Acute cor pulmonale during protective ventilation for acute respiratory distress syndrome: prevalence, predictors, and clinical impact.

RATIONALE: Increased right ventricle (RV) afterload during acute respiratory distress syndrome (ARDS) may induce acute cor pulmonale (ACP).

OBJECTIVES: To determine the prevalence and prognosis of ACP and build a clinical risk score for the early detection of ACP.

METHODS: This was a prospective study in which 752 patients with moderate-to-severe ARDS receiving protective ventilation were assessed using transesophageal echocardiography in 11 intensive care units. The study cohort was randomly split in a derivation (n = 502) and a validation (n = 250) cohort.

MEASUREMENTS AND MAIN RESULTS: ACP was defined as septal dyskinesia with a dilated RV [end-diastolic RV/left ventricle (LV) area ratio >0.6 (≥1 for severe dilatation)]. ACP was found in 164 of the 752 patients (prevalence of 22 %; 95 % confidence interval 19-25 %). In the derivation cohort, the ACP risk score included four variables [pneumonia as a cause of ARDS, driving pressure ≥18 cm H2O, arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) ratio <150 mmHg, and arterial carbon dioxide partial pressure ≥48 mmHg]. The ACP risk score had a reasonable discrimination and a good calibration. Hospital mortality did not differ between patients with or without ACP, but it was significantly higher in patients with severe ACP than in the other patients [31/54 (57 %) vs. 291/698 (42 %); p = 0.03]. Independent risk factors for hospital mortality included severe ACP along with male gender, age, SAPS II, shock, PaO2/FiO2 ratio, respiratory rate, and driving pressure, while prone position was protective.

CONCLUSIONS: We report a 22 % prevalence of ACP and a poor outcome of severe ACP. We propose a simple clinical risk score for early identification of ACP that could trigger specific therapeutic strategies to reduce RV afterload.