Pressure versus volume assist-control ventilation in Acute Respiratory Distress Syndrome: a randomised clinical trial.

Abstract Background: To compare the effect of a pressure-controlled strategy allowing non-synchronized unassisted spontaneous ventilation (PC-SV) to a conventional volume assist-control strategy (ACV) on the outcome of patients with Acute Respiratory Distress Syndrome (ARDS). Methods: Open-label randomized clinical trial in 22 ICUs in France. Seven hundred adults with moderate or severe ARDS (PaO2/FiO2 < 200 mmHg) were enrolled from February 2013 to October 2018. Patients were randomly assigned to PC-SV (n=348) or ACV (n=352) with similar objectives of tidal volume (6 mL/kg predicted body weight) and positive end-expiratory pressure (PEEP). Paralysis was stopped after 24h and sedation adapted to favour patients’ spontaneous ventilation. The primary endpoint was in-hospital death from any cause at day 60. Findings: Hospital mortality (34.6% vs 33.5%, p=.77, RR=1.03 (95% CI, 0.84-1.27)), 28-day mortality, as well as the number of ventilator-free days and organ failure-free days at day 28 did not differ between PC-SV and ACV groups. Patients in the PC-SV group received significantly less sedation and neuro-muscular blocking agents than in the ACV group. A lower proportion of patients required adjunctive therapy of hypoxemia (including prone positioning) in the PC-SV group than in the ACV group (33.1% vs 41.3%, p=.03, RR=0.80 (95% CI, 0.66-0.98)). The incidences of pneumothorax and refractory hypoxemia did not differ between the groups. Interpretation: A strategy based on a pressure-controlled mode that favours spontaneous ventilation did not significantly reduce mortality compared to ACV with similar tidal volume and PEEP levels but reduced the need for sedation and adjunctive therapies of hypoxemia. Funding: French Ministry of Health (PHRC 49RC-09-04-01) Trial registration: ClinicalTrials.gov Identifier: NCT01862016