Weaning the cardiac patient from mechanical ventilation.

Abstract

Because of heart-lung interactions, weaning from mechanical ventilation induces strong hemodynamic changes that can lead to weaning-induced cardiac failure. Cardiac patients are particularly at risk for this complication. In this review, we will summarize the most recent advances concerning the mechanisms, diagnosis and treatment of weaning-induced cardiac failure. The role of left ventricular diastolic abnormalities contributing to weaning-induced pulmonary edema has been recently emphasized. The most important recent findings concern the diagnostic tools that can be used as alternatives to the pulmonary artery catheter for detecting weaning-induced pulmonary edema during a spontaneous breathing trial, such as increase in estimates of left ventricular filling pressure with echocardiography, increase in B-type natriuretic peptide, increase in plasma protein and hemoglobin concentration and increase in extravascular lung water measured by transpulmonary thermodilution. Concerning the treatment, recent data suggest that fluid removal, which is often indicated in such instances, could be guided by the dosage of B-type natriuretic peptide. Nowadays, the diagnosis of weaning-induced pulmonary edema can be easily made. Identifying such an event is important as an appropriate treatment, guided by the suspected mechanisms leading to the cardiac failure, should hasten weaning from mechanical ventilation.