Proning in ARDS

Prone Positioning in Severe Acute Respiratory Distress Syndrome (PROSEVA) - 2013

• Previous trials had demonstrated that proning improved oxygenation in ARDS, but this did not translate to clinical outcomes.
• Meta-analyses suggested that survival was improved with severe hypoxemia secondary to ARDS.

Population

• Patients with ARDS for less than 36 hours
• Mechanically ventilated with severe ARDS: PEEP > 5 cm H2O and PaO2/FiO2 < 150 mmHg, FiO2 > 0.6, and VT about 6 mg/kg PBW (per ARDSNet)
• Stabilization period of 12 to 24 hours

Design

• 26 ICUs in France and 1 in Spain, experienced with proning
• Centralized and stratified randomization
• Data collectors not blinded, but adjudicators blinded

Intervention

• Prone group: turned to prone within 1 hour of randomization
• Completely prone for at least 16 consecutive hours
• Standard ICU beds
• Criteria for stopping prone treatment:
  • Improvement in PF ratio > 150 with PEEP < 10 and FiO2 < 0.6 at least 4 hours after end of last prone session
  • Decrease in PF ration of more than 20% relative to the raion in the supine position before two consecutive prone sessions
  • Complications during proning…
    • Nonscheduled extubation
    • Main stem bronchus intubation
    • ETT obstruction
    • Hemoptysis
    • SpO2 < 85% or PaO2 < 55 mmHg on FiO2 1.0
    • Cardiac arrest
    • Sustained bradycardia
    • Sustained hypotension
  • After patients in the prone group were turned to the supine position, the prone session could be resumed at any time before the planned assessment at 4 hours in the supine position if the criteria for oxygen saturation level, PaO2, or both were met

Comparator

• Semirecumbent position in the "supine group"
• Patients in the supine group could not be crossed over to the prone group except as a rescue measure

Ventilation

• Volume-controlled mode, constant inspiratory flow
• VT target 6 mL/kg PBW and PEEP via PEEP-FiO2 table
• Goal to maintain Pplat < 30 cm H2O, and arterial plasma pH 7.20 to 7.45
• Weaning from mechanical ventilation was conducted in the same way for both groups

Outcomes

1. 28 day mortality
2. Secondary outcomes
   1. 90 day mortality
   2. Successful extubation
   3. Time to successful extubation
   4. ICU LOS
   5. Complications
   6. NIV
   7. Tracheotomy rate
   8. Days free from organ dysfunction
   9. Ventilatory settings, ABG, and respiratory mechanics

Results

A total of 237 patients were assigned to the prone group, and 229 patients were assigned to the supine group.

The 28-day mortality was 16.0% in the prone group and 32.8% in the supine group (P<0.001). The hazard ratio for death with prone positioning was 0.39 (95% confidence interval [CI], 0.25 to 0.63).

Unadjusted 90-day mortality was 23.6% in the prone group versus 41.0% in the supine group (P<0.001), with a hazard ratio of 0.44 (95% CI, 0.29 to 0.67).

The incidence of complications did not differ significantly between the groups, except for the incidence of cardiac arrests, which was higher in the supine group.

References

1. Guérin C, Reignier J, Richard JC, et al. Prone Positioning in Severe ARDS. New England Journal of Medicine. 2013;368(23):2159-2168. doi:1056/NEJMoa1214103