Analysis of factors determining the resistance to diffusion in patients with liver cirrhosis

In 5 patients with liver cirrhosis the measured pulmonary diffusing capacity for oxygen (DLo2) was related to the diffusing capacity of the pulmonary membrane (DM) and to the volume of blood in the pulmonary capillary bed (Vc) as estimated from the measured pulmonary blood flow (Qc) and the value of the presumptive transit time. DL and DM were found to be diminished in 4 of the 5 cases, DM being only once 1,7 times greater than DL. The relationship between the resistance of the red blood cells to diffusion and the resistance of the pulmonary membrane to diffusion (see journal for formula) ranged between 5 and 35% indicating that the resistance of the pulmonary membrane to the uptake of O2 was of greater importance than the resistance of the red cells. A correlation was found to exist between D/Q and DM/ThetaVc (diffusing capacity/blood flow and membrane diffusing capacity/diffusing capacity of the red cells in the pulmonary capillary bed). The possible site and nature of the diffusion defect is discussed.