Short term Heart Rate Variability to predict blood pressure drops due to standing: a pilot study.

BACKGROUND: Standing from a bed or chair may cause a significant lowering of blood pressure (DeltaBP), which may have severe consequences such as, for example, falls in older subjects. The goal of this study was to develop a mathematical model to predict the DeltaBP due to standing in healthy subjects, based on their Heart Rate Variability, recorded in the 5 minutes before standing. METHODS: Heart Rate Variability was extracted from an electrocardiogram, recorded from 10 healthy subjects during the 5 minutes before standing. The blood pressure value was measured before and after rising. A mathematical model aiming to predict DeltaBP based on Heart Rate Variability measurements was developed using a robust multi-linear regression and was validated with the leave-one-subject-out cross-validation technique. RESULTS: The model predicted correctly the DeltaBP in 80% of experiments, with an error below the measurement error of sphygmomanometer digital devices (+/- 4.5 mmHg), a false negative rate of 7.5% and a false positive rate of 10%. The magnitude of the DeltaBP was associated with a depressed and less chaotic Heart Rate Variability pattern. CONCLUSIONS: The present study showes that blood pressure lowering due to standing can be predicted by monitoring the Heart Rate Variability in the 5 minutes before standing.