Effect of blood redistribution on exhaled and alveolar nitric oxide: A hypergravity model study

Alveolar (CANO) and exhaled nitric oxide (FENO) concentrations, mainly regarded as inflammation surrogates, may also be affected by perfusion redistribution changing alveolar transfer factor (DANO). A model of blood redistribution is hypergravity, Karlsson et al. (2009b) found, at 2 G, increases of 22% and 70%, for FENO, and CANO, respectively. The present study aimed at theoretically estimating the amplitude of DANO changes that mimic these experimental data.An equation describing convection, diffusion and NO sources was solved in a 2-trumpet model (parallel dependent and non-dependent lung units). Acinar airways lumen reduction was also simulated.A reduction of 33% of the overall DANO (−51% in the non-dependent unit) along with a 36% reduction of acinar airways lumen reproduced experimental findings.In conclusion, substantial FENO and CANO increases may be accounted for by a decrease of the alveolo-capillaries contact surface, here hypergravity-induced. Acinar airway constriction may also have a part in the overall FENO increase.