NCLEX Intracranial Pressure (ICP) Practice Exam

Raising the head of the bed to about 30 degrees helps venous drainage from the brain. Gravity assists the blood leaving the intracranial space through the sagittal sinuses, so venous pressure within the skull falls and cerebral venous blood volume decreases. This reduction in venous blood volume lowers the overall intracranial pressure. Think of cerebral perfusion pressure as the pressure that drives blood flow into the brain: CPP = mean arterial pressure minus ICP. When ICP drops (as it does with head elevation) and mean arterial pressure remains stable, CPP can stay the same or increase. The statement that head elevation reduces CPP due to lower systemic BP isn’t typically accurate in this context, because the beneficial effect is driven by lower ICP rather than a dangerous drop in systemic pressure. So, elevating the head to 30 degrees reduces sagittal sinus pressure and promotes drainage, which lowers ICP and can maintain or improve CPP.