Knowing who would respond to a recruitment maneuver before actually doing it – this might be a way to go

Using recruitment manoeuvres in acute lung injury remains a controversial issue because no convincing outcome data support their general use, although many physiological studies have demonstrated beneficial effects on lung compliance, end-expiratory lung volume and gas exchange. One of the reasons why physiologically meaningful observations do not translate into clear clinical benefit could be the heterogeneity of the studied patient population. In patients with consolidated lungs and only limited potential for recruitment, manoeuvres might be harmful, whereas in patients with high potential for recruitment they might be helpful. However, when those populations are mixed any signal may be lost because of counteracting effects, depending on how the patient population was mixed. We do not currently have any simple tool that may readily be applied at the bedside to assess the recruitment potential in an individual patient, which would be a sine qua non for identifying a homogeneous population in a recruitment study. Therefore, the method presented by Jacob Koefeld-Nielsen and colleagues in the previous issue of Critical Care provides us with a simple method that could be used at the bedside to assess recruitment potential before the manoeuvre is applied.