What is an effect of hyperventilating a patient?

Hyperventilation in a patient leads to a significant decrease in carbon dioxide levels in the blood, resulting in respiratory alkalosis. This reduction in carbon dioxide causes vasoconstriction of cerebral blood vessels, leading to decreased cerebral blood flow. The net result often includes a decrease in intracranial pressure, which can be beneficial in managing conditions such as traumatic brain injury.

While the other outcomes may seem plausible, they are not directly associated with hyperventilation. For instance, increased carbon dioxide retention would not occur as hyperventilation actively eliminates carbon dioxide. Similarly, hyperventilation is more likely to increase heart rate rather than lower it due to a stress response. Blood pressure may vary depending on individual patient factors and circumstances, but it typically is not directly increased by hyperventilation in the acute sense. Thus, the primary and immediate effect relevant to the question is the decrease in intracranial pressure.