During ebb, which of the following occurs?

• A. Loss of plasma volume
• B. Increase in plasma volume
• C. Increase in blood pressure
• D. Increased cardiac output

Answer: (A)

During ebb, the body experiences a rapid loss of intravascular fluid as capillary leakage and fluid shifts move plasma into the interstitial space. This decrease in plasma volume lowers venous return to the heart, which reduces stroke volume and cardiac output and often leads to lower blood pressure. So the event most characteristic of ebb is loss of plasma volume.

An increase in plasma volume would imply more circulating fluid, which isn’t seen in ebb. An increase in blood pressure or increased cardiac output would indicate better perfusion or a hyperdynamic state, not the hypovolemic, low-flow condition typical of ebb.