Background .– Acute increase in right ventricular overload secondary to acute respiratory distress syndrome (ARDS) may result in acute cor pulmonale (ACP). Hypoxemia could be worsened by the increased right-to-left shunting across a patent foramen ovale (PFO).

Objectives .– To assess the incidence of ACP and PFO in ventilated patients with ARDS during the first 48 hours. We secondary aimed to assess transthoracic echocardiography (TTE) feasibility and main measurements compared to transesophageal echocardiography (TEE).

Method .– This prospective observational study in nine intensive care units enrolled all patients with ARDS (new bilateral pulmonary infiltrates on chest X-ray, PaO2/FiO2 ratio ≤ 200 and no left ventricular pressure overload). TTE and TEE were performed by trained intensivists, digitally recorded and reviewed by two experts. ACP was diagnosed when right ventricle was dilated (end-diastolic right ventricle/left ventricle area ratio > 0.6 in the four-chamber views) associated with septal dyskinesia (eccentricity index > 1 on the short-axis view [TTE] and the transgastric short axis view [TEE]). PFO was detected by contrast study on the apical four-chamber view (TTE) and 0° and bicaval views (TTE).

Results .– Eighty-four patients were studied during 11 months (mean ± SD): age 54 ± 13 year-old, SAPS II 44 ± 17, PaO2/FiO2 118 ± 42, PEEP 11 ± 3 cmH2O. Day 28 mortality rate was 17%. Seventy-four patients were analysable (30 with TTE: 40.5%). ACP was diagnosed in 11 patients (14.9%) and PFO in 10 (13.5%). ACP and PFO were associated in four patients (5.4%). TTE compared to TEE measurements had sensitivity and specificity respectively of 25% and 100% (PFO) and 100% and 96% (ACP). TTE allowed measurement of other right ventricular function parameters: right ventricular fractional area change (38 ± 15%), tricuspid regurgitation velocity (273 ± 59 cm/s), tissue Doppler-derived tricuspid lateral annular systolic velocity (15 ± 4 cm/s) and tricuspid annular plane systolic excursion (20 ± 5 mm) (TAPSE). Median values (Wilcoxon test) were significantly different for right ventricular fractional area change ( P = 0.03) and TAPSE ( P = 0.05) between patients with ACP compared to patients without ACP.

Conclusion .– These preliminary results in patients with early severe ARDS under protective mechanical ventilation found low incidences of ACP and PFO. Good TTE sensitivity and specificity for ACP could allow easier follow-up when TTE is possible. ACP was associated with significantly decrease of right ventricular fractional area change and TAPSE.

Grant acknowledgement .– SRLF 2008.