Learning Objectives
By the end of this section, you will be able to:
- Discuss the pathophysiological changes to the patient’s neurological system when in the intensive care unit
- Describe the medical assessments and therapies that apply to the critical care patient’s neurological system
- Apply nursing concepts and plan associated nursing care for the critical care patient’s neurological system
The neurological system is involved in consciousness and the control of physical movement and vital functions in the medulla, such as breathing, heart rate, and thermoregulation. Critically ill patients often have neurological system dysfunction that may result in serious systemic complications and permanent physical disabilities. For many patients, frequent neurological assessment and interventions are key components of nursing care in the critical care setting.
Pathophysiological Insult to the Critical Care Patient’s Neurological System
The underlying pathophysiologic mechanism behind many neurological disorders observed in critical care settings is increased intracranial pressure (ICP). This pressure is normally between 1 and 20 mm Hg (Pinto, Tadi, & Adeyinka, 2023). Without intervention, sustained increased ICP can result in severe, permanent complications and death for the patient while in the hospital and upon discharge.
The cranium contains three main elements: the brain, CSF, and blood. The Monroe-Kellie Doctrine concludes that a change in one of these three components must be compensated for by another component (Teach Me Surgery, 2020). For example, if a patient is experiencing brain swelling, there needs to be a decrease in either blood or CSF volume to account for the extra space the swelling is now taking up. An elevation in ICP is observed when there is an increase in any one of the three components without adequate compensation from the other two. Some of the common causes of increased ICP are:
- brain tumors or hematomas
- cerebral edema (e.g., traumatic brain injury)
- increased CSF production (hydrocephalus)
- infections of the central nervous system (e.g., meningitis)
- structural abnormalities (e.g., stroke, aneurysms)
There are several key assessment findings that are indicative of increased ICP. The first sign, and one that is easy to miss, is a decrease in the level of consciousness (LOC). If the patient appears more drowsy than usual or slightly confused, it may indicate an early sign of increased ICP. The nurse can use the Glasgow Coma Scale (see Chapter 17 Nervous System and Chronic Diseases of the Nervous System) to observe neurological changes from the patient’s baseline.
Link to Learning
For more information, go to this website about the Glasgow Coma Score from First Aid for Free.
Another important assessment for patients at risk for increased ICP is the pupillary response. Pupillary dilation and lack of reactivity are associated with increased ICP and other neurological disorders. Another finding directly related to increased ICP is a combination of three factors, called Cushing’s triad: (1) bradycardia, (2) irregular respirations, and (3) systolic hypertension with widening pulse pressure, or the difference between the systolic and diastolic blood pressures
Additional signs of increased ICP include headache, blurred vision, and projectile vomiting, often without nausea. Abnormal posturing is another sign: with decorticate posturing, the patient pulls their arms into their chest; with decerebrate posturing, the patient’s arms are flexed at the sides (Figure 35.12). If any signs of increased ICP are noted, quick intervention is necessary to prevent severe neurological complications.
Exemplar: Traumatic Brain Injury
A common reason for admission to the ICU is traumatic brain injury (TBI). Annually, 2.8 million people in the United States will have a TBI, with more than 250,000 cases requiring hospitalization (Michael et al., 2023). Traumatic brain injury often occurs with trauma and can involve skull fractures, hematomas, and concussions, all of which have the potential to increase ICP. The treatment for TBI is similar to that for increased ICP, which is discussed in more detail in a later section.
Medical Assessments and Therapies
In addition to frequent neurological assessments, which are often a standard of care in the ICU, several other diagnostic tests are used to assess the function of the neurological system. These diagnostic tests and procedures are outlined in Table 35.9.
| Diagnostic Test | Description | Clinical Significance |
|---|---|---|
| Computed tomography (CT) scan | Use of X-rays to create three-dimensional images of internal brain structures | A CT scan is often the first diagnostic test used to detect neurological issues. If abnormalities are noted, further testing is usually indicated. Contrast dye is used cautiously with patients who have existing allergies and renal impairment. |
| Magnetic resonance imaging (MRI) | Use of magnetic fields and radio waves to generate detailed images of internal brain structures | MRI is often performed after abnormality is noted on a CT scan. MRI provides more detailed images of the brain, allowing for easier diagnosis. |
| Electroencephalogram (EEG) | Use of small electrodes attached to the scalp that transmit electrical brain activity | An EEG is used to detect seizure activity or a lack of electrical activity that may indicate severe brain injury or death. |
Pharmacological Supports
Several different medications are commonly administered in the ICU to treat neurological disorders. The main medication used for increased ICP is mannitol, which is an osmotic diuretic. Mannitol works by pulling water out of the brain and back into the vessels. It is administered intravenously and should only be given when ICP can be closely monitored and frequent neurological assessments can be performed. If administered too quickly, mannitol can cause severe shifts in brain fluid status, which will worsen neurologic dysfunction. Other side effects of mannitol include: dehydration, electrolyte imbalances, hypotension, and rebound cerebral edema.
For cerebral edema and swelling, corticosteroids such as dexamethasone (e.g., Decadron) or methylprednisolone (e.g., Solu-Medrol) are often used. These medications decrease inflammation by suppressing white blood cells, which can improve brain swelling. Lastly, patients at risk for or who are having active seizures can be treated with an IV antiseizure medication such as levetiracetam (e.g., Keppra). Side effects to monitor for with use of levetiracetam include anemia, muscle weakness, and suicidal ideation or psychosis.
Nursing Care
Most of the nursing care for patients experiencing neurological dysfunction in the ICU centers around interventions to decrease ICP. In addition to pharmacologic interventions, there are several other ways critical care nurses can reduce the patient’s ICP. First, the nurse should ensure the patient is receiving adequate oxygenation; if the brain is not receiving enough oxygen to function at its full capacity, hypoxia can make ICP worse. It may be necessary to change the settings on the mechanical ventilator to ensure adequate oxygenation and effective brain perfusion.
Another important aspect of nursing care for patients with neurological disorders and increased ICP is blood pressure management. It is vital that the nurse titrate medications or administer fluids as necessary to maintain an adequate mean arterial pressure (MAP). MAP must be between 70 and 90 mm Hg to ensure that cerebral perfusion pressure (CPP), or perfusion of oxygen and blood to the brain tissue, is adequate for optimal functioning. Lastly, the critical care nurse should implement interventions to decrease the body’s metabolic demands. Decreasing these demands permits the body and brain to rest and heal accordingly. Table 35.10 lists key interventions for reducing metabolic demands and ICP.
| Intervention | Description |
|---|---|
| Targeted temperature management (TTM) |
|
| Sedation |
|
| Surgical intervention |
|
| Maintain low-stimuli environment |
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| Body positioning |
|