12.2 Increased Intracranial Pressure (ICP) & Seizure Management

12.2 Increased Intracranial Pressure (ICP) & Seizure Management

Intracranial pressure (ICP) regulation and acute seizure management represent high-stakes clinical competencies in neuroscience nursing. In intensive care units (ICUs) and neurosurgical wards across Singapore, nurses must continuously monitor intracranial dynamics to prevent irreversible brain ischemia, brainstem herniation, and sudden neurological demise.

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1. Physiology of ICP & The Monro-Kellie Hypothesis

The rigid adult skull constitutes a closed vault containing three non-compressible anatomical components:

1. Brain Tissue / Parenchyma: ~80% of total volume.
2. Cerebrospinal Fluid (CSF): ~10% of total volume.
3. Intravascular Blood: ~10% of total volume.

The Monro-Kellie Hypothesis

The Monro-Kellie hypothesis dictates that because total intracranial volume is constant, an increase in the volume of any one component (e.g., cerebral edema, intracerebral hematoma, tumor) must be compensated by a reciprocal decrease in the volume of another. Once compensatory mechanisms (such as displacement of CSF into the spinal subarachnoid space and venous blood compression) are exhausted, ICP rises exponentially.

Pressure & Perfusion Parameters

• Normal ICP: 5 to 15 mmHg (in adults lying flat).
• Intracranial Hypertension: Sustained ICP >20 mmHg requires urgent medical and nursing interventions.
• Cerebral Perfusion Pressure (CPP): The net pressure gradient driving oxygenated blood flow to the brain tissue, calculated as: [ \text{CPP} = \text{Mean Arterial Pressure (MAP)} - \text{Intracranial Pressure (ICP)} ] (where $\text{MAP} = \text{Diastolic BP} + \frac{1}{3}(\text{Systolic BP} - \text{Diastolic BP})$)
• Target CPP Range: 60 to 70 mmHg. A CPP <50 mmHg leads to severe cerebral ischemia and tissue infarction, whereas CPP >70 mmHg increases the risk of hyperperfusion injury and cerebral edema.

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2. Clinical Manifestations: Early Signs vs. Late Cushing's Triad

Early recognition of rising ICP is critical to prevent secondary brain injury.

Early Signs of Elevated ICP

• Altered Level of Consciousness: The single most sensitive and earliest indicator (restlessness, lethargy, irritability, subtle GCS drop).
• Headache: Worse in the morning, aggravated by coughing, straining, or bending.
• Ocular Changes: Sluggish pupillary light response, blurred vision, diplopia, or weakness of cranial nerve VI (abducens nerve causing lateral rectus palsy).
• Vomiting: Sudden, projectile vomiting without prior nausea.

Late Signs of Elevated ICP & Cushing's Triad

As ICP approaches fatal levels and compresses the brainstem, classic late signs manifest:

• Cushing's Triad: A grave clinical emergency signaling impending brainstem herniation, characterized by:
  1. Severe Systolic Hypertension with a Widened Pulse Pressure (e.g., BP rises from 120/80 to 190/60 mmHg).
  2. Bradycardia (abnormally slow heart rate, e.g., 40–50 bpm with bounding pulse).
  3. Irregular, Bradypneic Respirations (Cheyne-Stokes breathing or Biot's respirations).
• Fixed Dilated Pupils: Unilateral or bilateral non-reactive pupils.
• Abnormal Posturing: Decorticate (flexion) progressing to decerebrate (extension) posturing, flaccidity, and loss of brainstem reflexes (corneal, gag, and cough reflexes).

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3. Medical & Nursing Interventions for Elevated ICP

Nursing management focuses on optimizing venous outflow, reducing metabolic demand, and executing physician-prescribed osmotic therapy.

Positioning & Environmental Controls

• Head of Bed (HOB): Elevate HOB to 30 degrees. Avoid flat elevation or positions >45 degrees (which can drop systemic MAP and decrease CPP).
• Head & Neck Alignment: Keep head in a strict neutral midline position. Avoid neck flexion, extreme rotation, or tight tracheostomy ties, which compress internal jugular veins and impair venous return.
• Avoiding Intra-Abdominal / Intra-Thoracic Straining: Instruct patient to avoid Valsalva maneuvers, hip flexion >90 degrees, coughing, and isometric exercises. Administer stool softeners as prescribed.

Respiratory & Ventilatory Management

• Controlled Mechanical Ventilation: Maintain PaO2 >100 mmHg and PaCO2 between 35 and 45 mmHg.
• Hyperventilation Protocol: Temporary hyperventilation to PaCO2 30–35 mmHg induces cerebral vasoconstriction and rapidly lowers ICP. However, it should only be used as a short-term rescue maneuver because prolonged hypocapnia causes severe cerebral ischemia.
• Suctioning Precautions: Endotracheal suctioning elevates ICP. Limit suctioning to <10 seconds per pass, hyperoxygenate with 100% O2 prior, and administer IV Lidocaine if prescribed to blunts cough reflex.

Pharmacological Interventions

• Osmotic Diuretics (20% Mannitol): Draws extravascular fluid from brain tissue into the vascular space. Must be administered via a dedicated line with an inline filter to catch crystals. Monitor serum osmolality (target <320 mOsm/kg) and electrolytes.
• Hypertonic Saline (3% or 23.4% NaCl): Expands intravascular volume and draws fluid from swollen brain tissue. Must be infused via a central venous line to prevent peripheral vein phlebitis and tissue necrosis.
• Sedation & Analgesia: IV Propofol, Midazolam, or Fentanyl reduce metabolic demand and ventilator dyssynchrony.
• Temperature Control: Treat fever aggressively with antipyretics and cooling blankets, as fever increases cerebral metabolic rate by 7% to 10% per degree Celsius.

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4. Seizure Disorders & Status Epilepticus Management

A seizure is a transient episode of abnormal, excessive, synchronous neuronal activity in the brain. Status Epilepticus is defined as continuous seizure activity lasting >5 minutes, or two or more discrete seizures without full recovery of consciousness between episodes.

Medical Emergency Protocol for Status Epilepticus

1. Airway & Oxygenation: Call for immediate assistance / resuscitation team. Maintain airway patency, apply high-flow oxygen (10–15 L/min via non-rebreather mask), and prepare suction equipment.
2. First-Line Pharmacotherapy (0–10 mins): Administer fast-acting IV Benzodiazepines:
   • IV Lorazepam: 4 mg IV bolus over 2 minutes (0.1 mg/kg).
   • IV Diazepam: 5–10 mg slow IV push if Lorazepam is unavailable.
3. Second-Line Antiseizure Medications (10–30 mins):
   • Infuse IV Levetiracetam (Keppra) (60 mg/kg, max 4500 mg) or IV Fosphenytoin / Phenytoin (20 mg PE/kg).
   • Note: IV Phenytoin must be diluted in 0.9% Normal Saline (never Dextrose) and infused no faster than 50 mg/min to prevent severe hypotension and cardiac arrhythmias.
4. Third-Line Anesthetic Agents (>30 mins): IV Propofol, Midazolam infusion, or Thiopental with endotracheal intubation and continuous EEG monitoring in ICU.

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5. Nursing Seizure Precautions & Patient Safety Standards

In accordance with SNB practice guidelines and hospital fall/safety bundles:

Primary Seizure Precautions (Pre-Seizure Setup)

• Pad side rails of the bed with foam/padded covers.
• Ensure functional suction apparatus, bag-valve-mask (BVM), and oxygen flowmeter are present at the bedside.
• Maintain low bed height with side rails up x4.

Nursing Actions During an Active Seizure

• Protect from Trauma: Ease patient to the floor if out of bed. Place a soft pad under the head. Clear surrounding furniture and sharp objects.
• Positioning: Turn patient onto their side (lateral recovery position) to facilitate drainage of oral secretions and prevent tongue obstruction.
• DO NOT Restrain: Never forcibly restrain limbs during clonic jerking, as this can cause bone fractures or tendon ruptures.
• DO NOT Insert Objects: NEVER force objects, tongue depressors, or airway tubes into the patient's mouth during a seizure.
• Observe & Time: Note exact time of onset, duration of tonic/clonic phases, eye deviation, extremity involvement, and post-ictal state.

Post-Ictal Nursing Care & Documentation

• Maintain lateral position, perform gentle airway suctioning, assess GCS and vital signs, reorient the patient, and document event semiology thoroughly in the electronic health record.