Proning for ARDS

PROSEVA

Protocol

Proned for at least 16 hours per day if:

• P:F 150 or less with PEEP 10 or more and FiO2 60% or more after 12-24h period of stability
• Head direction swapped every 2 hours
• Goal: Vt 6ml/kg, 7.2 - 7.45 pH, plat <30
• 87% received neuromuscular blockade.

Continued until there was:

• improvement above threshold for study inclusion
• deterioration in P:F of 20% or more relative to supine on 2 consecutive days
• mechanical or hemodynamic complication preventing proning
• 28 days.

Other analyses

https://pubmed.ncbi.nlm.nih.gov/14668608/

Retrospective analysis of intervention arm (n=225)

PaO2 responders (20% improvement) had similar outcomes to nonresponders PaCO2 responders - drop in PaCO2 of 1 or more (mediated by a reduction in deadspace ventilation) had an improved survival - 35.1% vs 52.2%

This fits with Vd/Vt (deadspace fraction) being predictive of an increased risk of mortality in ARDS, even after adjusting for P:F ratio and PEEP (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6363976/)

Changes in driving pressure seem like they ought to be even more predictive?