253 - Study Guide for Stressors Interfering with Normal Sensorium
Terms in this set (64)
What is normal intracranial pressure and what are normal values?
It is the hydrostatic force measured in the brain CSF compartment. Normal ICP is the total pressure exerted by the three components within the skull; brain tissue, blood, and CSF.
Normal values are 5-15.
What is the significance of IICP?
This is a life threatening situation that results from an increase in any or all of the three components (brain tissue, blood, CSF) within the skull.
Discuss briefly the 3 types of cerebral edema.
1. Vasogenic cerebral edema
2. Cytotoxic edema
3. Interstitial cerebral edema
(explained in questions 4,5,&6)
What is vasogenic cerebral edema?
Most common. Occurs mainly in the white matter and is attributed to changes in the endothelial lining of cerebral capillaries. These changes allow leakage of macromolecules from the capillaries into the surrounding extracellular space, resulting in an osmotic gradient that favors the flow of luid from the intravascular to the surrounding extravascular space. A variety of insults, such as brain tumors, abscesses and ingested toxins, may cause an increase in the permeability of the blood-brain barrier and produce an increase in the extracellular fluid volume. The edema may produce a continuium of symptoms ranging from focal neurologic deficits to disturbances in consciousness, including coma.
What is cytotoxic edema?
Results from local disruption of the functional or morphologic integrity of cell membranes and occurs most often in the grey matter. It develops from destructive lesions or trauma to brain tissue resulting in cerebral hypoxia or anoxia, sodium depletion, and SIADH secretion. Cerebral edema results as fluid and protein shift from the estracellular space directly into the cells, with subsequent swelling and loss of cellular function.
What is interstitial cerebral edema?
Is the result of periventricular diffussion of ventricular CSF in a patient with uncontrolled hydrocephalus. It can also be cause by enlargement of the extracellular space as a result of systemic water excess.
What is CPP and how do changes affect the patient? Know the formula to calculate CPP.
Cerebral perfusion pressure is the pressure needed to ensure blood flow to the brain. As the CPP decreases, autoregulation fails and CBF (cerebral blood flow) decreases. Normal CPP is 70-100. Below 30 results in ischemia and is incompatible with life. (CPP = MAP-ICP).
Describe the effects CO2 has on cerebral blood flow.
Affects cerebral vessel tone. An increase relaxes smooth muscle, dilates cerebral vessels, decreases cerebrovascular resistance, and increases CBF. A decrease constricts cerebral vessels, increases cerebrovascular resistance, and decreases CBF.
Describe the effects oxygen has on cerebral blood flow.
Cerebral O2 tension below 50 mm Hg results in cerebral vascular dilation. This dilation decreases cerebral vascular resistance, increases CBF, and raises O2 tension. If O2 tension is not raised, anaerobic metabolism befins, resulting in an accumulation of lactic acid. As lactic acid increases and hydrogen ions accumulate, the environment becomes more acidic. Within this acidic environment, further vasodilation occurs in a continued attempt to increase blood flow. The combination of a severely low partial pressure of oxygen in arterial blood (PaO2) and an elevated hydrogen ion concentration.
Describe the effects hydrogen ion concentration has on cerebral blood flow.
(acidosis), which are both potent cerebral vasodilators, may produce a state wherein autoregulation is lost and compensatory mechanisms fail to meet tissue metabolic demands.
Describe how changes in LOC are related to an increase in ICP.
The sensitive and reliable indicator of the patient's neurologic status. Changes are a result of impaired CBF, which deprives the cells of the cerebral cortex and the reticular activation system (RAS) of oxygen. Interruptions of impulses from the RAS or alterations in functioning of the cerebral hemispheses can cause unconsciousness.
Describe how changes in VS are related to an increase in ICP.
Caused by increasing pressure on the thalamus, hypothalamus, pons and medulla. A change in body temperature may also be noted because of increased ICP impacting the hypothalamus.
Describe how ocular signs are related to an increase in ICP.
Compression of cranial nerve III, the oculomotor nerve, results in dilation of the pupil on the same side as or ipsilateral to the mass lesion, sluggish or no response to light, inability to move the eye upward, and ptosis of the eyelid. These signs can be the result of a shifting of the brain from the midline, compressing the trunk of CN III and paralyzing the muscles, controlling papillary size and shape. A fixed, unilaterally dilated pupil is considered a neurologic emergency that indicates herniation of the brain.
Describe how decrease in motor function are related to an increase in ICP.
As the ICP continues to rise, that patient manifests changes in motor ability. A contralateral (opposite side of the mass legion) hemiparesis or hemiplegia may develop. depending on the location of the source of the increased ICP. If painful stimuli are used to elicit a motor response, the patient may localize to the stimuli or withdraw from it. Decorticate position consists of internal rotation and adduction of the arms with flexion of the elbows, wrists, and fingers as a result of interruptions of voluntary motor tracts in the cerebral cortex. Extension of the legs may also be seen. A decerebrate posture may indicate more serious damages and result from disruption of motor fibers in the midbrain and brainstem. In this position, the arms are stiffly extened, adducted, and hyperpronated. There is also hyperextension of the legs with plantar flexion of the feet.
Describe how a headache is related to an increase in ICP.
Although the brain itself in insensitive to pain, compression of other intracranial structures, such as the walls of arteries and veins and the cranial nerves, can produce headache. The headache is often continuous but worse in the morning. Straining or movement may accentuate the pain.
What diagnostic test is contraindicated for the patient with increased ICP and why?
A lumbar puncture is not performed when increased ICP is suspected because of the possibility of cerebral herniation from the sudden release of the pressure in the skull from the area above the lumbar puncture.
Discuss the role of osmotic diuretics in the treatment of IICP and associated nursing management.
Mannitol given IV, acts to decrease the ICP in two ways; plasma expansion and osmotic effect. There is an immediate plasma-expanding effect that reduces the hematocrit and blood viscosity, thereby increasing CBF and cerebral oxygen delivery. A vascular osmotic gradient is created by mannitol. Thus fluid moves from the tissues into the blood vessels. Therefore the ICP is reduced by a decrease in the total rain fluid content. Fluid and electrolyte status must be monitored when osmotic diurectics are used. Mannitol may be contraindicated if renal disease is present.
Discuss the role of loop diuretics in the treatment of IICP and associated nursing management.
Furosemide has shown beneficial effects as an adjunctive agent in the treatment of intracranial hypertension in patients undergoing surgery for intracranial hematomas or ruptured aneurysms. A 56% reduction in intracranial pressure following intravenous administration of 80 mg of furosemide following induction of anesthesia in patients receiving aneurysm repair. Furosemide's ability to control intracranial pressure has been related to the carbonic anhydrous benefit of reducing cerebral spinal fluid production, its effects on central venous pressure and its ability to induce diuresis.
Discuss the role of steroids in the treatment of IICP and associated nursing management.
dexamethason (Decadron). Thought to control the vasogenic edema surrounding tumors and abscesses but are not recommended in the management of head-injured patients. They act by stabilizing the cell membrane and by inhibiting the synthesis of protagladins, thus preventing the formation of proinflammatory mediators. Improves neuronal function by improving CBF and restoring autoregulation.
Discuss the role of barbiturates in the treatment of IICP and associated nursing management.
(phenobarbital, thiopental) High-doses are used in patients with increased ICP refractory to treatment. They produce a decrease in cerebral metabolism and a subsequent decrease in ICP. A secondary effect is a reduction in cerebreal edema and production of a more uniform blood supply to the brain. Capabilities to monitor the patient's ICP, blood flow, EEG, and metabolism should be available when this treatment is used.
Discuss the role of anticonvulsants in the treatment of IICP and associated nursing management.
Anti-seizure drugs such as phenytoin (Dilantin) also may be used because seizures can further increase ICP.
Discuss the role of antipyretics in the treatment of IICP and associated nursing management.
Maintaining normothermia with antipyretics is important to prevent shivering which increases IICP.
Explain the role of hyperventilation therapy in IICP.
The lowering of the PaCO2 leads to constriction of the cerebral blood vessels, reducing CBF and thereby decreasing the ICP. More recent evidence suggests that aggressive hyperventilation increases the risk of focal cerebral ischemia and adversely affects outcomes. Brief periods of less aggressive hyperventilation therapy (target PaCO2 30-35 mm Hg) may be useful for refractory intracranial hypertension.
Describe the Glasgow Coma Scale. (Know the values).
A quick, practical, and standarized system for assessing the degree of impaired consciousness.
Discuss the role of antipyretics in the treatment of IICP and associated nursing management.
(Scores in 25, 26, and 27)
Score 4 - Spontaneous response
Score 3 - Opening of eyes to name or command
Score 2 - Lack of opening eyes to previous stimuli, but opening to pain.
Score 1 - Lack of opening of eyes to any stimuli
Score U - untestable
Score 5 - Appropriate orient, conversant, correct id of self, place, year, month.
Score 4 - Confusion, disorient in one or more spheres.
Score 3 - Inappropriate or disorganized speech, lack of sustained conversation.
Score 2 - Incomprehensible works, sound (moaning)
Score 1 - Lack of sound, even with painful stimuli.
Score 6 - Obedience of command.
Score 5 - Localization of pain, lack of obedience but presences of attempts to remover offending stimulus.
Score 4 - Flexion withdrawal, flexion of arm in response to pain w/o abnormal flexion posture.
Score 3 - Abnormal flexion, of arm at elbow and pronation, making fist.
Score 2 - Abnormal extension, of arm at elbow usually with adduction and internal rotation of arm at shoulder.
Score 1 - Lack of response.
Score U - untestable
Which cranial nerve controls papillary response?
Cranial nerve III
Which cranial nerve controls eye movement and how do you asses its function?
Cranial nerves III, IV, and VI. Cannot be specifically tested in an unconscious patient. Eye movements of the uncooperative or unconscious patient can be elicited by reflex witht he use of head movements and caloric stimulation. To test the oculocephalic reflex (dolls-eye reflex) the nurse turms the patients head briskly to the left or right while holding the eyelids open. A normal response is movement of the eyes across the midline in the direction opposite that of the turning. Next, the nurse quickly flexes and then extends the neck. Eye movement should be opposite to the direction of the head movement-up when the neck is flexed, down when the neck is extended.
In caring for patients with increased ICP, some nursing activities should be modified. Identify the effects that respiratory suctioning would have on a patient.
Will cause transient decreases in the PaCO2 and increasees in the ICP. Suctioning should be kept to a minimum and should be less than 10 seconds in duration, with administration of 100% O2 before and after to prevent decreases in the PaCO2. To avoid cumulative increases in the ICP with suctioning, it should be limited to two passes per suction procedure if possible.
In caring for patients with increased ICP, some nursing activities should be modified. Identify the effects that body position would have on a patient.
The patient with increased ICP should be maintained in the head-up position. The nurse must take care to prevent extreme neck flexion, which can cause venous obstruction and contribute to elevated ICP.
In caring for patients with increased ICP, some nursing activities should be modified. Identify the effects that repositioning (i.e. turning) would have on a patient.
Airway patency can be aided by keeping the patient lying on one side, with frequent position changes. Care should be taken to turn the patient with slow, gentle movements because rapid changes in position may increase the ICP. Caution should be used to prevent discomfort in turning and positioning the patient because pain and agitation also increases pressure.
In caring for patients with increased ICP, some nursing activities should be modified. Identify the effects that abdominal distention would have on a patient.
This can interfere with respiratory function and should be prevented. Insertion of a NG tube to aspirate the stomach contents can prevent distention, vomiting, andpossible aspiration. However, in patients with facial and skull fractures, a NG tube in contraindicated, and oral insertion of a gastric tube is preferred.
In caring for patients with increased ICP, some nursing activities should be modified. Identify the effects that pain, anxiety and fear would have on a patient.
Can increase ICP and BP, thus complicating the management and recovery of the brain-injured patient. A combination of sedative, paralytics and analgesics for symptom management present a challenge to the ICU nurse team. Administration of theses agents may alter the neurologic state, thus making true neurological changes. It may be necessary to temporarily suspend drug therapy to appropriately assess neurologic status.
In caring for patients with increased ICP, some nursing activities should be modified. Identify the effects that narcotics would have on a patient.
Opiods, such as morphine sulfate and fentanyl are rapid-onet analgesics with minimal effect on CBF or oxygen metabolism. The IV anesthetic sedative propofol (Diprovan) has gained popularity in the management of anxiety and agitation in the ICU because of its rapid onset and short half-life, allowing an accurate neurologic assessment to be performed very soon after turning off the infusion.
Complications of increase ICP include brain herniation. Briefly discuss.
A major complication of uncontrolled increased ICP. The FLAX CEREBRI is a thin wall of dura that folds down between the cortex, separating the two cerebral hemispheres. The TENTORIM CEREBELLA is a rigid fold of dura that separates the cerebral hemisphere from the cerebellum. It is called the tentorium because it forms a tentlike cover over the cerbellum.
TENTORIAL HERNIATION occurs when a mass lesion in the cerebrum forces the brain to herniate downward through the opening created by the brainstem. UNCAL HERNIATION occurs when there is lateral and downward herniation. CINGLULATED HERNIATION occurs when ther is lateral displacement of brain tissue beneath the falx cerebri.
Complications of increase ICP include SIADH. Briefly discuss.
Urinary output is monitored to detect problems related to SIADH. The output will decrease with this. The serum sodium and osmolality are also used to diagnose SIADH. SIADH results in dilutional hyponatremia that may produce cerebral edema, changes in LOC, seizures, and coma.
Complications of increase ICP include DI. Briefly discuss.
Urinary output is monitored to detect problems related to diabetes insipidus. The output will increase with this. The serum sodium and osmolality are also used to diagnose DI. Di may result in severe dehydration unless treated. The usual treatment is fluid replacement, vasopressin, or desmospression acetate.
Patients with altered brain function may demonstrate abnormal posturing. Describe decorticate posturing.
Consist of internal rotation and adduction of the arms with flexion of the elbow, writs and fingers as a result of interruption of voluntary motor tracts in the cerebral cortex. Extension of the legs may also be seen. This is seen as ICP begins to rise; it is a response to painful stimuli.
Patients with altered brain function may demonstrate abnormal posturing. Describe decerbrate posturing.
May indicate more serious damage and results from disruption of motor fibers in the midbrain and brain stem. In this position, the arms are stiffly extented, adducted, and hyperpronated. There is also hyperextentision of the legs with plantar flexion of the feet.
A head injury refers to an injury to the scalp, the cranium or the brain. Discuss the role nurses play in health promotion/prevention regarding head injury.
One of the best ways to prevent head injuries is to prevent car and motorcycle collisions. The nurse can be active in campaigns that promote driving safety and can speak to diver education classes regarding the dangers of unsafe driving and of driving after drinking alcohol and using drugs. The use of seat belts in cars and the use of helmets for riding on motorcycles are the most effective measures for increasing survival after crashes. The wearing of protective helmets by lumberjacks, construction workers, miner, horseback riders, bicycle riders, snowboarders, and skydivers is also recommended. The nurse should be familiar with data on outcomes with and without safety devices in working with groups who oppose safety legislation as an infringement of personal freedom.
Describe the acute interventions that are appropriate for a patient with a head injury.
Management at the injury scene can have a significant impact on the outcome of the head injury. Goal of the management of the head injured patient is to maintain cerebral oxygenation and perfusion and prevent secondary cerebral ischemia. Surveillance or monitoring for changes in neurologic status is critically important because the patient's condition may deteriorate rapidly.
- Ensure patent airway.
- Stabilize cervical spine.
- Administer O2 via non-rebreather mask.
- Establish IV access with two large-bore caths to infuse NS or LR solution.
- Control external bleeding with sterile pressure dressing.
- Assess for rhinorrhea, otorrhea, and scalp wounds.
- Remove patients clothing.
Ongoing Monitoring Interventions
- Maintain patient warmth using blankets, warm IV fluids, overhead warming lights, warm humidified O2.
- Monitor vital signs, LOC, O2 saturation, cardiac rhythm.
- Glasgow coma scale, pupil size and reactivity.
- Anticipate need for intubation if gag reflex is impaired or absent.
- Assume neck injury with head injury.
- Administer fluids cautiously to prevent fluid overload and increasing ICP.
Describe the types of skull fractures, complications and what is the significance of raccoon eyes and Battle's sign.
Fractures may be closed or open, depending on the presence of scalp laceration or extension of the fracture into the air sinuses or dura. The type and severity of a skull fracture depend on the velocity, the momentum, the direction of the injuring agent and the site of impact. A basilar skull fracture is a specialized type of linear fracture that occurs when the fracture involves the base of the skull.
Linear skull fracture
Break in continuity of bone without alteration of relationship of parts.
Depressed skull fracture.
Inward indentation of skull.
Simple skull fracture
Linear or depressed skull fracture without fragmentation or communicating lacerations.
Comminuted skull fracture
Multiple linear fractures with fragmentation of bone into many pieces.
Compund skull fracture
Depressed skull fracture and scalp laceration with communicating pathway into intracranial cavity.
(postauricular ecchymosis) and periorbital ecchymosis (raccoon eyes): This fracture generally is associated with a tear in the dura and subsequent leakage of CSF. Rhinorrhea (CSF leakage from the nose) or otorrhea (CSF leakage from the ear) generally confirms that the fracture has traversed the dura.
Describe epidural hematoma including onset/signs and symptoms and management.
Results from bleeding between the dura and the inner surface of the skull. This is a neurologic emergency and is usually associated with linear fracture crossing a major artery in the dura, causing a tear. It can have a venous or an arterial origin. Hemorrhage occurs into the epidural space, which lies between the dura and inner surface of the skull. Classic signs typically include an initial period of unconsciousness at the scene, with a brief lucid interval followed by a decrease in LOC. Headache, nausea and vomiting, focal findings. Rapid surgical intervention to evacuate the hematoma and prevent cerebral herniation can dramatically improve the outcome.
Describe subdural hematoma including onset/signs and symptoms and management.
Occurs from bleeding between the dura mater and the arachnoid layer of the meninges. It usually results from injury to the brain substance and its parenchymal vessels. The hematoma may be slower to develop. It may be caused by an arterial hemorrhage, in which case it develops more rapidly. An acute subdural hematoma manifests signs within 48 hrs of the injury. Signs and symptoms are decreased LOC and headache. The patients may be drowsy and subdural hematoma usually occurs with 2-14 days of the injury. A chronic subdural hematoma develops over weeks or months after a seemingly minor head injury. The peak incidence of chronic subdural hematoma develops over weeks or months after a seemingly minor head injury. The peak incidence of chronic subdural hematoma is in the 50's and 60's when a potentially larger subdural space is available as a result of brain atrophy.
Describe intracerebral bleed including onset/signs and symptoms and management.
Usually occurs within the frontal and temporal lobes. The size and location of the hematoma is a key determinant of the patient outcome.
What are the clinical signs and symptoms of meningitis (include + meningeal signs)?
Fever, severe headache, nausea, vomiting, nuchal rigidity, positive Kernig's sign, positive Brudzinski's sign, photophobia, a decreased LOC, and signs of IICP.
Brudsinski's sign: involuntary flexion of the hip and knees is positive.
Kernig's sign: pain in the lower back and resistance to straightening the leg at the knees is positive.
Discuss appropriate antimicrobial therapy for a patient with meningitis.
Ampicillin, penicillin, vancomycin, cefuroxime (Ceftin), cefotaxime (Claforan), ceftriaxone (Rocephine, ceftizoxime (Cefizox), ceftazidime (Ceptez): When meningitis is suspected, antibiotic therapy is instituted after the collection of specimens for cultures, even before the diagnosis is confirmed.
What, if any, type of meningitis requires isolation?
Meningitis generally requires respiratory isolation until the cultures are negative. Meningococcal meningitis is highly contagious.
What is encephalitis and what medication therapy is most beneficial in its treatment?
Encephalitis is an acute inflammation of the brain, it's a serious and sometimes fatal disease. Acyclovir is the preferred treatment.
Define spinal cord injury and common causes.
Spinal cord injury can be due to cord compression by bone displacement, interruption of blood supply to the cord, or traction resulting from pulling on the cord. Penetrating trauma, such as gunshot. Causes of spinal cord injury include many types of trauma. Motor vehicle crashes account for 50%; falls 24%; violence 11%; sports injuries 9%; and other misc 6%.
Briefly describe spinal shock and management.
A temporary neurologic syndrome is known as spinal shock that is characterized by decreased reflexes, loss of sensation, and flaccid paralysis below the level of the injury. This syndrome lasts days to months and may mask post injury neurologic function. Active rehabilitation may begin in the presence of spinal shock.
Describe nursing interventions that would be useful in the acute care and rehabilitation/home care of the patient with a spinal cord injury.
Identification of high-risk populations, counseling, and education. Support of legislation related to sear belt use in cars, helmet for motorcyclists and bycyclists, child safety seats. and tougher penalties for drunk-driving offenses is a professional responsibility. After injury, health-promoting behaviors can have a significant impact on the health and well-being of the individual with a spinal cord injury. Nursing interventions include education, counseling, and referral to programs such as smoking cessation classes, recreation and exercise programs, and alcohol treatment programs, and maintaining routine physical examination for non-neurologic problems.
What is autonomic dyreflexia and its management?
The return of reflexes after the resolution of spinal shock means that patients with an injury level at T6 or higher may develop autonomic dysreflexia. Autonomic dysreflexia (also know as autonomic hyperreflexia) is a massive uncompensated cardiovascular reaction mediated by the sympathetic nervous system. The condition is a life-threatening situation that requires immediate resolution. If resolution does not occur, this condition can lead to status epilepticus, stroke, myocardial infarction, and even death. Nursing interventions are elevation of the head of the bed 45 degrees or sitting the patient upright, notification of the physician, and assessment to determine the cause. The most common cause is bladder irritation. Immediate catheterization to relieve bladder distention may be necessary. Lidocaine jelly should be instilled in the urethra before catheterization. If a catheter is already in place, it should be checked for kinks or folds.
What are the most common types of brain tumors and their clinical manifestations?
Brain tumors may be primary, arising from tissues within the brain, or secondary, resulting from a metastasis from a malignant neoplasm elsewhere in the body. Secondary brain tumors are the most common type. Brain tumors are generally classified according to the tissue from which they arise.
Manifestation of brain tumors: headache worse at night, may awaken the patient, usually dull and constant but occasionally throbbing; seizures; nausea; vomiting; memory problems; mood or personality changes; muscle weakness; aphasia; visuospatial dysfuntion.
What is the current treatment for brain tumors. Describe the care of the patient.
Treatment goals are aimed at identifying the tumor type and location, removing or decreasing the tumor mass and preventing or managing increased ICP. Surgical removal is the preferred treatment for brain tumors. Radiation therapy is commonly used as a follow-up measure after surgery. Chemotherapy, the effectiveness of this has been limited by difficulty getting drugs across the brain-barrier, tumor cell heterogeneity, and tumor cell drug resistance. Care of the patient includes assisting the family in understanding what is happening to the patient and supporting the family through this diagnostic phase. Protect patient from self harm. Close supervision of activity, use of side rails, judicious use of restraints, appropriate sedative medications, padding of the rails and the area around the bed, and a calm, reassuring approach to care are all essential techniques in the care of these patients. Minimize environmental stimuli, creation of a routine, and use of reality orientation.
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