Reproducibility of cerebral and peripheral haemodynamic responses to active, passive and motor imagery paradigms in older healthy volunteers: a fTCD study.

Cerebral blood flow velocity (CBFv) changes to sensorimotor and cognitive paradigms have been used to assess the integrity of haemodynamic responses, though the reproducibility of these responses has not been properly assessed. Continuous recordings of blood pressure, end-tidal CO(2), heart rate and bilateral CBFv were obtained during 60s of active, passive and mental imagined paradigms on two different occasions over a 1-week period in 13 healthy subjects. The correlation coefficient, standard error of measurement (SEM), intra-class correlation (ICC) and its 95% CI (confidence intervals) for each variable were calculated at the beginning and end of each paradigm. The temporal patterns of haemodynamic responses revealed substantial reproducibility. For the CBFv response, the SEM ranged from 2.4 to 5.5% for the different manoeuvres, whilst the ICC ranged from 0.5 to 0.8 with better reproducibility occurring at the beginning of the paradigm. These findings have important implications for the design of studies of the natural history of haemodynamic changes following ageing and disease.