What occurs during inverse steal when a patient with an ischemic area of the brain is hyperventilated?

In the context of inverse steal, hyperventilation in a patient with an ischemic area of the brain leads to a redistribution of blood flow. During hyperventilation, there is a decrease in carbon dioxide (CO2) levels, which causes vasoconstriction in non-ischemic areas of the brain.

This vasoconstriction in healthy brain tissue results in a relative increase in blood flow to the ischemic area, the area that is already struggling due to reduced perfusion. This physiological response aids in directing more blood, and therefore oxygen, towards the areas that are deprived, effectively improving perfusion in the compromised region.

This mechanism is specifically beneficial during situations where hyperventilation occurs, leading to the term "inverse steal," where the ischemic zone, rather than a healthy tissue region, receives greater blood flow due to the altered availability and responsiveness to CO2 levels in the blood.