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Zhong X, Liang Y, Wang X, Lan H, Bai X, Jin L, Guan BO. Free-moving-state microscopic imaging of cerebral oxygenation and hemodynamics with a photoacoustic fiberscope. LIGHT, SCIENCE & APPLICATIONS 2024; 13:5. [PMID: 38163847 PMCID: PMC10758391 DOI: 10.1038/s41377-023-01348-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 11/22/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024]
Abstract
We report the development of a head-mounted photoacoustic fiberscope for cerebral imaging in a freely behaving mouse. The 4.5-gram imaging probe has a 9-µm lateral resolution and 0.2-Hz frame rate over a 1.2-mm wide area. The probe can continuously monitor cerebral oxygenation and hemodynamic responses at single-vessel resolution, showing significantly different cerebrovascular responses to external stimuli under anesthesia and in the freely moving state. For example, when subjected to high-concentration CO2 respiration, enhanced oxygenation to compensate for hypercapnia can be visualized due to cerebral regulation in the freely moving state. Comparative studies exhibit significantly weakened compensation capabilities in obese rodents. This new imaging modality can be used for investigating both normal and pathological cerebrovascular functions and shows great promise for studying cerebral activity, disorders and their treatments.
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Affiliation(s)
- Xiaoxuan Zhong
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Yizhi Liang
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Xiaoyu Wang
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Haoying Lan
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Xue Bai
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
| | - Long Jin
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China.
| | - Bai-Ou Guan
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China.
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Rieger MG, Tallon CM, Perkins DR, Smith KJ, Stembridge M, Piombo S, Radom-Aizik S, Cooper DM, Ainslie PN, McManus AM. Cardiopulmonary and cerebrovascular acclimatization in children and adults at 3800 m. J Physiol 2022; 600:4849-4863. [PMID: 36165275 DOI: 10.1113/jp283419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 09/20/2022] [Indexed: 12/24/2022] Open
Abstract
Maturational differences exist in cardiopulmonary and cerebrovascular function at sea-level, but the impact of maturation on acclimatization responses to high altitude is unknown. Ten children (9.8 ± 2.5 years) and 10 adults (34.7 ± 7.1 years) were assessed at sea-level (BL), 3000 m and twice over 4 days at 3800 m (B1, B4). Measurements included minute ventilation ( V ̇ E ${\dot{V}}_{\rm{E}}$ ), end-tidal partial pressures of oxygen ( P ETO 2 ${P}_{{\rm{ETO}}_{\rm{2}}}$ ) and carbon dioxide, echocardiographic assessment of pulmonary artery systolic pressure (PASP) and stroke volume (SV) and ultrasound assessment of blood flow through the internal carotid and vertebral arteries was performed to calculate global cerebral blood flow (gCBF). At 3000 m, V ̇ E ${\dot{V}}_{\rm{E}}$ was increased from BL by 19.6 ± 19.1% (P = 0.031) in children, but not in adults (P = 0.835); SV was reduced in children (-11 ± 13%, P = 0.020) but not adults (P = 0.827), which was compensated for by a larger increase in heart rate in children (+26 beats min-1 vs. +13 beats min-1 , P = 0.019). Between B1 and B4, adults increased V ̇ E ${\dot{V}}_{\rm{E}}$ by 38.5 ± 34.7% (P = 0.006), while V ̇ E ${\dot{V}}_{\rm{E}}$ did not increase further in children. The rise in PASP was not different between groups; however, ∆PASP from BL was related to ∆ P ETO 2 ${P}_{{\rm{ETO}}_{\rm{2}}}$ in adults (R2 = 0.288, P = 0.022), but not children. At BL, gCBF was 43% higher in children than adults (P = 0.017), and this difference was maintained at high altitude, with a similar pattern and magnitude of change in gCBF between groups (P = 0.845). Despite V ̇ E ${\dot{V}}_{\rm{E}}$ increasing in children but not adults at a lower altitude, the pulmonary vascular and cerebrovascular responses to prolonged hypoxia are similar between children and adults. KEY POINTS: Children have different ventilatory and metabolic requirements from adults, which may present differently in the pulmonary and cerebral vasculature upon ascent to high altitude. Children (ages 7-14) and adults (ages 23-44) were brought from sea level to high altitude (3000 to 3800 m) and changes in ventilation, pulmonary artery systolic pressure (PASP) and cerebral blood flow (CBF) were assessed over 1 week. Significant increases in ventilation and decreases in left ventricle stroke volume were observed at a lower altitude in children than adults. PASP and CBF increased by a similar relative amount between children and adults at 3800 m. These results help us better understand age-related differences in compensatory responses to prolonged hypoxia in children, despite similar changes in pulmonary artery pressure and CBF between children and adults.
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Affiliation(s)
- M G Rieger
- Centre for Heart, Lung & Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
| | - C M Tallon
- Centre for Heart, Lung & Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
| | - D R Perkins
- Cardiff School of Sport & Health Sciences, Cardiff Metropolitan University, Cardiff, UK.,Youth Physical Development Centre, Cardiff School of Sport & Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - K J Smith
- Cerebrovascular Health, Exercise, and Environmental Research Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - M Stembridge
- Cardiff School of Sport & Health Sciences, Cardiff Metropolitan University, Cardiff, UK.,Youth Physical Development Centre, Cardiff School of Sport & Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - S Piombo
- Pediatric Exercise and Genomics Research Center, University of California Irvine School of Medicine, Irvine, CA, USA
| | - S Radom-Aizik
- Pediatric Exercise and Genomics Research Center, University of California Irvine School of Medicine, Irvine, CA, USA
| | - D M Cooper
- Pediatric Exercise and Genomics Research Center, University of California Irvine School of Medicine, Irvine, CA, USA
| | - P N Ainslie
- Centre for Heart, Lung & Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
| | - A M McManus
- Centre for Heart, Lung & Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
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Tallon CM, Talbot JS, Smith KJ, Lewis N, Nowak-Flück D, Stembridge M, Ainslie P, McManus AM. Dynamic onset response of the internal carotid artery to hypercapnia is blunted in children compared with adults. Physiol Rep 2022; 10:e15406. [PMID: 36017901 PMCID: PMC9413871 DOI: 10.14814/phy2.15406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 06/24/2022] [Accepted: 07/14/2022] [Indexed: 11/24/2022] Open
Abstract
Intracranial blood velocity reactivity to a steady‐state hypercapnic stimulus has been shown to be similar in children and adults, but the onset response to hypercapnia is slower in the child. Given the vasodilatory effect of hypercapnia on the cerebrovasculature, assessment of vessel diameter, and blood flow are vital to fully elucidate whether the temporal hypercapnic response differs in children versus adults. Assessment of internal carotid artery (ICA) vessel diameter (ICAd), blood velocity (ICAv), volumetric blood flow (QICA), and shear rate (ICASR) in response to a 4 min hypercapnic challenge was completed in children (n = 14, 8 girls; 9.8 ± 0.7 years) and adults (n = 17, 7 females; 24.7 ± 1.8 years). The dynamic onset responses of partial pressure of end‐tidal CO2 (PETCO2), QICA, ICAv, and ICASR to hypercapnia were modeled, and mean response time (MRT) was computed. Following 4 min of hypercapnia, ICA reactivity and ICAd were comparable between the groups. Despite a similar MRT in PETCO2 in children and adults, children had slower QICA (children 108 ± 60 s vs. adults 66 ± 37 s; p = 0.023), ICAv (children 120 ± 52 s vs. adults 52 ± 31 s; p = 0.001), and ICASR (children 90 ± 27 s vs. adults 47 ± 36 s; p = 0.001) MRTs compared with adults. This is the first study to show slower hypercapnic hyperemic kinetic responses of the ICA in children. The mechanisms determining these differences and the need to consider the duration of hypercapnic exposure when assessing CVR in children should be considered in future studies.
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Affiliation(s)
- Christine M Tallon
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Jack S Talbot
- School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, Wales, UK
| | - Kurt J Smith
- Cerebrovascular Health, Exercise, and Environmental Research Sciences Laboratory, School of Exercise Science and Physical Health Education, University of Victoria, Victoria, British Columbia, Canada
| | - Nia Lewis
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Daniela Nowak-Flück
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Mike Stembridge
- School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, Wales, UK
| | - Philip Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Ali M McManus
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
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Zhu X, Huang Q, DiSpirito A, Vu T, Rong Q, Peng X, Sheng H, Shen X, Zhou Q, Jiang L, Hoffmann U, Yao J. Real-time whole-brain imaging of hemodynamics and oxygenation at micro-vessel resolution with ultrafast wide-field photoacoustic microscopy. LIGHT, SCIENCE & APPLICATIONS 2022; 11:138. [PMID: 35577780 PMCID: PMC9110749 DOI: 10.1038/s41377-022-00836-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/27/2022] [Accepted: 05/04/2022] [Indexed: 05/10/2023]
Abstract
High-speed high-resolution imaging of the whole-brain hemodynamics is critically important to facilitating neurovascular research. High imaging speed and image quality are crucial to visualizing real-time hemodynamics in complex brain vascular networks, and tracking fast pathophysiological activities at the microvessel level, which will enable advances in current queries in neurovascular and brain metabolism research, including stroke, dementia, and acute brain injury. Further, real-time imaging of oxygen saturation of hemoglobin (sO2) can capture fast-paced oxygen delivery dynamics, which is needed to solve pertinent questions in these fields and beyond. Here, we present a novel ultrafast functional photoacoustic microscopy (UFF-PAM) to image the whole-brain hemodynamics and oxygenation. UFF-PAM takes advantage of several key engineering innovations, including stimulated Raman scattering (SRS) based dual-wavelength laser excitation, water-immersible 12-facet-polygon scanner, high-sensitivity ultrasound transducer, and deep-learning-based image upsampling. A volumetric imaging rate of 2 Hz has been achieved over a field of view (FOV) of 11 × 7.5 × 1.5 mm3 with a high spatial resolution of ~10 μm. Using the UFF-PAM system, we have demonstrated proof-of-concept studies on the mouse brains in response to systemic hypoxia, sodium nitroprusside, and stroke. We observed the mouse brain's fast morphological and functional changes over the entire cortex, including vasoconstriction, vasodilation, and deoxygenation. More interestingly, for the first time, with the whole-brain FOV and micro-vessel resolution, we captured the vasoconstriction and hypoxia simultaneously in the spreading depolarization (SD) wave. We expect the new imaging technology will provide a great potential for fundamental brain research under various pathological and physiological conditions.
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Affiliation(s)
- Xiaoyi Zhu
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Qiang Huang
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Department of Pediatric Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Anthony DiSpirito
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Tri Vu
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Qiangzhou Rong
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Xiaorui Peng
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Huaxin Sheng
- Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Xiling Shen
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Qifa Zhou
- Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, 90089, USA
| | - Laiming Jiang
- Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, 90089, USA.
| | - Ulrike Hoffmann
- Department of Anesthesiology, Duke University, Durham, NC, 27708, USA.
| | - Junjie Yao
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA.
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Tallon CM, Smith KJ, Nowak-Flück D, Koziol AV, Rieger MG, Lutes LD, Green DJ, Tremblay MS, Ainslie PN, McManus AM. The influence of sex and maturation on carotid and vertebral artery hemodynamics and associations with free-living (in)activity in 6-17-year-olds. J Appl Physiol (1985) 2021; 131:1575-1583. [PMID: 34617820 DOI: 10.1152/japplphysiol.00537.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We explored the influence of sex and maturation on resting cervical artery hemodynamics (common carotid artery, CCA; internal carotid artery, ICA; and vertebral artery, VA), free-living physical activity, and sedentary behavior in children 6-17 yr of age. In addition, we investigated the relationship between physical activity, sedentary behavior, and cervical artery hemodynamics. Seventy-eight children and adolescents, girls (n = 42; mean age, 11.4 ± 2.5 yr) and boys (n = 36; mean age, 11.0 ± 2.6 yr), completed anthropometric measures, duplex ultrasound assessment of the cervical arteries, and wore an activPAL accelerometer to assess physical activity (indexed by steps/day) and sedentary behavior for 7 days. The ICA and VA diameters were similar between prepubertal and pubertal groups, as was volumetric blood flow (Q); however, the CCA diameter was significantly larger in the pubertal group (P < 0.05). Boys were found to have larger diameters in all cervical arteries than girls, as well as higher QCCA, QICA, and global cerebral blood flow (P < 0.05). The pubertal group was more sedentary (100 min/day more; P < 0.05) and took 3,500 fewer steps/day than the prepubertal group (P < 0.05). Shear rate (SR) and Q of the cervical arteries showed no relationship to physical activity or prolonged bouts of sedentary behavior; however, a significant negative relationship was apparent between total sedentary time and internal carotid artery shear rate (ICASR) after covarying for steps/day and maturation (P < 0.05). These findings provide novel insight into the potential influence sedentary behavior may have on cerebrovascular blood flow in healthy girls and boys.NEW & NOTEWORTHY Cerebral blood flow is known to change with age; however, assessing these age-related changes is complex and requires consideration of pubertal status. This, to our knowledge, is the first study to investigate the influence of sex and maturation on resting cervical artery hemodynamics and subsequently explore associations with physical activity and sedentary behavior in healthy children and adolescents. Our findings suggest that habitual sedentary behavior may influence cervical artery hemodynamics in youth, independent of physical activity, maturation, and sex.
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Affiliation(s)
- Christine M Tallon
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Kurt J Smith
- Cerebrovascular Health, Exercise, and Environmental Research Sciences Laboratory, School of Exercise Science and Physical Health Education, University of Victoria, Victoria, British Columbia, Canada
| | - Daniela Nowak-Flück
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Alyssa V Koziol
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Mathew G Rieger
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Lesley D Lutes
- Department of Psychology, Centre for Obesity and Well-Being Research Excellence, University of British Columbia, Kelowna, British Columbia, Canada
| | - Daniel J Green
- School of Human Science (Sport and Exercise Science), The University of Western Australia, Perth, Western Australia, Australia
| | - Mark S Tremblay
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Ali M McManus
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
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Keough JRG, Cates VC, Tymko MM, Boulet LM, Jamieson AN, Foster GE, Day TA. Regional differences in cerebrovascular reactivity in response to acute isocapnic hypoxia in healthy humans: Methodological considerations. Respir Physiol Neurobiol 2021; 294:103770. [PMID: 34343693 DOI: 10.1016/j.resp.2021.103770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/15/2021] [Accepted: 07/29/2021] [Indexed: 11/30/2022]
Abstract
The cerebrovasculature responds to blood gas challenges. Regional differences (anterior vs. posterior) in cerebrovascular responses to increases in CO2 have been extensively studied. However, regional cerebrovascular reactivity (CVR) responses to low O2 (hypoxia) are equivocal, likely due to differences in analysis. We assessed the effects of acute isocapnic hypoxia on regional CVR comparing absolute and relative (%-change) responses in the middle cerebral artery (MCA) and posterior cerebral artery (PCA). We instrumented 14 healthy participants with a transcranial Doppler ultrasound (cerebral blood velocity), finometer (beat-by-beat blood pressure), dual gas analyzer (end-tidal CO2 and O2), and utilized a dynamic end-tidal forcing system to elicit a single 5-min bout of isocapnic hypoxia (∼45 Torr PETO2, ∼80 % SpO2). During exposure to acute hypoxia, absolute responses were larger in the anterior compared to posterior cerebral circulation (P < 0.001), but were not different when comparing relative responses (P = 0.45). Consistent reporting of CVR to hypoxia will aid understanding normative responses, particularly in assessing populations with impaired cerebrovascular function.
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Affiliation(s)
- Joanna R G Keough
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Valerie C Cates
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Michael M Tymko
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada; Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Lindsey M Boulet
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Alenna N Jamieson
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Glen E Foster
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada.
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Friend AT, Rogan M, Rossetti GMK, Lawley JS, Mullins PG, Sandoo A, Macdonald JH, Oliver SJ. Bilateral regional extracranial blood flow regulation to hypoxia and unilateral duplex ultrasound measurement error. Exp Physiol 2021; 106:1535-1548. [PMID: 33866627 DOI: 10.1113/ep089196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 04/14/2021] [Indexed: 02/05/2023]
Abstract
NEW FINDINGS What is the central question of this study? Is blood flow regulation to hypoxia different between the internal carotid arteries (ICAs) and vertebral arteries (VAs), and what is the measurement error in unilateral extracranial artery assessments compared to bilateral? What is the main finding and its importance? ICA and VA blood flow regulation to hypoxia is comparable when factoring for vessel type and vessel side. Compared to bilateral assessment, vessels assessed unilaterally had individual measurement errors of up to 37%. Assessing the vessel with the larger resting blood flow, not the left or right vessel, reduces unilateral measurement error. ABSTRACT Whether blood flow regulation to hypoxia is similar between left and right internal carotid arteries (ICAs) and vertebral arteries (VAs) is unclear. Extracranial blood flow is regularly calculated by doubling a unilateral assessment; however, lateral artery differences may lead to measurement error. This study aimed to determine extracranial blood flow regulation to hypoxia when factoring for vessel type (ICAs or VAs) and vessel side (left or right) effects, and to investigate unilateral assessment measurement error compared to bilateral assessment. In a repeated-measures crossover design, extracranial arteries of 44 participants were assessed bilaterally by duplex ultrasound during 90 min of normoxic and poikilocapnic hypoxic (12.0% fraction of inspired oxygen) conditions. Linear mixed model analyses revealed no Condition × Vessel Type × Vessel Side interaction for blood flow, vessel diameter and flow velocity (all P > 0.05) indicating left and right ICA and VA blood flow regulation to hypoxia was similar. Bilateral hypoxic reactivity was comparable (ICAs, 1.4 (1.0) vs. VAs, 1.7 (1.1) Δ%·Δ S p O 2 -1 ; P = 0.12). Compared to bilateral assessment, unilateral mean measurement error of the relative blood flow response to hypoxia was up to 5%, but individual errors reached 37% and were greatest in ICAs and VAs with the smaller resting blood flow due to a ratio-scaling problem. In conclusion, left and right ICA and VA regulation to hypoxia is comparable when factoring for vessel type and vessel side. Assessing the ICA and VA vessels with the larger resting blood flow, not the left or right vessel, reduces unilateral measurement error.
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Affiliation(s)
- Alexander T Friend
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Matthew Rogan
- Bangor Imaging Unit, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
| | - Gabriella M K Rossetti
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK.,Centre for Integrative Neuroscience and Neurodynamics, School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK
| | - Justin S Lawley
- Department of Sport Science, Division of Physiology, University of Innsbruck, Innsbruck, Austria
| | - Paul G Mullins
- Bangor Imaging Unit, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
| | - Aamer Sandoo
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Jamie H Macdonald
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Samuel J Oliver
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
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Morris LE, Flück D, Ainslie PN, McManus AM. Cerebrovascular and ventilatory responses to acute normobaric hypoxia in girls and women. Physiol Rep 2017; 5:e13372. [PMID: 28774953 PMCID: PMC5555897 DOI: 10.14814/phy2.13372] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 07/05/2017] [Accepted: 07/08/2017] [Indexed: 01/21/2023] Open
Abstract
Physiological responses to hypoxia in children are incompletely understood. We aimed to characterize cerebrovascular and ventilatory responses to normobaric hypoxia in girls and women. Ten healthy girls (9.9 ± 1.7 years; mean ± SD; Tanner stage 1 and 2) and their mothers (43.9 ± 3.5 years) participated. Internal carotid (ICA) and vertebral artery (VA) velocity, diameter and flow (Duplex ultrasound) was recorded pre- and post-1 h of hypoxic exposure (FIO2 = 0.126;~4000 m) in a normobaric chamber. Ventilation (V˙E) and respiratory drive (VT/TI) expressed as delta change from baseline (∆%), and end-tidal carbon-dioxide (PETCO2) were collected at baseline (BL) and 5, 30 and 60 min of hypoxia (5/30/60 HYP). Heart rate (HR) and oxygen saturation (SpO2) were also collected at these time-points. SpO2 declined similarly in girls (BL-97%; 60HYP-80%, P < 0.05) and women (BL-97%; 60HYP-83%, P < 0.05). Global cerebral blood flow (gCBF) increased in both girls (BL-687; 60HYP-912 mL·min-1, P < 0.05) and women (BL-472; 60HYP-651 mL·min-1, P < 0.01), though the ratio of ICA:VA (%) contribution to gCBF differed significantly (girls, 75:25%; women, 61:39%). The relative increase in V˙E peaked at 30HYP in both girls (27%, P < 0.05) and women (19%, P < 0.05), as did ∆%VT/TI (girls, 41%; women, 27%, P's < 0.05). Tidal volume (VT) increased in both girls and women at 5HYP, remaining elevated above baseline in girls at 30 and 60 HYP, but declined back toward baseline in women. Girls elicit similar increases in gCBF and ventilatory parameters in response to acute hypoxia as women, though the pattern and contributions mediating these responses appear developmentally divergent.
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Affiliation(s)
- Laura E Morris
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia, Kelowna, Canada
| | - Daniela Flück
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia, Kelowna, Canada
| | - Philip N Ainslie
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia, Kelowna, Canada
| | - Ali M McManus
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia, Kelowna, Canada
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