Orthostatic Postural Hypotension

A symptomatic fall in BP on standing common in elderly, check drugs first. The definition is a systolic drop of > 20 mmHg but it does depend on from where and what to e.g. 200mmHg to 180mmHg is not quite the same as 100mmHg to 80 mmHg

About

• Not uncommon in elderly and cause often not found

Physiology of standing

• There is pooling of 1 L of blood in leg veins
• Transient fall in venous return reduces CO and BP
• Aortic arch baroreceptors activate autonomic reflexes
• Sudden increased sympathetic tone and HR and contractility
• Increased tone of capacitance vessels
• Parasympathetic (vagal) inhibition also increases heart rate
• Standing activates RAA system and ADH release with salt and water retention

Causes

• Peripheral / Autonomic - diabetes, amyloid, nutritional
• Parkinson disease, Multiple systems atrophy
• Drugs and Polypharmacy e.g. antihypertensives, GTN, diuretics, L Dopa, antidepressants, Viagra
• Dehydration, Addison's, Overdiuresis, Post dialysis, Idiopathic

Clinical

• Lightheadedness, weakness, blurred vision
• Syncope and presyncope and falls

Investigations

• Bloods: FBC U&E, Ca
• 24 hr tape: no Brady/tachyarrhythmias or POTS
• Implantable loop recorder for some
• Short Synacthen in some
• Echo: Exclude obstructive disease e.g AS or HOCM
• Tilt table may be needed - see TLOC

Management

• Stop causative or contributory drugs. It is very common in the elderly. Due to decreased baroreceptor sensitivity.
• Stop or reduce diuretics, CCB, alpha-blockers, dehydration, beta-blockers, vasodilators, anti-parkinsonian drugs, sedatives, neuroleptics.
• Consider TED stockings, Head-up tilt at night
• Increased salt intake and Fludrocortisone 100-200 mcg given at night but can cause low potassium and fluid retention
• Midodrine 2.5-10 mg TDS usual maintenance 10 mg TDS, avoid administration at night; the last daily dose should be taken at least 4 hours before bedtime
• Pendant alarm for assistance after fall can help. In severe cases, avoidance of walking and wheelchair use may help. Each case needs an individualized plan.

References