Normal Values of Arterial Blood Gas Fractions for the Healthy Elderlies

Abstract

Arterial blood gas studies were made on sixty healthy elderlies over sixty years of age and the results compared to those of the fifty young adults in good health under the age. Normal values for the aged and the effects of aging on them were evaluated as follows:
1) Mean value of PaO₂ for each age group from the third to the ninth decade is in order: 93.3±5.8torr. (mean±SD), 85.9±5.4, 85.2±5.1, 84.3±5.6, 82.9±6.1, 81.6±7.8, and 79.4±7.7. The same of AaDO₂ is, 4.9±4.7, 11.5±6.8, 16.4±5.6, 14.6±5.6, 16.3±6.6, 18.0±8.5, and 19.2±10.3.
2) The correlation coefficients and regression equations of those values on aging are: PaO₂=-0.2340×(AGE)+96.4520, r=-0.435 and AaDO₂ 0.287×(AGE)+0.642, r=0.502 for the young, and PaO₂=-0.0621×(AGE)+86.413, r=-0.047, and AaDO²=0.095×(AGE)+10.570, r=0.066 for the elderly. Correlativity between the fractions and age for the elderly is less and the abatement rate of regression curve much milder for the aged.
3) Others as PaCO₂ and PH did not disclose any inconsistency. In conclusion, the PaO₂ regression line in this study demonstrates good accordance in the abatement rate for the young with that in the previous reports, but does not for the elderly; that is, much more gradual at the rate in the present report.