Emergency Management of Increased Intracranial Hypertension - Indication and Technique

Introduction:

A commonly encountered medical emergency is a traumatic brain injury. An injury to the head and brain results in bleeding, swelling (edema), and intracranial hematoma (a pool of clotted blood) formation in and around the brain. The rise in pressure around the brain is known as intracranial hypertension. The intracranial pressure can also increase in other conditions, including growths, cancerous masses, abscess, or other critical illnesses affecting the intracranial pressure. It adversely affects the brain and requires immediate management to relieve the pressure to prevent permanent damage to the brain or death.

Why Is Emergency Management of Increased Intracranial Pressure Essential?

The normal intracranial pressure is lesser than or equal to 15 millimeters of mercury (15 mmHg). When the intracranial pressure rises to greater than or equal to 20 millimeters of mercury (≥ 20 mm Hg) in adults, it denotes pathologic intracranial hypertension. Aggressive treatment is essential to improve the survival rate when a patient has intracranial hypertension. Elevated intracranial pressure complicates the existing pathologies such as tumors, central nervous system conditions, and trauma management. If left untreated, the following can occur:

1. Reduced blood and oxygen supply to the brain (ischemia and hypoxia).

2. Possibility of brain herniation.

3. When the pressure around the brain is extremely high, the brain tissue presses against the skull and gets damaged.

4. Loss of vision.

5. Permanent disability due to brain damage.

6. Death.

What Are the Classical Signs of Intracranial Hypertension?

The following triad is seen if the intracranial pressure increases:

1. Hypertension (an increase in systemic blood pressure).

2. Bradycardia (heart beats at a slower rate).

3. Respiratory irregularities (gasping or breathing problems).

What Are the Prehospital Management Strategies for Intracranial Hypertension?

Head injuries can cause primary brain injury at the same time as the trauma, which cannot be prevented. However, brain injury which develops after the trauma (secondary injuries) can be prevented by prompt treatment on time. These include injuries due to elevated intracranial pressure, such as reduced blood and oxygen supply to the brain. If there is a head injury, prehospital care should focus on preventing secondary injury to the brain. Advanced airway management, such as intubations and fluid resuscitation with intravenous saline in unconscious head injury patients, should be initiated with care as it affects the patient’s survival (delayed transfer, transient hypoxia, and prolonged intervention time). Rapid transfer to a hospital for definitive care and focusing on basic life support strategies to maintain oxygen levels can help to improve survival rates.

How Is Increased Intracranial Pressure Managed in the Emergency Department?

1. General Management: If the cause of intracranial hypertension is severe trauma (as in road traffic accidents), the patients are managed similarly to all trauma emergencies. At the hospital, the emergency personnel promptly check and assess the injury's severity. The focus is on assessing and restoring the airway, breathing, and circulation (blood flow). Advanced trauma life support strategies are used to stabilize the patient initially. The following steps are initiated to manage the patients:

• Assessment of the airway (passage to the lungs) is done immediately on first contact with the patient. The airway is made clear to ensure sufficient oxygen-rich air reaches the lungs.

• The breathing is assessed (including the breathing pattern and oxygen saturation).

• The circulation and vital signs (blood pressure, heart rate) are assessed. The heart function is checked to ensure sufficient blood flow and oxygen supply to all body parts and organs. Cardiopulmonary resuscitation and defibrillation are initiated if required.

• Oxygen supplementation is done whenever required. Depending on the patient's condition, there are various ways to provide oxygen to the body. These include bag-mask ventilation, in which oxygen is pumped through a bag attached to the mask, and noninvasive positive pressure ventilation (NPPV), in which tubes or masks are used to blow mild air into the airway to keep it open. In case of airway obstruction, invasive emergency techniques such as tracheostomy (a hole is made in the windpipe to facilitate breathing) and ventilators may be used.

• Access into veins (intravenous access) is obtained to give medications if needed.

• Measures are also initiated to prevent hypothermia (a dangerously low core body temperature).

• Next, rapid neurological examinations are performed to test the patient’s consciousness and assess the extent of the damage.

• After the initial resuscitation, the patients suspected of traumatic brain injury usually undergo a special imaging scan (non-contrast head computed tomography scan).

• The patient is monitored periodically to check if the symptoms are resolved or worsening.

1. Specific Management of Intracranial Hypertension: A three-tiered strategy is used to manage increased intracranial pressure. These include:

• Tier One Management:

  • The head of the bed is elevated at 30 degrees to improve blood out-flow.

  • Short-acting medications such as Propofol, Midazolam, Fentanyl, and Ketamine are used for sedation and analgesia in intubated patients.

  • The cerebrospinal fluid is drained intermittently from the compartments in and around the brain (intermittent ventricular drainage) to relieve pressure. However, a continuous drain is not recommended unless an intracranial pressure monitor is placed, as it does not accurately reflect the actual intracranial pressure.

  • Repeating computed tomography imaging and neurological examination should be considered to guide treatment and rule out the development of lesions in the brain.

  • Special imaging, such as angiography (along with computed tomography and magnetic resonance imaging), is done if blood vessel damage is suspected.

  • If the intracranial blood pressure remains high, tier two management is initiated.

• Tier Two Management:

  • An external ventricular drain is considered to relieve intracranial pressure. In this temporary method, gravity is used to drain the cerebrospinal fluid out of the ventricles (brain compartments). A thin tube drains the fluid from the head to a chamber and a bag.

  • Hyperosmolar therapy is administered intermittently. The osmolar difference between blood, brain, and cerebrospinal fluid is used to reduce intracranial pressure. Mannitol is administered in intermittent boluses of 0.25 to 1 gram per kilogram of body weight.

  • The levels of sodium and osmolality in the blood are assessed every six hours, and the additional dose of hyperosmolar therapy is altered accordingly.

  • The cerebral autoregulation is assessed, and treatment is modified accordingly.

  • The partial pressure of carbon dioxide is maintained at 30 to 35 millimeters of mercury (as long as brain hypoxia does not occur).

  • The computed tomography scans and neurological examinations are repeated to check for any brain lesions and to guide treatment.

  • Neuromuscular blocking agents or medications are administered (infusion).

  • If the intracranial pressure continues to remain high, tier-three management is initiated.

• Tier Three Management:

  • These management strategies are not a part of the initial management done in the emergency department.

  • These require the presence of specialists and brain surgeons who can perform surgical interventions such as decompressive hemicraniectomy or bilateral craniectomy.

  • Continuous infusion of neuromuscular blocking agents is provided.

  • Anesthesia dosage of medications such as Propofol or Barbiturate can be used to induce coma in patients who do not respond to aggressive measures to control intracranial hypertension. These can cause a decrease in systemic blood pressure. Thus, appropriate fluid resuscitation strategies are employed to manage the patients.

  • Hypothermia treatment (using a temperature less than 36 degrees Celsius) is used as the last resort after reasonable attempts at decreasing the intracranial pressure.

Conclusion:

The rise in the pressure in and around the brain is termed intracranial hypertension. Intracranial pressure increases during traumatic brain injuries and in other conditions, including growths, cancerous masses, abscesses, or other critical illnesses. The emergency management strategies include prompt airway, breathing, and circulation resuscitation, rapid imaging and neurological examination, hyperosmolar therapy, neuromuscular blocking agents, and other medications and surgical interventions. Prompt evaluation of intracranial pressure and management is essential to prevent brain damage and death.