Chapter 38: Neurologic Formulas and Parameters

INTRACRANIAL PRESSURE

• Normal 0 to 20 mmHg

CEREBRAL PERFUSION PRESSURE (CPP)

Formula: CPP = Mean Arterial Pressure (MAP) − Intracranial Pressure (ICP)

• Infants: 40 mmHg

• Adults: 65 mmHg

  • Changes throughout development: parallels changes in systemic blood pressure (BP); increases gradually throughout development to adult levels.

  • Consider patient's baseline BP: Baseline MAP should be considered when considering therapeutic target for CPP in setting of acute neurologic injury. A patient with baseline hypertension will need blood pressure supported to a level that approximates their baseline physiology.

  • In adults poor outcomes are associated with sustained CPP <40 mmHg.

CEREBRAL BLOOD FLOW (CBF)

• Infants: 40 mL/100 g/min

• Children (4 years): 100 mL/100 g/min

• Children (9 years): 50 to 70 mL/100 g/min

• Adults: 50 mL/100 g/min

CEREBRAL METABOLIC RATE FOR OXYGEN (CMRO₂)

• Normal: 3.0 to 3.8 mL O₂/100 g brain/min

CEREBROSPINAL FLUID (CSF)

Normal values:

• White blood cell count (WBC): 0 to 5

• Total protein: 22 to 38 mg/dL

• Glucose: 60% to 80% of serum glucose

GLASGOW COMA SCALE (GCS)

• See Table 38-1.

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