Respiratory Drive, Effort, and Lung-Distending Pressure during Transitioning from Controlled to Spontaneous Assisted...

Objectives: To investigate the impact of patient characteristics and treatment factors on excessive respiratory drive, effort, and lung-distending pressure during transitioning from controlled to spontaneous assisted ventilation in patients with acute respiratory distress syndrome (ARDS). Methods: Multicenter cohort observational study of patients with ARDS at four academic intensive care units. Respiratory drive (P_0.1), diaphragm electrical activity (EAdi), inspiratory effort derived from EAdi (∆Pmus_EAdi) and from occlusion of airway pressure (∆Pocc) (Pmus_ΔPocc), and dynamic transpulmonary driving pressure (ΔP_L,dyn) were measured at the first transition to assisted spontaneous breathing. Results: A total of 4171 breaths were analyzed in 48 patients. P_0.1 was >3.5 cmH₂O in 10%, EAdi_PEAK > 15 µV in 29%, ∆Pmus_EAdi > 15 cmH₂O in 28%, and ΔP_L,dyn > 15 cmH₂O in 60% of the studied breaths. COVID-19 etiology of ARDS was the strongest independent risk factor for a higher proportion of breaths with excessive respiratory drive (RR 3.00 [2.43-3.71], p < 0.0001), inspiratory effort (RR 1.84 [1.58-2.15], p < 0.0001), and transpulmonary driving pressure (RR 1.48 [1.36-1.62], p < 0.0001). The P/F ratio at ICU admission, days of deep sedation, and dose of steroids were additional risk factors for vigorous inspiratory effort. Age and dose of steroids were risk factors for high transpulmonary driving pressure. Days of deep sedation (aHR 1.15 [1.07-1.24], p = 0.0002) and COVID-19 diagnosis (aHR 6.96 [1-48.5], p = 0.05) of ARDS were independently associated with composite outcome of transitioning from light to deep sedation (RASS from 0/-3 to -4/-5) or return to controlled ventilation within 48 h of spontaneous assisted breathing. Conclusions: This study identified that specific patient characteristics, including age, COVID-19-related ARDS, and P/F ratio, along with treatment factors such as the duration of deep sedation and the dosage of steroids, are independently associated with an increased likelihood of assisted breaths reaching potentially harmful thresholds of drive, effort, and lung-distending pressure during the initial transition to spontaneous assisted breathing. It is noteworthy that patients who were subjected to prolonged deep sedation under controlled mechanical ventilation, as well as those with COVID-19, were more susceptible to failing the transition from controlled to assisted breathing.