Low Tidal Volumes for All?

lunginjurydevelopment(RR,0.33;95%CI,0.23-0.47),pulmonary infection (RR, 0.45; 95% CI, 0.22-0.92), and mortality (RR, 0.64; 95% CI, 0.46-0.89). Although these data seem compelling, several factors must be considered in their interpretation. A total of 15 randomized controlled trials were combined with 5 observational studies, but the observational studies (in which inferences of causality may be problematic) account for approximately 85% of both the total number of patients and events in the primary analysis of lung injury prevention. Furthermore, the randomized trials had limitations related to quality, with some trials lacking allocation concealment and many not following an intention-to-treat analysis. In addition, many trials focused on short-term intraoperative ventilation under anesthesia, and these may not be generalizable to other clinical situations. As the authors acknowledge, their findings are not definitive but rather are hypothesis generating and support the need to conduct large randomized trials. Why should intensive care physicians not simply move immediately to implement low tidal volume ventilation for all patients receiving mechanical ventilation? The medical literature has many examples in which physiological rationale, meta-analyses of small or low-quality studies, or both