Impact of mechanical power on mortality in ventilated critically ill patients. Retrospective study with continuous real-life data

Abstract

Background Over the past decade, numerous studies on potential factors contributing to ventilation-induced lung injury have been carried out. Mechanical power has been pointed out as the parameter that encloses all ventilation-induced lung injury-contributing factors. However, studies conducted to date provide data regarding mechanical power during the early hours of mechanical ventilation that may not correspond to the real scenario. Methods Retrospective observational study conducted at a single center in Spain. Patients admitted to the intensive care unit, > o = 18 years of age, and ventilated for over 24 hours were included. We extracted the mechanical power values throughtout the entire mechanical ventilation period from the clinical information system every two minutes. First, we calculate the cutoff-point for mechanical power beyond which there was a greater change in the probability of death. After, the sum of time values above the safe cut-off point was calculated to obtain the value in hours. We analyzed if the number of hours the patient was under ventilation with a mechanical power above the safe threshold was associated with mortality, invasive mechanical ventilation days, and intensive care unit length of stay. We repeated the analysis in different subgroups based on the degree of hypoxemia and in patients with SARS CoV-2 pneumonia. Results The cut-off point of mechanical power at with there is a higher increase in mortality was 18J/min. The greater the number or hours patients were under mechanical power > 18 J/min the higher the mortality in all the study population, in patients with SARS CoV-2 pneumonia and in mild to moderate hyopoxemic respiratory failure. The risk of death inceases 0.1% for each our with mechanical power exceeding 18 J/min. The number of hours with mechanical power > 18 J/min also affected the days of invasive mechanical ventilation and intensive care unit length of stay. Conclusions Continuous monitoring of mechanical power using an automated clinical information system shows that the number of hours with mechanical power > 18 J/min increases mortality in critically ill patients.