Reference — Critical Care

ICP and CPP Reference

Quick-access reference for ICP and CPP values, the CPP formula, signs of elevated ICP, nursing interventions, and hyperosmolar therapy monitoring at the bedside.

Educational use only. ICP management requires physician-directed care. Follow institutional protocols for all clinical decisions. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.

The CPP Formula

CPP = MAP − ICP

To protect cerebral perfusion: keep MAP up and ICP down.
Example: MAP 85 − ICP 22 = CPP 63 mmHg (adequate).
MAP 75 − ICP 30 = CPP 45 mmHg (inadequate — ischemia risk).

Key Values and Thresholds

Parameter	Value	Action
Normal ICP	0–15 mmHg	Continue routine monitoring
Intracranial hypertension	>20 mmHg (sustained)	Notify physician; initiate ordered interventions
Normal CPP	50–70 mmHg	Maintain MAP and manage ICP to sustain CPP
Inadequate CPP	<50 mmHg	Urgent — MAP augmentation and ICP reduction needed
Target MAP (ICP patient)	≥80–90 mmHg	Vasopressors as ordered; avoid hypotension

Signs of Elevated ICP

Stage	Findings
Early elevated ICP	Headache, nausea, restlessness, mild LOC change, visual disturbance
Cushing's triad (late/herniation)	Hypertension + bradycardia + irregular respirations — STAT notification
Blown pupil (unilateral)	Fixed and dilated pupil — CN III compression from uncal herniation
Motor posturing	Decorticate (arms flexed) or decerebrate (arms and legs extended) — severe dysfunction

Nursing Interventions

Intervention	Expected Effect
HOB 30–45°, head midline	↓ ICP via improved venous drainage
Minimize stimulation	Prevents ICP spikes from noxious stimuli
Normoxia (SpO₂ ≥94%)	Avoids hypoxia-induced cerebral vasodilation
Normocapnia (PaCO₂ 35–45)	Avoids hypercapnia-induced cerebral vasodilation
Maintain MAP ≥80 mmHg	Sustains adequate CPP
Normothermia (treat fever)	Reduces cerebral metabolic demand
Prevent straining/Valsalva	Avoids ↑ intrathoracic pressure → ↑ ICP
Mannitol (per order)	Osmotic diuresis; monitor osmolarity <320 mOsm/kg
Hypertonic saline (per order)	↑ Serum Na⁺ / osmolarity; monitor serum Na⁺

Key Reminders

•Cushing's triad is a late, ominous sign — do not wait for all three components.

•Head must remain midline — neck rotation or flexion obstructs venous drainage.

•Hyperventilation (↓PaCO₂) reduces ICP temporarily via vasoconstriction — bridge only, not sustained.

•Do not cluster stimulating interventions — space them to avoid cumulative ICP spikes.

•Mannitol: hold if serum osmolarity >320 mOsm/kg.

•Hypertonic saline: concentrated solutions require central access.

Related Resources

ICP Monitoring and CPP GuideMonro-Kellie doctrine, causes, signs, and full nursing management

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Standards & sources

Fact-checked Jun 20, 2026

This page is written to align with Society of Critical Care Medicine (SCCM) · Surviving Sepsis Campaign · American Association of Critical-Care Nurses (AACN). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →