Abstract
In order to estimate the pulmonary blood volume between the pulmonary artery trunk and the left atrium (PBVPAT-LA), simultaneously with the pulmonary extravascular water volume (PEWV) in the chronically stable cardiac patients, we employed the double indicator dilution method using heat as a diffusible indicator and indocyanine green as a non-diffusible indicator. The PEWV was obtained as the extravascular lung thermal volume estimated in the aortic root (LTVAo). In the group of hemodynamically normal patients, in spite of ischemic heart disease (G-N, n=22), the mean pulmonary artery wedge (PAW) pressure was 9.3±3.9 mmHg (mean ± SD), PBVPAT-LA was 89.5±1.71 ml/kg, LTVAo was 5.71±1.37 ml/kg and PBVPAT-LA /LTVAo ratio was 1.64±0.44. In the group of hemodynamically slightly compromised patients with mitral stenosis (G-MS, n=13), the mean PAW pressure was 14.2±2.6 mmHg, PBVPAT-LA was 11.12±2.86 ml/kg, LTVAo was 5.68±1.41 ml/kg and PBVPAT-LA/LTVAo ratio was 2.020.58. Between the two groups, LTVAo was not statistically significant, whereas the mean PAW pressure, PBVPAT-LA and PBVPAT-LA/LTVAo> ratio were all significantly increased in G-MS (p<0.05). Neither PBVPAT-LA nor LTVAo correlated with the mean PAW pressure in both groups. From PBVPAT-LA/LTVAo ratio, fluid volume in the intravascular space was greater than that in the extravascular space in both groups. From LTVAo, PEWV in G-MS was identical with that in G-N, in spite of the elevated mean PAW pressure. Therefore, even in the patients with mitral stenosis, the interstitium in the lung is kept dry under conditions of the mean PAW pressure below 20 mmHg. The safety factors that prevent pulmonary edema, as evidenced in animal studies, seem to operate effectively in man.
