ABSTRACT
Pregnancy is a unique physiologic condition that differs from the nonpregnant state. This chapter describes those differences from a systems-based perspective. Physical changes in the parturient lead to functional changes in many organ systems. The chin to chest ratio is shortened with elevation of the diaphragm. In addition, airway mucosa receives more blood flow and may be edematous. During pregnancy a woman's basal metabolic rate increases, as does her oxygen consumption. The elevation of the diaphragm leads to decreases in expiratory reserve volume, residual volume, and functional reserve capacity. As a result, the hemoglobin of the pregnant woman desaturates more quickly than that of the nonpregnant woman. However,both the minute ventilation and the tidal volume are increased. Therefore, pregnancy is a state of compensated respiratory alkalosis.
