Early versus Delayed Switching from Controlled to Assisted Ventilation: A Target Trial Emulation

Abstract

Rationale: In critically ill patients receiving invasive mechanical ventilation, switching from controlled to assisted ventilation is a crucial milestone toward ventilator liberation. The optimal timing for switching to assisted ventilation has not been studied. Objectives: Our objective was to determine whether a strategy of early compared with delayed switching affects the duration of invasive mechanical ventilation, ICU length of stay, and mortality. Methods: We conducted a target trial emulation using the prospective, global WEAN SAFE (the WorldwidE AssessmeNt of Separation of pAtients From ventilatory assistancE) dataset. Patients were eligible for switching if they were still on controlled mechanical ventilation, were not receiving neuromuscular blockers, and had Pa_O2:Fi_O2 ratios >150 mm Hg. We compared an "early switching" strategy (switch within 1 day after reaching switching eligibility criteria) with a "delayed switching" strategy (switch 1 or more days after reaching the switching eligibility criteria). The primary outcome was the 28-day cumulative incidence of successful extubation. Secondary outcomes included 28-day and 90-day ICU discharge and ICU mortality. Measurements and Main Results: A total of 1,489 patients met the switching eligibility criteria. The early-switch group had, on average, 4 additional days of being successfully extubated over the 28-day period (95% confidence interval [CI], 3-6 days; P < 0.001) compared with the delayed group, with a higher difference in cumulative incidence of successful extubation at Day 28 (7% [95% CI, 0-13%]; P = 0.04). Early switching was associated with an 11% higher cumulative incidence of ICU discharge at Day 28 (95% CI, 7-18%; P < 0.001) and an average of 7 additional days discharged from the ICU over the 90-day period (95% CI, 4-12 days; P < 0.001) compared with delayed switching. ICU mortality rates did not differ between the strategies. Conclusions: Early switching from controlled to assisted ventilation is associated with shorter duration of invasive mechanical ventilation and ICU stay compared with delayed switching.

Keywords: airway extubation; controlled mode; length of stay; mechanical ventilation; ventilator weaning.