Neonatal Nurse Practitioner Practice Exam

In the context of newborns, which condition is most likely to cause a left shift in the oxygen-hemoglobin dissociation curve?

1. Increased temperature

2. Increased levels of 2-3DPG

3. Decreased pH

4. Transfusion reaction

The correct answer is: Transfusion reaction

A left shift in the oxygen-hemoglobin dissociation curve indicates an increased affinity of hemoglobin for oxygen, meaning that hemoglobin holds onto oxygen more tightly and releases it less readily to the tissues. This shift can occur under certain physiological and pathological conditions. In the case of a transfusion reaction, the infusion of incompatible blood can lead to massive hemolysis and associated complications. This process can elevate levels of certain substances in the blood or alter the local environment, contributing to a leftward shift. Transfusion reactions can also produce systemic effects such as increased blood viscosity or the release of cytokines, both of which can influence oxygen loading at the lungs and release at the tissues. In contrast, conditions such as increased temperature, increased levels of 2-3DPG, and decreased pH all typically result in a right shift in the curve. Increased temperature enhances oxygen release from hemoglobin to tissues, while elevated levels of 2-3DPG (a byproduct of red blood cell metabolism) facilitate the unloading of oxygen. A decrease in pH, commonly known as the Bohr effect, also promotes the release of oxygen from hemoglobin under acidic conditions. Thus, in the context of newborns and their physiological responses during stress or