A patient with a head injury has an intracranial pressure (ICP) of 18 mm Hg, the blood pressure is 144/90 mm Hg and mean arterial pressure (MAP) is 108 mm Hg. What is the cerebral perfusion pressure (CPP)?

Rationale: 2 mm Hg – Far too low and does not match the calculation. 90 mm Hg –Matches the calculation (MAP − ICP). Given: MAP = 108 mm Hg ICP = 18 mm Hg Calculation: CPP = 108 − 18 CPP = 90 mm Hg A CPP of 70–100 mm Hg is generally considered adequate to maintain cerebral perfusion in adults. Values below 60 mm Hg can result in cerebral ischemia C. 126 mm Hg – This would be MAP + ICP, which is not correct for CPP. D. 54 mm Hg – Likely results from an incorrect calculation. Cerebral perfusion pressure (CPP) is calculated using the formula: CPP = MAP − ICP.