Acute Respiratory Distress Syndrome in the Perioperative Period of Cardiac Surgery: Predictors, Diagnosis, Prognosis, Management Options, and Future Directions
Acute respiratory distress syndrome (ARDS) after cardiac surgery is reported with a widely variable incidence (from 0.4%-8.1%). Cardiac surgery patients usually are affected by several comorbidities, and the development of ARDS significantly affects their prognosis. Herein, evidence regarding the current knowledge in the field of ARDS in cardiac surgery is summarized and is followed by a discussion on therapeutic strategies, with consideration of the peculiar aspects of ARDS after cardiac surgery.Prevention of lung injury during and after cardiac surgery remains pivotal. Blood product transfusions should be limited to minimize the risk, among others, of lung injury. Open lung ventilation strategy (ventilation during cardiopulmonary bypass, recruitment maneuvers, and the use of moderate positive end-expiratory pressure) has not shown clear benefits on clinical outcomes. Clinicians in the intraoperative and postoperative ventilatory settings carefully should consider the effect of mechanical ventilation on cardiac function (in particular the right ventricle). Driving pressure should be kept as low as possible, with low tidal volumes (on predicted body weight) and optimal positive end-expiratory pressure.Regarding the therapeutic options, management of ARDS after cardiac surgery challenges the common approach. For instance, prone positioning may not be easily applicable after cardiac surgery. In patients who develop ARDS after cardiac surgery, extracorporeal techniques may be a valid choice in experienced hands. The use of neuromuscular blockade and inhaled nitric oxide can be considered on a case-by-case basis, whereas the use of aggressive lung recruitment and oscillatory ventilation should be discouraged.
More research in the setting of ARDS after cardiac surgery is needed at multiple levels (risk factors, diagnosis, treatment options). Prevention of lung injury appears to be of the utmost importance, and a better characterization of the risk factors is needed. Avoiding excessive perioperative transfusions and the optimization of ventilation and hemodynamics seem to be the most modifiable risk factors. In patients who develop ARDS after cardiac surgery, extracorporeal techniques may represent a valid choice in experienced hands. The use of NMBAs, prone positioning, and iNO can be considered on a case-by-case basis, whereas aggressive lung recruitment and oscillatory ventilation probably should be avoided.
