B –natriuritic peptide and troponin for diagnosis of cardiac origin weaning failure from mechanical ventilation: An observational study.

Patients were categorized into 3 groups according to spontaneous breathing trial outcome: Group I: Heart failure group (heart failure as a cause of weaning failure). Group II: Respiratory failure group (respiratory cause of weaning failure). Group III: Success group. Demographic data, causes of mechanical ventilation and severity score APACHE II (Acute Physiology And Chronic Health Evaluation) score; were recorded at admission to intensive care unit. Clinical, laboratory and echocardiographic data have been obtained immediately before and at the end of the spontaneous breathing trial. Sample collection and biomarker assays: All arterial blood gases were measured using a blood gas analyzer. BNP and troponin I were measured in venous whole blood by staff blinded to clinical and echocardiographic findings. Echocardiography Transthoracic echocardiograms were performed in all patients immediately before and at the end of spontaneous breathing trial. Diastolic function was evaluated with pulse-wave doppler imaging and pulmonary flow measuring blood flow through the mitral valve. Systolic function was assessed in the apical four-chamber view. All echocardiography measurements were performed by cardiologist blinded to the natriuretic peptide, troponin I concentrations and SBT results. Heart failure will be diagnosed by the presence of echocardiography indices suggestive of filling pressures