Certified Clinical Transplant Nurse (CCTN) Practice Exam

Pulmonary edema occurs when excess fluid accumulates in the lungs, which can result from various underlying mechanisms. In the context of the options given, low protein levels in the blood can lead to pulmonary edema through a process known as hypoalbuminemia.

Albumin, a protein found in the blood, plays a critical role in maintaining oncotic pressure—the force that keeps fluid within the blood vessels. When protein levels, particularly albumin, are low, oncotic pressure diminishes, allowing fluid to leak out of the capillaries and into the interstitial spaces and ultimately the alveoli of the lungs. This fluid accumulation in the lungs causes the hallmark symptoms of pulmonary edema, such as shortness of breath and decreased oxygenation.

This understanding of the relationship between low protein levels and fluid dynamics helps clarify the pathophysiology behind pulmonary edema in certain clinical situations, such as malnutrition or liver disease, where protein synthesis is impaired or protein loss is increased.