Reproducibility of orthostatic changes in cerebral oxygenation in healthy subjects aged 70 years or older

In the elderly, standing can frequently be accompanied by blood pressure (B P) changes and cerebral symptoms such as dizziness, fall, or even syncope, but this may vary from day-to-day. Therefore, we aimed to investigate the r eproducibility of orthostatic responses of cerebral cortical oxygenation an d systemic haemodynamics in elderly subjects. In 27 healthy elderly subject s (age 70-84 years), changes in systolic BP (SBP), diastolic BP (DBP), hear t rate (HR) and stroke volume (SV) were continuously monitored by Finapres (Finger Arterial Pressure), and changes in oxyhaemoglobin ([O(2)Hb]) and de oxyhaemoglobin ([HHb]) concentrations were continuously measured over the r ight frontal cortex by near infrared spectroscopy (NIRS) during supine rest and 10 min of active standing on two separate occasions. SBP and DBP incre ased by 6.7 +/- 15.4 mmHg (P <0.05, mean +/- SD) and 8.2 +/- 6.4 mmHg (P <0 .01), respectively, whereas HR increased by 9.5 +/- 5.0 bpm (P <0.01) and S V decreased by -8.3 +/- 7.4 ml (P <0.01) during standing on the first occas ion. [O(2)Hb] decreased by -3.9 +/- 2.9 mu mol l(-1) (P <0.01), while [HHb] increased by 1.8 +/- 2.2 mu mol l(-1) (P <0.01). Group-averaged orthostati c changes in cortical oxygenation and systemic haemodynamics were very simi lar on the two occasions, although an intraindividual variation was found. Cortical oxygenation changes were not accompanied by severe cerebral sympto ms. Active standing induced reproducible group-averaged frontal cortical ox ygenation declines in healthy elderly subjects, although an intraindividual day-to-day variability was present, possibly related to the variability of orthostatic BP responses. These findings indicate that cerebral autoregula tion fails to compensate completely for postural changes in elderly subject s, which might predispose elderly subjects to ischaemic cerebral symptoms.