A nurse is caring for a patient with severe TBI receiving mechanical ventilation. ICP is 28 mmHg.CPP (cerebral perfusion pressure) is 55 mmHg. The patient's PaCO2, is 60 mmHg.

A. Normal ICP is incorrect because normal intracranial pressure ranges from 5 to 15 mmHg in adults. Values above 20 mmHg are considered elevated, and sustained ICP above 20–25 mmHg is critically high and requires urgent intervention. B. Mildly elevated ICP is incorrect because ICP of 28 mmHg exceeds mild elevation, which is generally considered 20–25 mmHg. This patient’s ICP is above that range and represents a dangerous level. C. Critically elevated ICP is correct. An ICP of 28 mmHg indicates critically elevated intracranial pressure, especially when accompanied by low CPP (normal 60–70 mmHg) and hypercapnia (PaCO2 60 mmHg). Hypercapnia causes cerebral vasodilation, further increasing ICP and worsening cerebral perfusion. Immediate interventions are required to reduce ICP, optimize CPP, and prevent secondary brain injury.