Oxygen Deficit is a Sensitive Measure of Mild Gas Exchange Impairment at Inspired O2 between 12.5%-21.

Oxygen Deficit is a Sensitive Measure of Mild Gas Exchange Impairment at Inspired O2 between 12.5%-21.
Am J Physiol Lung Cell Mol Physiol. 2020 May 13;:
Authors: Liu MA, Stark PC, Prisk GK, West JB
Abstract
The oxygen deficit (OD) is the difference between the end-tidal alveolar PO2 and the calculated PO2 of arterial blood based on measured oxygen saturation that acts as a proxy for the alveolar-arterial PO2 difference. Previous work has shown that the Alveolar Gas Meter (AGM100) can measure pulmonary gas exchange, via the OD, in patients with a history of lung disease and in normal subjects breathing 12.5% O2. The present study measured how the OD varied at different values of inspired O2. Healthy subjects were split by age (young 22-31, n=23; older 42-90, n=13). Across all inspired O2 levels (12.5, 15, 17.5 and 21%), the OD was higher in the older cohort 10.6 ± 1.0 mmHg compared to the young -0.4 ± 0.6 mmHg (p <0.0001, repeated measures ANOVA), the difference being significant at all O2 levels (all p<0.0001). The OD difference between age groups and its variance was greater at higher O2 values (age x O2 interaction p=0.002). The decrease in OD with lower values of inspired O2in both cohorts is consistent with the increased accuracy of the calculated arterial PO2 based on the O2-Hb dissociation curve and with the expected decrease in the alveolar-arterial PO2 difference due to a lower arterial saturation. The persisting high...

Source: American Journal of Physiology. Lung Cellular and Molecular Physiology - May 12, 2020 Category: Cytology Authors: Liu MA, Stark PC, Prisk GK, West JB Tags: Am J Physiol Lung Cell Mol Physiol Source Type: research