Final answer:
The respiratory minute volume increases during pregnancy to meet the increased oxygen demands, while the diaphragm's upward movement reduces the volume of each breath. Some aspects, such as the oxygen-carrying capacity of the blood, remain unchanged during pregnancy. Lightening towards the end of pregnancy often decreases experienced dyspnea.
Step-by-step explanation:
Respiratory Mechanics During Pregnancy
Throughout pregnancy, there are significant changes in respiratory mechanics to meet the oxygen demands of the fetus and the increased metabolic rate of the mother. Notably, during the second half of pregnancy, the respiratory minute volume, which is the amount of gas that is inhaled or exhaled from the lungs per minute, increases significantly, by approximately 50%. This increase serves to satisfy both the oxygen needs of the fetus and the greater metabolic rate of the pregnant person.
The enlarging uterus places pressure on the diaphragm, which can reduce the volume of each inspiration, thus leading to potential shortness of breath or dyspnea. However, some components of respiratory mechanics do remain unchanged during pregnancy. For instance, the oxygen-carrying capacity of the blood, which encompasses factors such as the total volume of red blood cells and hemoglobin concentration, does not significantly change during pregnancy.
As pregnancy progresses, particularly during the last several weeks, the pelvis becomes more elastic and the fetus descends in a process known as lightening. This action can generally lessen the dyspnea that pregnant individuals may experience. Furthermore, the levels of pulmonary surfactant are enhanced closer to term, which is crucial for lung compliance and the functionality of alveoli after birth.