significant survival benefit (3). Mortality at 28 days was 16.0% in prone patients versus 32.8% in supine patients (p<0.001; HR 0.39 with 95% CI, 0.29 – 0.67) (3). Mortality was also lower in prone patients at 90 days (3). A meta-analysis of 4 additional randomized-controlled trials confirmed the survival benefits (1).
In patients with Covid-19 and ARDS, a small retrospective study involving 12 patients showed a significant association between prone positioning and lung recruitability (ie, lung tissue in which aeration can be restored) (p = 0.020) (5).
Physiologically, numerous mechanisms have been proposed for these findings, including the possbility that while blood flow consistently favors the dorsal alveoli regardless of position, the prone position allows dorsal alveoli to reopen, improving ventilation/perfusion matching (6).
Of note, some institutions find difficulties with prone positioning, including higher rates of pressure sores and endotracheal tube obstruction (1).
Contributed by Grant Steele, Harvard Medical Student, Boston, MA.
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1. Fan E, Del Sorbo L, Goligher E, et al. An official American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine clinical practice guideline: mechanical ventilation in adult patients with acute respiratory distress syndrome.” Am J Respir Crit Care Med 2017;195:1253-1263. https://www.atsjournals.org/doi/abs/10.1164/rccm.201703-0548ST
2. Murthy S, Gomersall C, & Fowler R. Care for critically ill patients with COVID-19. JAMA – Published online March 11, 2020. doi:10.1001/jama.2020.3633 https://jamanetwork.com/journals/jama/fullarticle/2762996
3. Guérin C, Reignier J, Richard J-C, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med 2013;368:2159-2168. https://www.nejm.org/doi/full/10.1056/nejmoa1214103
4. Abroug F, Ouanes-Besbes L, Elatrous S, et al. The effect of prone positioning in acute respiratory distress syndrome or acute lung injury: a meta-analysis. Areas of uncertainty and recommendations for research. Intensive Care Medicine – Published online March 19, 2008. doi: 10.1007/s00134-008-1062-3 https://link.springer.com/article/10.1007/s00134-008-1062-3
5. Pan C, Chen L, Lu C, et al. Lung Recruitability in SARS-CoV-2 Associated Acute Respiratory Distress Syndrome: A Single-center, Observational Study. Am J Respir Crit Care Med – Published online March 23, 2020. doi: 10.1164/rccm.202003-0527LE. https://www.atsjournals.org/doi/pdf/10.1164/rccm.202003-0527LE
6. Nyrén S, Mure M, Jacobsson H, et al. Pulmonary perfusion is more uniform in the prone than in the supine position: scintigraphy in healthy humans. J Appl Physiol 1999;86:1135-1141. https://www.physiology.org/doi/abs/10.1152/jappl.19188.8.131.525
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