The skull is filled with brain tissue, blood and cerebrospinal fluid (CSF). Cerebral autoregulation allows these components to adjust to each other to preserve cerebral blood flow. Intracranial pressure (ICP) is normally ≤15 mmHg in adults. Pathologic intracranial hypertension occurs when ICP ≥ 20 mmHg (Smith and Amin-Hanjani, 2019).
The development of increased intracranial pressure (ICP) may be acute or chronic. It is a common clinical problem in neurology or neurosurgical units. Many diseases or insults can result in the loss of cerebral autoregulation and lead to increased ICP, including traumatic brain injury, large acute ischemic stroke, intracerebral hemorrhage, aneurysms, brain tumors and infection, such as abscess or severe meningitis. See Nursing Pocket Card: Recognizing and Managing Increased Intracranial Pressure (ICP).
Acute sustained elevations in ICP will result in reduced cerebral perfusion pressure (CPP)
and cause cerebral ischemia. Management of patients with elevated ICP requires prompt recognition, ICP and CPP monitoring, and interventions directed at lowering ICP and optimizing blood pressure.
If a patient is suspected of having increased ICP, immediate interventions should include securing the airway, maintaining adequate oxygenation and ventilation, and providing circulatory support as needed. Interventions to lower or stabilize ICP include elevating the head of the bed to thirty degrees, keeping the neck in a neutral position, maintaining a normal body temperature, and preventing volume overload. The patient must be stabilized before transport to radiology for brain imaging. A (computed tomography (CT) scan is the most efficient test for confirming the diagnosis of increased ICP and determining its cause. In many cases, invasive ICP monitoring is required to guide medical and nursing interventions.
Patients who require ICP monitoring should be cared for by trained critical care neuroscience nurses competent in neurologic assessment and management of the monitoring device. Patient assessment should include hourly monitoring for signs and symptoms associated with changing ICP, or more frequently as the clinical situation warrants. Notify the physician immediately if ICP exceeds established parameters. If no parameter is specified, notify the physician if ICP is >20 mmHg or CPP
falls outside of the 50-70 mmHg range (Thompson, 2012).
The two most common devices for ICP monitoring are an intraparenchymal monitor and an intraventricular monitor using a ventriculostomy or external ventricular drain (EVD). The EVD is preferred because the catheter can also drain CSF and hence decrease intracranial pressure. For detailed information about the nursing care of patients with ICP monitoring devices, refer to the American Association of Neuroscience Nurses (AANN) Clinical Practice Guideline: Care of the Patient Undergoing Intracranial Pressure Monitoring/External Ventricular Drainage or Lumbar Drainage
Acute intracranial hypertension
Acute intracranial hypertension (AIH) is a clinical syndrome in which homeostatic mechanisms are overwhelmed causing a rapid increase in ICP. AIH is a medical emergency requiring immediate treatment to prevent irreversible neurologic damage or death. Patients at risk for AIH should be monitored in a critical care setting. AIH can be managed through a variety of medical and surgical interventions:
- CSF drainage using an external ventricular drain or lumbar drain.
- Sedation/analgesia to control pain, agitation, and excessive muscular activity (eg, due to delirium).
- Hydration with isotonic fluids. If there are no signs of dehydration or fluid overload, IV fluids with normal saline can be started at 50 to 75 mL/h. The rate can be adjusted based on serum sodium, osmolality, urine output, and physical assessment (Maiese, 2019).
- Osmotic diuretics to lower ICP and maintain serum osmolality between 295 to 320 mOsm/kg. A 3% saline solution is another osmotic agent used to control ICP. Fluid and electrolyte balance should be monitored closely while either therapy is used (Maiese, 2019).
- Blood pressure (BP) control when hypertension is severe (> 180/95 mm Hg). Mean arterial pressure needs to be high enough to maintain CPP even when ICP increases (Maiese, 2019). Hypotension should be promptly treated to avoid cerebral hypoperfusion.
- Corticosteroids are effective only for vasogenic edema (from disruption of the blood-brain barrier) due to brain tumors and sometimes abscesses.
- Hyperventilation causes hypocapnia, which causes vasoconstriction, thus decreasing cerebral blood flow. Hyperventilation to moderate levels (PaCO2 = 25-35) is generally considered a short-term temporizing measure to decrease ICP. Extreme hyperventilation (PaCO2 <25mmHg) should be avoided (Levin et al., 2010).
- Decompressive craniectomy involves removing a portion of the skull to reduce ICP and is often a last resort for impending herniation.
More on Nursing Care
The neuroscience ICU nurse must have an extensive knowledge of brain physiology and the ways in which it changes as patients deteriorate or recover. Nursing measures – including the ABCs of Managing Increased Intracranial Pressure
– are targeted to assessing for changes in the neurologic exam, preserving cerebral blood flow through optimizing CPP
, and protecting the brain from secondary injury. Neuro-critical care nurses are expected to manage patient care by adjusting ventilator settings, medications, fluid, nutritional support, and therapeutic devices to keep the patient stabilized during the recovery process. Patients with increased ICP will receive care from a multidisciplinary team, including physicians from a variety of specialties, respiratory therapists, nutritionists, and physical and occupational therapists. Neuroscience nurses are care coordinators and patient safety advocates.
In addition, the nurse provides family education and emotional support in a high-technology environment. It is important for the nurse to explain the effects of the environment and external stimuli on the patient’s ICP and involve the family in plans to control stimuli to minimize elevation of ICP readings.
The prompt recognition and management of patients with increased ICP requires knowledge of at-risk patient populations and the signs and symptoms of elevated ICP. AIH resulting from rapid elevation of intracranial pressure is a medical emergency requiring immedate stabilization of airway, breathing and circulation followed by immedate brain imaging for confirmation and diagnosis of the underlying etiology. ICP monitoring, and in certain cases CSF drainage, is a cornerstone of management. The neuroscience ICU nurse provides a calm, quiet environment, vigilant monitoring, and interventions to optimize cerebral blood flow and prevent complications.