A Simple Holistic Model to Characterize Pulmonary Oxygen Transfer

Evaluation of pulmonary oxygen transfer usually requires measurement of inspired and expired gases in laboratories during exercise. In this research, we sought to develop a simplified model and a noninvasively assessable coefficient to characterize oxygen transfer from supply air to pulmonary blood.

A holistic model was developed by combining the transport resistances into one overall coefficient, D_o, as a characteristic of response to an oxygen partial pressure difference. The usefulness of D_o in detecting responses to environmental changes was compared with existing noninvasive measures (oxygen uptake and Oxygen Deficit (OD)) with measurements from 29 healthy adults (14 M/15F, 29 ± 4 yrs) during resting normoxia, cold pressor test (CPT), steady-state hypoxia (80% S_pO₂, SSH), and SSH + CPT.

D_oincreased significantly, as expected, during SSH (p < 0.01) and CPT (p = 0.01) from resting normoxia. It also detected changes during SSH + CPT from SSH alone (p = 0.04). showed a change from resting normoxia during CPT (p < 0.01) but not during SSH (p = 0.36). The OD method was applicable to a subset of participants and did not show differences among the treatments (p > 0.05).

The simple model and resulting coefficient (D_o) exhibited promise as a noninvasive way to assess the ability to respond to changes in oxygen supply and/or demand.