Acute cor pulmonale in acute respiratory distress syndrome submitted to protective ventilation: Incidence, clinical implications, and prognosis

Context., The incidence of acute cor pulmonale (ACP), a frequent and usually lethal complication of acute respiratory distress syndrome (ARDS) during traditional respiratory support, has never been re-evaluated since protective ventilation gained acceptance. Objective: We performed a longitudinal transesophageal echocardiographic (TEE) study to determine whether this incidence, and its severe implications for prognosis, might have changed in our unit as we altered respiratory strategy. Design: Prospective open clinical study. Setting. Medical intensive care unit of a university hospital. Patients: Seventy-five consecutive ARDS patients given respiratory support with airway pressure limitation (plateau pressure less than or equal to 30 cm H2O). Interventions: ACP was defined as a ratio of right ventricular end-diastolic area to left ventricular end-diastolic area in the long axis >0.6 associated with septal dyskinesia in the short axis during TEE examination. Results: Normal right ventricular function was present in 56 patients, whereas right ventricular dysfunction was observed in 19 patients after 2 days of respiratory support. ACP was associated with pulmonary artery hypertension, increased heart rate, and decreased stroke index. Significant impairment of left ventricular diastolic function was also seen. All echo-Doppler abnormalities were reversible in patients who recovered, and the mortality rate was the same in both groups (32%). However, ACP patients who recovered required a longer period of respiratory support. A multivariate analysis individualized Paco2 level as the sole factor independently associated with ACP, suggesting that ACP development in ARDS is influenced by the severity of lung damage and/or the respiratory strategy. Conclusion: Evaluation of right ventricular function by TEE in a group of 75 ARDS patients submitted to protective ventilation revealed the persistence of a 25% incidence of ACP, resulting in detrimental hemodynamic consequences associated with tachycardia. However, ACP was reversible in patients who recovered and did not increase mortality.