Mechanical ventilation is an effective life-support technique widely deployed across a variety of clinical settings in the care of many millions of patients each year worldwide. However, it is not a panacea. A central issue is that artificial ventilation works by pushing air into the lungs via positive pressure, whereas physiologic respiration works by generating negative pressure to draw air into the lungs. Pushing air into the lungs is a challenge because not all lung areas distend and collapse at the same driving pressure. Thus, a positive pressure breath may overstretch one lung area while failing to open another one, compromising gas exchange and causing direct mechanical injury to the lung (so-called ventilator-induced lung injury). Both the volume and pressure settings on a ventilator have been implicated in ventilator-induced lung injury, with tidal volumes that are too large implicated in overdistension and positive end-expiratory pressure (PEEP) settings that are too low implicated in alveolar collapse. Thus, current guidelines endorse a low tidal volume and a high or at least avoidance of low PEEP level. But, these “one size fits all” recommendations may not be optimal for all patients.
Serpa Neto A, Schultz MJ. Optimizing the Settings on the VentilatorHigh PEEP for All?. JAMA. 2017;317(14):1413–1414. doi:10.1001/jama.2017.2570