Acute lung injury in thoracic surgery

This review will analyze the risk factors of acute lung injury (ALI) in patients undergoing thoracic surgery. Evidence for the occurrence of lung injury following mechanical ventilation and one-lung ventilation (OLV) and the strategies to avoid it will also be discussed.

Post-thoracotomy ALI has become one of the leading causes of operative death. The pathogenesis of ALI implicates a multiple-hit sequence of various triggering factors (e.g. preoperative conditions, surgery-induced inflammation, ventilator-induced injury, fluid overload, and transfusion). Conventional ventilation during OLV is performed with high tidal volumes equal to those being used in two-lung ventilation, high FiO(2), and without positive end-expiratory pressure. This practice was originally recommended to improve oxygenation and decrease shunt fraction during OLV. However, a number of recent studies using experimental models or human patients have shown low tidal volumes to be associated with a decrease in inflammatory mediators and a reduction in pulmonary postoperative complications. However, the application of such protective strategies could be harmful if not still properly used.

The goal of ventilation is to minimize lung trauma by avoiding overdistension and repetitive alveolar collapse, while providing adequate oxygenation. Protective ventilation is not simply synonymous of low tidal volume ventilation, but it also involves positive end-expiratory pressure, lower FiO(2), recruitment maneuvers, and lower ventilatory pressures.