Orthostatic Hypotension

Orthostatic hypotension is a sustained fall in blood pressure within 3 minutes of standing (or head up tilt to at least 60 degrees) because the compensatory rise in vascular tone and heart rate is inadequate or the circulating volume is depleted. It is common in older adults and is a frequent cause of falls, syncope and fractures in primary care.

• Definition: a fall of at least 20 mmHg systolic or at least 10 mmHg diastolic within 3 minutes of standing. In patients with supine hypertension, a fall of at least 30 mmHg systolic is often used.
• Delayed (onset after 3 minutes, whereas classical onset is within 3 minutes) forms occur in early autonomic failure.
• Mechanisms: volume depletion (haemorrhage, diarrhoea, vomiting, poor intake, diuretics, adrenal insufficiency); drugs (alpha blockers, diuretics, nitrates, antihypertensives, tricyclics, antipsychotics, levodopa, dopamine agonists, sildenafil, tamsulosin, alcohol); neurogenic autonomic failure (diabetes, Parkinson disease, multiple system atrophy, pure autonomic failure, amyloidosis, alcohol neuropathy, B12 deficiency); venous pooling (varicose veins, prolonged bed rest, pregnancy); cardiac causes (severe aortic stenosis, bradyarrhythmia, heart failure).
• Risk factors: age over 65, diabetes, Parkinson disease, polypharmacy, prolonged recumbency, dehydration.

• Light headedness, dizziness, visual blurring or greying out, weakness and unsteadiness on standing, relieved by sitting or lying.
• Syncope or presyncope, falls, "coat hanger" neck and shoulder pain (trapezius ischaemia), dyspnoea or angina on standing.
• Symptoms worse in the morning, after meals, after hot baths, with exertion and with prolonged standing.
• Neurogenic type: no compensatory rise in pulse (heart rate rise less than 0.5 beats per minute per mmHg fall in systolic pressure), supine hypertension, nocturia, anhidrosis, constipation, erectile dysfunction, urinary retention.
• Non-neurogenic (volume or drug related): heart rate rises by more than 15 beats per minute on standing.
• Examination: dry mucosa and reduced skin turgor if volume depleted, tremor or rigidity (parkinsonism), peripheral neuropathy, cardiac murmur.
• Red flags: syncope with chest pain or palpitations, focal neurology, melaena or other bleeding, abdominal pain with shock, recurrent falls with injury.

• Lie the patient supine for 5 minutes, record blood pressure and pulse, then repeat at 1 and 3 minutes of standing (and at 5 minutes if delayed onset is suspected). Use the same arm at heart level.
• Full medication review including over-the-counter and herbal products.
• Bedside tests: random glucose, haemoglobin, urea and electrolytes, creatinine, sodium, potassium, calcium, HbA1c, thyroid function, vitamin B12 and folate.
• ECG in all; ambulatory ECG if palpitations, bradycardia or syncope without clear postural trigger.
• Early morning cortisol or short synacthen test if hyponatraemia, hyperkalaemia, pigmentation or weight loss.
• Referral for tilt table or autonomic function testing when diagnosis is unclear or neurogenic disease is suspected. Echocardiography for murmurs.
• Differentials: vasovagal syncope, arrhythmia, aortic stenosis, hypovolaemia, adrenal insufficiency, postural orthostatic tachycardia syndrome, cerebrovascular disease.

Non-pharmacological (first line for everyone)

• Stop or reduce culprit drugs where safe: for example substitute a thiazide with a lower dose, change tamsulosin to bedtime dosing, withdraw nitrates or alpha blockers if possible.
• Correct volume depletion: oral rehydration, 1.5 to 2.5 litres of fluid daily (unless heart failure or renal limitation), and a cold water bolus of 500 mL taken over 5 minutes before rising can raise standing pressure for about an hour.
• Increase dietary salt to 6 to 10 g daily if there is no hypertension, heart failure or renal disease.
• Rise slowly in stages (sit for 1 to 2 minutes before standing), avoid hot baths, large carbohydrate meals and straining.
• Physical counter manoeuvres: leg crossing, squatting, buttock clenching, calf pumping.
• Waist high compression stockings or abdominal binder (20 to 40 mmHg), worn on rising and removed at night.
• Raise the head of the bed by 10 to 20 degrees (about 15 to 30 cm) to reduce supine hypertension and nocturnal diuresis.
• Avoid alcohol, and graded exercise training (recumbent exercise or swimming).

Pharmacological (persistent symptoms despite these measures, in primary care usually initiated with specialist advice)

• Fludrocortisone 0.05 to 0.1 mg orally once daily in the morning, titrated by 0.05 to 0.1 mg every 1 to 2 weeks to a maximum of 0.3 mg daily. Monitor for supine hypertension, hypokalaemia, oedema and heart failure. Check potassium and blood pressure at 1 to 2 weeks, then every 3 months. Avoid in heart failure or severe renal impairment.
• Midodrine 2.5 mg orally three times daily (morning, midday and mid-afternoon, last dose at least 4 hours before bedtime), increased by 2.5 mg per dose weekly to a usual 10 mg three times daily. Caution in urinary retention, severe cardiac disease and supine hypertension; monitor blood pressure supine and standing.
• Droxidopa 100 mg orally three times daily, titrated every 24 to 48 hours up to 600 mg three times daily (specialist use only).
• Pyridostigmine 30 to 60 mg orally two or three times daily is an option for mild neurogenic disease with less supine hypertension.
• Treat supine hypertension in neurogenic cases cautiously with short acting agents at night, for example losartan 25 to 50 mg or a glyceryl trinitrate patch 0.1 mg per hour at bedtime and removed in the morning.

Special groups

• Older adults: start low, proceed slowly, review for falls risk, vitamin D and bone health.
• Diabetes: improve glycaemic control but avoid hypoglycaemia; review antihypertensives.
• Parkinson disease: review levodopa and dopamine agonist dosing.
• Pregnancy: left lateral position, fluids, compression stockings. Avoid midodrine and fludrocortisone unless specialist advised.

Follow up and referral

• Recheck lying and standing pressure at 2 to 4 weeks after every medicine change, then 3 monthly.
• Refer if syncope, injurious falls, suspected autonomic failure, no response to first line measures, or severe supine hypertension.