Unique cutpoints for sitting-to-standing orthostatic vital signs

The study objective was to describe the distribution of normal changes in vital signs related to moving from a sitting to a standing position. Subjects were free of cardiovascular disease and determined to be euvolemic by structured interview. Vital signs were measured after a minimum of 5 minutes of sitting and after 1 minute of standing. Among 176 subjects, mean differences in parameters (± standard deviation) were as follows: pulse increase, 5.3 ± 6.6 beats per minute (bpm); systolic blood pressure (SBP) decrease, 1.2 ± 9.8 mmHg; and shock index (SI) increase, 0.05 ± 0.07 bpm/mmHg. These changes are less extreme than those previously published for changes from lying to standing. Unique tilt test positivity criteria and their expected specificities are as follows: pulse increase ≥20 bpm (0.98), SBP decrease ≥20 mmHg (0.97), SI increase ≥0.2 (0.99), ROSI ≥1.3 (0.95). Sitting-to-standing tilt tests require positivity criteria distinct from those published for lying-to-standing tilt tests.