Positive orthostatic vital signs are defined by which change in blood pressure?

• A. Oxygen saturation decreases to 90%
• B. Temperature rises by 1 degree
• C. Systolic BP drops by at least 20 mmHg or diastolic BP drops by at least 10 mmHg
• D. Heart rate increases by 30 bpm

Answer: (C)

The key concept here is how orthostatic vital signs are defined by blood pressure changes when a person moves from lying down to standing. When you stand, gravity causes blood to pool in the legs, and the body normally compensates by increasing heart rate and constricting blood vessels to keep blood pressure steady. If the compensatory mechanism isn’t enough, blood pressure drops.

A positive result is defined by a drop in blood pressure after standing: a systolic decrease of at least 20 mmHg or a diastolic decrease of at least 10 mmHg within about 3 minutes of standing. This threshold identifies orthostatic hypotension and helps confirm that standing causes a meaningful BP decline.

Oxygen saturation dropping to 90% isn’t related to the BP change involved in orthostatic testing. A temperature rise isn’t relevant to this measurement either. An increased heart rate can occur as the body tries to compensate, but it doesn’t define the orthostatic BP change by itself; the diagnosis relies on the specified blood pressure drops.