Adaptive mechanical ventilation with automated minimization of mechanical power-a pilot randomized cross-over study

Adaptive mechanical ventilation automatically adjusts respiratory rate (RR) and tidal volume (V ) to deliver the clinically desired minute ventilation, selecting RR and V based on Otis' equation on least work of breathing. However, the resulting V may be relatively high, especially in patients with more compliant lungs. Therefore, a new mode of adaptive ventilation (adaptive ventilation mode 2, AVM2) was developed which automatically minimizes inspiratory power with the aim of ensuring lung-protective combinations of V and RR. The aim of this study was to investigate whether AVM2 reduces V , mechanical power, and driving pressure (ΔP ) and provides similar gas exchange when compared to adaptive mechanical ventilation based on Otis' equation. A prospective randomized cross-over study was performed in 20 critically ill patients on controlled mechanical ventilation, including 10 patients with acute respiratory distress syndrome (ARDS). Each patient underwent 1 h of mechanical ventilation with AVM2 and 1 h of adaptive mechanical ventilation according to Otis' equation (adaptive ventilation mode, AVM). At the end of each phase, we collected data on V , mechanical power, ΔP, PaO /FiO ratio, PaCO , pH, and hemodynamics. Comparing adaptive mechanical ventilation with AVM2 to the approach based on Otis' equation (AVM), we found a significant reduction in V both in the whole study population (7.2 ± 0.9 vs. 8.2 ± 0.6 ml/kg, p