Pulmonary artery wedge pressure and extravascular lung water in patients with acute cardiogenic pulmonary edema requiring mechanical ventilation

This study describe the values of pulmonary artery wedge pressure (PAWP) and the extravascular lung water (EVLW) index in patients with acute cardiogenic pulmonary edema who require mechanical ventilation. Ten consecutive patients with acute cardiogenic pulmonary edema who required mechanical ventilation were studied. Cardiac index was determined with thermodilution. Central venous pressure and PAWP were measured with a pulmonary artery catheter. EVLW index was determined with the thermal dye dilution technique, using a commercially available computer system. Measurements were made at regular preset intervals after the initiation of mechanical ventilation. PAWP was normal at baseline (11.6 ± 0.9 mm Hg, range 8 to 17) and did not change. EVLW index was elevated at baseline (13.7 ± 1.5 ml/kg) and decreased to a normal value after 24 hours (8.6 ± 1.2 ml/kg, p = 0.02). Concomitantly cardiac index increased from 2.61 ± 0.24 to 3.61 ± 0.14 L/min/m2 (p = 0.05). There was no correlation between PAWP and EVLW index. Fluid balance was +1,221 ± 908 ml after 24 hours and there was a weight gain of 0.88 ± 1.06 kg after 24 hours. Thus, patients with acute cardiogenic pulmonary edema requiring mechanical ventilation may have a normal PAWP after mechanical ventilation has been initiated. In a hemodynamic unstable situation, these patients may require fluid challenges to improve cardiac output, despite the presence of pulmonary edema. The pulmonary edema, measured as EVLW index, resolves rapidly when cardiac performance improves, despite positive fluid balances and weight gain in the first 24 hours.