Signal-to-noise ratio of bilateral nonimaging transcranial Doppler recordings of the middle cerebral artery is not affected by age and sex.

Differences between transcranial Doppler ultrasonography (TCD) recordings of symmetrical vessels can show true physiologic differences, but can also be caused by measurement error and other sources of noise. The aim of this project was to assess the influence of noise on estimates of dynamic cerebral autoregulation (dCA), and of age, sex and breathing manoeuvres on the signal-to-noise ratio (SNR). Cerebral blood flow (CBF) was monitored in 30 young (<40 years) and 30 older volunteers (age >60 years) during baseline conditions, breath-holding and hyperventilation.

Dynamic cerebral autoregulation is compromised acutely following mild ischaemic stroke but not transient ischaemic attack.

Background: Dynamic cerebral autoregulation (dCA), the process by which the cerebral blood flow (CBF) is normally maintained relatively constant despite fluctuations in beat-to-beat blood pressure (BP), is impaired acutely following major ischaemic stroke. It is uncertain if dCA is impaired acutely after mild ischaemic stroke or transient ischaemic attack (TIA). We assessed dCA in patients acutely and sub-acutely following TIA or mild ischaemic stroke.

Long-term changes in dynamic cerebral autoregulation: a 10 years follow up study.

This study takes a novel approach to describing time-related changes in dynamic cerebral autoregulation (dCA). It is well-recognized that dCA exhibits both intra- and inter- subject variability, and this study seeks to characterize the extent to which intra-subject variability occurs after a significant period of time by studying the same subjects 10 years apart, thus eliminating inter-subject variability as a source of error. Ten healthy subjects were identified in 1998 and followed up in 2008.

Reliability of dynamic cerebral autoregulation measurement using spontaneous fluctuations in blood pressure.

Spontaneous fluctuations in BP (blood pressure) and subsequent change in CBFV (cerebral blood flow velocity) in the MCA (middle cerebral artery) can be used to assess dynamic cerebral autoregulation using transfer function analysis; however, the reliability of this technique has not been assessed, in particular the contribution of intra-subject variability relative to inter-subject variability. Three bilateral CBFV, BP and RR interval recordings were performed in ten healthy volunteers on four separate occasions over a 2-week period. Data were analysed to provide the ARI (autoregulatory index), CBFV, RAP (resistance-area product) and CrCP (critical closing pressure).

Factors influencing white-coat effect.

Background: The transient blood pressure (BP) rise during clinical visits is usually referred to as white-coat effect (WCE). The aim of the present study was to investigate factors that may influence the WCE.

Methods: A total of 2004 subjects underwent office BP measurements and 24-h ambulatory BP monitoring (ABPM) on the same day.