From the Guidelines
Positive orthostatic criteria are met when there is a heart rate increase of at least 30 beats per minute (or to ≥120 beats per minute) within 10 minutes of standing from a supine position, in the absence of orthostatic hypotension, and accompanied by symptoms of orthostatic intolerance such as lightheadedness, dizziness, blurred vision, weakness, or syncope. To properly assess for postural orthostatic tachycardia syndrome (POTS), heart rate should be measured after the patient has been lying down for at least 5 minutes, then immediately upon standing, and again at 1,3,5, and 10 minutes after standing 1. The diagnosis of POTS is often characterized by a sustained increase in heart rate of ≥30 bpm within 10 min of moving from a recumbent to a quiet (nonexertional) standing position (or ≥40 bpm in individuals 12–19 y of age) 1. Proper technique is essential, as is ensuring the patient hasn't recently eaten a large meal, exercised, or consumed alcohol, as these factors can influence results. Orthostatic changes can indicate volume depletion, autonomic dysfunction, medication effects, or other underlying conditions requiring further evaluation and management. Some patients with POTS may also experience symptoms such as palpitations, tremor, generalized weakness, exercise intolerance, and fatigue upon standing 1. It is also important to note that POTS can be associated with other conditions, such as deconditioning, recent infections, chronic fatigue syndrome, joint hypermobility syndrome, and a spectrum of non-specific symptoms such as headache and chest pain 1. Therefore, a comprehensive evaluation and management plan should be developed to address the underlying causes and symptoms of POTS.
From the Research
Criteria for Orthostatic Hypotension
The criteria for orthostatic hypotension, as defined in several studies 2, 3, 4, 5, include:
- A decrease in systolic blood pressure of at least 20 mm Hg
- A decrease in diastolic blood pressure of at least 10 mm Hg
- These changes occur within 3 minutes of standing from a supine or seated position
- Alternatively, a head-up tilt of at least 60 degrees can be used to diagnose orthostatic hypotension
Diagnostic Tests
Diagnostic tests for orthostatic hypotension include:
- Bedside simplified Schellong test, which measures blood pressure and heart rate after 5 minutes in the supine position and 3 minutes after standing 4
- Head-up tilt table testing, which can aid in confirming a diagnosis of suspected orthostatic hypotension when standard orthostatic vital signs are nondiagnostic 2, 5
Classification of Orthostatic Hypotension
Orthostatic hypotension can be classified as:
- Neurogenic or nonneurogenic, depending on the etiology and heart rate response 4
- Acute or chronic, as well as symptomatic or asymptomatic 2
Symptoms of Orthostatic Hypotension
Common symptoms of orthostatic hypotension include: