Cerebral perfusion pressure, intracranial pressure, and head elevation

Area of Science:

• Neurosurgery
• Critical Care Medicine
• Neurology

Background:

• Intracranial pressure (ICP) waves are linked to reduced cerebral perfusion pressure (CPP).
• Head elevation, a common practice in managing intracranial hypertension, may affect CPP and ICP.
• Previous studies noted increased pressure waves with head elevation.

Purpose of the Study:

• To investigate the effect of head elevation on CPP and ICP in patients with intracranial hypertension.
• To determine the optimal head position for maximizing CPP.
• To assess the relationship between head elevation, CPP, and the occurrence of cerebrospinal fluid pressure waves.

Main Methods:

• 18 patients with intracranial hypertension were studied.
• Systemic arterial blood pressure (SABP) was monitored at head and heart levels.
• ICP and central venous pressure were measured at 10-degree increments of head elevation (0-50 degrees).

Main Results:

• Each 10-degree head elevation decreased ICP by 1 mm Hg and CPP by 2-3 mm Hg.
• Maximal CPP (73 +/- 3.4 mm Hg) occurred at 0-degree head elevation.
• Head elevation caused CPP decrements in all patients and precipitated pressure waves in 4 of 18.
• Pressure waves were avoided if CPP remained at or above 70-75 mm Hg.

Conclusions:

• 0-degree head elevation maximizes CPP and minimizes pressure wave occurrence.
• Head elevation can decrease CPP and induce pressure waves in susceptible patients.
• Maintaining adequate hydration and avoiding hypotensive agents is essential when head elevation is necessary.