• CABG
• cardiac surgery
• cardiopulmonary interaction
• echocardiography
• Weaning

The process of weaning from mechanical ventilation imposes an additional workload on the cardiovascular system, which may result in impaired myocardial function, increase in left ventricular filling pressure and respiratory distress. These mechanisms may ultimately result in weaning failure and need for prolonged respiratory support, which in turn increases the length of stay in the intensive care unit and the risk of complications. Among surgical patients, those undergoing heart surgery are particularly susceptible to cardiac dysfunction induced by weaning because of inadequate cardiovascular reserve. Early identification of patients at risk has potential therapeutic implications. The aim of this study was to depict the pathophysiological changes in hemodynamics assessed by echocardiography during the steps of weaning and to identify possible predictors of weaning failure. We enrolled 34 consecutive patients undergoing isolated coronary artery bypass grafting in our institution; data were collected by intraoperative transesophageal echocardiography before sternotomy (T0), and by transthoracic echocardiography at the beginning of weaning (T1) and at the time of extubation (T2). Weaning failure was defined as deferral of planned extubation or respiratory failure needing reintubation or non-invasive mechanical ventilation within 48 hours. Left ventricular outflow tract velocity–time index (LVOT-VTI) and ventricular-arterial coupling (VAC) measured at the beginning of the weaning process showed a significant correlation with outcome, with LVOT-VTI emerging as the best predictor of weaning failure. Significant increase in E/e’ suggested a cardiogenic etiology of respiratory distress in patients who failed the weaning trial. Overall, our study showed that serial assessment of hemodynamic parameters by means of echocardiography is feasible in cardiac surgical patients and can provide insight into pathophysiological changes during weaning. Although these preliminary data need to be confirmed in a larger population sample, LVOT-VTI emerged as a promising predictor of subsequent weaning failure.