What defines a positive orthostatic test?

Definition of Positive Orthostatic Test

A positive orthostatic test is defined as a sustained decrease in systolic blood pressure ≥20 mmHg, diastolic blood pressure ≥10 mmHg, or a 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, 2

Diagnostic Criteria

• The European Society of Cardiology defines positive orthostatic vitals as a sustained decrease in systolic blood pressure ≥20 mmHg, diastolic blood pressure ≥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
• In patients with supine hypertension, a more stringent criterion applies - a systolic BP drop ≥30 mmHg should be considered positive 1
• The test should be performed after the patient has been lying supine for 5 minutes, followed by measurements after 1 or 3 minutes of standing 2

Testing Methodology

• Sphygmomanometer (standard blood pressure cuff) is adequate for routine clinical testing due to its ubiquity and simplicity 3
• Blood pressure should be measured after 5 minutes of lying supine, then continued after standing for 3 minutes 1, 2
• Continuous beat-to-beat non-invasive pressure measurement may be helpful in cases of doubt, particularly for detecting initial orthostatic hypotension 3, 1
• When using a sphygmomanometer, no more than four measurements per minute can be obtained without causing venous obstruction in the arm 3

Special Considerations

• In patients aged 12-19 years with Postural Orthostatic Tachycardia Syndrome (POTS), a heart rate increase of >40 beats per minute is considered positive 1
• For adults with POTS, an inappropriate heart rate increase (>30 beats per minute or >120 beats per minute within 10 minutes of standing) without concomitant BP fall is diagnostic 1
• The reproducibility of orthostatic blood pressure drops is an important consideration in diagnosis 4
• Symptoms depend more on the absolute BP level reached than the magnitude of the fall 1

Clinical Significance

• Orthostatic hypotension is associated with increased mortality, cardiovascular disease prevalence, and falls 1, 2
• The prevalence of orthostatic hypotension in community settings is approximately 20% in older adults and 5% in middle-aged adults 5
• Orthostatic hypotension is associated with up to a 50% increase in relative risk of all-cause mortality 5

Common Pitfalls in Diagnosis

• Using seated rather than supine position as baseline can produce smaller depressor responses due to reduced gravitational stress 6
• Automatic arm-cuff devices may be disadvantageous for orthostatic testing as they are programmed to repeat and confirm measurements when discrepant values are recorded, which can delay readings during rapidly falling BP 3
• Although interval BP measurement devices are more commonly used in daily practice, they show low concordance with continuous BP measurement devices, resulting in low positive and negative proportions of agreement in the diagnosis of orthostatic hypotension 7
• Heart rate responses to standing should be concomitantly measured to assess integrity of baroreflex function and help distinguish neurogenic from non-neurogenic causes 6