Learning Objectives
By the end of this section, you will be able to:
- Explain the Monro-Kellie doctrine
- Discuss the pathophysiology, risk factors, and clinical manifestations for intracranial pressure changes
- Describe the diagnostics and laboratory values in the disease of intracranial pressure changes
- Apply nursing concepts and plan associated nursing care for the patient with intracranial pressure changes
- Evaluate the efficacy of nursing care for the patient with intracranial pressure changes
- Describe the medical therapies that apply to the care of intracranial pressure changes
To stay healthy and function optimally, the brain must have stable intracranial pressure (ICP), which refers to the pressure within the rigid confines of a skull. In the skull, brain tissue, blood, and cerebral spinal fluid (CSF)—a colorless fluid found within the subarachnoid space of the meninges of the brain, which surrounds both brain and spinal cord, acting to maintain health and functioning of the brain—exist together. Proper regulation of ICP is vital to achieve an ideal cerebral perfusion pressure (CPP), which is the net pressure gradient required to ensure sufficient oxygen delivery to the brain and allow optimal pressure levels for proper brain health.
This first part of this section covers the Monro-Kellie doctrine, which helps explain why maintaining ICP is so critical. The section discusses the pathophysiology, risk factors, and clinical manifestations for intracranial pressure changes and describes the expected diagnostics and laboratory values for the disease of intracranial pressure changes. The remainder of the section describes nursing concepts and explains the role of nurses in caring for patients who experience intracranial pressure changes as well as techniques and therapies that enable nurses to provide the best possible care to these patients.
Monro-Kellie Doctrine
The Monro-Kellie doctrine is an important concept in neurology and neurosurgery that establishes relationships among brain, blood, and CSF volumes within the rigid confinement of a skull (Figure 17.2). Scottish doctors Alexander Monro, George Kellie, and John Hughlings Jackson independently contributed to the doctrine’s development between 1795 and 1810. The doctrine’s basic principle recognizes that craniums are closed and nonexpandable structures that house the brain, blood, and CSF. Because skulls have rigid constraints, intracranial volume remains constant. As such, if the volume of the brain, blood, or CSF increases or decreases, this change in volume must be counterbalanced by a corresponding change in the volume of one or both of the other components inside the skull. Nurses must apply the concepts of this doctrine to understand and treat conditions that affect ICP, such as traumatic brain injuries, tumors, cerebral edema, and hemorrhages.
Increased ICP
ICP is determined by measuring the pressure exerted by fluids in the brain, such as CSF. Typically, ICP levels are measured in millimeters of mercury (mm Hg). While a patient is in a prone position, normal ICP should be between 7 and 15 mm Hg. When a patient is upright, this measurement should not be more than 15 mm Hg (Munakomi & Das, 2024).
ICP can be affected by many factors, including changes to blood volume, changes in the rates of CSF production and absorption, fluctuations in brain tissue volume, and obstruction of CSF flow. When increased intracranial pressure (IICP) occurs, it can cause compression of brain tissues and blood vessels, making it a serious condition with the potential to damage the brain.
Pathophysiology of Increased ICP
Common causes for IICP include head trauma, brain tumors, bleeding within the brain (intracerebral hemorrhage), vascular disorders such as aneurysms, and conditions such as infections that cause brain swelling. When any of these occur in the brain, they cause displacements of brain tissue, blood, and/or CSF, and may lead to IICP.
Clinical Manifestations of IICP
The clinical manifestations of IICP may include headaches, nausea, vomiting, altered mental status and level of consciousness (LOC), seizures with sensory and motor function impairments, and changes to speech patterns. Patients may also have visual disturbances, such as impaired eye movement, pupillary changes, and swelling in the optic disks known as papilledema.
Some patients with IICP may experience abnormal body posturing, including the following: decerebrate posturing, which is a neurological reflex movement of muscles causing the limbs to extend and hold rigidly at the sides of the body; decorticate posturing, which is a neurological reflex movement of muscles causing the limbs to flex and hold rigidly across the chest; and flaccid posturing, which occurs when muscles lack tension and go limp. IICP may also cause changes in a patient’s vital signs that result in Cushing’s triad, which is a combination of widened pulse pressure (or larger distance between diastolic and systolic measurements) in the blood pressure, bradycardia (low pulse rate), and irregular breathing patterns. In infants, IICP may cause issues such as bulging fontanels, cranial suture separation, increased head circumference, and a high-pitched cry.
Assessment and Diagnosis of IICP
To assess IICP, health-care professionals, including nurses, should obtain the patient’s medical history and do a physical examination that assesses the patient’s mental alertness, orientation, reflexes, bodily movements and functions, pupils and eyes, and overall behavior. This process may include using the Glasgow Coma Scale (GCS) to assess a patient’s consciousness level, evaluating the patient’s motor response, eye openings, and verbal responses. Patients with a GCS score lower than 8 should be monitored for IICP (Munakomi & Das, 2024).
Link to Learning
The Glasgow Coma Scale (GCS) can be a vital tool to assess a patient’s level of consciousness. The GCS has been used by health-care professionals since 1974 and is recognized as an accurate, reliable resource.
Diagnostics and Laboratory Values
The diagnostic tools generally used for IICP include computed tomography (CT) scans, magnetic resonance imaging (MRI), and lumbar punctures. CT scans or MRIs may show structural abnormalities, tumors, hemorrhages, or other conditions that change the volumes of a patient’s brain, blood, or CSF, causing IICP. Also useful is cerebral angiography, a type of x-ray that creates digital images of the anatomy of the brain with a focus on the blood vessels within and around the brain. Cerebral angiography identifies blockages and other abnormalities in the blood vessels of a patient’s head and neck that may be causing IICP. CSF analysis, which examines the actual contents of CSF, including pathogens, may help determine the cause of IICP.
Link to Learning
CSF can help determine the cause of IICP testing by evaluating the concentrations and levels of cells and various substances in CSF.
ICP monitoring with vital signs is also necessary. Monitoring devices include intraventricular catheters and parenchymal monitors. Intraventricular catheters are inserted through a hole in the skull and put in place to measure the skull’s internal pressure as well as drain excess CSF (Figure 17.3). Parenchymal monitors are placed inside brain tissue to monitor pressure. In other words, intraventricular catheters and parenchymal monitors may reveal abnormal pressure readings. Pressures greater than 20 mm Hg require treatment (Munakomi & Das, 2024).
Life-Stage Context
Age-Related Changes in Intracranial Pressure
Consider age-related changes in ICP from the very young to older adults when assessing neurological status. For example, in pediatric patients, an important consideration is fontanelle assessment. In infants, the fontanelles are soft and can even be visually bulging when the infant is experiencing IICP or sunken with decreased ICP. Bulging fontanelles may be a sign of IICP from inflammation and infection caused by hydrocephalus or meningitis.
In older adults, as well as younger patients with decreased mental functioning, mental status may be more challenging to assess for changes in the patient with major neurocognitive disorder (MND) or Alzheimer disease. Sudden confusion or disorientation, however, is never a good sign and is cause for further investigation.
Communication of symptoms is difficult in both the very young, older adults, or those who have trouble communicating. Motor functions may be difficult to assess in an infant who does not yet walk, or in an immobile older person. Verbalizing headache symptoms can be difficult in a nonverbal infant or a confused adult.
Nursing Care of the Patient with IICP
IICP is generally an acute clinical concern that needs immediate medical attention. To provide care for patients with IICP, nurses use a physical examination and patient’s subjective statements to gather data from a patient’s vital signs, neurological status, and response to interventions.
Recognizing Cues and Analyzing Cues
The cues that indicate IICP include confusion, high blood pressure, headache, slurred speech, muscle weakness, difficulty breathing, blurred vision, and vomiting. Using patient statements, as well as test results, nurses should analyze these cues to identify causes of or contributors to IICP. Test results may reveal an underlying condition such as an infection, head injuries, high blood pressure, tumors, aneurysm, and swelling in the brain. If the patient has an ICP monitoring device, the nurse should include data from this device as part of the process to determine if the patient’s ICP is above normal.
Prioritizing Hypotheses, Generating Solutions, and Taking Action
Prioritize according to severity for patients with IICP, including urgency of intervention and potential impact of ICP levels. For instance, sudden neurological changes or signs of herniation, which is a protrusion of tissue displacing the brain, may necessitate immediate medical intervention. As noted precedingly, the cues and signs may include changes to a patient’s mental alertness, blood pressure, ability to breathe, vision, bodily functions, muscle weakness, and general behavior. Solutions generated should be aimed at decreasing ICP as well as decreasing the risk of further harm caused by the IICP.
As with all diseases and conditions, the process to generate solutions should include collaborating with the patient’s health-care team members, including neurologists and neurosurgeons. Use interdisciplinary approaches and include health-care professionals such as physical therapists, respiratory therapists, and pharmacists to develop a comprehensive care plan that also anticipates potential complications related to IICP, such as seizures or declining neurological status. Act by implementing the nursing interventions described in Table 17.1.
| Nursing Care | Rationale |
|---|---|
| Complete focused neurological assessments | Changes in LOC, pupillary response and shape, motor function, speech, and vital signs indicate health issues. |
| Monitor vital signs. | VS are controlled in the medulla oblongata/brain stem, and worsening changes can signal herniation in the brain from IICP. |
| Elevate head of bed (HOB) 30 degrees. | Elevation of HOB can help with venous drainage to decrease ICP. Keep the body in alignment to protect spinal cord. |
| Avoid Valsalva maneuvers; use stool softeners/laxatives to avoid bowel straining. | Avoiding or minimizing bowel straining, coughing, or bearing down will reduce the risk of increases in ICP. |
| Monitor and maintain fluid and electrolyte balance. | Disruptions in hydration could affect ICP. |
| Implement measures to prevent fever. | Fever can increase ICP and exacerbate IICP. |
| Administer analgesics and complementary pain relief measures. | Pain and stress can cause IICP. |
| Support oxygenation and ventilation. | Adequate oxygenation and ventilation helps maintain appropriate ICP. |
| Monitor intracranial pressure. | Changes in ICP readings may indicate improvement, as well as declining health that needs attention. |
| Implement seizure precautions. | IICP can cause seizures. |
Evaluation of Nursing Care for the Patient with IICP
The desired outcome for patients with IICP is a lower level of ICP. To determine if the patient’s ICP is lower, nurses should evaluate the ICP pressure levels and GCS results, as well as the results of the patient’s lab tests, including data for glucose and white blood cell (WBC) levels.
Medical Therapies and Related Care for IICP
Once IICP is diagnosed, treatment for these patients should focus on the cause of IICP. For example, patients with brain swelling may need medications, such as diuretics and corticosteroids, which help reduce swelling. Patients with tumors or hematomas may need surgical interventions to remove lesions. If the patient’s IICP is caused by CSF drainage problems, the patient may need a ventriculoperitoneal shunt, external ventricular drainage system, or lumbar drain to control CSF drainage. A ventriculoperitoneal shunt is a thin tube that is inserted into the brain’s ventricles to drain excess CSF. With an external ventricular drainage system, the patient’s head is positioned to allow intracerebral pressure and gravity to work together to drain CSF. A lumbar drain is a small tube that is placed in the lumbar spine, rather than the brain’s ventricles, to drain excess CSF.
Patients who have IICP due to infection or metabolic disturbances may need medications, such as antibiotics or aspirin. To determine the appropriate therapy to meet the needs of each patient, nurses should have a thorough understanding of the patient’s condition, including the cues that indicate IICP, and should collaborate with other members of the patient’s health-care team.
Decreased Intracranial Pressure
Although not as common as IICP, some patients experience decreased ICP, or intracranial hypotension. As noted previously, normal ICP should be between 7 and 15 mm Hg when a patient is lying down (Munakomi & Das, 2024).
Pathophysiology
When pressure within the skull and brain drops below normal, decreased intracranial pressure presents. Generally, this results from CSF leakage, which may occur as a result of trauma, surgery, or conditions such as dehydration. Decreased ICP may also occur because of brain atrophy, which is a loss of neurons and synapses sometimes caused by disorders such as MND, infections, and cerebral palsy. Keep in mind the principle of the Monro-Kellie doctrine that any change in the volumes of a patient’s brain, blood, or CSF causes intracranial pressure changes.
Clinical Manifestations
The clinical manifestations of decreased ICP typically include headaches, which may vary from mild to severe and may be dull or throbbing. Often, patients can relieve their headaches by lying flat. Other clinical manifestations of decreased ICP may include poor reflexes, dizziness, lightheadedness, lack of orientation, and blurred vision as changes occur in cerebral blood flow. Patients may also experience ringing in the ears, along with a sense of imbalance, and their neck may feel stiff and/or painful. Some patients with ICP also have gastrointestinal symptoms, such as nausea and vomiting.
Assessment and Diagnostics
As with IICP, to assess decreased ICP, nurses and other members of the patient’s health-care team should review the patient’s medical history and conduct a physical examination. The assessment should consider the patient’s overall behavior, visual acuity, reflexes, orientation, and coordination and functioning.
Diagnostics and Laboratory Values
Diagnostic tests to identify decreased ICP may include MRIs, CSF pressure measurements, and a neurological examination. MRIs may show problems such as sinus engorgement, pituitary enlargement, and subdural hematomas that are causing decreased ICP. CSF pressure measurement may yield a low pressure reading. Imaging may show a problem such as brain sagging, which is a disorder that causes cognitive dysfunction and other issues typically associated with MND. Brain sagging causes decreased ICP and is diagnosed when imaging shows the brain in a sagging position (Liaquat & Jain, 2023).
Nursing Care of the Patient with Decreased ICP
Low intracranial pressure is generally not considered an acute clinical concern like IICP, which is life-threatening and requires emergency treatment. However, because normal range ICP is necessary to ensure proper cerebral perfusion and neurological function, patients should receive treatment to restore their ICP to an appropriate level.
Recognizing Cues and Analyzing Cues
To recognize the cues of decreased ICP, nurses should conduct a physical examination of the patient and note issues in their level of consciousness, pupillary response, motor function, speech, and vital signs. Issues that provide cues of decreased ICP include positive or negative changes in a patient’s blood pressure, mental alertness, ability to speak, reflexes, visual acuity, and other vital signs and behaviors, including nausea and gastrointestinal issues. If applicable, nurses may also find cues in the readings of the patient’s ICP monitoring device, such as a parenchymal monitor. To analyze these cues, nurses should consider whether they deviate from normal for the patient.
Prioritizing Hypotheses, Generating Solutions, and Taking Action
The analysis of the data gained through the nursing assessment can enable the nurse to prioritize hypotheses. The findings may include cues, such as a lack of mental alertness, blurred vision, and low blood pressure, as well as test results such as sagging brain or low CSF pressures. When such cues are part of the findings, the nurse may conclude that the patient has decreased ICP. The nurse should generate solutions to decrease or maintain ICP and take actions to help the patient, which may include those portrayed in Table 17.2.
| Nursing Care | Rationale |
|---|---|
| Complete focused neurological assessments. | Changes in LOC, pupillary response and shape, motor function, speech, and vital signs indicate health issues. |
| Monitor vital signs. | VS are controlled in the medulla oblongata/brain stem, and worsening changes can signal dehydration of brain tissue. |
| Place patient in flat HOB position. | Flat HOB positioning can increase ICP because ICP tends to be higher when patients are in a flat position. |
| Monitor and maintain fluid and electrolyte balance. | Disruptions in hydration could affect ICP. |
| Monitor ICP levels. | Compare ICP levels to baseline. |
| Support oxygenation and ventilation. | Maintain patient’s airway and assist with respiratory care to ensure adequate oxygenation and ventilation. Patients with head trauma may be in an induced coma and on ventilator support. |
| Monitor intracranial pressure. | Follow hospital protocols to obtain ICP readings and alert the provider of any worsening trends. |
Evaluation of Nursing Care for the Patient with Decreased ICP
The desired outcome for patients with a decreased ICP is a higher level of ICP. To determine if the patient’s ICP is higher, nurses should use pressure measurements as well as evaluate the results of the patient’s lab tests, such as MRIs and neurology examination.
Medical Therapies and Related Care
As with IICP, once patients are diagnosed with decreased ICP, treatment and medical therapies should focus on the cause of the condition. Because the most common cause of decreased ICP is a CSF leak in the brain or lumbar spine, treatment options may include an epidural blood patch, which is the process of injecting a small amount of autologous blood into a patient’s epidural space to plug the leak. If the patient’s decreased ICP is caused by other issues, such as dehydration, treatment should focus on therapies, such as rehydration, to restore equilibrium to the brain’s water balance. Therapies such as potassium supplements and salt tablets, as prescribed by the patient’s provider, may be helpful.