[Continuous spectrophotometry as a method to study pulmonary edema in isolated canine pulmonary lobe]

The aim of this paper is to introduce the spectrophotometric method to the study of pulmonary edema in isolated ex-vivo canine pulmonary lobe preparation. This spectrophotometric method is based on the on-line measure of light transmission in a column of blood, that is proportional to hematocrit. A second light is used to follow Evans blue dyed proteins. With this method we were able to measure the amount of edema in 10 isolated canine lobes. Both the filtration and reflection coefficient of the membrane as well as the characteristics of the filtrate could be calculated. The filtration coefficient was 0.6 +/- 0.4 ml/min (1.3 +/- 0.9 ml/min/100 g pulmonary, tissue) at maximum capillary pressure and the reflection coefficient was 0.53 +/- 0.07. With the spectrophotometric method we have the capability to study different aspects of lung edema formation. This method has the advantage of being exact and independent from pressure and volume induced vascular changes. It also allows the measurement of solute transport.