ASSESSMENT OF PULMONARY-EDEMA BASED ON EXTRAVASCULAR THERMAL VOLUME IN DOGS

To establish criteria of pulmonary edema by extravascular thermal volu me (ETV), ETV and a roentgenogram of the thorax were compared in norma l and experimental hydrostatic pulmonary edema dogs. ETV was measured by the double indicator dilution technique using heat as a diffusible indicator and sodium ions as a non-diffusible indicator (thermal-Na me thod). Mean ETV in 14 dogs under physiologic conditions was 8.20 +/- 1 .44 ml/kg. Comparison of ETV with the roentgenogram indicated the dens ity of thoracic the roentgenogram to increase when ETV exceeded II ml/ kg. Pulmonary edema was recognized clearly in the thoracic roentgenogr am at more than 15 ml/kg of ETV. Further increase in ETV did not occur with additional radiographic change. ETV was significantly (P<0.01) c orrelated with arterial oxygen tension (PaO2) but not statistically co rrelated with colloid oncotic pressure (COP), pulmonary arterial wedge pressure (PAWP) or PAWP-COP. Measurement of ETV would thus appear to be a reliable method for evaluating the severity of pulmonary edema, w hich has been difficult to diagnose by roentgenography and should faci litate the early diagnosis and management of pulmonary edema.