Thermal dye measurements of extravascular lung water in critically ill patients. Intravascular Starling forces and extravascular lung water in the adult respiratory distress syndrome

Abstract

To assess the concurrent influence on extravascular lung water (EVLW) content of the intravascular Starling forces, the pulmonary capillary wedge pressure (PCWP), and the colloid osmotic pressure (COP), we measured EVLW by the thermal green dye technique in 174 patients with and without radiographically defined pulmonary edema; in the former group, patients with cardiac (CPE) and noncardiac (NCPE) causes of pulmonary edema were compared (study A). In 119 patients, EVLW was again measured one to three days later (study B). Patients with CPE demonstrated a significantly lower EVLW (9.3 +/- 3.9 ml/kg) (mean +/- SD) than patients with NCPE (14.5 +/- 4.9 ml/kg; p less than 0.05), despite a higher mean PCWP in the former group (20 +/- 7 mm Hg) than in the latter (12 +/- 6 mm Hg; p less than 0.05). In patients potentially with only a hydrostatic cause of pulmonary edema in study A, regression analysis demonstrated the following: EVLW = 3.2 + 0.30 PCWP (r2 = 0.38; p less than 0.005); and in patients with NCPE, EVLW = 10.9 + 0.304 PCWP (r2 = 0.17; p less than 0.01). In study B the change (delta) in EVLW between the two studies was described as follows: delta EVLW = 0.25 + 0.173 delta PCWP (p less than 0.01) + 0.663 group NCPE (p, not significant) + 0.236 group NCPE X delta PCWP (p less than 0.01). This latter equation indicated that the EVLW content manifested a greater change with concurrent alterations in the PCWP in patients with NCPE than was found in patients with only a hydrostatic influence to EVLW formation. Therefore, NCPE is characterized by a greater measurable thermal green dye EVLW than is observed in CPE at any given PCWP, and the PCWP synergistically influences EVLW accumulation in both CPE and NCPE.