What lung capacity is typically decreased in the third trimester of pregnancy?

What lung capacity is typically decreased in the third trimester of pregnancy?

• A. Total lung capacity
• B. Functional residual capacity
• C. Vital capacity
• D. Inspiratory reserve volume

Answer: (B)

During the third trimester of pregnancy, functional residual capacity (FRC) typically decreases due to the physical changes occurring in a pregnant woman's body. As the uterus expands to accommodate the growing fetus, it elevates the diaphragm, reducing the space available in the thoracic cavity. This upward displacement of the diaphragm limits lung expansion, thus leading to a decrease in FRC, which is the volume of air that remains in the lungs after a normal, passive expiration. FRC plays a critical role in maintaining adequate gas exchange, and its reduction can contribute to some of the respiratory changes experienced during pregnancy, such as shortness of breath. Understanding the implications of this decreased lung capacity is important in managing the respiratory health of pregnant individuals and ensuring a safe environment during anesthesia and surgery, should they require it. In contrast, total lung capacity, vital capacity, and inspiratory reserve volume may not show significant changes or can even be maintained in certain aspects, making them less relevant to the specific changes that occur during the third trimester when considering lung capacity.

During the third trimester of pregnancy, functional residual capacity (FRC) typically decreases due to the physical changes occurring in a pregnant woman's body. As the uterus expands to accommodate the growing fetus, it elevates the diaphragm, reducing the space available in the thoracic cavity. This upward displacement of the diaphragm limits lung expansion, thus leading to a decrease in FRC, which is the volume of air that remains in the lungs after a normal, passive expiration.

FRC plays a critical role in maintaining adequate gas exchange, and its reduction can contribute to some of the respiratory changes experienced during pregnancy, such as shortness of breath. Understanding the implications of this decreased lung capacity is important in managing the respiratory health of pregnant individuals and ensuring a safe environment during anesthesia and surgery, should they require it.

In contrast, total lung capacity, vital capacity, and inspiratory reserve volume may not show significant changes or can even be maintained in certain aspects, making them less relevant to the specific changes that occur during the third trimester when considering lung capacity.