Orthostatic/Postural hypotension (Complete) Flashcards
Define postural hyoptension.
Fall in systolic blood pressure of at least 20 mmHg (at least 30 mmHg in patients with hypertension) or a fall in diastolic blood pressure of at least 10 mmHg within 3 minutes of standing
What is the aetiology around postural hypotension?
Occurs due to decreased autonomic buffering capacity. (E.g. age, medication, peripheral neuropathy)
Why is postural hypotension more common in older people?
With age there is decreased autonomic buffering capacity.
Therefore if on medication which dampens autonomic response, increases the likelihood of a postural hyptensive episode.
What are the main risk factors for psotural hypotension? (7)
Frailty and prolonged physical deconditioning (e.g. bed rest)
Medications (e.g. diuretics, calcium channel blockers, alpha blockers, anti-hypertensives)
Diabetes melitus (Due to peripheral neuropathy)
Parkinsons disease
Dementia with lewy bodies
Volume depletion
Anaemia
Paraneoplastic syndromes (can cause subacute presentations due to effect on autonomic system)
Cardiac causes: E.g. myocardial infarction, aortic stenosis
What medications can cause postural hypotension? (6)
Diuretics
Alpha-adrenoceptor blockers (for prostatic hypertrophy)
Antihypertensive drugs (e.g. ACE, ARB, CCB, Thiazide diuretics)
Insulin
Levodopa
Tricyclic antidepressants
What are the main characteristics of postural hypotension?
Postural light-headedness (occurs when standing and better when sitting or lying down)
Syncope (due to cerbral hypoperfusion)
Symptoms of cerebral hypoperfusion: Visual changes, weakness, fatigue, trouble concentrating, nausea)
Increased ventilation and dyspnoea
What exacerbating factors can worsen postural hypotension? (9)
Rising quickly after prolonged sitting
Prolonged motionless standing
Time of day (early morning after nocturnal diuresis)
Dehydration
Physical exertion
Alcohol intake
Carbohydrate-heavy meals
Straining during micturition or defecation
Fever
What investigation can be performed to confirm postural hypotension?
Posture test: SBP >20 mmHg (>30 mmHg in patients with hypertension) DBP falls >10 mmHg within 3 minutes of standing upright;
What investigations should be considered in patients with postural hypotension to determine possible causes? (3)
Chest CT: If paraneoplastic syndrome suspected
Nerve conduction studies (EMG): Diabetes and other peripheral neuropathic causes.
ECG: RR variablity suggests some degree of autonomic dysfunction, MI and signs of aortic stenosis (Left ventricular hypertrophy)
What is the management plan for postural hypotension? (5)
Avoidance of aggravating factors such as:
Avoidance of high-risk situations: E.g. getting up too quickly, prolonged standing, hot environments, large meals.
Counter-manoeuvres: e.g. Toe raising, leg elevation and leg crossing.
Keeping the head of the bed elevated (reverse Trendelenburg)
Increased salt and water intake
Consider stopping potential exacerbating medications
Medicine:
Midodrine (Alpha-adrenergic agonists)
Fludrocortisone (Corticosteroid)
What pharmacological treatment options should be considered for postural hypotension if patients have not responded well to non-phramacological measures? (3)
Fludrocortisone (Mineralocorticoid that expands plasma volume)
Midodrine (Short-acting vassopresor) [useful if neurogenic cause but ineffective if low plasma volume]
Pyridostigmine (acetylcholinesterase inhibitor)
Why is it important that postural hypotension is treated immediately?
Greatly increases the risk of falls especially in elderly.
What are the two main complications of postural hypotension?
Falls
Supine hypertension (can lead to end-organ failure)
What other differentials should be considered in patients with postural hypotension? (4)
Vertigo
Psychogenic syncope
Vasovagal syncope
Non-specific falls in older people
How does vertigo differ in comparison to postural hypotension?
Related to changes in head and neck positioning.
Pre-syncope and syncope unlikely
Neurological examination reveals cerebellar ataxia or nystagmus.
