 How well does open lung ventilation work for patients undergoing cardiac surgery? Open lung ventilation consists of combining recruitment maneuvers with moderate to high levels of positive end-experitory pressure ventilation and maintaining ventilation during cardiopulmonary bypass, which might reduce the number of collapsed alveoli and improve outcomes. But in a new study published in Anesthesiology, researchers in France found that the benefits did not last even to the end of surgery, and the technique led to increased susceptibility to lung injury. Previous clinical studies have suggested that an open lung strategy can homogenize lung aeration, improve lung mechanics, and prevent intraoperative inflammation. But the technique remains controversial because of the risk of over-distinction, which may be especially relevant to cardiac surgery patients. To find out whether the approach is worth doing, researchers turned to a sub-study of the Protective Ventilation in Cardiac Surgery trial. The trial previously found that open lung ventilation did not improve clinical outcomes of patients undergoing cardiopulmonary bypass surgery, compared to a control low-stretch strategy. But researchers had not yet analyzed additional physiological data, which might indicate a benefit. The authors of the current study looked at pulmonary electrical impedance tomography measurements as well as biomarkers of lung injury. They found that, at the onset of anesthesia, open lung ventilation enhanced the dorsal distribution of tidal volumes and improved the compliance of the dorsal lung compared to controls. However, these differential effects were not apparent at the end of surgery or two days later. The team also looked at plasma biomarkers of lung injury, finding a higher intraoperative concentration of S-rage, a marker of epithelial injury, in the blood coming from pulmonary veins of open lung patients. There was no difference in angiopoietin II plasma concentrations, a marker of endothelial injury between the two groups. Consequently, the biological response to open lung ventilation was consistent with intraoperative epithelial lung injury. The researchers conclude that there was only a temporary improvement in dorsal ventilation among the open lung patients. Further, the open lung patients may be at higher risk for lung injury. As a result, the use of the open lung approach during cardiac surgery appears limited. The authors suggested that these results may have to do with the lung distention facilitated by opening of the chest during cardiac surgery, which changes the mechanical properties of the respiratory system. Under those specific circumstances, alveolar recruitment may have already been maximized with the control treatment, while the open lung strategy may have produced over-distention.