A patient with severe traumatic brain injury has an intracranial pressure of 22 mmHg and a mean arterial pressure of 90 mmHg. Calculate the cerebral perfusion pressure and state whether it is acceptable.
- A 112 mmHg, dangerously high and requiring reduction
- B 68 mmHg, within the accepted target range ✓
- C 44 mmHg, critically low and requiring urgent vasopressors
- D 22 mmHg, normal and requiring no intervention
Correct answer: B. 68 mmHg, within the accepted target range
Explanation
Cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure: 90 minus 22 equals 68 mmHg. The Brain Trauma Foundation target in severe head injury is 60 to 70 mmHg, so 68 mmHg is within range. Values persistently below 60 mmHg are associated with cerebral ischaemia and worse outcome. Option C results from subtracting twice the ICP, option A from adding the values, and option D confuses ICP itself with perfusion pressure.
Reference: ATLS Student Course Manual, American College of Surgeons, 10th ed.
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