It has been almost for 40 years that the positive effect of prone positioning in ARDS patients was recognised. But even up to 2012 no benefit on mortality could be found in several studies and also the duration of prone positioning was not found to make any difference.
In June 2013 Guerin et al. published the PROSEVA trial which indeed showed some amazing results. It is the 5th biggest trial of it’s kind and finally was able to actually now show a dramatic reduction in mortality: the 28 day mortality was 32.8% in the supine group (229 patients), compared to only 16% in the prone group (237 patients). This benefit in outcome persisted also after 90 days… a miracle?
Most probably these results reflect the very strict adherence to the guidelines of ARDSnet in regards of paralysation and use of very low tidal volumes. One thing that has to be mentioned is the high number of patients with ARDS which have excluded from the trial for several reasons.
So should we now follow this study and prone more aggressively?
One answer might be the just recently published meta-analysis by Lee at al. in Critical Care Medicine. This paper looked at a total of 11 randomised controlled trials and therefore takes all recent publications into account. The authors come to the conclusion that prone positioning indeed does reduce mortality significantly and were marked in the subgroup where the duration of prone positioning was more than 10 hours. This is the first time somebody actually comments on the length of prone positioning in terms of benefit for the patient.
As always though there are also adverse effects of this therapy as prone positioning was significantly associated with pressure sores and maybe most importantly major airway problems.
Overall, the concept of prone positioning in severe ARDS seems to be well established and should be implemented in the clinical procedures of every intensive care unit. This is particularly true for regions where quick access to extra corporal CO2 removal or oxygenation devices is difficult.