Transcript LWW PPT Slide Template Master

Chapter 34:
Patient Management: Nervous
System
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Intracranial Pressure and Hypertension
Intracranial pressure: pressure inside the skull; around 0 to 15
mm Hg
Intracranial hypertension: when pressure inside the skull is high;
any pressure >15 mm Hg
Monro-Kellie doctrine: Brain is composed of blood (3-10%), CSF
(8-12%) and brain tissue (80%). Brain tissue is mostly water.
Any change in one must create a change in the others for the
brain to maintain a balanced intracranial pressure. CSF can
increase due to overproduction or block in circulation. Brain
tissue can increase if tumor.
Brain compliance: when it can compensate for an increased
pressure. It can do this for only a small amount.
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Autoregulation
• Ability of the brain to maintain constant pressures
despite wide fluctuations
– Changes in oxygen (hypoxia) and carbon dioxide
(hypercarbia) can disrupt this balance
• Cerebral blood flow (CBF) is the blood flow to the brain;
it is maintained by a balance between the mean blood
pressure (MAP) and the ICP. Blood pressure to the brain
is called the cerebral perfusion pressure (CPP).
• MAP – ICP = CPP
• Normal CBF is 60-100 mm Hg
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Question
A patient is admitted to the ICU with an intraventricular catheter
in place. Her intracranial pressure (ICP) is recorded steady at
20. An arterial line is placed and her mean arterial pressure
(MAP) is 80. What is this patient’s CPP?
A. 20
B. 40
C. 60
D. 80
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Answer
C. 60
Rationale: This patient’s CPP is 60. The CPP is calculated by
taking the MAP (80) minus the ICP (20). This is a low
normal CPP for this patient.
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Why Use ICP Monitoring?
• Earlier detection of life-threatening problems
• Detection of desired response to treatment protocols
• Can remove CSF to help in brain compensation
• Improves patient outcomes
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Conditions That Might Require ICP
Monitoring
• Cerebral edema
–
Common in many neurologic conditions: trauma, tumor, abscess,
intracerebral bleeds, stroke, anoxia and hypoxia
• Cushing’s syndrome
–
Mostly posterior fossa mass expanding lesions
–
Signs include widening of pulse pressure, bradycardia, and
respiratory and pupillary changes
• Herniation suspected
–
Pressure builds up in the brain and compliance is decreased
–
Herniation occurs down the tentorium and then to the foramen
magnum
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Indications
• Head injury
• Hemorrhages
• Stroke
– Subarachnoid (SAH)
• Tumors
– Intracerebral
• Cardiac arrest
• Infection
• Brain surgery
• Hydrocephalus
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Question
A patient is admitted to the ICU after massive head trauma
to the cerebrum. Initial VS are 100.8 – 120 – 28 and BP
148/90. Which of the following assessment findings
would most likely indicate Cushing’s syndrome?
A. 98.9 – 90 – 24 – 120/80
B. 102 – 50 – 12 – 158/60
C. 100.9 – 120 – 38 – 160/90
D. 104 – 140 – 24 – 80/40
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Answer
B. 102 – 50 – 12 – 158/60
Rationale: There is a rise in temperature suggestive of
brain injury, bradycardia as the respiratory centers are
depressed, and hypoventilation. Answer A is normal for
this patient answer C is more suggestive of early
hypovolemia, and answer D is more suggestive of
hemorrhagic shock.
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Types of ICP Monitors
• Type used depends on:
– Speed and onset of symptoms; cause
– Type of neurological condition
– Cost and staff available
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IVC and Subarachnoid Screw
• Intraventricular catheter (IVC)
– Tube placed in the ventricles
– Accurate and reliable
– Easily inserted at bedside or in OR
– Can also be used to treat increased ICP by draining CSF
• Subarachnoid screw
– Into subarachnoid space
– No disruption in skull
– Readings often inaccurate
– Obstructs more easily
– Refer to Figure 34-2.
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Wave Forms and What They Mean
• A waves
– Plateau
• Raise quickly and stay up for
5–20 minutes; increased ICP
• B waves
• Small and sharp, stay up for
1/2 to 2 minutes; respiratory
in nature
• C waves
• Small rhythmic at 6
waves/min; severe brain
pressure
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Complications and Troubleshooting
• Infection: Frequent temps, C&S and color of CSF
• Obstruction: Are the readings accurate or
dampened?
• Displacement: Leveled with each patient position
change
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Pharmacological Management and Nursing Care
of the Patient
• FIRST TIER (conventional treatment regimens)
– Mannitol
– Respiratory support
– Pain control and sedation
• SECOND TIER (if first-line therapy doesn’t work)
– Hypothermia
– Barbiturate coma
– Antihypertensive therapy
– Decompressive craniotomy
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First-Tier Therapy: Mannitol
• What it is? Hypertonic crystalloid medication
• What are the expected outcomes? Removing excess fluid
from the brain
• What is the dose? 0.25 mg – 2 g/kg over 10-30 min
• What complications must the nurse assess for? Use Foley
catheter for q1h outputs. Monitor BUN, creatinine, GFR
for acute tubular necrosis. Replace fluids if patient is also
hypervolemic or BP will drop (this will decrease CPP).
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First Tier: Respiratory Support
• What it is? Intubation, mechanical ventilation, and airway
clearance by suctioning. Hyperventilation to decrease
CO2 (vasoconstrictive) should be used with caution and
not in the first 24 hr of head trauma unless there is a
drastic increase in ICP.
• What are the expected outcomes? Stabilization of ICP
and CPP, decrease in coughing, SaO2 > 93%
• What complications should the nurse monitor for? With
positive-pressure ventilation to correct for hypoxia, the
MAP can go down, decreasing the CPP. Suction only when
necessary and for no more than 10 seconds.
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First Tier: Pain Control (Analgesia)
• What it is? Nonpharmacological support by distraction,
back rubs, etc.
• What are the expected outcomes? The patient will be
calm and report that pain is controlled, without agitation.
A decrease in the use of opioid analgesics.
• What is the dose? Continuous PCA of morphine
sulfate/fentanyl
• What complications should the nurse monitor for?
Respiratory depression with high opioid doses; have
naloxone available. Unrelieved pain needs should be
addressed.
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Question
An expected outcome for a patient with a nursing diagnosis
of acute pain would be easy breathing and synchrony
with the ventilator.
A. True
B. False
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Answer
A. True
Rationale: “Bucking” the ventilator can be a sign of
increased need for oxygen or sedation. Agitation can
increase oxygen needs and therefore increase intracranial
pressure. Pain and anxiety control will increase CPP by
decreasing ICP and MAP. Pain and anxiety control will
decrease the heart rate, increase cooperation, and lead
to easy and unlabored respirations.
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First Tier: Patient Sedation
• What it is? Use of benzodiazepines to control anxiety.
Propofol is used for extreme agitation.
• What are the expected outcomes? Control of anxiety and
increase in CBF. Calmness and ease of breathing.
• What is the dose? The lowest possible dose to ensure
arousal but decrease anxiety
• What complications should the nurse monitor for?
Propofol can cause apnea, hypotension, and infection.
The patient on the ventilator is monitored for pO2,
respiratory rate, and anxiety. The bag and tubing are
changed q12h.
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Pharmacological Management of
Increased ICP
• Second-tier management is used if the first tier is
ineffective
• Hypothermia – increased temperature increases
metabolic rates and increases ICP. Keep temp down with
antipyretics and cooling blankets.
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Barbiturate Coma
–
What it is? Use of pentobarbital, thiopental to induce a metabolic
coma. Controls seizure activity. All vital signs are suppressed and
life support is needed.
–
What are the expected outcomes? Decreased ICP, decreased
temperature, decreased BP, decreased work of breathing via
ventilator
–
What is the dose? Pentobarbital 5-10 mg/kg loading dose over
30 minutes, then a drip at 1 mg/kg/hr
–
What complications should the nurse monitor for? Respiratory
support via intubation/mechanical ventilation. BP support with
vasopressors like dopamine and Levophed. Monitor for muscular
weakness when drip is discontinued.
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Other Nursing Activities for All Levels of
Care
• Calm, supportive environment for patient/significant others
– Rest and sleep periods planned
• Positioning: head of bed elevated 15-30%; increases venous
drainage
• Head and neck alignment; log rolling – increases venous
drainage
• Stool softeners – to prevent excessive intra-abdominal
pressures, which can be transmitted into the cranial cavity
• Monitor for BP and rhythm disturbances – treat them as they
occur with antihypertensives and antiarrhythmics
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Other Nursing Responsibilities
• Antihypertensives
– What it is? Beta-blockers and calcium channel blockers to
decrease extremely high systolic pressures
– What are the expected outcomes? BP slowly lowered but
on the higher side to allow CPP
– What is the dose? Depends on the medication
– What complications should the nurse monitor for? Not
lowering the BP or lowering it too much
• Decompression craniotomy
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Nursing Management of Neuromuscular
Blockade
What it is? Use of neuromuscular paralyzers like
pancuronium
What are the expected outcomes? Synchrony with
ventilator
What complications should the nurse monitor for? The
patient is totally dependent on life-support systems
and the nurse. Always give pain medication and
remember the patient can hear, see, and feel; he or
she is NOT in a coma. BP support.
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Nursing Management of Seizures
What it is? The abnormal movements caused by a
seizure increase metabolic demands and therefore
can increase ICP.
What are the expected outcomes? No seizure activity
and ICP < 15 mm Hg
What is the dose? Varies; more on this with next
chapter. Usual medications include diazepam,
lorazepam, phenytoin.
What complications should the nurse monitor for?
Status epilepticus (more in next chapter)
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