Neonatal Nurse Practitioner Practice Exam

An increase in cerebral blood flow is likely to occur with which condition?

1. Decreased PCO₂

2. Decreased PaO₂

3. Increased Kt level

4. Increased blood viscosity

The correct answer is: Decreased PaO₂

An increase in cerebral blood flow is commonly associated with decreased levels of oxygen in the blood, known as hypoxemia, which corresponds to the condition of decreased PaO₂. The brain is highly sensitive to oxygen levels; when there is a drop in the oxygen concentration, the body responds by dilating blood vessels in the brain (cerebral vasodilation) to increase blood flow and thus enhance oxygen delivery to the tissues. This physiological response is crucial for maintaining adequate oxygen levels in the brain, which is vital for neuronal function and survival. In contrast, decreased PCO₂ typically leads to vasoconstriction of cerebral vessels, resulting in reduced blood flow. Increased Kt levels, which could refer to an increase in potassium levels in the blood, may have various effects, but hyperkalemia is more closely associated with potential cardiac issues than directly increasing cerebral blood flow. An increase in blood viscosity can impede blood flow and may lead to higher resistance in the cerebral vasculature, thereby decreasing cerebral blood flow rather than increasing it. Thus, the correct linkage of decreased PaO₂ with an increase in cerebral blood flow aligns with the body's regulatory mechanisms to ensure adequate oxygen supply to the brain.