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

Abstract 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.