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Improved Mortality Rates with Prone Positioning in Severe ARDS


Clinical question

Do patients with severe acute respiratory distress syndrome who require mechanical ventilation fare better with early prone positioning?

Bottom line

Prone positioning decreased 28-day and 90-day mortality rates in patients with severe acute respiratory distress syndrome (ARDS) who required mechanical ventilation. You would have to use prone positioning for 6 such patients to prevent one death. It is important to note that the intensive care units involved in this study were staffed with providers who were skilled at "proning patients." Although the technical difficulty of this process may be a limiting factor, it is one that can likely be overcome with time and experience, especially given the evident benefit. (LOE = 1b)


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

Study design

Randomized controlled trial (nonblinded)

Funding source





Inpatient (ICU only)


These investigators enrolled patients with severe ARDS -- defined as a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (FiO2) of >150mm/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 of 6 mL/kg of predicted body weight -- who were using mechanical ventilation for less than 36 hours. Patients were excluded from the study if they showed improvement in symptoms during an initial 12-hour to 24-hour stabilization period. Patients with contraindications to prone positioning such as those with elevated intracranial pressure or recent tracheal surgery were also excluded. Using concealed allocation, eligible patients were randomized to be part of a prone group (n = 237) or a supine group (n = 229). Patients in the prone group were placed in prone position while on mechanical ventilation for at least 16 consecutive hours per day up to day 28. Prone treatment was discontinued if patients had improved oxygenation while in a sustained supine position or if complications arose during prone positioning such as accidental extubation or cardiac arrest. Patients in the supine group were maintained in a semirecumbent position throughout the study. The 2 groups had similar average age and comorbidities. However, at baseline, the supine group used vasopressors more frequently, used neuromuscular blockers less frequently, and had a significantly higher mean Sepsis-related Organ Failure Assessment (SOFA) score as compared with the prone group. Patients in the prone group remained in the prone position for 73% of the time from the start of the first prone session to the end of the last session. Mortality was lower in the prone group than in the supine group at day 28 (16% vs 33%; P < .001; number needed to treat [NNT] = 6) and at day 90 (24% vs 41%; P < .001; NNT = 6). The decrease in mortality with prone positioning persisted after adjustment for SOFA scores and the use of neuromuscular blockers and vasopressors. Although the prone group had more successful extubations at day 90 (81% vs 65%; P < .001), there were no significant differences detected in duration of mechanical ventilation or number of tracheotomies placed.

Dr. Kulkarni is an assistant professor of hospital medicine at Northwestern University in Chicago.

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