Definition of Orthostatic Hypotension
Orthostatic hypotension is defined as a sustained decrease in systolic blood pressure ≥20 mmHg and/or diastolic blood pressure ≥10 mmHg within 3 minutes of standing from a supine position. 1
Types of Orthostatic Hypotension
Orthostatic hypotension can be classified into three main types:
Classical orthostatic hypotension: A sustained decrease in systolic BP ≥20 mmHg and/or diastolic BP ≥10 mmHg within 3 minutes of standing, or a sustained decrease in systolic BP to an absolute value <90 mmHg 1
Initial (immediate) orthostatic hypotension: A BP decrease >40 mmHg systolic and/or >20 mmHg diastolic within 15 seconds of standing, with spontaneous return to normal within 40 seconds 1
Delayed orthostatic hypotension: A sustained reduction of systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg that takes >3 minutes of upright posture to develop 1
Diagnostic Measurement Protocol
For accurate diagnosis of orthostatic hypotension, blood pressure should be measured using the following protocol:
- Measure BP after 5 minutes in the supine position
- Measure BP at 1 minute after standing
- Measure BP at 3 minutes after standing
- Record both BP and heart rate at each measurement point 1
Important Diagnostic Considerations
- Extended monitoring beyond the standard 3-minute period may be necessary to detect delayed orthostatic hypotension, which is common in conditions like Parkinson's disease 1
- Some guidelines consider a fall in systolic blood pressure of 30 mmHg as significant for orthostatic hypotension diagnosis, particularly in patients with supine hypertension 1
- Key diagnostic pitfalls include not monitoring long enough to detect delayed OH, failing to account for supine hypertension, and not considering the absolute BP level 1
Clinical Significance
Orthostatic hypotension is associated with:
- Increased all-cause mortality (up to 50% increase in relative risk) 2
- Increased cardiovascular disease prevalence 1
- Higher risk of falls and syncope 2
Orthostatic hypotension is particularly prevalent in:
- 20% of older adults in community settings
- 5% of middle-aged adults
- Higher percentages in those with conditions like diabetes mellitus 2
Understanding the precise definition and proper diagnostic technique for orthostatic hypotension is essential for accurate diagnosis and effective management of this condition, which significantly impacts morbidity, mortality, and quality of life.