A Pragmatic Pilot Trial Comparing Patient Triggered Adaptive Pressure Control to Patient Triggered Volume Control Ventilation in Critically ill Adults

Background: Patient triggered Adaptive Pressure Control (APC-CMV) has been widely adopted as an alternative ventilator mode to patient-triggered Volume control (VC-CMV). However, the comparative effectiveness of the two ventilator modes remain uncertain.

Research Question: We sought to explore clinical and implementation factors pertinent to a future definitive RCT assessing APC-CMV vs VC-CMV as an initial ventilator mode strategy. The research objectives in our pilot trial test clinician adherence and explore clinical outcomes.

Methods: In a single-center pragmatic sequential cluster crossover pilot trial, we enrolled all eligible adults admitted during a nine week period to the Medical Intensive Care Unit (ICU) with acute respiratory failure requiring mechanical ventilation. 2-week time epochs were assigned a priori in which subjects received either APC-CMV or VC-CMV The primary outcome of the trial was feasibility, defined as 80% of patients receiving the assigned mode within 1 hour of initiation of ICU ventilation. The secondary outcome was proportion of the first 24 hours on the assigned mode. Finally, we surveyed clinician stakeholders to understand potential facilitators and barriers to conducting a definitive randomized trial.

Results: We enrolled 137 subjects undergoing 152 discreet episodes of mechanical ventilation during time epochs assigned to APC-CMV (n=61) and VC-CMV (n=91). 131 episodes were included in the prespecified primary outcome. 126 (96%) received the assigned mode within the first hour of ICU admission (60 of 61 subjects assigned APC-CMV and 66 of 70 assigned VC-CMV). VC-CMV subjects spent a lower proportion of first 24 hours (84% [95% CI: 78%-89%]) on the assigned mode than APC-CMV recipients (95% [95% CI: 91%-100%]). Mixed-methods analyses identified pre-conceived perceptions of subject comfort by clinicians and need for real-time education to address this concern.

Conclusion: In this pilot pragmatic, sequential crossover trial, unit-wide allocation to a ventilator mode was feasible and acceptable to clinicians.