Objectives: To explore the association of early symptoms of orthostatic intolerance (OI) with systolic (SBP), diastolic (DBP) and mean arterial (MAP) blood pressure changes in a sample of community-dwelling older people undergoing an active stand test; and to establish whether SBP and DBP changes have different symptomatic correlates during early orthostasis.
Methods: A total of 224 community-dwelling older subjects (mean age 72.6 years, 68.8% females) were included. All had a Mini-Mental State Examination score >or=23 and no risk factors for autonomic neuropathy. Subjects were monitored with the Finometer Pro device. Variables reflecting blood pressure changes (absolute low: nadir, magnitude of drop: delta, and speed of recovery) were extracted for SBP, DBP and MAP with the BeatScope software (5-s averages method), and correlated with self-reported OI during active stand.
Results: Of the 224 subjects, 62 (27.7%) reported OI. SBP changes had strong bivariate associations with OI, but not DBP changes. A logistic regression model suggested that the rate of recovery of SBP during the first 30 s following active stand is more important as a determinant of OI than SBP nadir or delta. Subjects who recovered at least 80% of their baseline SBP within 30 s post-stand were very unlikely to report OI.
Interpretation: Our study suggests that orthostatic SBP changes may be more important than DBP changes as determinants of early OI during active stand. The crucial importance of the quick recovery of SBP in order to avoid OI is biologically plausible and is discussed in the context of initial OH pathophysiology.