Which factor causes the oxygen-hemoglobin dissociation curve to shift to the left?

The oxygen-hemoglobin dissociation curve shifts to the left under conditions that enhance hemoglobin's affinity for oxygen. A key factor that contributes to this shift is a decrease in carbon dioxide levels (PaCO2). When the concentration of carbon dioxide decreases, it results in an increase in blood pH (more alkaline conditions). This increase in pH leads to a higher affinity of hemoglobin for oxygen, meaning hemoglobin holds on to oxygen more tightly.

In the context of neonatal care, understanding this relationship is crucial because it can influence oxygen delivery to tissues. For instance, if a neonate is in a state where carbon dioxide levels are low, this could indicate hyperventilation or other metabolic adjustments. Recognizing these physiological responses helps nurses manage appropriate oxygen therapy and monitor the respiratory status of neonates effectively.

In contrast, other factors leading to a rightward shift, such as increased temperature, decreased pH (more acidic conditions), or higher levels of carbon dioxide, would indicate a scenario where hemoglobin releases oxygen more readily, which is not the focus of this question.