Continuous measurement of cerebral blood flow velocity using transcranial Doppler reveals significant moment-to-moment variability of data in healthy volunteers and in patients with subarachnoid hemorrhage*

Cerebrovascular dysfunction occurs early in dementia and can be identified by transcranial Doppler ultrasonography (TCD). Few studies have examined cerebral blood flow velocity (CBFv) responses to a detailed cognitive battery. This study aimed to characterize all CBFv responses, and the effect of hemispheric dominance, to the Addenbrooke’s Cognitive Examination (ACE-III) in healthy volunteers. Forty volunteers underwent continuous bilateral TCD, beat-to-beat blood pressure (MAP; Finapres), heart rate (HR; electrocardiogram), and end-tidal CO2 (ETCO2; capnography) monitoring. After a 5-min baseline period, all tasks from the ACE-III were performed in 3 sections (A: attention, fluency, memory; B: language; C: visuospatial, memory). Data are population mean normalized percentage (PM%) change from a 20-s baseline period before task initiation. Forty bilateral data sets were obtained (27 women, 37 right-hand dominant). All paradigms produced a sharp increase in CBFv in both dominant (PM% range: 3.29 to 9.70%) and nondominant (PM% range: 4.34 to 11.63%) hemispheres at task initiation, with associated increases in MAP (PM% range: 3.06 to 16.04%). ETCO2 did not differ significantly at task initiation (PM% range: −1.1 to 2.4%, P > 0.05). HR differed significantly across A and C tasks at initiation (PM% range: −1.1 to 2.4%, P < 0.05), but not B tasks. In conclusion, all tasks resulted in increases in CBFv, differing significantly between paradigms. These results require further investigation in a cognitively impaired population. NEW & NOTEWORTHY This study is the first to provide a normative data set of cerebral blood flow velocity (CBFv) responses to a complete cognitive assessment (Addenbrooke’s Cognitive Examination, ACE-III) in a large sample ( n = 40) of healthy volunteers. All tasks produced peak and sustained increases in CBFv to different extents. The ACE-III is a feasible tool to assess neurovascular coupling with transcranial Doppler ultrasonography. These data can be used to inform the most appropriate cognitive task to elicit CBFv responses for future studies.

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Association of transcranial Doppler blood flow velocity slow waves with delayed cerebral ischemia in patients suffering from subarachnoid hemorrhage: a retrospective study

Intensive Care Medicine Experimental ◽

10.1186/s40635-021-00378-8 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Vasilios E. Papaioannou ◽

Karol P. Budohoski ◽

Michal M. Placek ◽

Zofia Czosnyka ◽

Peter Smielewski ◽

...

Keyword(s):

Blood Flow ◽

Subarachnoid Hemorrhage ◽

Cerebral Ischemia ◽

Flow Velocity ◽

Transcranial Doppler ◽

Blood Flow Velocity ◽

Cerebral Blood Flow Velocity ◽

Delayed Cerebral Ischemia ◽

Area Under The Curve ◽

Slow Waves

Abstract Background Cerebral vasospasm (VS) and delayed cerebral ischemia (DCI) constitute major complications following subarachnoid hemorrhage (SAH). A few studies have examined the relationship between different indices of cerebrovascular dynamics with the occurrence of VS. However, their potential association with the development of DCI remains elusive. In this study, we investigated the pattern of changes of different transcranial Doppler (TCD)-derived indices of cerebrovascular dynamics during vasospasm in patients suffering from subarachnoid hemorrhage, dichotomized by the presence of delayed cerebral ischemia. Methods A retrospective analysis was performed using recordings from 32 SAH patients, diagnosed with VS. Patients were divided in two groups, depending on development of DCI. Magnitude of slow waves (SWs) of cerebral blood flow velocity (CBFV) was measured. Cerebral autoregulation was estimated using the moving correlation coefficient Mxa. Cerebral arterial time constant (tau) was expressed as the product of resistance and compliance. Complexity of CBFV was estimated through measurement of sample entropy (SampEn). Results In the whole population (N = 32), magnitude of SWs of ipsilateral to VS side CBFV was higher during vasospasm (4.15 ± 1.55 vs before: 2.86 ± 1.21 cm/s, p < 0.001). Ipsilateral SWs of CBFV before VS had higher magnitude in DCI group (N = 19, p < 0.001) and were strongly predictive of DCI, with area under the curve (AUC) = 0.745 (p = 0.02). Vasospasm caused a non-significant shortening of ipsilateral values of tau and increase in SampEn in all patients related to pre-VS measurements, as well as an insignificant increase of Mxa in DCI related to non-DCI group (N = 13). Conclusions In patients suffering from subarachnoid hemorrhage, TCD-detected VS was associated with higher ipsilateral CBFV SWs, related to pre-VS measurements. Higher CBFV SWs before VS were significantly predictive of delayed cerebral ischemia.

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