Does gradual change in head positioning affect cerebrovascular physiology?

Lam, Man Y.; Haunton, Victoria J.; Robinson, Thompson G.; Panerai, Ronney B.

doi:10.14814/phy2.13603

Cited by 16 publications

(23 citation statements)

References 56 publications

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“…Assessments for AIS patients were taken in three separate visits, for up to three months post-stroke symptom onset. 'Visit 1' took place straight after admission into the hospital (acute: within 24 h of symptom onset), 'visit 2' was within 7 days ± 24 h post-stroke onset (sub-acute), and 'visit 3' was 3 months ± 7 days post-stroke onset (chronic) [18]. Data obtained from the 5-min assessments in the HP down and the 5-min assessments in the HP up were analysed and compared.…”

Section: Resultsmentioning

confidence: 99%

“…A small number of AIS patients were unable to participate in subsequent visits, due to inpatient transfer for ongoing rehabilitation at another hospital. Eighteen healthy control subjects were recruited, but two were excluded from the study due to poor insonation of their temporal windows [18]. Data from 16 (8 women) remaining healthy control participants (age of 57 ± 16 years) were analysed.…”

Section: Resultsmentioning

confidence: 99%

“…Over a 30-s time period, the angle of the bed was returned to an HP down , where another 2-min recording was performed. This protocol (timing and degree of head position change) was validated through pilot work [18], demonstrating reproducibility of key parameters before, during and after head position changes. Mean values of all cerebral and peripheral haemodynamic variables, lasting a minimum of 30 s were extracted.…”

Section: Methodsmentioning

confidence: 98%

“…The assessments were carried out by a trained TCD operator (MYL) with more than 5 years experience. The reproducibility of GHP changes on cerebral haemodynamic parameters (healthy controls) [18] and comparisons between AIS patients and healthy controls in rapid head positioning changes [19], were carried out by the same research group and helped inform the design of this analysis.…”

Section: Methodsmentioning

confidence: 99%

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The Effects of Gradual Change in Head Positioning on the Relationship between Systemic and Cerebral Haemodynamic Parameters in Healthy Controls and Acute Ischaemic Stroke Patients

et al. 2020

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(1) Background: Larger blood pressure variability (BPv) in the first 3 h post-stroke onset increases pathophysiological effects such as infarct size, and leads to greater risk of disability, comorbidities and mortality at 90 days. However, there is limited information on the relationship between systemic and cerebral haemodynamic and variability parameters. (2) Objectives: This study determined the effect of a gradual change in head position (GHP) on cerebral blood flow velocity variability (CBFVv) and mean arterial blood pressure variability (MABPv), in healthy controls and acute ischaemic stroke (AIS) patients. Methods: CBFVv and MABPv were expressed as standard deviation (SD) and coefficient of variation. A total of 16 healthy controls (mean age 57 ± 16 years) were assessed over two visits, 12 ± 8 days apart, and 15 AIS patients (mean age 69 ± 8.5 years) were assessed over three visits (V1: 13.3 ± 6.9 h, V2: 4.9 ± 3.2 days and V3: 93.9 ± 11.5 days post-stroke). (3) Results: In response to GHP, MABPv does not initially increase, but over time MABPv showed a significant increase in response to GHP in AIS (visits 2 and 3) and controls (visit 2). Additionally, in response to GHP in AIS, CBFVv increased in the affected hemisphere. Lastly, in AIS, a significant correlation between CBFVv and MABPv, assessed by SD, was seen in the unaffected hemisphere, whereas this relationship was not demonstrated in the affected hemisphere. (4) Conclusions: To our knowledge, this is the first study to analyse the relationship between CBFVv and MABPv. Shedding light on the effect of head position on the relationship between cerebral blood flow and blood pressure is important to improve our understanding of the underlying effects of cerebral autoregulation impairment. This early mechanistic study provides evidence supporting supine head positioning in healthy controls and stroke patients, through demonstration of a reduction of MABPv and increase in CBFVv.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

The Effects of Gradual Change in Head Positioning on the Relationship between Systemic and Cerebral Haemodynamic Parameters in Healthy Controls and Acute Ischaemic Stroke Patients

et al. 2020

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“…A custom-made head frame was used to secure the ultrasound probes in position and to minimize movement. All TCD measurements were carried out by the first author who has been formally trained with significant experiences in operating TCD and published reproducibility data [21].…”

Section: Methodsmentioning

confidence: 99%

Cerebral hemodynamics in stroke thrombolysis (CHiST) study

et al. 2020

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Despite careful patient selection, successful recanalization in intravenous thrombolysis is only achieved in approximately 50% of cases. Understanding changes in cerebral autoregulation during and following successful recanalization in acute ischemic stroke patients who receive intravenous thrombolysis, may inform the management of common physiological perturbations, including blood pressure, in turn reducing the risk of reperfusion injury. Cerebral blood velocity (Transcranial Doppler), blood pressure (Finometer) and end-tidal carbon dioxide (capnography) were continuously recorded in 11 acute ischemic stroke patients who received intravenous thrombolysis (5 female, mean ± SD age 68±12 years) over 4-time points, during and at the following time intervals after intravenous thrombolysis: 23.9±2.6 hrs, 18.1±7.0 days and 89.6±4.2 days. Reductions in blood pressure (p = 0.04) were observed during intravenous thrombolysis. Reductions in heart rate (p<0.005) and critical closing pressure [Affected hemisphere (p = 0.02) and non-affected hemisphere (p<0.005)] were observed post intravenous thrombolysis. End-tidal CO 2 increased during the subacute and chronic stages (p = 0.028). Reduction in affected hemisphere phase at low frequency was observed during intravenous thrombolysis (p = 0.021) and at subsequent visits (p = 0.048). No changes were observed in cerebral blood velocity, coherence, gain and Autoregulation Index during the follow-up period. Intravenous thrombolysis in acute ischemic stroke patients induced changes in affected hemisphere phase and other key hemodynamic parameters, but not Autoregulation Index. Further investigation of cerebral autoregulation is warranted in a larger acute ischemic stroke cohort to inform its potential role in individualized management plans.

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