Elevated Intracranial Pressure in Adults

Background

• Elevated intracranial pressure (ICP) is typically defined as cerebrospinal fluid (CSF) pressure sustained > 20 mm Hg.
  • Elevated ICP may be a medical emergency due to the potential to cause cerebral ischemia, brain herniation, and death.
  • It can occur with expansion of the brain, blood, or CSF compartments within the rigid skull.
• Cerebral blood flow depends on cerebral perfusion pressure (CPP) (estimated CPP = mean arterial pressure - ICP)

Evaluation

• A patient evaluation includes a history, a clinical exam, computed tomography, and possibly a lumbar puncture with a cerebrospinal fluid (CSF) analysis.
  • A clinical exam can identify manifestations of global mass effect, focal mass effect, and herniation syndromes.
  • Computed tomography can identify signs of elevated intracranial pressure (ICP), including midline shift and ventricular enlargement or distortion, and can identify possible causes, such as mass lesions, edema, and infarction.
  • Lumbar puncture and CSF analysis is an option to evaluate for a suspected infection, but it may be contraindicated with clinical or imaging signs of potential herniation in patients with elevated ICP.
• ICP monitoring:
  • ICP monitoring may be indicated for patients with acute neurologic process with risk of elevated ICP or a worsening neurologic exam.
  • An external ventricular drain allows for both monitoring and a means to drain CSF to lower ICP.
  • Treatment is typically indicated for ICP > 20 mm Hg (BTF Level II), but varies with pathology.

Management

• Supportive treatment:
  • Monitor continuously for signs of impending herniation and the need for emergent treatment to reduce intracranial pressure (ICP).
  • Monitor and maintain normal cerebral perfusion pressure, oxygen saturation, ventilation, volume status, blood pressure, and body temperature (unless inducing therapeutic hypothermia).
  • Monitor hemoglobin, sodium, and blood glucose.
• Emergency airway management in patients with acutely increased ICP is often initiated before identifying the underlying cause, and typically involves preoxygenation followed by rapid sequence intubation.
• Emergency surgical options:
  • Surgical evacuation of intracranial focal mass lesions may be appropriate to reduce elevated ICP caused by a tumor, an abscess, or a hematoma.
  • Decompressive craniectomy is reasonable to consider as a last-resort option in certain circumstances after the conventional measures have failed (patient is deteriorating rapidly or ICP continues to rise despite medical management).
• Treatment to lower elevated ICP:
  • The choice of treatment is influenced by the patient diagnosis and pathophysiology.
  • Intubation and mechanical ventilation allow the use of first-line therapies.
  • First-line therapies:
    • Provide sedation to control elevated ICP, to treat agitation, and to prevent arterial hypertension and patient-ventilator dyssynchrony.
      • Propofol is recommended for control of ICP, but high-dose propofol can be associated with significant morbidity. The ceiling dose is 5 mg/kg/hour.
      • Short-acting benzodiazepines, such as midazolam may also be used.
    • Hyperosmolar agents (IV mannitol or hypertonic saline) can rapidly reduce brain volume and ICP in most cases of cerebral edema.
    • Hyperventilation:
      • Hyperventilation can be used as a temporizing measure for the reduction of elevated ICP.
      • Hyperventilation rapidly lowers ICP by inducing arterial blood hypocarbia which causes vasoconstriction and reduced blood flow, which may carry a serious risk of cerebral ischemia if hyperventilation is prolonged.
      • Prophylactic hyperventilation (partial pressure of carbon dioxide in the blood [PaCO₂] ≤ 25 mm Hg) is not recommended.
    • Cerebrospinal fluid (CSF) drainage is simple and effective for reducing elevated ICP and is the treatment of choice when the cause is CSF overproduction or outflow disturbance.
  • Second-line therapies:
    • Moderate hypothermia (32-34 degrees C [89.6-93.2 degrees F]) can reduce ICP by about 10 mm Hg and may be considered if other medical measures fail.
    • High-dose barbiturates, such as pentobarbital (loading dose 10 mg/kg over 30 minutes; 5 mg/kg every hour for 3 doses; maintenance dose 1 mg/kg/hour) can be considered for controlling elevated ICP refractory to maximum standard medical and surgical treatment; hemodynamic stability is essential before and during therapy with barbiturates.