Week 8: Acute Neurological Deterioration Flashcards
What are some causes of unconsciousness?
Decreased oxygen to brain Decreased BP Hypo/hyperglycaemia Opiates Seizures Infection Toxins MODS Alcohol
How does hypoxia cause cerebral oedema?
Inadequate O2 to brain inhibits production of ATP necessary for Na-K pump to move Na out of cells. As Na builds up in brain cells, water is drawn in as well by osmosis, causing cytotoxic cerebral oedema
How can carbon dioxide affect cerebral blood flow?
Hypercarbia –> cerebrovascular vasodilation
Hypocarbia –> cerebrovascular vasoconstriction
Vasodilation increases ICP
What is the Monro Hellie Hypothesis?
Brain, intravascular volume and CSF are in dynamic equilibrium. If one component icnreases in volume then another must decrease otherwise ICP will increase
What are compensatory mechanisms for volume-pressure changes in the intracranial space?
Displacement of CSF to spinal subarachnoid space
Compression of low pressure venous system
Decreased CSF production
Vasoconstriction
What are factors which affect cerebral blood flow?
CO2
O2
Blood vessel integrity (multi infarct dementia)
Blood viscosity
Other: arousal and pain, seizures, hyperthermia, REM sleep
What is a Cushing response?
Ischemia to brain stem:
Elevated SBP
Widening pulse pressure
Bradycardia
Why is temperature an important sign in neurological conditions?
Hyperthermia:
Lesions of hypothalamus
Petechial haemorrhage
Infection
Hypothermia:
Spinal shock (vasodilation)
Exposure
Lesions on brain stem tract
What metabolic problems can cause seizures?
Acidosis Electrolyte imbalance Hypoglycaemia Hypoxia Alcohol or barbiturate withdrawal Dehydration Water intoxication
What extracranial disorders can cause seizures?
Heart, lung, kidney or liver disease
NIDDUM
HTN
Sepsis
What are some typical assessment findings of a person with a seizure?
Aura LOC Incontinence Tachycardia Diaphoresis Tonic clonic movements
Post ictal:
Lethargy
Reduced LOC
Confusion and headache
What is the emergency management for a person with a seizure?
Protect from injury Do not force jaw open or restrain Remove loose or tight clothing Stay with patient Suction if needed Observe length of seizure, precipitating events Conduct A-G
What is delirium?
Sudden, transient and organic: confusion, disorientation, agitation, disturbed sleep or hallucinations
Who is at risk of delirium?
➢ Older adults ➢ People who have been in ICU ➢ Use of physical restraints ➢ Pain ➢ Emotional stress ➢ Sleep deprivation ➢ Immobility ➢ Visual or hearing impairment ➢ People on anticholinergic drugs ➢ People on multiple drugs ➢ Sedatives ➢ Alcohol withdrawal ➢ Drug withdrawal
What are common precipitating factors for delirium?
➢ 1/ Hypoxia ➢ 2/ Hypotension ➢ 3/ Hypoglycaemia ➢ 4/ Major electrolyte disturbance ➢ 5/ All of medication history ➢ 6/ Infections ➢ 7/ Urinary retention ➢ 8/ Constipation or faecal impaction ➢ 9/ Thirst, hunger, pain ➢ 10/ Alcohol withdrawal
What are the 3 subtypes of delirium?
Hyperalert: Restless Agitated Oversensitive to stimuli Hallucinations
Hypoalert:
Lethargy
Slowness
Reduced speech
Fluctuating symptoms:
Alternating between hyper and hypo
How do you manage delirium?
Prevention: anticipate precipitating factors and reduce them, regularly assess
Reverse cause
Non-pharma: fluids and nutrition, ambulation, optomise senses, sleep
Pharma: pain management, constipation management, psychotropic medication
What is a stroke?
Sudden interruption of blood flow to a part of the brain, killing the cells and destroying/impairing the functions controlled by that part of the brain
What is the difference between a haemorrhagic and ischemic stroke?
Haemorrhagic: rupture of blood vessel damages surrounding tissue
Higher mortality
Ischemic: embolism or thrombus obstructs cerebral artery which blocks blood flow to part of the brain
More common
What are the types of haemorrhagic stroke?
Intracerebral: bleeding into brain tissue due to ruptured small artery
Subarachnoid: bleeding into subarachnoid space due to ruptured aneurysm or anteriovenous malformation
What is stenosis?
Gradual process of atherosclerotic plaque accumulating in cerebral artery and occluding it. Ischemia and neurological deficits occur over hours to days
What is a thrombotic stroke?
Blood clot formed in cerebral blood vessel and blocks blood flow
What is an embolic stroke?
Embolus travels from a distant site and is caught in cerebral blood vessel
Sudden deficit
AF: blood pools in atria, clots and travels to cerebral artery
Atherosclerosis: plaque breaks off and travels to cerebral artery
What occurs during an ischemic stroke?
Blood flow interruption
After 4-5 minutes, cellular metabolism ceases:
O2, glucose and glycogen cannot be delivered to cells
No ATP
No Na-K pump
Na builds up in cells, attracts water –> cell swells
Blood vessel walls also swell, further diminishing blood flow
Cytotoxic oedema
Electrical paralysis
Excessive glutamate-calcium influx and oxygen free radicals further damage cells
What are the two zones of an ischemic stroke?
Primary zone:
Cell death, cannot be salvaged
Secondary zone: supplied by collateral blood flow, cells intact although have minimal metabolic activity
Affected by reduced blood flow, oedema and toxic substances released by damaged cells
Need to maintain airway, circulation and administer TPA