Early PReserved SPONtaneous Breathing Activity in Mechanically Ventilated Patients With ARDS (PReSPON)

The potential benefits of preserved early spontaneous breathing activity during mechanical ventilation are an increased aeration of dependent lung regions, less need for sedation, improved cardiac filling, and better matching of pulmonary ventilation and perfusion and thus oxygenation. Two small randomized controlled trials (RCTs) in patients with acute respiratory distress syndrome (ARDS) reported less time on mechanical ventilation and in the intensive care unit (ICU) with preserved early spontaneous breathing activity during Airway Pressure Release Ventilation (APRV). Debate exists over the net effects of preserved early spontaneous breathing activity with regard to ventilator-associated lung injury (VALI). In fact, by taking advantage of the potential improvement in oxygenation and recruitment at lower inflation pressures associated with APRV, physicians could possibly reduce potentially harmful levels of inspired oxygen, tidal volume, and positive end-expiratory pressure (PEEP). However, spontaneous breathing during mechanical ventilation has the potential to generate less positive pleural pressures that may add to the alveolar stretch applied from the ventilator and contribute to the risk of VALI. This has led to an ongoing controversy whether an initial period of controlled mechanical ventilation with deep sedation and neuromuscular blockade or preserved early spontaneous breathing activity during mechanical ventilation is advantageous with respect to outcomes in ARDS patients. A RCT investigating the effects of early spontaneous breathing activity on mortality in moderate to severe ARDS has been highly recommended in the research agenda for intensive care medicine. The objective of this study is to evaluate the efficacy and safety of preserved spontaneous breathing activity during APRV in the early phase of moderate to severe ARDS.