3. Blackout Flashcards
What are the most common causes of a transient loss of consciousness (LOC)?
- Reflex- ‘playing dead’ heart rate slows and blood pressure drops
- cardiac - pathologies causing a reduction in cardiac output
- Orthostatic - low blood pressure whilst being upright
- Cerebrovascular - non-cardiac structural causes of reduced cerebral perfusion
What is the main reflex causes of LOC?
what are minor reflex causes of LOC?
Vasovagal syncope - occurs due to reflex bradycardia and vasodilation caused by emotion, pain, or standing up too long. Unconsciousness is for less than 2 mins and recovery is rapid
carotid sinus hypersensitivity - Increased carotid sinus sensitivity so when pressure is applied blood pressure decreases
Situational syncope - Vagotonic, peripheral vascular dilation caused by coughing or swallowing
What is the main cardiac cause of LOC?
Arrhythmia - Bradycardia/tachycardia → ↓ ejection fraction
Structural cardiac pathology causing outflow obstruction eg. due to MI or aortic stenosis or massive pulmonary embolism
What is the main orthostatic cause of LOC?
Drugs- anti-hypertensives, anti-sympathetic
Dehydration
autonomic instability
baroreceptor dysfunction
What are the main causes of LOC in the following:
25 yo
55 yo
85 yo
25- vasovagal syncope (presyncope syndrome)
55- vasovagal syncope and arrhythmia caused by atherosclerotic disease
85- orthostatic hypotension caused by medications
How do you split up your questions in a LOC history?
Before, during and after
What questions should you ask about before the LOC?
- Were there any precipitating factors
if no then it is probably cardiac or cerebrovascular
- Were there any precipitating factors? eg. exercise, standing up, fear or pain
postural triggers suggest orthostatic hypotension
turning head suggests carotid sinus hypersensitivity
blackout whilst sitting or lying is suggestive of cardiac arrhythmia
- Was there any recent head trauma?
Be wary of subdural hemorrhages especially in alcoholics and elderly
What questions should you ask about regarding what happened during a LOC?
- how long was the patient unconscious for?
seconds or minutes suggests vasovagal or arrhythmia
- tongue biting or incontinence?
tongue biting = epileptic seizure
twitching and incontinence = vasovagal
What questions should you ask about after a LOC?
- How long was the recovery time?
slow recovery with confusion = epileptic seizure
rapid recovery = vasovagal or arrhythmia
what is past medical history relating to blackout?
- has it happened before
- diabetes (orthostatic hypotension)
- cardiac illness (arrhythmias)
- peripheral vascular disease
- epilepsy
- anemia
- psychiatric illness
What drugs are you looking out for in someone who has had a LOC?
- insulin - hypoglycemia
- antihypertensives - all can cause hypotension
- vasodilators - these can all cause hypotension especially in elderly patients
- antiarrhythmics - these predispose to arrhythmias
- antidepressants Hypotension can be a side-effect
- warfarin - more vulnerable to subdural haemorrhages
What things in the Shx and Fhx should you look out for in someone with a LOC?
Shx: Alcohol intake and stimulant recreational drugs (cocaine)
Fhx: sudden death in any relations under 65
suggests exercise-induced syncope which can be hereditary
What are the first line investigations in someone with a LOC?
Blood glucose, FBC, UEs, ECG
key findings of examination in blackout?
- bitten tongue
- dehydration
- head trauma
- heart murmur or irregular pulse
- carotid bruit is a vascular murmur sound
- blood pressure (orthostatic hypotension)
- focal neurological signs (peripheral neuropathy due to diabetes or alcohol)
first line investigations for anyone with blackout?
- bloods - blood glucose, FBC, Us and Es
- ECG
less typical …
- echocardiogram
- carotid sinus massage
- brain scan
