Red cell distortion and conceptual basis of diffusing capacity estimates: finite element analysis
Compute the uptake of CO across a two-dimensional geometric capillary model containing a variable number of equally spaced RBCs (circular or parachute shaped, with the same perimeter length). Total CO diffusing capacity (DLCO) and membrane diffusing capacity (DMCO) were calculated by a finite element method. DLCO calculated at two levels of alveolar PO2 were used to estimate DMCO by the Roughton-Forster (RF) technique or by the morphometric random linear intercept method. Results: shape distortion of RBCs reduces diffusive gas uptake, & exaggerates errors in the RF technique at a high capillary hematocrit. Shape distortion error in morphometric estimates of DMCO are exaggerated at a low hematocrit.
Adapted from Hsia CCW, et al. J Appl Physiol 1997 83:1397-404..