Cerebral blood flow changes during tilt table testing in healthy volunteers, as assessed by Doppler imaging of the carotid and vertebral arteries

Campen, C. M. C. van; Verheugt, Freek W.A.; Visser, Frans C.

doi:10.1016/j.cnp.2018.02.004

Cited by 31 publications

(30 citation statements)

References 42 publications

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“…When considering the effects of partial gravity levels on cranial venous parameters, one must also consider the effects of cranial arterial flow. In this study, we did not observe an effect of G z -level on CCA diameter; although CCA flow was higher during 1-G z supine than during 1-G z seated, similar to previous observations (Sato et al, 2012;van Campen et al, 2018), the effects during partial gravity levels were not consistent. While an increase in CCA flow might be suggestive of elevated cerebral blood, middle cerebral artery flow velocity does not increase during weightlessness produced by parabolic flight due to systemic vasodilation (Ogoh et al, 2015), even though central blood volume and cardiac output may be higher (Ogoh et al, 2005).…”

Section: Arterial Flow To the Headsupporting

confidence: 80%

Venous and Arterial Responses to Partial Gravity

et al. 2020

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Introduction: Chronic exposure to the weightlessness-induced cephalad fluid shift is hypothesized to be a primary contributor to the development of spaceflight-associated neuro-ocular syndrome (SANS) and may be associated with an increased risk of venous thrombosis in the jugular vein. This study characterized the relationship between gravitational level (G z-level) and acute vascular changes. Methods: Internal jugular vein (IJV) cross-sectional area, inferior vena cava (IVC) diameter, and common carotid artery (CCA) flow were measured using ultrasound in nine subjects (5F, 4M) while seated when exposed to 1.00-G z , 0.75-G z , 0.50-G z , and 0.25-G z during parabolic flight and while supine before flight (0-G analog). Additionally, IJV flow patterns were characterized. Results: IJV cross-sectional area progressively increased from 12 (95% CI: 9-16) mm 2 during 1.00-G z seated to 24 (13-35), 34 (21-46), 68 (40-97), and 103 (75-131) mm 2 during 0.75-G z , 0.50-G z , and 0.25-G z seated and 1.00-G z supine, respectively. Also, IJV flow pattern shifted from the continuous forward flow observed during 1.00-G z and 0.75-G z seated to pulsatile flow during 0.50-G z seated, 0.25-G z seated, and 1.00-G z supine. In contrast, we were unable to detect differences in IVC diameter measured during 1.00-G seated and any level of partial gravity or during 1.00-G z supine. CCA blood flow during 1.00-G seated was significantly less than 0.75-G z and 1.00-G z supine but differences were not detected at partial gravity levels 0.50-G z and 0.25-G z. Conclusions: Acute exposure to decreasing G z-levels is associated with an expansion of the IJV and flow patterns that become similar to those observed in supine subjects and in astronauts during spaceflight. These data suggest that G z-levels greater than 0.50-G z may be required to reduce the weightlessness-induced headward fluid shift that may contribute to the risks of SANS and venous thrombosis during spaceflight.

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Section: Arterial Flow To the Headsupporting

confidence: 80%

Venous and Arterial Responses to Partial Gravity

et al. 2020

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“…Total cerebral blood flow was calculated by adding the flow of the four arteries. We previously demonstrated that this methodology had good intra-and inter-observer variability [3].…”

Section: Discussionmentioning

confidence: 99%

“…Measurements were performed as described previously [3], with the main exception being that patients were positioned supine for 20 min before being tilted head-up to 20 degrees for a maximum of 15 min instead of the more classic approach of 70 degrees for 25-30 min. They were investigated in the morning, at least 3 h after a light breakfast or in the afternoon 3 h after a light lunch.…”

Section: Head-up Tilt Test With Cerebral Blood Flow and Stroke Volumementioning

confidence: 99%

“…In a study of 429 adult ME/CFS patients, we recently demonstrated that 86% had orthostatic intolerance symptoms during daily life. Moreover, during a 30-min head-up tilt table test, 90% had an abnormal cerebral blood flow (CBF) reduction as assessed by extracranial Doppler measurements [2,3]. This abnormal CBF reduction was not only present in ME/CFS patients with well-defined heart rate and blood pressure abnormalities during tilt testing, like orthostatic hypotension, postural orthostatic tachycardia syndrome (POTS) and syncope [4][5][6], but also in ME/CFS patients with a normal heart rate and blood pressure response to upright posture [2].…”

Section: Introductionmentioning

confidence: 99%

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Cerebral Blood Flow Is Reduced in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients During Mild Orthostatic Stress Testing: An Exploratory Study at 20 Degrees of Head-Up Tilt Testing

2020

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Introduction: In a study of 429 adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), we demonstrated that 86% had symptoms of orthostatic intolerance in daily life. Using extracranial Doppler measurements of the internal carotid and vertebral arteries during a 30-min head-up tilt to 70 degrees, 90% had an abnormal reduction in cerebral blood flow (CBF). A standard head-up tilt test of this duration might not be tolerated by the most severely affected bed-ridden ME/CFS patients. This study examined whether a shorter 15-min test at a lower 20 degree tilt angle would be sufficient to provoke reductions in cerebral blood flow in severe ME/CFS patients. Methods and results: Nineteen severe ME/CFS patients with orthostatic intolerance complaints in daily life were studied: 18 females. The mean (SD) age was 35(14) years, body surface area (BSA) was 1.8(0.2) m2 and BMI was 24.0(5.4) kg/m2. The median disease duration was 14 (IQR 5–18) years. Heart rate increased, and stroke volume index and end-tidal CO2 decreased significantly during the test (p ranging from <0.001 to <0.0001). The cardiac index decreased by 26(7)%: p < 0.0001. CBF decreased from 617(72) to 452(63) mL/min, a 27(5)% decline. All 19 severely affected ME/CFS patients met the criteria for an abnormal CBF reduction. Conclusions: Using a less demanding 20 degree tilt test for 15 min in severe ME/CFS patients resulted in a mean CBF decline of 27%. This is comparable to the mean 26% decline previously noted in less severely affected patients studied during a 30-min 70 degree head-up tilt. These observations have implications for the evaluation and treatment of severely affected individuals with ME/CFS.

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“…HUT was performed to enhance LFOs at~0.1 Hz. The protocol of 70 HUT has been widely used to induce MAP variation and challenge CA in previous studies [40][41][42][43], including ours [22,44]. This is a standard clinical protocol used to evaluate orthostatic hypotension and vagal reflex integrity.…”

Section: Introductionmentioning

confidence: 99%

Diffuse optical assessment of cerebral‐autoregulation in older adults stratified by cerebrovascular risk

Bahrani

Kong

Shang

et al. 2020

Journal of Biophotonics

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Diagnosis of cerebrovascular disease (CVD) at early stages is essential for preventing sequential complications. CVD is often associated with abnormal cerebral microvasculature, which may impact cerebral-autoregulation (CA). A novel hybrid near-infrared diffuse optical instrument and a finger plethysmograph were used to simultaneously detect low-frequency oscillations (LFOs) of cerebral blood flow (CBF), oxy-hemoglobin concentration ([HbO 2 ]), deoxy-hemoglobin concentration ([Hb]) and mean arterial pressure (MAP) in older adults before, during and after 70 headup-tilting (HUT). The participants with valid data were divided based on Framingham risk score (FRS, 1-30 points) into low-risk (FRS ≤15, n = 13) and high-risk (FRS >15, n = 11) groups for developing CVD. The LFO gains were determined by transfer function analyses with MAP as the input, and CBF, [HbO 2 ] and [Hb] as the outputs (CA / 1/Gain). At resting-baseline, LFO gains

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Cerebral blood flow changes during tilt table testing in healthy volunteers, as assessed by Doppler imaging of the carotid and vertebral arteries

Abstract: HighlightsExtracranial cerebral artery Doppler imaging show CBF changes during tilt testing.Total CBF during tilt testing decreases 6% in healthy volunteers.Flow decrease of internal carotid and vertebral arteries during tilting is similar.

Cited by 31 publications

References 42 publications

Venous and Arterial Responses to Partial Gravity

Venous and Arterial Responses to Partial Gravity

Cerebral Blood Flow Is Reduced in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients During Mild Orthostatic Stress Testing: An Exploratory Study at 20 Degrees of Head-Up Tilt Testing

Diffuse optical assessment of cerebral‐autoregulation in older adults stratified by cerebrovascular risk

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