What are the causes of increased intracranial pressure (ICP)?

From the Guidelines

Intracranial hypertension should be managed with a balanced approach, starting with simple measures such as head positioning, analgesia, and sedation, and progressing to more aggressive measures as clinically indicated, with careful monitoring of ICP and CPP in a critical care unit. This approach is supported by the American Heart Association/American Stroke Association guidelines, which suggest that treatment of intracranial hypertension has evolved around patients with head injuries and may not apply to the specifics of patients with intracerebral hemorrhage (ICH) 1. The guidelines also note that no controlled clinical trial has demonstrated the superiority of either the "Lund protocol" or CPP-guided therapy, and that various potent treatments to combat intracranial hypertension are available, but are associated with serious adverse events.

Some key considerations in managing intracranial hypertension include:

• Monitoring ICP and CPP to guide medical and surgical therapy, as recommended by the Neurocritical Care Society and the European Society of Intensive Care Medicine 1
• Using medications such as mannitol, barbiturates, and hyperventilation to reduce ICP, but being aware of their potential adverse effects
• Considering surgical interventions such as CSF drainage via intraventricular catheter insertion, but being aware of the potential risks of intracranial bleeding and infection
• Maintaining a balanced approach to ICP management, with careful consideration of the potential benefits and risks of each treatment option.

It is also important to note that the exact frequency of increased ICP in patients with ICH is not known, and that many patients with smaller ICHs may not have increased ICP and require no measures to decrease ICP 1. However, for those patients with clinical evidence of increased ICP, prompt treatment is essential to prevent permanent vision loss and other complications. Regular ophthalmologic monitoring is also essential to track papilledema and visual function, and patients should be advised to report worsening headaches, visual changes, or pulsatile tinnitus immediately as these may indicate worsening pressure.

From the FDA Drug Label

Reduction of intracranial pressure and brain mass.

Reduction of Intracranial Pressure and Brain Mass: Adults: 0. 25 to 2 g/kg body weight as a 15% to 25% solution administered over a period of 30 to 60 minutes

Mannitol, when administered intravenously, exerts its osmotic diuretic effect as a solute of relatively small molecular size largely confined to the extracellular space.

By increasing the osmotic pressure of plasma and the extracellular space, intravenously administered mannitol will induce the movement of intracellular water to the extracellular and vascular spaces. This action underlies the role of mannitol in reducing intracranial pressure, intracranial edema, and intraocular pressure.

Mannitol (IV) is indicated for the reduction of intracranial pressure and brain mass in adults and pediatric patients. The recommended dosage for adults is 0.25 to 2 g/kg body weight as a 15% to 25% solution administered over a period of 30 to 60 minutes. The mechanism of action of mannitol involves increasing the osmotic pressure of plasma and the extracellular space, which induces the movement of intracellular water to the extracellular and vascular spaces, thereby reducing intracranial pressure and intracranial edema 2 2.

• Key points:
  • Mannitol (IV) is used to reduce intracranial pressure and brain mass.
  • The recommended dosage for adults is 0.25 to 2 g/kg body weight.
  • The mechanism of action involves increasing the osmotic pressure of plasma and the extracellular space.

From the Research

Treatment Options for Intracranial Hypertension

• Hypertonic saline solutions have been found to be effective in reducing intracranial hypertension, particularly in cases of subarachnoid haemorrhage, brain trauma, and cerebral edema in acute liver failure 3
• Mannitol is also a commonly used treatment for intracranial hypertension, but its use may be limited by the risk of acute renal failure if serum osmolarity exceeds 320 mOsm/L 4
• The choice between hypertonic saline and mannitol depends on the individual patient's condition and the specific clinical scenario, with no clear benefit in regards to long-term neurologic outcome reported in comparative studies 5

Management Strategies

• The maintenance of normal intracranial pressure and cerebral perfusion pressure is crucial to prevent secondary brain injury, and general prophylactic measures such as patient's head elevation, fever control, adequate analgesia, and sedation depth should be applied immediately to all patients with suspected intracranial hypertension 6
• Surgical resection of mass lesions and cerebrospinal fluid drainage may be considered as an initial treatment for lowering intracranial pressure, based on specific indications and conditions 6
• Hyperosmolar therapy, including mannitol or hypertonic saline, represents the cornerstone of medical treatment of acute intracranial hypertension, while hyperventilation should be limited to emergency management of life-threatening raised intracranial pressure 6

Clinical Considerations

• The therapeutic strategy for intracranial hypertension should be based on a staircase approach and be individualized for each patient, taking into account the specific clinical scenario and the patient's response to treatment 6
• Clinicians treating patients with acute brain injury should be familiar with the principles of management of increased intracranial pressure, and have a high index of suspicion and a low threshold for diagnostic and therapeutic strategies to improve patient care 7