Respiratory and Metabolic Changes Corresponding to Gestational Stages

Abstract

Pregnancy and delivery bring complexed influences to the metabolism of the respiratory system.
The purpose of this investigation is to make accurate measurements of the respiratory function corresponding each gestational stage and to analyze the efficiency of gas exchange in the lung tissue.
The fundamental data during a certain breathing pattern, like that for Lamaze's method, were also studied for the educational guidance of the pregnant women. Eight normal pregnant women were examined. and the results were as follows:
The vital capacity did not change through the pregnancy process. Energy consumption in the second and third trimesters of pregnancy increased significantly as compared with the first trimester of pregnancy.
In the second and third trimesters of pregnancy, the ventilatory volume and the heart rate during physical exercises have much more significantly increased than the first trimester of pregnancy.
Oxygen uptake and carbon dioxide (CO2) exhaustion were gradedly increased with the additional breathing exercises.
Decreasing ratio of the tissue partial pressure of carbon dioxide (tcPCO₂) showed 3 to 5% during abdominal and thoracic deep breathing patterns, while 2 to 3% during tachypneic breathing. There were significant differences between above two conditions.
These results revealed that the tachypneic breathing pattern was less effective for wash out function of CO₂ from the tissue than the above mentioned deep breathing patterns.
In the breath holding operation, after more than one minute the tcPCO₂ has been its maximum level. Therefore, it is indispensable to guide the deep breathing exercise just after bear down period.