Neuro Perfusion Bench: CPP, the Glasgow Coma Scale and the Territory
Two equations carry this whole chapter: mean arterial pressure is diastolic plus one third of the pulse pressure, and cerebral perfusion pressure equals MAP minus intracranial pressure. Move the numbers below and watch perfusion succeed or fail, then score the exam that would have warned you first. Level of consciousness changes before the pupils, before the motor exam and long before the vital signs.
1 · Set the pressures
Intracranial pressure12 mmHg
Normal adult intracranial pressure is 5–15 mmHg; sustained values above 20–22 mmHg are treated. In a monitored patient the perfusion target is a CPP of 60–70 mmHg. Autoregulation holds flow steady across a MAP of roughly 60–150 mmHg — and injured brain loses it.
2 · Score the exam
Eye opening — max 4
Verbal response — max 5
Best motor response — max 6
Pupils
Score the best response in the best limb — a hemiplegic patient is scored on the unaffected side. Record verbal as T if the patient is intubated.