Increased Intracranial Pressure (ICP)

Dr. Belal Hijji, RN, PhD

February 20 & 22, 2012

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Learning Outcomes

By the end of this lecture, students will be able to:

1. Define ICP and recognise the causes of increased ICP and its consequences

2. Discuss the pathophysiology of increased ICP and its clinical manifestations

3. Describe the assessment and diagnostic findings of increased ICP

4. Recognise the medical and nursing management of a patient with increased ICP

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Introduction

• The cranium contains brain tissue (1,400 g), blood (75 mL), and CSF (75 mL). The volume and pressure of these three components are usually in a state of equilibrium and produce the ICP, which is 10 to 20 mm Hg and represents the pressure within the rigid skull.

• Causes of increased ICP include a rise in cerebrospinal fluid pressure, increased pressure within the brain matter, bleeding into the brain or fluid around the brain, or swelling within the brain matter itself.

• An increase in intracranial pressure is a serious medical problem. The pressure itself can damage the brain or spinal cord by pressing on important brain structures and by restricting blood flow into the brain.

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Subdural hematoma develops when blood vessels that are located between the membranes covering the brain (the meninges) leak blood after an injury to the head. This is a serious condition since the increase in intracranial pressure can cause damage to brain tissue and loss of brain function.

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Pathophysiology

• Increased ICP is a syndrome that affects many patients with acute neurologic conditions. An elevated ICP is most commonly associated with head injury, secondary effect in other conditions, such as brain tumors, subarachnoid hemorrhage, and toxic and viral encephalopathies.

• Increased ICP from any cause decreases cerebral perfusion, stimulates further swelling (edema), and shifts brain tissue through openings in the rigid dura, resulting in brain herniation (next slide), a frequently fatal event.

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Clinical Manifestations

• When ICP increases to the point at which the brain’s ability to adjust has reached its limits, neural function is impaired; this may be manifested by clinical changes first in LOC and later by abnormal respiratory and vasomotor responses. Slowing of speech and delay in response to verbal suggestions are other early indicators.

• Restlessness (without apparent cause), confusion, or increasing drowsiness, has neurologic significance.

• These signs may result from compression of the brain due to swelling from hemorrhage or edema, an expanding intracranial lesion (hematoma or tumor), or a combination of both.

Continued…..

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• As ICP increases, the patient becomes stuporous, reacting only to loud auditory or painful stimuli. At this stage, serious impairment of brain circulation is probably taking place, and immediate intervention is required.

• As neurologic function deteriorates further, the patient becomes comatose and exhibits abnormal motor responses in the form of decorticate or decerebrate posture (see next slide). When the coma is profound, with the pupils dilated and fixed and respirations impaired, death is usually inevitable.

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Assessment and Diagnostic Findings

• The patient may undergo cerebral angiography, computed tomography (CT) scanning, or magnetic resonance imaging (MRI).

• Transcranial Doppler studies provide information about cerebral blood flow. The patient with increased ICP may also undergo electrophysiologic monitoring to monitor the pressure (next slide).

• Lumbar puncture is avoided in patients with increased ICP

because the sudden release of pressure can cause the brain to herniate.

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Intracranial pressure monitoring is performed by inserting a catheter into the head with a sensing device to monitor the pressure around the brain.

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Medical Management

• Increased ICP is a true emergency and must be treated immediately through:

– Invasive monitoring of ICP to identify increased pressure early in its course (before cerebral damage occurs), to quantify the degree of elevation, to initiate appropriate treatment, to provide access to CSF for sampling and drainage, and to evaluate the effectiveness of treatment.

– Decreasing cerebral edema: Osmotic diuretics (mannitol) may be given to dehydrate the brain tissue and reduce cerebral edema. They reduce the volume of brain and extracellular fluid. Corticosteroids (eg, dexamethasone) help reduce cerebral edema when a brain tumor is the cause of increased ICP.

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– Maintaining cerebral perfusion: The cardiac output may be manipulated to provide adequate perfusion to the brain. Inotropic agents such as dobutamine hydrochloride are used. The effectiveness of the cardiac output is reflected in the cerebral perfusion pressure, which is maintained at greater than 70 mm Hg. A lower cerebral perfusion pressure indicates that the cardiac output is insufficient to maintain adequate cerebral perfusion.

• Cerebral perfusion pressure (CPP) is defined as the difference between mean arterial and intracranial pressures. Mean arterial pressure is the diastolic pressure plus one third of the pulse pressure (difference between the systolic and diastolic). MAP is thus between systolic and diastolic pressures.

• CPP = MAP - ICP

• Normal cerebral perfusion pressure is 80 mmHg, nearer diastolic.

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– Lowering the volume of CSF and cerebral blood: CSF drainage is frequently performed because the removal of CSF with a ventriculostomy drain may dramatically reduce ICP and restore cerebral perfusion pressure.

– Controlling fever: Preventing a temperature elevation is critical because fever increases cerebral metabolism and the rate at which cerebral edema forms.

– Maintaining oxygenation: Arterial blood gases must be monitored to ensure that systemic oxygenation remains optimal. Hemoglobin saturation can also be optimized to provide oxygen more efficiently at the cellular level.

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– Reducing metabolic demands: Cellular metabolic demands may be reduced through the administration of high doses of barbiturates when the patient is unresponsive to conventional treatment. Another method is the administration of pharmacologic paralyzing agents. Because the patient who receives these agents cannot respond or report pain, sedation and analgesia must be provided.

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Nursing Process:The Patient With Increased ICP

• Assessment:– Obtain a history of events leading to the present illness; it may

be necessary to obtain this information from significant others. – The neurologic examination should include an evaluation of

mental status, level of consciousness (LOC), cranial nerve function, cerebellar function (balance and coordination), reflexes, and motor and sensory function. Assessment of LOC includes eye opening; verbal and motor responses; pupils (size, equality, reaction to light).

– Because the patient is critically ill, ongoing assessment will be more focused, including pupil checks, assessment of selected cranial nerves, frequent measurements of vital signs and intracranial pressure, and use of the Glasgow Coma Scale (next slide), which is a tool for assessing a patient’s LOC. Scores range from 3 (deep coma) to 15 (normal)..

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Glasgow Coma ScaleEye opening response Spontaneous 4

To voice 3To pain 2None 1

Best verbal response Oriented 5Confused 4Inappropriate words 3Incomprehensible sounds 2None 1

Best motor response Obeys command 6Localizes pain 5Withdraws 4Flexion (decorticate) 3Extension (decerebrate) 2None 1

Total 3 to 15

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• Nursing diagnoses:

– Ineffective airway clearance related to diminished protective reflexes (cough, gag)

– Ineffective breathing patterns related to neurologic dysfunction (brain stem compression, structural displacement)

– Ineffective cerebral tissue perfusion related to the effects of increased ICP

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• Planning and goals

– Maintenance of a patent airway

– Normalization of respiration

– Adequate cerebral tissue perfusion through reduction in ICP

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• Nursing Interventions: – Maintaining patent airway.

• Assess the patency of the airway.

• Suction with care the secretions obstructing the airway, because transient elevations of ICP occur with suctioning.

• The patient is hyperoxygenated before and after suctioning to maintain adequate oxygenation.

• Discourage coughing because it increases ICP.

• Auscultate the lung fields at least every 8 hours to determine the presence of abnormal breath sounds.

• Elevate the head of the bed may aid in clearing secretions as well as improving venous drainage of the brain.

Continued….

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– Achieving an adequate breathing pattern

• Monitor the patient constantly for respiratory irregularities. This includes Cheyne-Stokes respirations (alternating periods of hyperpnea and apnea) (See picture below) and hyperventilation (increased rate and depth of breathing) (Next slide).

Continued on Slide 23

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Hyperventilation

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• Monitor PaCO2 (normal range 35 to 45 mm Hg) if hyperventilation therapy has been decided to reduce ICP (by causing cerebral vasoconstriction and a decrease in cerebral blood volume).

• Maintain a neurologic observation record. Repeated assessments of the patient are made frequently to immediately note improvement or deterioration.

• Prepare for surgical intervention in case of deterioration.

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– Optimising cerebral tissue perfusion

• Maintain head alignment and elevate head of bed 30 degrees. The rationale is that hyperextension, rotation, or hyperflexion of the neck causes decreased venous return.

• Avoid extreme hip flexion as this increases intra-abdominal and intrathoracic pressures, leading to rise in ICP.

• Avoid the Valsalva maneuver (straining at stool) as it raises ICP. Administer stool softeners as prescribed. If appropriate, provide high fiber diet.

• Note abdominal distention. Avoid enemas and cathartics (sorbitol, magnesium citrate, sodium sulfate).

Continued……

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• When moving or being turned in bed, instruct the patient to exhale to avoid the Valsalva maneuver.

• If the patient is on mechanical ventilation, preoxygenate and hyperventilate him, before suction, using 100% oxygen on the ventilator. Suctioning should not last longer than 15 seconds.

• Avoid activities that raise ICP if possible. Space nursing interventions; this may prevent transient increases in ICP.

• During nursing interventions, the ICP should not rise above 25 mm Hg and should return to baseline levels within 5 minutes. Patients with

• Patients with the potential for a significant increase in ICP should receive sedation or “paralyzation” before initiation of many nursing activities.

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• Avoid emotional stress, frequent arousal from sleep, and environmental stimuli (noise, conversation).

• Isometric muscle contractions (Pushing against an immovable wall) are also contraindicated because they raise the systemic blood pressure and hence the ICP.