Blackout Flashcards
What is the commonest cause of loss of consciousness in a patient…
1) 25yrs old?
2) 55yrs old?
3) 85yrs old?
1)
- Vasovagal syncope
2)
- Arrythmias - due to increased atherosclerotic burden with age
3)
- Orthostatic hypotension - more likely due to the medications older people take such as beta-blockers, ACEI’s, CCBs, alpha-blockers etc
In which causes of blackout can you get a warning prior to the blackout episode?
- Epileptic seizure - ‘aura’ warning
- Vasovagal episode - dizziness before the episode - you know you are about to faint
What precipitating factors are there that can cause different types of blackout?
- Postural changes - orthostatic hypotension
- Upon turning head - carotid sinus hypersensitivity
- Rapid arm movement - subclavian steal
- Exercise - suggests cardiac pathology
- Aortic stenosis
- Cardiomyopathy (e.g. hypertrophic obstructive cardiomyopathy)
- Cardiac channelopathy (e.g. long QT syndrome)
Blackout following head trauma should alert you to the possibility of what?
- Subdural haemmorhages
- Subarachnoid haemorrhages
- Haematomas
- Subdural
- Extradural
What are the characteristic features in the presentation of vasovagal blackout - before, during and after?
BEFORE
- PRECIPITANT CAUSING IT e.g. fear etc
- VAGAL symptoms:
- Sweating
- Pallor
- Nausea
- Dizziness and the sense that you are about to faint just before fainting
DURING
- Lasts seconds
- Twitch / incontinence sometimes
AFTER
- Rapid recovery on sitting or lying
What are the characteristic features in the presentation of Epileptic blackout - before, during and after?
BEFORE
- ‘Aura’ symptoms in partial seizure
- No warning in general seizure
DURING
- Tongue biting is pathognomic of epileptic seizures
- Lasts minutes
- Twitching and incontinence may also occur but not specific to epilepsy
AFTER
- Slow recovery for 5-30 minutes
- Post-ictal confusion
What are the characteristic features in the presentation of arrythmia causing blackout - before, during and after?
BEFORE
- No warning
DURING
- Lasts seconds
- May twitch or be incontinent
AFTER
- Rapid spontaneous recovery
What things might you consider about the past medical history in patients who have had a blackout episode?
- Previous epileptic seizure / epilepsy?
- Diabetes? Predisposes to PVD, hypoglycaemia (cause of blackout), polyuria and dehydration (in orthostatic hypotension) and autonomic dysfunction (in orthostatic hypotension)
- Cardiac illness? Arryhtmias (cause of blackout) my arise following MI. Left ventricular outflow obstruction may occur secondary to aortic stenosis, HOCM
- PVD? Associated with CVAs such as stroke, TIA (rarely cause blackout though)
- Anaemia? Can contribute to hypoxia
- Psychiatric illness? Panic attacks → hyperventilation → loss of consciousness. anaon-epileptic seizure also more common in people with psychiatric illness
What drugs in the drug history are important in the context of blackout?
- Insulin? - hypoglycaemia as a cause of blackout
-
Anti-hypertensives? Cause hypotension
- Diuretics
- ACEIs
- Beta-blockers
- CCBs
-
Vasodilators? Cause hypotension
- GTN
- Isosorbide mononitrate
- Antiarrythmics? These can ironically predispose to arrythmias
- Antidepressants? E.g. TCAs can cause hypotension
- Warfarin / other anticoagulants? More vulnerable to subdural haemorrhages
What 2 things from the social history are important to derive that are important in the context of blackout?
- Alcohol
- Stimulant recreational drug use
- Cocaine
- Methamphetamines
- Both cause tachyarrythmias and potentially a drop in cardiac output
Why is family history important in the context of blackout?
- Some cardiomyopathies and arrythmias are hereditary
- Sudden death in any relations < 65 years old. Particularly informative regarding exercise-induced syncope
What might carotid bruits on examination in the context of blackout point towards?
- Carotid artery stenosis as a cause of blackout
How do you investigate possible orthostatic hypotension and what would you find?
- Take the BP lying down and standing up repeatedly for 3 minutes
- Orthostatic HOTN → 20mmHg SBP drop or 10mmHg DBP drop
What focal neurological signs might you find on examination in the context of blackout and what diagnoses do these point towards?
- Signs of peripheral neuropathy (e.g. due to DM, chronic alcohol abuse)
- Parkinsonism - associated with autonomic dysfunction - in some cases of orthostatic hypotension
What investigations would you carry out in a typical suspected vasovagal blackout episode (after examination), including bloods?
-
BLOODS
- Capillary blood glucose - exclude hypoglycaemia, check for DM - can lead to polyuria and dehydration or autonomic dysfunction causing HOTN or be a risk factor for CVAs - stroke, TIA - rare cause of blackout
- FBC - Anaemia may be a contributing factor
- U&Es - check for dehydration raised urea : creatinine. Exclude electrolyte abnormalities predisposing to arrythmias
- ECG