OBJECTIVE The purpose of this study was to identify the time of blood pressure (BP) drop in the orthostatic hypotension test, and to propose a realistic and appropriate duration in the orthostatic hypotension test.

METHODS A total of 879 consecutive patients (61-year-old and 44% women) with positive on the orthostatic hypotension test in the emergency department were retrospectively reviewed. Orthostatic hypotension was defined as drop in standing SBP of at least 20 mmHg or standing DBP of at least 10 mmHg from their supine values after standing for 5 min. BP measurements was made at 1, 3, and 5 min after standing.

RESULTS Six hundred and eighty-four (77.8%), 152 (17.3%) and 43 (4.9%) patients had BP drop meeting orthostatic hypotension criteria at 1, 3, and 5 min, respectively. In multivariable analysis, older age (≥60 years) and higher blood urea nitrogen (BUN) (≥15.5 mg/dl) were independently associated with early BP drop at 1 min, and younger age (<40 years) was independently associated with later BP drop at 5 min even after controlling for potential confounders.

CONCLUSION To measure orthostatic BP for orthostatic hypotension diagnosis at emergency department, older patients (≥60 years) with high BUN (≥15.5 mg/dl) should be monitored carefully as BP can drop quickly within 1 min. On the contrary, in younger people (<40 years), BP drop occurred slowly after 3 min, suggesting that clinicians measure BP for a longer time.