Is Prone Ventilation Limited for Patients With Mild or Moderate ARDS?

Guidelines and review articles recommending that prone ventilation should be used only for patients with ratios of arterial oxygen concentration to fraction of inspired oxygen (P/F) <100 or <150 may have been too conservative, according to a review published in the Annals of the American Thoracic Society.¹

The author, Richard K. Albert, MD, of the University of Colorado Anschutz Medical Campus in Aurora, made the following observations questioning the recommendations from the landmark publication by Guerin and colleagues² demonstrating that prone ventilation reduced mortality in patients with acute respiratory distress syndrome (ARDS):

• All studies and meta-analyses reporting that prone ventilation does not reduce mortality among patients with mild or moderate ARDS are markedly underpowered
• Confidence intervals from meta-analyses indicate that prone ventilation may decrease mortality to a clinically important extent in patients with moderate ARDS
• The strongest evidence that prone ventilation does not reduce mortality in moderate ARDS comes from a study that is limited by 3 concerns: the study was underpowered; no difference in mortality was found in patients with P/F <100, which raises questions about the results differing from those of the PROSEVA (Effect of Prone Positioning on Mortality in Patients With Severe and Persistent ARDS) study; and the complication rates were far higher than in other study on prone ventilation
• The beneficial effect of prone ventilation on mortality is not related to the P/F ratio
• The likely mechanism by which prone ventilation reduces mortality does not depend on the extent of lung injury
• Concerns about the complications of prone ventilation are not supported by the literature¹

“Use of any intervention in critical care should be based on the risk:benefit ratio,” Dr Albert wrote.¹

“Given the high mortality rates in these ARDS subtypes, the frequency and severity of the possible risks, a reasonable chance of improving survival to a clinically meaningful extent (based on published confidence intervals) and a strong physiological rationale, limiting prone ventilation to patients with P/F ratios <100 or <150 seems overly conservative,” Dr Albert added.¹

References

1. Albert RK. Prone ventilation for patients with mild or moderate ARDS [published online September 18, 2019]. Ann Am Thorac Soc. doi:10.1513/AnnalsATS.201906-456IP

2. Guérin C, Reignier J, Richard J-C, et al; for the PROSEVA Study Group. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med. 2013;368(23):2159-2168.