What is orthostatic (postural) hypotension?

From the Guidelines

Orthostatic hypotension is a condition characterized by a sustained decrease in systolic blood pressure of >20 mmHg, diastolic blood pressure of >10 mmHg, or a sustained decrease in systolic blood pressure to an absolute value <90 mmHg within 3 minutes of active standing or head-up tilt of at least 60 degrees, often causing symptoms such as dizziness, lightheadedness, and fainting. This condition occurs when the body fails to adequately compensate for gravity's effects on blood flow, leading to insufficient blood reaching the brain temporarily 1. The pathophysiology of orthostatic hypotension involves impaired increase in total peripheral resistance and heart rate in autonomic failure, resulting in pooling of blood in the lower extremities 1.

Types of Orthostatic Hypotension

There are different types of orthostatic hypotension, including:

• Initial OH: characterized by a BP decrease on standing of >40 mmHg for systolic BP and/or >20 mmHg for diastolic BP within 15 seconds of standing 1
• Classical OH: defined as a sustained decrease in systolic BP >20 mmHg, diastolic BP >10 mmHg, or a sustained decrease in systolic BP to an absolute value <90 mmHg within 3 minutes of active standing or head-up tilt of at least 60 degrees 1
• Delayed OH: defined as OH occurring beyond 3 minutes of head-up tilt or active standing, characterized by a slow progressive decrease in BP 1

Symptoms and Associated Conditions

Symptoms of orthostatic hypotension include dizziness, lightheadedness, fatigue, weakness, visual and hearing disturbances, and sometimes fainting 1. This condition is associated with increased mortality and cardiovascular disease prevalence, and is often seen in patients with frailty, autonomic failure, hypovolaemia, and those taking certain medications such as alpha-blockers, diuretics, and vasoactive drugs 1.

Management

Management of orthostatic hypotension includes simple measures like rising slowly from seated or lying positions, staying well-hydrated, avoiding alcohol, wearing compression stockings, and increasing salt intake if appropriate 1. For persistent cases, medications such as fludrocortisone or midodrine may be prescribed to help retain sodium and increase blood volume or directly constrict blood vessels to maintain pressure 1.

From the FDA Drug Label

INDICATIONS AND USAGE Midodrine hydrochloride tablets are indicated for the treatment of symptomatic orthostatic hypotension (OH) CLINICAL PHARMACOLOGY Mechanism of Action: Midodrine forms an active metabolite, desglymidodrine, that is an alpha1-agonist, and exerts its actions via activation of the alpha-adrenergic receptors of the arteriolar and venous vasculature, producing an increase in vascular tone and elevation of blood pressure. Administration of midodrine results in a rise in standing, sitting, and supine systolic and diastolic blood pressure in patients with orthostatic hypotension of various etiologies

Orthostatic (postural) hypotension is a condition characterized by a significant drop in blood pressure when standing up, resulting in symptoms such as dizziness, lightheadedness, and unsteadiness. It is not explicitly defined in the provided drug labels, but it is described as a condition where there is a supine-to-standing fall of systolic blood pressure of at least 15 mmHg accompanied by at least moderate dizziness/lightheadedness 2 2.

From the Research

Definition of Orthostatic Hypotension

• Orthostatic hypotension is defined as a decrease in blood pressure of 20 mm Hg or more systolic or 10 mm Hg or more diastolic within three minutes of standing from the supine position or on assuming a head-up position of at least 60 degrees during tilt table testing 3, 4, 5.
• This condition can be symptomatic or asymptomatic, and its prevalence varies with age, ranging from 5% in patients <50 years of age to 30% in those >70 years of age 6.

Symptoms and Risk Factors

• Symptoms of orthostatic hypotension include headache, lightheadedness, shoulder and neck pain (coat hanger syndrome), visual disturbances, dyspnea, and chest pain 3.
• Risk factors such as diabetes mellitus increase the prevalence of orthostatic hypotension in all age groups 3.
• Orthostatic hypotension is associated with a significant increase in cardiovascular risk and falls, and up to a 50% increase in relative risk of all-cause mortality 3.

Diagnosis and Classification

• Diagnosis is confirmed by performing a bedside simplified Schellong test, which consists of blood pressure and heart rate measurements after five minutes in the supine position and three minutes after moving to a standing position 3.
• Orthostatic hypotension is classified as neurogenic or nonneurogenic, depending on etiology and heart rate response 3.

Treatment and Management

• Treatment goals for orthostatic hypotension are reducing symptoms and improving quality of life 3, 4.
• Initial treatment focuses on the underlying cause and adjusting potentially causative medications 3, 5.
• Nonpharmacologic strategies include dietary modifications, compression garments, physical maneuvers, and avoiding environments that exacerbate symptoms 3, 7.
• First-line medications include midodrine and droxidopa, while fludrocortisone may also be used, although it has concerning long-term effects 3, 4, 7.