Progressive Care Nursing Certification (PCCN) Practice Exam

Which of the following parameters would lead to increased fluid retention in patients undergoing cardiopulmonary bypass?

1. Increased aldosterone secretion

2. Decreased antidiuretic hormone (ADH)

3. Lowered renal perfusion pressure

4. Increased cortisol release

The correct answer is: Increased aldosterone secretion

Increased aldosterone secretion leads to fluid retention due to its role in promoting sodium reabsorption in the kidneys. When aldosterone levels rise, the kidneys increase the reabsorption of sodium back into the bloodstream while simultaneously enhancing the excretion of potassium. This process of sodium retention is accompanied by water retention, as water follows sodium osmotically. Therefore, in patients undergoing cardiopulmonary bypass, heightened aldosterone levels contribute significantly to fluid retention and can lead to increased plasma volume, ultimately influencing hemodynamics and fluid balance. While other factors like decreased renal perfusion pressure may affect kidney function and fluid output, they do not directly promote fluid retention in the same way that increased aldosterone does. Decreased levels of antidiuretic hormone (ADH) would generally lead to increased urine output rather than retention. Although increased cortisol can have various effects on metabolism and fluid balance, its direct relation to aldosterone's effects on sodium and fluid retention is less pronounced in this specific context.