Which of the following statements regarding physiologic changes in pregnancy is false?
A. Blood volume increases by 45% B. Cardiac output is increased by 40% C.Increase in the functional residual capacity by 20% D. Gastrointestinal sphincter tone is decreased E. E.Hematocrit changes to 32-34%
Increase in functional residual capacity by 20%. Functional residual capacity is the amount of air that can be contained in the lungs. In pregnancy, there’s a decrease in functional residual capacity, not an increase. The other changes are true. Blood volume increases dramatically, which leads to an increased heart rate and cardiac output.
These are necessary to deal with the extra volume of blood. The extra blood volume is mostly made up of plasma rather than red blood cells, so the hematocrit (measure of red blood cells per unit of volume) is reduced by 32-34%. And the gastrointestinal sphincter tone is reduced, along with the tone of other ‘valves’ in the gastrointestinal tract. This can lead to increased incidence of reflux problems.