251
|
Lam MY, Haunton VJ, Robinson TG, Panerai RB. Does gradual change in head positioning affect cerebrovascular physiology? Physiol Rep 2018; 6:e13603. [PMID: 29417750 PMCID: PMC5803526 DOI: 10.14814/phy2.13603] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 12/29/2017] [Indexed: 11/24/2022] Open
Abstract
We studied cerebral blood velocity (CBV), and associated hemodynamic parameters during gradual changes in head positioning in a nonstroke group. CBV (transcranial Doppler ultrasound), beat-to-beat blood pressure (BP, Finometer), and end-tidal carbon dioxide (ETCO2 , capnography) were recorded between lying flat (0°) and sitting up (30°) head positions, in 18 volunteers (10 female, mean age, 57 ± 16 years), at two visits (12 ± 8 days). A significant reduction was found between 5-min FLAT (0°) and 5-min SIT (30°) positions in CBV (visit 1: 4.5 ± 3.3%, P = 0.006; visit 2: 4.1 ± 3.5%, P = 0.003), critical closing pressure (CrCP; visit 1: 15.5 ± 14.0%, P = 0.0002; visit 2: 14.1 ± 7.8%, P = 0.009) and BP (visit 1: 8.3 ± 7.4%, P = 0.001; visit 2: 11.0 ± 11.3%, P < 0.001). For 5 min segments of data, the autoregulation index and other hemodynamic parameters did not show differences either due to head position or visit. For 30 sec time intervals, significant differences were observed in the following: (BP, P < 0.001; dominant hemisphere (DH) CBV, P < 0.005; nondominant hemisphere (NDH) CBV, P < 0.005; DH CrCP, P < 0.001; NDH CrCP, P < 0.001; DH resistance area product (RAP), P = 0.002; NDH RAP, P = 0.033). Significant static changes in BP, CBV and CrCP, and large transient changes in key hemodynamic parameters occur during 0° to 30°, and vice versa, with reproducible results. Further studies are needed following acute ischemic stroke to determine if a similar responses is present.
Collapse
Affiliation(s)
- Man Y. Lam
- Department of Cardiovascular SciencesUniversity of LeicesterLeicesterUnited Kingdom
| | - Victoria J. Haunton
- Department of Cardiovascular SciencesUniversity of LeicesterLeicesterUnited Kingdom
- National Institute for Health Research Leicester Biomedical Research CentreUniversity of LeicesterLeicesterUnited Kingdom
| | - Thompson G. Robinson
- Department of Cardiovascular SciencesUniversity of LeicesterLeicesterUnited Kingdom
- National Institute for Health Research Leicester Biomedical Research CentreUniversity of LeicesterLeicesterUnited Kingdom
| | - Ronney B. Panerai
- Department of Cardiovascular SciencesUniversity of LeicesterLeicesterUnited Kingdom
- National Institute for Health Research Leicester Biomedical Research CentreUniversity of LeicesterLeicesterUnited Kingdom
| |
Collapse
|
252
|
A comparison of static and dynamic cerebral autoregulation during mild whole-body cold stress in individuals with and without cervical spinal cord injury: a pilot study. Spinal Cord 2018; 56:469-477. [PMID: 29330514 DOI: 10.1038/s41393-017-0021-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/14/2017] [Accepted: 09/14/2017] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN Experimental study. OBJECTIVES To characterize static and dynamic cerebral autoregulation (CA) of individuals with cervical spinal cord injury (SCI) compared to able-bodied controls in response to moderate increases in mean arterial pressure (MAP) caused by mild whole-body cold stress. SETTING Japan METHODS: Five men with complete autonomic cervical SCI (sustained > 5 y) and six age-matched able-bodied men participated in hemodynamic, temperature, catecholamine and respiratory measurements for 60 min during three consecutive stages: baseline (10 min; 33 °C water through a thin-tubed whole-body suit), mild cold stress (20 min; 25 °C water), and post-cold recovery (30 min; 33 °C water). Static CA was determined as the ratio between mean changes in middle cerebral artery blood velocity and MAP, dynamic CA as transfer function coherence, gain, and phase between spontaneous changes in MAP to middle cerebral artery blood velocity. RESULTS MAP increased in both groups during cold and post-cold recovery (mean differences: 5-10 mm Hg; main effect of time: p = 0.001). Static CA was not different between the able-bodied vs. the cervical SCI group (mean (95% confidence interval (CI)) of between-group difference: -4 (-11 to 3) and -2 (-5 to 1) cm/s/mm Hg for cold (p = 0.22) and post-cold (p = 0.24), respectively). At baseline, transfer function phase was shorter in the cervical SCI group (mean (95% CI) of between-group difference: 0.6 (0.2 to 1.0) rad; p = 0.006), while between-group differences in changes in phase were not different in response to the cold stress (interaction term: p = 0.06). CONCLUSIONS This pilot study suggests that static CA is similar between individuals with cervical SCI and able-bodied controls in response to moderate increases in MAP, while dynamic CA may be impaired in cervical SCI because of disturbed sympathetic control.
Collapse
|
253
|
Curtelin D, Morales-Alamo D, Torres-Peralta R, Rasmussen P, Martin-Rincon M, Perez-Valera M, Siebenmann C, Pérez-Suárez I, Cherouveim E, Sheel AW, Lundby C, Calbet JA. Cerebral blood flow, frontal lobe oxygenation and intra-arterial blood pressure during sprint exercise in normoxia and severe acute hypoxia in humans. J Cereb Blood Flow Metab 2018; 38:136-150. [PMID: 28186430 PMCID: PMC5757439 DOI: 10.1177/0271678x17691986] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cerebral blood flow (CBF) is regulated to secure brain O2 delivery while simultaneously avoiding hyperperfusion; however, both requisites may conflict during sprint exercise. To determine whether brain O2 delivery or CBF is prioritized, young men performed sprint exercise in normoxia and hypoxia (PIO2 = 73 mmHg). During the sprints, cardiac output increased to ∼22 L min-1, mean arterial pressure to ∼131 mmHg and peak systolic blood pressure ranged between 200 and 304 mmHg. Middle-cerebral artery velocity (MCAv) increased to peak values (∼16%) after 7.5 s and decreased to pre-exercise values towards the end of the sprint. When the sprints in normoxia were preceded by a reduced PETCO2, CBF and frontal lobe oxygenation decreased in parallel ( r = 0.93, P < 0.01). In hypoxia, MCAv was increased by 25%, due to a 26% greater vascular conductance, despite 4-6 mmHg lower PaCO2 in hypoxia than normoxia. This vasodilation fully accounted for the 22 % lower CaO2 in hypoxia, leading to a similar brain O2 delivery during the sprints regardless of PIO2. In conclusion, when a conflict exists between preserving brain O2 delivery or restraining CBF to avoid potential damage by an elevated perfusion pressure, the priority is given to brain O2 delivery.
Collapse
Affiliation(s)
- David Curtelin
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,2 Emergency Medicine Department, Insular Universitary Hospital of Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - David Morales-Alamo
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Rafael Torres-Peralta
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Peter Rasmussen
- 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Marcos Martin-Rincon
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Mario Perez-Valera
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Christoph Siebenmann
- 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Ismael Pérez-Suárez
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Evgenia Cherouveim
- 5 Department of Physical Education and Sport Sciences, National and Kapodistrian University of Athens, Athens, Greece
| | - A William Sheel
- 6 School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - Carsten Lundby
- 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - José Al Calbet
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| |
Collapse
|
254
|
Peace A, van Mil A, Jones H, Thijssen DH. Similarities and Differences Between Carotid Artery and Coronary Artery Function. Curr Cardiol Rev 2018; 14:254-263. [PMID: 30198437 PMCID: PMC6300794 DOI: 10.2174/1573403x14666180910125638] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Cardiovascular Disease (CVD) remains one of the leading causes of morbidity and mortality. Strategies to predict development of CVD are therefore key in preventing and managing CVD. One stratergy in predicting CVD is by examining the role of traditional risk factors for CVD (e.g. age, sex, weight, blood pressure, blood lipids, blood glucose, smoking and physical activity). Although these measures are non-invasive and simple to perform, they provide limited information of CVD prediction. Directly examining functional characteristics of arteries that are involved in the pathophysiological changes that contribute to the development of CVD improve prediction of future CVD. Nevertheless, examining the function of arteries susceptible to atherosclortic changes, such as the coronary arteries, is invasive, expensive, and associated with high risk for complications. More accessible arteries can be used as a surrogate measure of coronary artery function. For example, the carotid artery may be a superior surrogate measure of coronary artery function given that, the carotid artery represents a central vessel that shows similarities in vasomotor function and anatomical structure with coronary arteries. CONCLUSION This review summarises the similarities between the carotid and coronary arteries, describes how both arteries respond to specific vasoactive stimuli, and discusses if the easily assessible carotid artery can provide information about vascular function (e.g. vasomotor reactivity to sympathetic stimulation) which is prognostic for future cardiovascular events. Finally, the impact of older age and lifestyle interventions (e.g. exercise training) on carotid artery function will be discussed.
Collapse
Affiliation(s)
| | | | | | - Dick H.J. Thijssen
- Address correspondence to this author at the Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street L3 3AF, Liverpool, United Kingdom;
Tel: +441519046264; E-mail:
| |
Collapse
|
255
|
Václavů L, Baldew ZAV, Gevers S, Mutsaerts HJMM, Fijnvandraat K, Cnossen MH, Majoie CB, Wood JC, VanBavel E, Biemond BJ, van Ooij P, Nederveen AJ. Intracranial 4D flow magnetic resonance imaging reveals altered haemodynamics in sickle cell disease. Br J Haematol 2017; 180:432-442. [PMID: 29270975 DOI: 10.1111/bjh.15043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 09/30/2017] [Indexed: 11/28/2022]
Abstract
Stroke risk in children with sickle cell disease (SCD) is currently assessed with routine transcranial Doppler ultrasound (TCD) measurements of blood velocity in the Circle of Willis (CoW). However, there is currently no biomarker with proven prognostic value in adult patients. Four-dimensional (4D) flow magnetic resonance imaging (MRI) may improve risk profiling based on intracranial haemodynamics. We conducted neurovascular 4D flow MRI and blood sampling in 69 SCD patients [median age 15 years (interquartile range, IQR: 12-50)] and 14 healthy controls [median age 21 years (IQR: 18-43)]. We measured velocity, flow, lumen area and endothelial shear stress (ESS) in the CoW. SCD patients had lower haematocrit and viscosity, and higher velocity, flow and lumen area, with lower ESS compared to healthy controls. We observed significant age-related decline in haemodynamic 4D flow parameters; velocity (Spearman's ρ = -0·36 to -0·61), flow (ρ = -0·26 to -0·52) and ESS (ρ = -0·14 to -0·54) in SCD patients. Further analysis in only adults showed that velocity values were similar in SCD patients compared to healthy controls, but that the additional 4D flow parameters, flow and lumen area, were higher, and ESS lower, in the SCD group. Our data suggest that 4D flow MRI may identify adult patients with an increased stroke risk more accurately than current TCD-based velocity.
Collapse
Affiliation(s)
- Lena Václavů
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Zelonna A V Baldew
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Sanna Gevers
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Henri J M M Mutsaerts
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Karin Fijnvandraat
- Paediatric Haematology, Emma Children's Hospital, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Marjon H Cnossen
- Paediatric Haematology, Erasmus University Hospital-Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Charles B Majoie
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - John C Wood
- Paediatric Cardiology, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Ed VanBavel
- Biomedical Engineering and Physics, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Bart J Biemond
- Haematology, Internal Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Pim van Ooij
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Aart J Nederveen
- Radiology & Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| |
Collapse
|
256
|
Ju KJ, Zhong LL, Ni XY, Xia L, Xue LJ, Cheng GL. Effects of low oxygen dead space ventilation and breath-holding test in evaluating cerebrovascular reactivity: A comparative observation. Biomed Mater Eng 2017; 28:393-400. [PMID: 28869425 DOI: 10.3233/bme-171679] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE This study aims to explore the application prospect of low oxygen dead space ventilation (LODSV) in evaluating vasomotor reactivity (VMR) by comparison between LODSV and breath-holding test (BHT). METHODS Outpatient or inpatient patients who underwent transcranial Doppler sonography (TCD) were enrolled into this study. These patients successively underwent BHT and LODSV. The cooperation degree, tolerance conditions and adverse reactions in patients were recorded, and VMR was calculated, compared and analyzed. RESULTS Patients had poor cooperation during BHT. Except for compensatory tachypnea after BHT, patients basically had no adverse reaction. The main manifestations of patients undergoing LODSV were deepened breathing and accelerated frequency in the end of the ventilation, and increased heart rate and a slight decline in pulse oxygen that rapidly recovered after ventilation. The increase rate of blood flow velocity in patients undergoing LODSV was significantly higher than in BHT (P<0.001), and its calculated VMR value was approximately 15% higher than BHT (P<0.001). BHT revealed a monophasic curve that slightly descends and rapidly increases, and LODSV revealed a curve that descends for a short time and slowly increases with a platform. CONCLUSION LODSV can effectively eliminate the affect of poor cooperation in patients, and avoid intolerance caused by hypoxia. Hence, VMR value is more accurate than that determined by BHT; and this can reflect the maximum reaction ability of the blood vessels. Therefore, this method has higher clinical application value.
Collapse
Affiliation(s)
- Ke-Ju Ju
- Department of Neurology, Huai'an First People's Hospital, Nanjing Medical University, 6 Beijing Road West, Huai'an, Jiangsu 223300, P.R. China
| | - Ling-Ling Zhong
- Department of Neurology, Huai'an First People's Hospital, Nanjing Medical University, 6 Beijing Road West, Huai'an, Jiangsu 223300, P.R. China
| | - Xiao-Yu Ni
- Department of Neurology, Huai'an First People's Hospital, Nanjing Medical University, 6 Beijing Road West, Huai'an, Jiangsu 223300, P.R. China
| | - Lei Xia
- Department of Neurology, Huai'an First People's Hospital, Nanjing Medical University, 6 Beijing Road West, Huai'an, Jiangsu 223300, P.R. China
| | - Liu-Jun Xue
- Department of Neurology, Huai'an First People's Hospital, Nanjing Medical University, 6 Beijing Road West, Huai'an, Jiangsu 223300, P.R. China
| | - Guan-Liang Cheng
- Department of Neurology, Huai'an First People's Hospital, Nanjing Medical University, 6 Beijing Road West, Huai'an, Jiangsu 223300, P.R. China
| |
Collapse
|
257
|
Smale BA, Northey JM, Smee DJ, Versey NG, Rattray B. Compression garments and cerebral blood flow: Influence on cognitive and exercise performance. Eur J Sport Sci 2017; 18:315-322. [PMID: 29239696 DOI: 10.1080/17461391.2017.1413139] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This study aimed to describe the effect of compression garments on middle cerebral artery blood flow velocity (MCAv) in relation to cognitive and exercise performance whilst cycling. In a randomised-controlled-cross-over design, 15 well-trained male cyclists were recruited to participate in three identical trials wearing loose fitting shorts (control), low-grade, or medium-grade compression garments. The protocol involved four 8 min increments of cycling at 30%, 50%, 70%, and 85% maximal power output and a 4 km time-trial. Participants undertook a cognitive Stroop task at baseline and at the midpoint of each increment. MCAv was monitored with Transcranial Doppler Ultrasonography. Mean arterial pressure (MAP) and partial pressure of end-tidal CO2 (PetCO2) were measured throughout. MCAv, MAP, PetCO2, and reaction time of the complex Stroop task were influenced by exercise intensity, but not compression garments. Compression garments significantly affected cognitive accuracy in the complex Stroop task such that low-grade compression appeared to enhance cognitive accuracy in comparison to the control condition at the highest intensity (p = .010). Time-trial performance did not differ between the control (338.0 ± 17.3 s), low-grade (338.7 ± 18.7 s), or medium-grade (342.2 ± 19.3 s) conditions (p = .114). Compression garments did not affect MCAv during exercise or time-trial performance, but compression may be beneficial for improved cognitive accuracy during high-intensity exercise. Further research is required to elucidate the potential impact on cognitive performance.
Collapse
Affiliation(s)
- Brittany A Smale
- a Discipline of Sport and Exercise Science, Faculty of Health , University of Canberra , Canberra , Australia.,b The University of Canberra Research Institute for Sport and Exercise (UCRISE) , Canberra , Australia
| | - Joseph M Northey
- a Discipline of Sport and Exercise Science, Faculty of Health , University of Canberra , Canberra , Australia.,b The University of Canberra Research Institute for Sport and Exercise (UCRISE) , Canberra , Australia
| | - Disa J Smee
- a Discipline of Sport and Exercise Science, Faculty of Health , University of Canberra , Canberra , Australia
| | - Nathan G Versey
- c Physiology , Australian Institute of Sport , Canberra , Australia
| | - Ben Rattray
- a Discipline of Sport and Exercise Science, Faculty of Health , University of Canberra , Canberra , Australia.,b The University of Canberra Research Institute for Sport and Exercise (UCRISE) , Canberra , Australia
| |
Collapse
|
258
|
Zhang LF, Hargens AR. Spaceflight-Induced Intracranial Hypertension and Visual Impairment: Pathophysiology and Countermeasures. Physiol Rev 2017; 98:59-87. [PMID: 29167331 DOI: 10.1152/physrev.00017.2016] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 12/21/2022] Open
Abstract
Visual impairment intracranial pressure (VIIP) syndrome is considered an unexplained major risk for future long-duration spaceflight. NASA recently redefined this syndrome as Spaceflight-Associated Neuro-ocular Syndrome (SANS). Evidence thus reviewed supports that chronic, mildly elevated intracranial pressure (ICP) in space (as opposed to more variable ICP with posture and activity on Earth) is largely accounted for by loss of hydrostatic pressures and altered hemodynamics in the intracranial circulation and the cerebrospinal fluid system. In space, an elevated pressure gradient across the lamina cribrosa, caused by a chronic but mildly elevated ICP, likely elicits adaptations of multiple structures and fluid systems in the eye which manifest themselves as the VIIP syndrome. A chronic mismatch between ICP and intraocular pressure (IOP) in space may acclimate the optic nerve head, lamina cribrosa, and optic nerve subarachnoid space to a condition that is maladaptive to Earth, all contributing to the pathogenesis of space VIIP syndrome. Relevant findings help to evaluate whether artificial gravity is an appropriate countermeasure to prevent this seemingly adverse effect of long-duration spaceflight.
Collapse
Affiliation(s)
- Li-Fan Zhang
- Department of Aerospace Physiology, Fourth Military Medical University, Xi'an, China; and Department of Orthopaedic Surgery, University of California, San Diego, California
| | - Alan R Hargens
- Department of Aerospace Physiology, Fourth Military Medical University, Xi'an, China; and Department of Orthopaedic Surgery, University of California, San Diego, California
| |
Collapse
|
259
|
Barnes SC, Ball N, Haunton VJ, Robinson TG, Panerai RB. The cerebrocardiovascular response to periodic squat-stand maneuvers in healthy subjects: a time-domain analysis. Am J Physiol Heart Circ Physiol 2017; 313:H1240-H1248. [DOI: 10.1152/ajpheart.00331.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Squat-stand maneuvers (SSMs) have been used to improve the coherence of transfer function analysis (TFA) estimates during the assessment of dynamic cerebral autoregulation (dCA). There is a need to understand the influence of peripheral changes resulting from SSMs on cerebral blood flow, which might confound estimates of dCA. Healthy subjects ( n = 29) underwent recordings at rest (5-min standing) and 15 SSMs (0.05 Hz). Heart rate (three-lead ECG), end-tidal CO2 (capnography), blood pressure (Finometer), cerebral blood velocity (CBV; transcranial Doppler, middle cerebral artery), and the angle of the thigh (tilt sensor) were measured continuously. The response of CBV to SSMs was decomposed into the relative contributions of mean arterial pressure (MAP), resistance-area product (RAP), and critical closing pressure (CrCP). Upon squatting, a rise in MAP (83.6 ± 21.1% contribution) was followed by increased CBV. A dCA response could be detected, determined by adjustments in RAP and CrCP (left hemisphere) with peak contributions of 24.8 ± 12.7% and 27.4 ± 22.8%, respectively, at different times during SSMs. No interhemispheric differences were detected. During standing, the contributions of MAP, RAP, and CrCP changed considerably. In conclusion, the changes of CBV subcomponents during repeated SSMs indicate a complex response of CBV to SSMs that can only be partially explained by myogenic mechanisms. More work is needed to clarify the potential contribution of other cofactors, such as breath-to-breath changes in Pco2, heart rate, stroke volume, and the neurogenic component of dCA. NEW & NOTEWORTHY Here, we describe the different contributions to the cerebral blood flow response after squat-stand maneuvers. Furthermore, we demonstrate the complex interaction of peripheral and cerebral parameters for the first time. Moreover, we show that the cerebral blood velocity response to squatting is likely to include a significant metabolic component.
Collapse
Affiliation(s)
- Sam C. Barnes
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Naomi Ball
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Victoria Joanna Haunton
- National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom
| | - Thompson G. Robinson
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom
| | - Ronney B. Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom
| |
Collapse
|
260
|
van der Velpen IF, Yancy CW, Sorond FA, Sabayan B. Impaired Cardiac Function and Cognitive Brain Aging. Can J Cardiol 2017; 33:1587-1596. [DOI: 10.1016/j.cjca.2017.07.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 07/16/2017] [Accepted: 07/16/2017] [Indexed: 12/25/2022] Open
|
261
|
Caldwell HG, Ainslie PN, Ellis LA, Phillips AA, Flück D. Stability in neurovascular function at 3800 m. Physiol Behav 2017; 182:62-68. [DOI: 10.1016/j.physbeh.2017.09.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/26/2017] [Accepted: 09/26/2017] [Indexed: 01/19/2023]
|
262
|
Wright AD, Smirl JD, Bryk K, van Donkelaar P. A Prospective Transcranial Doppler Ultrasound-Based Evaluation of the Acute and Cumulative Effects of Sport-Related Concussion on Neurovascular Coupling Response Dynamics. J Neurotrauma 2017. [DOI: 10.1089/neu.2017.5020] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Alexander D. Wright
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Jonathan D. Smirl
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Kelsey Bryk
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Paul van Donkelaar
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| |
Collapse
|
263
|
Brassard P, Tymko MM, Ainslie PN. Sympathetic control of the brain circulation: Appreciating the complexities to better understand the controversy. Auton Neurosci 2017; 207:37-47. [DOI: 10.1016/j.autneu.2017.05.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 05/03/2017] [Accepted: 05/04/2017] [Indexed: 12/24/2022]
|
264
|
Baran U, Choi WJ, Li Y, Wang RK. Tail artifact removal in OCT angiography images of rodent cortex. JOURNAL OF BIOPHOTONICS 2017; 10:1421-1429. [PMID: 27600882 PMCID: PMC5340634 DOI: 10.1002/jbio.201600194] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/16/2016] [Accepted: 08/21/2016] [Indexed: 05/11/2023]
Abstract
Optical coherence tomography angiography (OCTA) is a surging non-invasive, label-free, in vivo volumetric imaging method, currently being translated to clinical ophthalmology and becoming popular in neuroscience. Despite its attractiveness, there is an inherent issue of using OCT angiograms for quantitative cerebrovascular studies: The dynamic scattering of moving erythrocytes within pial vasculature creates tail-like artifacts that shadow the capillary vessels in the deeper layers of cortex. This false flow effect is relatively benign for qualitative visualization purposes, but it might have a significant impact on quantitative interpretation of angiographic results. In this work, we propose a simple image processing method to remove these tail artifacts in depth-resolved OCTA images using an adaptive enface mask generated with OCT structural images. We demonstrate the effectiveness of our method by comparing vessel densities and vessel similarities of depth-resolved OCT angiograms in a stroke study in a rodent model, in vivo. Thanks to the ability of seeing through the tails of pial vessels, capillary vessels beneath these vessels could be recovered to some extend in the deeper layers of mouse cerebral cortex, leading to a more accurate quantification. Tail artifact removed enface OCT angiogram of deeper layer in vivo mouse cortex.
Collapse
Affiliation(s)
- Utku Baran
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA
| | - Woo June Choi
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Yuandong Li
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| |
Collapse
|
265
|
Tymko MM, Rickards CA, Skow RJ, Ingram-Cotton NC, Howatt MK, Day TA. The effects of superimposed tilt and lower body negative pressure on anterior and posterior cerebral circulations. Physiol Rep 2017; 4:4/17/e12957. [PMID: 27634108 PMCID: PMC5027361 DOI: 10.14814/phy2.12957] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 08/14/2016] [Indexed: 11/24/2022] Open
Abstract
Steady-state tilt has no effect on cerebrovascular reactivity to increases in the partial pressure of end-tidal carbon dioxide (PETCO2). However, the anterior and posterior cerebral circulations may respond differently to a variety of stimuli that alter central blood volume, including lower body negative pressure (LBNP). Little is known about the superimposed effects of head-up tilt (HUT; decreased central blood volume and intracranial pressure) and head-down tilt (HDT; increased central blood volume and intracranial pressure), and LBNP on cerebral blood flow (CBF) responses. We hypothesized that (a) cerebral blood velocity (CBV; an index of CBF) responses during LBNP would not change with HUT and HDT, and (b) CBV in the anterior cerebral circulation would decrease to a greater extent compared to posterior CBV during LBNP when controlling PETCO2 In 13 male participants, we measured CBV in the anterior (middle cerebral artery, MCAv) and posterior (posterior cerebral artery, PCAv) cerebral circulations using transcranial Doppler ultrasound during LBNP stress (-50 mmHg) in three body positions (45°HUT, supine, 45°HDT). PETCO2 was measured continuously and maintained at constant levels during LBNP through coached breathing. Our main findings were that (a) steady-state tilt had no effect on CBV responses during LBNP in both the MCA (P = 0.077) and PCA (P = 0.583), and (b) despite controlling for PETCO2, both the MCAv and PCAv decreased by the same magnitude during LBNP in HUT (P = 0.348), supine (P = 0.694), and HDT (P = 0.407). Here, we demonstrate that there are no differences in anterior and posterior circulations in response to LBNP in different body positions.
Collapse
Affiliation(s)
- Michael M Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science University of British Columbia, Kelowna, Canada Department of Biology, Faculty of Science and Technology Mount Royal University, Calgary, Alberta, Canada
| | - Caroline A Rickards
- Institute for Cardiovascular & Metabolic Diseases, University of North Texas Health Science Centre, Fort Worth, Texas
| | - Rachel J Skow
- Department of Biology, Faculty of Science and Technology Mount Royal University, Calgary, Alberta, Canada Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Nathan C Ingram-Cotton
- Department of Biology, Faculty of Science and Technology Mount Royal University, Calgary, Alberta, Canada
| | - Michael K Howatt
- Department of Biology, Faculty of Science and Technology Mount Royal University, Calgary, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology Mount Royal University, Calgary, Alberta, Canada
| |
Collapse
|
266
|
Tymko MM, Kerstens TP, Wildfong KW, Ainslie PN. Cerebrovascular response to the cold pressor test - the critical role of carbon dioxide. Exp Physiol 2017; 102:1647-1660. [DOI: 10.1113/ep086585] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/15/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Michael M. Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science; University of British Columbia; Kelowna BC Canada
| | | | - Kevin W. Wildfong
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science; University of British Columbia; Kelowna BC Canada
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science; University of British Columbia; Kelowna BC Canada
| |
Collapse
|
267
|
Malenfant S, Brassard P, Paquette M, Le Blanc O, Chouinard A, Nadeau V, Allan PD, Tzeng YC, Simard S, Bonnet S, Provencher S. Compromised Cerebrovascular Regulation and Cerebral Oxygenation in Pulmonary Arterial Hypertension. J Am Heart Assoc 2017; 6:e006126. [PMID: 29025748 PMCID: PMC5721836 DOI: 10.1161/jaha.117.006126] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 08/28/2017] [Indexed: 12/18/2022]
Abstract
BACKGROUND Functional cerebrovascular regulatory mechanisms are important for maintaining constant cerebral blood flow and oxygen supply in heathy individuals and are altered in heart failure. We aim to examine whether pulmonary arterial hypertension (PAH) is associated with abnormal cerebrovascular regulation and lower cerebral oxygenation and their physiological and clinical consequences. METHODS AND RESULTS Resting mean flow velocity in the middle cerebral artery mean flow velocity in the middle cerebral artery (MCAvmean); transcranial Doppler), cerebral pressure-flow relationship (assessed at rest and during squat-stand maneuvers; analyzed using transfer function analysis), cerebrovascular reactivity to CO2, and central chemoreflex were assessed in 11 patients with PAH and 11 matched healthy controls. Both groups also completed an incremental ramp exercise protocol until exhaustion, during which MCAvmean, mean arterial pressure, cardiac output (photoplethysmography), end-tidal partial pressure of CO2, and cerebral oxygenation (near-infrared spectroscopy) were measured. Patients were characterized by a significant decrease in resting MCAvmean (P<0.01) and higher transfer function gain at rest and during squat-stand maneuvers (both P<0.05). Cerebrovascular reactivity to CO2 was reduced (P=0.03), whereas central chemoreceptor sensitivity was increased in PAH (P<0.01), the latter correlating with increased resting ventilation (R2=0.47; P<0.05) and the exercise ventilation/CO2 production slope (V˙E/V˙CO2 slope; R2=0.62; P<0.05) during exercise for patients. Exercise-induced increases in MCAvmean were limited in PAH (P<0.05). Reduced MCAvmean contributed to impaired cerebral oxygen delivery and oxygenation (both P<0.05), the latter correlating with exercise capacity in patients with PAH (R2=0.52; P=0.01). CONCLUSIONS These findings provide comprehensive evidence for physiologically and clinically relevant impairments in cerebral hemodynamic regulation and oxygenation in PAH.
Collapse
Affiliation(s)
- Simon Malenfant
- Pulmonary Hypertension and Vascular Biology Research Group, Université Laval, Quebec City, Canada
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Canada
| | - Patrice Brassard
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Canada
| | - Myriam Paquette
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Canada
| | - Olivier Le Blanc
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Canada
| | - Audrey Chouinard
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Canada
| | - Valérie Nadeau
- Pulmonary Hypertension and Vascular Biology Research Group, Université Laval, Quebec City, Canada
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
| | - Philip D Allan
- Wellington Medical Technology Group, Center for Translational Physiology, University of Otago, Wellington, New Zealand
| | - Yu-Chieh Tzeng
- Wellington Medical Technology Group, Center for Translational Physiology, University of Otago, Wellington, New Zealand
| | - Sébastien Simard
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
| | - Sébastien Bonnet
- Pulmonary Hypertension and Vascular Biology Research Group, Université Laval, Quebec City, Canada
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, Canada
| | - Steeve Provencher
- Pulmonary Hypertension and Vascular Biology Research Group, Université Laval, Quebec City, Canada
- Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, Canada
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, Canada
| |
Collapse
|
268
|
Barnes SC, Ball N, Panerai RB, Robinson TG, Haunton VJ. Random squat/stand maneuvers: a novel approach for assessment of dynamic cerebral autoregulation? J Appl Physiol (1985) 2017. [DOI: 10.1152/japplphysiol.00316.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Squat/stand maneuvers (SSM) have been used to assess dynamic cerebral autoregulation (dCA), but always at a fixed frequency (FF). This study aimed to assess the use of random-frequency (RF) SSMs as a stimulus for measuring dCA and determine the reproducibility of FF and RFSSMs. Twenty-nine healthy volunteers [19 male, mean age 23.0 (4.9) yr] completed the study; 11 returned for a repeat visit (median 45 days). Heart rate, beat-to-beat blood pressure, middle cerebral artery (MCA) blood flow velocity, end-tidal CO2, and angle of the squat movement were measured. Subjects underwent four recordings: 5 min sitting, 5 min standing, FFSSMs (0.05Hz), and RFSSMs. Subjects were asked to rate the degree of exertion experienced while performing these maneuvers. Twenty-nine subjects completed the protocol; nine data sets were deemed unsuitable for further analysis. Mean ARI of 6.21 (1.04) while standing was significantly greater than during the SSMs ( P < 0.01), with mean (SD) ARI during the FF and RFSSMs being 5.16 (1.43) and 5.37 (1.21), respectively. However, no significant difference was found between the ARI estimates from the two SSMs ( P = 0.856) or for each of the four recordings between the two visits ( P = 0.645). RFSSMs were found to be significantly less tiring than FFSSMs ( P < 0.01). In conclusion, RFSSMs are an effective and noninvasive method of assessing dCA. There is no difference in the ARI estimates in comparison with FFSSMs. Although FFSSMs have been well tolerated previously, RFSSMs are preferred by healthy subjects and thus may be better tolerated by a patient population in a clinical setting. NEW & NOTEWORTHY RFSSMs provided comparable estimates of autoregulatory indices to FFSSMs. Instead of point estimates at the driven frequency, RFSSMs generate a broader power spectrum of changes in arterial blood pressure and cerebral blood flow velocity, allowing direct comparison with spontaneous fluctuations through transfer function analysis. Moreover, random-frequency SSMs are preferred by participants. They are a novel tool by which larger blood pressure oscillations can be elicited for the reliable measurement of dynamic cerebral autoregulation.
Collapse
Affiliation(s)
- Sam C. Barnes
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; and
| | - Naomi Ball
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; and
| | - Ronney B. Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; and
- National Institute for Health Research, Biomedical Research Unit in Cardiovascular Sciences, Clinical Sciences Wing, Glenfield Hospital, Leicester, United Kingdom
| | - Thompson G. Robinson
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; and
- National Institute for Health Research, Biomedical Research Unit in Cardiovascular Sciences, Clinical Sciences Wing, Glenfield Hospital, Leicester, United Kingdom
| | - Victoria J. Haunton
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; and
- National Institute for Health Research, Biomedical Research Unit in Cardiovascular Sciences, Clinical Sciences Wing, Glenfield Hospital, Leicester, United Kingdom
| |
Collapse
|
269
|
Marsh CE, Carter HH, Guelfi KJ, Smith KJ, Pike KE, Naylor LH, Green DJ. Brachial and Cerebrovascular Functions Are Enhanced in Postmenopausal Women after Ingestion of Chocolate with a High Concentration of Cocoa. J Nutr 2017; 147:1686-1692. [PMID: 28794213 DOI: 10.3945/jn.117.250225] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/02/2017] [Accepted: 06/26/2017] [Indexed: 11/14/2022] Open
Abstract
Background: Cocoa contains polyphenols that are thought to be beneficial for vascular health.Objective: We assessed the impact of chocolate containing distinct concentrations of cocoa on cerebrovascular function and cognition.Methods: Using a counterbalanced within-subject design, we compared the acute impact of consumption of energy-matched chocolate containing 80%, 35%, and 0% single-origin cacao on vascular endothelial function, cognition, and cerebrovascular function in 12 healthy postmenopausal women (mean ± SD age: 57.3 ± 5.3 y). Participants attended a familiarization session, followed by 3 experimental trials, each separated by 1 wk. Outcome measures included cerebral blood flow velocity (CBFv) responses, recorded before and during completion of a computerized cognitive assessment battery (CogState); brachial artery flow-mediated dilation (FMD); and hemodynamic responses (heart rate and blood pressure).Results: When CBFv data before and after chocolate intake were compared between conditions through the use of 2-factor ANOVA, an interaction effect (P = 0.003) and main effects for chocolate (P = 0.043) and time (P = 0.001) were evident. Post hoc analysis revealed that both milk chocolate (MC; 35% cocoa; P = 0.02) and dark chocolate (DC; 80% cocoa; P = 0.003) induced significantly lower cerebral blood flow responses during the cognitive tasks, after normalizing for changes in arterial pressure. DC consumption also increased brachial FMD compared with the baseline value before chocolate consumption (P = 0.002), whereas MC and white chocolate (0% cocoa) caused no change (P-interaction between conditions = 0.034).Conclusions: Consumption of chocolate containing high concentrations of cocoa enhanced vascular endothelial function, which was reflected by improvements in FMD. Cognitive function outcomes did not differ between conditions; however, cerebral blood flow responses during these cognitive tasks were lower in those consuming MC and DC. These findings suggest that chocolate containing high concentrations of cocoa may modify the relation between cerebral metabolism and blood flow responses in postmenopausal women. This trial was registered at www.ANZCTR.orgau as ACTRN12616000990426.
Collapse
Affiliation(s)
- Channa E Marsh
- School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Western Australia, Australia
| | - Howard H Carter
- School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Western Australia, Australia
| | - Kym J Guelfi
- School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Western Australia, Australia
| | - Kurt J Smith
- School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Western Australia, Australia
| | - Kerryn E Pike
- School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Louise H Naylor
- School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Western Australia, Australia
| | - Daniel J Green
- School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Western Australia, Australia; .,Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom; and.,National Health and Medical Research Council, Canberra, Australia
| |
Collapse
|
270
|
Bain AR, Ainslie PN, Barak OF, Hoiland RL, Drvis I, Mijacika T, Bailey DM, Santoro A, DeMasi DK, Dujic Z, MacLeod DB. Hypercapnia is essential to reduce the cerebral oxidative metabolism during extreme apnea in humans. J Cereb Blood Flow Metab 2017; 37:3231-3242. [PMID: 28071964 PMCID: PMC5584699 DOI: 10.1177/0271678x16686093] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The cerebral metabolic rate of oxygen (CMRO2) is reduced during apnea that yields profound hypoxia and hypercapnia. In this study, to dissociate the impact of hypoxia and hypercapnia on the reduction in CMRO2, 11 breath-hold competitors completed three apneas under: (a) normal conditions (NM), yielding severe hypercapnia and hypoxemia, (b) with prior hyperventilation (HV), yielding severe hypoxemia only, and (c) with prior 100% oxygen breathing (HX), yielding the greatest level of hypercapnia, but in the absence of hypoxemia. The CMRO2 was calculated from the product of cerebral blood flow (ultrasound) and the radial artery-jugular venous oxygen content difference (cannulation). Secondary measures included net-cerebral glucose/lactate exchange and nonoxidative metabolism. Reductions in CMRO2 were largest in the HX condition (-44 ± 15%, p < 0.05), with the most severe hypercapnia (PaCO2 = 58 ± 5 mmHg) but maintained oxygen saturation. The CMRO2 was reduced by 24 ± 27% in NM ( p = 0.05), but unchanged in the HV apnea where hypercapnia was absent. A net-cerebral lactate release was observed at the end of apnea in the HV and NM condition, but not in the HX apnea (main effect p < 0.05). These novel data support hypercapnia/pH as a key mechanism mediating reductions in CMRO2 during apnea, and show that severe hypoxemia stimulates lactate release from the brain.
Collapse
Affiliation(s)
- Anthony R Bain
- 1 Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Philip N Ainslie
- 1 Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Otto F Barak
- 2 School of Medicine, University of Split, Split, Croatia
| | | | - Ivan Drvis
- 4 School of Kinesiology, University of Zagreb, Zagreb, Croatia
| | - Tanja Mijacika
- 2 School of Medicine, University of Split, Split, Croatia
| | - Damian M Bailey
- 5 Faculty of Life Sciences and Education, University of South Wales, Glamorgan, UK
| | | | | | - Zeljko Dujic
- 2 School of Medicine, University of Split, Split, Croatia
| | | |
Collapse
|
271
|
The influence of prenatal exercise and pre-eclampsia on maternal vascular function. Clin Sci (Lond) 2017; 131:2223-2240. [PMID: 28798074 DOI: 10.1042/cs20171036] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/03/2017] [Accepted: 07/06/2017] [Indexed: 01/10/2023]
Abstract
During healthy pregnancy, the cardiovascular system undergoes diverse adaptations to support adequate transfer of oxygen and nutrients from mother to fetus. In order to accommodate the large expansion of blood volume and associated cardiac output, the structure, mechanics, and function of the arteries are altered. Specifically, in healthy pregnancy there is a remodeling of arteries (increased angiogenesis and vasodilation), a generalized reduction in arterial stiffness (increased compliance), and an enhanced endothelial function. The development of pregnancy complications, specifically pre-eclampsia, is associated with poor placentation (decreased angiogenesis), increased arterial stiffness, and vascular dysfunction (reduced endothelial function). Many of the positive adaptations that occur in healthy pregnancy are enhanced in response to chronic exercise. Specifically, placental angiogenesis and endothelial function have been shown to improve to a greater extent in women who are active during their pregnancy compared with those who are not. Prenatal exercise may be important in helping to reduce the risk of vascular dysfunction in pregnancy. However, our knowledge of the vascular adaptations resulting from maternal exercise is limited. This review highlights maternal vascular adaptations occurring during healthy pregnancy, and contrasts the vascular maladaptation associated with pre-eclampsia. Finally, we discuss the role of prenatal exercise on vascular function in the potential prevention of vascular complications associated with pre-eclampsia.
Collapse
|
272
|
Rieger MG, Hoiland RL, Tremblay JC, Stembridge M, Bain AR, Flück D, Subedi P, Anholm JD, Ainslie PN. One session of remote ischemic preconditioning does not improve vascular function in acute normobaric and chronic hypobaric hypoxia. Exp Physiol 2017; 102:1143-1157. [PMID: 28699679 DOI: 10.1113/ep086441] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Accepted: 06/30/2017] [Indexed: 01/12/2023]
Abstract
NEW FINDINGS What is the central question of this study? It is suggested that remote ischemic preconditioning (RIPC) might offer protection against ischaemia-reperfusion injuries, but the utility of RIPC in high-altitude settings remains unclear. What is the main finding and its importance? We found that RIPC offers no vascular protection relative to pulmonary artery pressure or peripheral endothelial function during acute, normobaric hypoxia and at high altitude in young, healthy adults. However, peripheral chemosensitivity was heightened 24 h after RIPC at high altitude. Application of repeated short-duration bouts of ischaemia to the limbs, termed remote ischemic preconditioning (RIPC), is a novel technique that might have protective effects on vascular function during hypoxic exposures. In separate parallel-design studies, at sea level (SL; n = 16) and after 8-12 days at high altitude (HA; n = 12; White Mountain, 3800 m), participants underwent either a sham protocol or one session of four bouts of 5 min of dual-thigh-cuff occlusion with 5 min recovery. Brachial artery flow-mediated dilatation (FMD; ultrasound), pulmonary artery systolic pressure (PASP; echocardiography) and internal carotid artery (ICA) flow (ultrasound) were measured at SL in normoxia and isocapnic hypoxia (end-tidal PO2 maintained at 50 mmHg) and during normal breathing at HA. The hypoxic ventilatory response (HVR) was measured at each location. All measures at SL and HA were obtained at baseline (BL) and at 1, 24 and 48 h post-RIPC or sham. At SL, RIPC produced no changes in FMD, PASP, ICA flow, end-tidal gases or HVR in normoxia or hypoxia. At HA, although HVR increased 24 h post-RIPC compared with BL [2.05 ± 1.4 versus 3.21 ± 1.2 l min-1 (% arterial O2 saturation)-1 , P < 0.01], there were no significant differences in FMD, PASP, ICA flow and resting end-tidal gases. Accordingly, a single session of RIPC is insufficient to evoke changes in peripheral, pulmonary and cerebral vascular function in healthy adults. Although chemosensitivity might increase after RIPC at HA, this did not confer any vascular changes. The utility of a single RIPC session seems unremarkable during acute and chronic hypoxia.
Collapse
Affiliation(s)
- Mathew G Rieger
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Mike Stembridge
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, UK
| | - Anthony R Bain
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada.,University of Colorado, Boulder, Department of Integrative Physiology, Integrative Vascular Biology Laboratory, Boulder, CO, USA
| | - Daniela Flück
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Prajan Subedi
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System, Loma Linda, CA, USA
| | - James D Anholm
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System, Loma Linda, CA, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| |
Collapse
|
273
|
Intra-individual variability in cerebrovascular and respiratory chemosensitivity: Can we characterize a chemoreflex “reactivity profile”? Respir Physiol Neurobiol 2017; 242:30-39. [DOI: 10.1016/j.resp.2017.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/14/2017] [Accepted: 02/24/2017] [Indexed: 01/05/2023]
|
274
|
PARFITT RHODRI, HENSMAN MARIANNEY, LUCAS SAMUELJE. Cerebral Blood Flow Responses to Aquatic Treadmill Exercise. Med Sci Sports Exerc 2017; 49:1305-1312. [DOI: 10.1249/mss.0000000000001230] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
275
|
Hoiland RL, Smith KJ, Carter HH, Lewis NC, Tymko MM, Wildfong KW, Bain AR, Green DJ, Ainslie PN. Shear-mediated dilation of the internal carotid artery occurs independent of hypercapnia. Am J Physiol Heart Circ Physiol 2017; 313:H24-H31. [DOI: 10.1152/ajpheart.00119.2017] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 04/03/2017] [Accepted: 04/03/2017] [Indexed: 12/29/2022]
Abstract
Evidence for shear stress as a regulator of carotid artery dilation in response to increased arterial CO2 was recently demonstrated in humans during sustained elevations in CO2 (hypercapnia); however, the relative contributions of CO2 and shear stress to this response remains unclear. We examined the hypothesis that, after a 30-s transient increase in arterial CO2 tension and consequent increase in internal carotid artery shear stress, internal carotid artery diameter would increase, indicating shear-mediated dilation, in the absence of concurrent hypercapnia. In 27 healthy participants, partial pressures of end-tidal O2 and CO2, ventilation (pneumotachography), blood pressure (finger photoplethysmography), heart rate (electrocardiogram), internal carotid artery flow, diameter, and shear stress (high-resolution duplex ultrasound), and middle cerebral artery blood velocity (transcranial Doppler) were measured during 4-min steady-state and transient 30-s hypercapnic tests (both +9 mmHg CO2). Internal carotid artery dilation was lower in the transient compared with steady-state hypercapnia (3.3 ± 1.9 vs. 5.3 ± 2.9%, respectively, P < 0.03). Increases in internal carotid artery shear stress preceded increases in diameter in both transient (time: 16.8 ± 13.2 vs. 59.4 ± 60.3 s, P < 0.01) and steady-state (time: 18.2 ± 14.2 vs. 110.3 ± 79.6 s, P < 0.01) tests. Internal carotid artery dilation was positively correlated with shear rate area under the curve in the transient ( r2 = 0.44, P < 0.01) but not steady-state ( r2 = 0.02, P = 0.53) trial. Collectively, these results suggest that hypercapnia induces shear-mediated dilation of the internal carotid artery in humans. This study further promotes the application and development of hypercapnia as a clinical strategy for the assessment of cerebrovascular vasodilatory function and health in humans. NEW & NOTEWORTHY Shear stress dilates the internal carotid artery in humans. This vasodilatory response occurs independent of other physiological factors, as demonstrated by our transient CO2 test, and is strongly correlated to shear area under the curve. Assessing carotid shear-mediated dilation may provide a future avenue for assessing cerebrovascular health and the risk of cerebrovascular events.
Collapse
Affiliation(s)
- Ryan L. Hoiland
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Kurt J. Smith
- School of Sport Science, Exercise, and Health, The University of Western Australia, Crawley, Western Australia, Australia
| | - Howard H. Carter
- Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Nia C.S. Lewis
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Michael M. Tymko
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Kevin W. Wildfong
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Anthony R. Bain
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
- Integrative Vascular Biology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado; and
| | - Daniel J. Green
- School of Sport Science, Exercise, and Health, The University of Western Australia, Crawley, Western Australia, Australia
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Philip N. Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| |
Collapse
|
276
|
Flück D, Ainslie PN, Bain AR, Wildfong KW, Morris LE, Fisher JP. Extra- and intracranial blood flow regulation during the cold pressor test: influence of age. J Appl Physiol (1985) 2017; 123:1071-1080. [PMID: 28663374 DOI: 10.1152/japplphysiol.00224.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/30/2017] [Accepted: 06/26/2017] [Indexed: 11/22/2022] Open
Abstract
We determined how the extra- and intracranial circulations respond to generalized sympathetic activation evoked by a cold pressor test (CPT) and whether this is affected by healthy aging. Ten young [23 ± 2 yr (means ± SD)] and nine older (66 ± 3 yr) individuals performed a 3-min CPT by immersing the left foot into 0.8 ± 0.3°C water. Common carotid artery (CCA) and internal carotid artery (ICA) diameter, velocity, and flow were simultaneously measured (duplex ultrasound) along with middle cerebral artery and posterior cerebral artery mean blood velocity (MCAvmean and PCAvmean) and cardiorespiratory variables. The increases in heart rate (~6 beats/min) and mean arterial blood pressure (~14 mmHg) were similar in young and older groups during the CPT (P < 0.01 vs. baseline). In the young group, the CPT elicited an ~5% increase in CCA diameter (P < 0.01 vs. baseline) and a tendency for an increase in CCA flow (~12%, P = 0.08); in contrast, both diameter and flow remained unchanged in the older group. Although ICA diameter was not changed during the CPT in either group, ICA flow increased (~8%, P = 0.02) during the first minute of the CPT in both groups. Whereas the CPT elicited an increase in MCAvmean and PCAvmean in the young group (by ~20 and ~10%, respectively, P < 0.01 vs. baseline), these intracranial velocities were unchanged in the older group. Collectively, during the CPT, these findings suggest a differential mechanism(s) of regulation between the ICA compared with the CCA in young individuals and a blunting of the CCA and intracranial responses in older individuals.NEW & NOTEWORTHY Sympathetic activation evoked by a cold pressor test elicits heterogeneous extra- and intracranial blood vessel responses in young individuals that may serve an important protective role. The extra- and intracranial responses to the cold pressor test are blunted in older individuals.
Collapse
Affiliation(s)
- Daniela Flück
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada; and
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada; and
| | - Anthony R Bain
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada; and
| | - Kevin W Wildfong
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada; and
| | - Laura E Morris
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada; and
| | - James P Fisher
- School of Sport, Exercise, and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| |
Collapse
|
277
|
Whittaker JR, Bright MG, Driver ID, Babic A, Khot S, Murphy K. Changes in arterial cerebral blood volume during lower body negative pressure measured with MRI. Neuroimage 2017; 187:166-175. [PMID: 28668343 PMCID: PMC6414398 DOI: 10.1016/j.neuroimage.2017.06.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/19/2017] [Indexed: 01/12/2023] Open
Abstract
Cerebral Autoregulation (CA), defined as the ability of the cerebral vasculature to maintain stable levels of blood flow despite changes in systemic blood pressure, is a critical factor in neurophysiological health. Magnetic resonance imaging (MRI) is a powerful technique for investigating cerebrovascular function, offering high spatial resolution and wide fields of view (FOV), yet it is relatively underutilized as a tool for assessment of CA. The aim of this study was to demonstrate the potential of using MRI to measure changes in cerebrovascular resistance in response to lower body negative pressure (LBNP). A Pulsed Arterial Spin Labeling (PASL) approach with short inversion times (TI) was used to estimate cerebral arterial blood volume (CBVa) in eight healthy subjects at baseline and −40 mmHg LBNP. We estimated group mean CBVa values of 3.13 ± 1.00 and 2.70 ± 0.38 for baseline and lbnp respectively, which were the result of a differential change in CBVa during −40 mmHg LBNP that was dependent on baseline CBVa. These data suggest that the PASL CBVa estimates are sensitive to the complex cerebrovascular response that occurs during the moderate orthostatic challenge delivered by LBNP, which we speculatively propose may involve differential changes in vascular tone within different segments of the arterial vasculature. These novel data provide invaluable insight into the mechanisms that regulate perfusion of the brain, and establishes the use of MRI as a tool for studying CA in more detail.
Collapse
Affiliation(s)
- Joseph R Whittaker
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff CF24 4HQ, United Kingdom; Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and Astronomy, Cardiff University, Queen's Buildings, The Parade, Cardiff CF24 3AA, United Kingdom.
| | - Molly G Bright
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham NG7 2RD, United Kingdom; Division of Clinical Neurosciences, School of Medicine, University of Nottingham, Nottingham NG7 2UH, United Kingdom
| | - Ian D Driver
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff CF24 4HQ, United Kingdom
| | - Adele Babic
- Department of Anaesthesia and Intensive Care Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Sharmila Khot
- Department of Anaesthesia and Intensive Care Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Kevin Murphy
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff CF24 4HQ, United Kingdom; Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and Astronomy, Cardiff University, Queen's Buildings, The Parade, Cardiff CF24 3AA, United Kingdom
| |
Collapse
|
278
|
Flück D, Morris LE, Niroula S, Tallon CM, Sherpa KT, Stembridge M, Ainslie PN, McManus AM. UBC-Nepal expedition: markedly lower cerebral blood flow in high-altitude Sherpa children compared with children residing at sea level. J Appl Physiol (1985) 2017; 123:1003-1010. [PMID: 28572497 DOI: 10.1152/japplphysiol.00292.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/28/2017] [Accepted: 05/30/2017] [Indexed: 12/12/2022] Open
Abstract
Developmental cerebral hemodynamic adaptations to chronic high-altitude exposure, such as in the Sherpa population, are largely unknown. To examine hemodynamic adaptations in the developing human brain, we assessed common carotid (CCA), internal carotid (ICA), and vertebral artery (VA) flow and middle cerebral artery (MCA) velocity in 25 (9.6 ± 1.0 yr old, 129 ± 9 cm, 27 ± 8 kg, 14 girls) Sherpa children (3,800 m, Nepal) and 25 (9.9 ± 0.7 yr old, 143 ± 7 cm, 34 ± 6 kg, 14 girls) age-matched sea level children (344 m, Canada) during supine rest. Resting gas exchange, blood pressure, oxygen saturation and heart rate were assessed. Despite comparable age, height and weight were lower (both P < 0.01) in Sherpa compared with sea level children. Mean arterial pressure, heart rate, and ventilation were similar, whereas oxygen saturation (95 ± 2 vs. 99 ± 1%, P < 0.01) and end-tidal Pco2 (24 ± 3 vs. 36 ± 3 Torr, P < 0.01) were lower in Sherpa children. Global cerebral blood flow was ∼30% lower in Sherpa compared with sea level children. This was reflected in a lower ICA flow (283 ± 108 vs. 333 ± 56 ml/min, P = 0.05), VA flow (78 ± 26 vs. 118 ± 35 ml/min, P < 0.05), and MCA velocity (72 ± 14 vs. 88 ± 14 cm/s, P < 0.01). CCA flow was similar between Sherpa and sea level children (425 ± 92 vs. 441 ± 81 ml/min, P = 0.52). Scaling flow and oxygen uptake for differences in vessel diameter and body size, respectively, led to the same findings. A lower cerebral blood flow in Sherpa children may reflect specific cerebral hemodynamic adaptations to chronic hypoxia.NEW & NOTEWORTHY Cerebral blood flow is lower in Sherpa children compared with children residing at sea level; this may reflect a cerebral hemodynamic pattern, potentially due to adaptation to a hypoxic environment.
Collapse
Affiliation(s)
- Daniela Flück
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada;
| | - Laura E Morris
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Shailesh Niroula
- Institute of Medicine, Tribhuvan University, Kirtipur, Nepal.,Khunde Hospital, Khunde, Nepal; and
| | - Christine M Tallon
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| | | | - Mike Stembridge
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Ali M McManus
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| |
Collapse
|
279
|
Jenks CL, Hernandez A, Stavinoha PL, Morris MC, Tian F, Liu H, Garg P, Forbess JM, Koch J. Elevated cranial ultrasound resistive indices are associated with improved neurodevelopmental outcomes one year after pediatric cardiac surgery: A single center pilot study. Heart Lung 2017; 46:251-257. [PMID: 28511778 DOI: 10.1016/j.hrtlng.2017.04.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 10/19/2022]
Abstract
OBJECTIVE To determine if a non-invasive, repeatable test can be used to predict neurodevelopmental outcomes in patients with congenital heart disease. METHODS This was a prospective study of pediatric patients less than two months of age undergoing congenital heart surgery at the Children's Health Children's Medical Center at Dallas. Multichannel near-infrared spectroscopy (NIRS) was utilized during the surgery, and ultrasound (US) resistive indices (RI) of the major cranial vessels were obtained prior to surgery, immediately post-operatively, and prior to discharge. Pearson's correlation, Fischer exact t test, and Fischer r to z transformation were used where appropriate. RESULTS A total of 16 patients were enrolled. All had US data. Of the sixteen patients, two died prior to the neurodevelopmental testing, six did not return for the neurodevelopmental testing, and eight patients completed the neurodevelopmental testing. There were no significant correlations between the prior to surgery and prior to discharge US RI and neurodevelopmental outcomes. The immediate post-operative US RI demonstrated a strong positive correlation with standardized neurodevelopmental outcome measures. We were able to demonstrate qualitative differences using multichannel NIRS during surgery, but experienced significant technical difficulties implementing consistent monitoring. CONCLUSIONS A higher resistive index in the major cerebral blood vessels following cardiac surgery in the neonatal period is associated with improved neurological outcomes one year after surgery. Obtaining an ultrasound with resistive indices of the major cerebral vessels prior to and after surgery may yield information that is predictive of neurodevelopmental outcomes.
Collapse
Affiliation(s)
- Christopher L Jenks
- Department of Pediatrics, Division of Critical Care Medicine, Baylor College of Medicine, Texas Children's Hospital, USA.
| | | | - Peter L Stavinoha
- Department of Psychiatry, University of Texas Southwestern Medical Center and Children's Health, Children's Medical Center at Dallas, USA
| | - Michael C Morris
- Department of Radiology, University of Texas Southwestern Medical Center and Children's Health, Children's Medical Center at Dallas, USA
| | - Fenghua Tian
- Department of Bioengineering, University of Texas at Arlington, USA
| | - Hanli Liu
- Department of Bioengineering, University of Texas at Arlington, USA
| | - Parvesh Garg
- Department of Pediatrics, Ichan School of Medicine, Elmhurst Hospital Center, USA
| | - Joseph M Forbess
- Department of Cardiovascular and Thoracic Surgery, Division of Pediatric Cardiothoracic, University of Texas Southwestern Medical Center and Children's Health, Children's Medical Center at Dallas, USA
| | - Joshua Koch
- Department of Pediatrics, Division of Critical Care Medicine, University of Texas Southwestern Medical Center, Children's Health Children's Medical Center at Dallas, USA
| |
Collapse
|
280
|
Connaughton VM, Amiruddin A, Clunies-Ross KL, French N, Fox AM. Assessing hemispheric specialization for processing arithmetic skills in adults: A functional transcranial doppler ultrasonography (fTCD) study. J Neurosci Methods 2017; 283:33-41. [DOI: 10.1016/j.jneumeth.2017.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 03/08/2017] [Accepted: 03/09/2017] [Indexed: 12/29/2022]
|
281
|
Middle cerebral artery blood flow velocity during a 4 km cycling time trial. Eur J Appl Physiol 2017; 117:1241-1248. [DOI: 10.1007/s00421-017-3612-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 04/10/2017] [Indexed: 11/26/2022]
|
282
|
Ellis LA, Ainslie PN, Armstrong VA, Morris LE, Simair RG, Sletten NR, Tallon CM, McManus AM. Anterior cerebral blood velocity and end-tidal CO 2 responses to exercise differ in children and adults. Am J Physiol Heart Circ Physiol 2017; 312:H1195-H1202. [PMID: 28389601 DOI: 10.1152/ajpheart.00034.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 03/24/2017] [Accepted: 03/28/2017] [Indexed: 11/22/2022]
Abstract
Little is known about the response of the cerebrovasculature to acute exercise in children and how these responses might differ with adults. Therefore, we compared changes in middle cerebral artery blood velocity (MCAVmean), end-tidal Pco2 ([Formula: see text]), blood pressure, and minute ventilation (V̇e) in response to incremental exercise between children and adults. Thirteen children [age: 9 ± 1 (SD) yr] and thirteen sex-matched adults (age: 25 ± 4 yr) completed a maximal exercise test, during which MCAVmean, [Formula: see text], and V̇e were measured continuously. These variables were measured at rest, at exercise intensities specific to individual ventilatory thresholds, and at maximum. Although MCAVmean was higher at rest in children compared with adults, there were smaller increases in children (1-12%) compared with adults (12-25%) at all exercise intensities. There were alterations in [Formula: see text] with exercise intensity in an age-dependent manner [F(2.5,54.5) = 7.983, P < 0.001; η2 = 0.266], remaining stable in children with increasing exercise intensity (37-39 mmHg; P > 0.05) until hyperventilation-induced reductions following the respiratory compensation point. In adults, [Formula: see text] increased with exercise intensity (36-45 mmHg, P < 0.05) until the ventilatory threshold. From the ventilatory threshold to maximum, adults showed a greater hyperventilation-induced hypocapnia than children. These findings show that the relative increase in MCAVmean during exercise was attenuated in children compared with adults. There was also a weaker relationship between MCAVmean and [Formula: see text] during exercise in children, suggesting that cerebral perfusion may be regulated by different mechanisms during exercise in the child.NEW & NOTEWORTHY These findings provide the first direct evidence that exercise increases cerebral blood flow in children to a lesser extent than in adults. Changes in end-tidal CO2 parallel changes in cerebral perfusion in adults but not in children, suggesting age-dependent regulatory mechanisms of cerebral blood flow during exercise.
Collapse
Affiliation(s)
- Lindsay A Ellis
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, 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
| | - Victoria A Armstrong
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Laura E Morris
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Ryan G Simair
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Nathan R Sletten
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Christine M Tallon
- 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
| |
Collapse
|
283
|
Romac R, Barak O, Glavas D, Susilovic Grabovac Z, Lozo P, Roje I, Caljkusic K, Drmic-Hofman I, Davis JT, Dujic Z, Lovering AT. Characterization of blood flow through intrapulmonary arteriovenous anastomoses and patent foramen ovale at rest and during exercise in stroke and transient ischemic attack patients. Echocardiography 2017; 34:676-682. [DOI: 10.1111/echo.13519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Rinaldo Romac
- Department of Neurology; University Hospital Center Split; Split Croatia
| | - Otto Barak
- Department of Integrative Physiology; University of Split School of Medicine; Split Croatia
- Faculty of Medicine; University of Novi Sad; Novi Sad Serbia
| | - Duska Glavas
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Zora Susilovic Grabovac
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Petar Lozo
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Igor Roje
- Department of Neurology; University Hospital Center Split; Split Croatia
| | - Kresimir Caljkusic
- Department of Anesthesiology; University Hospital Center Split; Split Croatia
| | - Irena Drmic-Hofman
- Department of Pathology, Forensic Medicine and Cytology; University Hospital Center Split; Split Croatia
- Department of Medical Chemistry and Biochemistry; University of Split School of Medicine; Split Croatia
| | - James T. Davis
- Department of Kinesiology, Recreation and Sport; Indiana State University; Terre Haute IN USA
| | - Zeljko Dujic
- Department of Integrative Physiology; University of Split School of Medicine; Split Croatia
| | | |
Collapse
|
284
|
Niemann MJ, Sørensen H, Siebenmann C, Lundby C, Secher NH. Carbon monoxide reduces near-infrared spectroscopy determined ‘total’ hemoglobin: a human volunteer study. Scandinavian Journal of Clinical and Laboratory Investigation 2017; 77:259-262. [DOI: 10.1080/00365513.2017.1299209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
285
|
Tymko MM. How to build a lower-body differential pressure chamber integrated on a tilt-table: A pedagogy tool to demonstrate the cardiovagal baroreflex. Facets (Ott) 2017. [DOI: 10.1139/facets-2016-0012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The cardiovagal baroreflex is an important physiological reflex that is commonly taught in health-related university physiology courses. This reflex is responsible for the rapid maintenance of blood pressure through dynamic changes in heart rate (HR) and vascular resistance. The use of lower-body negative pressure (LBNP) and lower-body positive pressure (LBPP) can manipulate these stretch sensitive baroreceptors. High performance and relatively inexpensive homemade LBNP and LBPP chambers can be easily constructed providing a valuable tool for both research and teaching purposes. There has been previous documentation of how to build a LBNP chamber; however, the information available usually lacks appropriate construction details, and there is currently no literature on how to build a chamber that can accommodate both LBNP and LBPP. In addition, a recently developed novel LBNP/LBPP chamber positioned on a 360° tilt-table provided the unique utility of superimposing both LBNP/LBPP and body position as independent or combined stressors to alter central blood volume. The primary purposes of this manuscript are to (1) provide step-by-step instructions on how to build a tilt-table LBNP/LBPP chamber, and (2) demonstrate the effectiveness of a tilt-table LBNP/LBPP chamber to facilitate undergraduate and graduate learning in the laboratory by effectively demonstrating the cardiovagal baroreflex.
Collapse
Affiliation(s)
- Michael M. Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, Faculty of Health and Social Development, University of British Columbia, 3333 University Way, Kelowna, BC V1V 1V7, Canada
| |
Collapse
|
286
|
Washio T, Sasaki H, Ogoh S. Transcranial Doppler-determined change in posterior cerebral artery blood flow velocity does not reflect vertebral artery blood flow during exercise. Am J Physiol Heart Circ Physiol 2017; 312:H827-H831. [PMID: 28188214 DOI: 10.1152/ajpheart.00676.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 11/22/2022]
Abstract
We examined whether a change in posterior cerebral artery flow velocity (PCAv) reflected the posterior cerebral blood flow in healthy subjects during both static and dynamic exercise. PCAv and vertebral artery (VA) blood flow, as an index of posterior cerebral blood flow, were continuously measured during an exercise trial using transcranial Doppler (TCD) ultrasonography and Doppler ultrasound, respectively. Static handgrip exercise significantly increased both PCAv and VA blood flow. Increasing intensity of dynamic exercise further increased VA blood flow from moderate exercise, while PCAv decreased to almost resting level. During both static and dynamic exercise, the PCA cerebrovascular conductance (CVC) index significantly decreased from rest (static and high-intensity dynamic exercise, -11.5 ± 12.2% and -18.0 ± 16.8%, means ± SD, respectively) despite no change in the CVC of VA. These results indicate that vasoconstriction occurred at PCA but not VA during exercise-induced hypertension. This discrepancy in vascular response to exercise between PCA and VA may be due to different cerebral arterial characteristics. Therefore, to determine the effect of exercise on posterior cerebral circulation, at least, we need to carefully consider which cerebral artery to measure, regardless of exercise mode.NEW & NOTEWORTHY We examined whether transcranial Doppler-determined flow velocity in the posterior cerebral artery can be used as an index of cerebral blood flow during exercise. However, the changes in posterior cerebral artery flow velocity during exercise do not reflect vertebral artery blood flow.
Collapse
Affiliation(s)
- Takuro Washio
- Department of Biomedical Engineering, Toyo University, Kawagoe-shi, Japan
| | - Hiroyuki Sasaki
- Department of Biomedical Engineering, Toyo University, Kawagoe-shi, Japan
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-shi, Japan
| |
Collapse
|
287
|
Imhoff S, Malenfant S, Nadreau É, Poirier P, Bailey DM, Brassard P. Uncoupling between cerebral perfusion and oxygenation during incremental exercise in an athlete with postconcussion syndrome: a case report. Physiol Rep 2017; 5:5/2/e13131. [PMID: 28122826 PMCID: PMC5269417 DOI: 10.14814/phy2.13131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 12/21/2016] [Accepted: 12/23/2016] [Indexed: 11/24/2022] Open
Abstract
High-intensity exercise may pose a risk to patients with postconcussion syndrome (PCS) when symptomatic during exertion. The case of a paralympic athlete with PCS who experienced a succession of convulsion-awakening periods and reported a marked increase in postconcussion symptoms after undergoing a graded symptom-limited aerobic exercise protocol is presented. Potential mechanisms of cerebrovascular function failure are then discussed.
Collapse
Affiliation(s)
- Sarah Imhoff
- Department of Kinesiology, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada.,Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada
| | - Simon Malenfant
- Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada.,Pulmonary Hypertension Research Group, Quebec Heart and Lungs Institute Research Center, Laval University, Quebec City, Quebec, Canada
| | - Éric Nadreau
- Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada
| | - Paul Poirier
- Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, South Wales, United Kingdom.,Sondes Moléculaires en Biologie, Laboratoire Chimie Provence UMR 6264 CNRS, Université de Provence Marseille, Marseille, France
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada .,Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada
| |
Collapse
|
288
|
Hoiland RL, Bain AR, Tymko MM, Rieger MG, Howe CA, Willie CK, Hansen AB, Flück D, Wildfong KW, Stembridge M, Subedi P, Anholm J, Ainslie PN. Adenosine receptor-dependent signaling is not obligatory for normobaric and hypobaric hypoxia-induced cerebral vasodilation in humans. J Appl Physiol (1985) 2017; 122:795-808. [PMID: 28082335 DOI: 10.1152/japplphysiol.00840.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 01/09/2017] [Accepted: 01/09/2017] [Indexed: 01/11/2023] Open
Abstract
Hypoxia increases cerebral blood flow (CBF) with the underlying signaling processes potentially including adenosine. A randomized, double-blinded, and placebo-controlled design, was implemented to determine if adenosine receptor antagonism (theophylline, 3.75 mg/Kg) would reduce the CBF response to normobaric and hypobaric hypoxia. In 12 participants the partial pressures of end-tidal oxygen ([Formula: see text]) and carbon dioxide ([Formula: see text]), ventilation (pneumotachography), blood pressure (finger photoplethysmography), heart rate (electrocardiogram), CBF (duplex ultrasound), and intracranial blood velocities (transcranial Doppler ultrasound) were measured during 5-min stages of isocapnic hypoxia at sea level (98, 90, 80, and 70% [Formula: see text]). Ventilation, [Formula: see text] and [Formula: see text], blood pressure, heart rate, and CBF were also measured upon exposure (128 ± 31 min following arrival) to high altitude (3,800 m) and 6 h following theophylline administration. At sea level, although the CBF response to hypoxia was unaltered pre- and postplacebo, it was reduced following theophylline (P < 0.01), a finding explained by a lower [Formula: see text] (P < 0.01). Upon mathematical correction for [Formula: see text], the CBF response to hypoxia was unaltered following theophylline. Cerebrovascular reactivity to hypoxia (i.e., response slope) was not different between trials, irrespective of [Formula: see text] At high altitude, theophylline (n = 6) had no effect on CBF compared with placebo (n = 6) when end-tidal gases were comparable (P > 0.05). We conclude that adenosine receptor-dependent signaling is not obligatory for cerebral hypoxic vasodilation in humans.NEW & NOTEWORTHY The signaling pathways that regulate human cerebral blood flow in hypoxia remain poorly understood. Using a randomized, double-blinded, and placebo-controlled study design, we determined that adenosine receptor-dependent signaling is not obligatory for the regulation of human cerebral blood flow at sea level; these findings also extend to high altitude.
Collapse
Affiliation(s)
- Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada;
| | - Anthony R Bain
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Mathew G Rieger
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Christopher K Willie
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Alex B Hansen
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Daniela Flück
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Kevin W Wildfong
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| | - Mike Stembridge
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, United Kingdom; and
| | - Prajan Subedi
- VA Loma Linda Healthcare System and Loma Linda University School of Medicine, Loma Linda, California
| | - James Anholm
- VA Loma Linda Healthcare System and Loma Linda University School of Medicine, Loma Linda, California
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, School of Health and Exercise Sciences, Kelowna, British Columbia, Canada
| |
Collapse
|
289
|
Letra L, Sena C. Cerebrovascular Disease: Consequences of Obesity-Induced Endothelial Dysfunction. ADVANCES IN NEUROBIOLOGY 2017; 19:163-189. [PMID: 28933065 DOI: 10.1007/978-3-319-63260-5_7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Despite the well-known global impact of overweight and obesity in the incidence of cerebrovascular disease, many aspects of this association are still inconsistently defined. In this chapter we aim to present a critical review on the links between obesity and both ischemic and hemorrhagic stroke and discuss its influence on functional outcomes, survival, and current treatments to acute and chronic stroke. The role of cerebrovascular endothelial function and respective modulation is also described as well as its laboratory and clinical assessment. In this context, the major contributing mechanisms underlying obesity-induced cerebral endothelial function (adipokine secretion, insulin resistance, inflammation, and hypertension) are discussed. A special emphasis is given to the participation of adipokines in the pathophysiology of stroke, namely adiponectin, leptin, resistin, apelin, and visfatin.
Collapse
Affiliation(s)
- Liliana Letra
- Institute of Physiology, Institute for Biomedical Imaging and Life Sciences-IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal. .,Neurology Department, Centro Hospitalar do Baixo Vouga, Aveiro, Portugal.
| | - Cristina Sena
- Institute of Physiology, Institute for Biomedical Imaging and Life Sciences-IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| |
Collapse
|
290
|
Bruce CD, Steinback CD, Chauhan UV, Pfoh JR, Abrosimova M, Vanden Berg ER, Skow RJ, Davenport MH, Day TA. Quantifying cerebrovascular reactivity in anterior and posterior cerebral circulations during voluntary breath holding. Exp Physiol 2016; 101:1517-1527. [DOI: 10.1113/ep085764] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 09/05/2016] [Indexed: 12/12/2022]
Affiliation(s)
- Christina D. Bruce
- Department of Biology; Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Craig D. Steinback
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Uday V. Chauhan
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Jamie R. Pfoh
- Department of Biology; Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Maria Abrosimova
- Department of Biology; Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Emily R. Vanden Berg
- Department of Biology; Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- Department of Biology; Faculty of Science; University of Victoria; Victoria BC Canada
| | - Rachel J. Skow
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Margie H. Davenport
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Trevor A. Day
- Department of Biology; Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| |
Collapse
|
291
|
Carter HH, Atkinson CL, Heinonen IH, Haynes A, Robey E, Smith KJ, Ainslie PN, Hoiland RL, Green DJ. Evidence for Shear Stress–Mediated Dilation of the Internal Carotid Artery in Humans. Hypertension 2016; 68:1217-1224. [DOI: 10.1161/hypertensionaha.116.07698] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 08/09/2016] [Indexed: 12/29/2022]
Abstract
Increases in arterial carbon dioxide tension (hypercapnia) elicit potent vasodilation of cerebral arterioles. Recent studies have also reported vasodilation of the internal carotid artery during hypercapnia, but the mechanism(s) mediating this extracranial vasoreactivity are unknown. Hypercapnia increases carotid shear stress, a known stimulus to vasodilation in other conduit arteries. To explore the hypothesis that shear stress contributes to hypercapnic internal carotid dilation in humans, temporal changes in internal and common carotid shear rate and diameter, along with changes in middle cerebral artery velocity, were simultaneously assessed in 18 subjects at rest and during hypercapnia (6% carbon dioxide). Middle cerebral artery velocity increased significantly (69±10–103±17 cm/s;
P
<0.01) along with shear in both the internal (316±52–518±105 1/s;
P
<0.01) and common (188±40–275±61 1/s;
P
<0.01) carotids. Diameter also increased (
P
<0.01) in both carotid arteries (internal: +6.3±2.9%; common: +5.8±3.0%). Following hypercapnia onset, there was a significant delay between the onset of internal carotid shear (22±12 seconds) and diameter change (85±51 seconds). This time course is associated with shear-mediated dilation of larger conduit arteries in humans. There was a strong association between change in shear and diameter of the internal carotid (
r
=0.68;
P
<0.01). These data indicate, for the first time in humans, that shear stress is an important stimulus for hypercapnic vasodilation of the internal carotid artery. The combination of a hypercapnic stimulus and continuous noninvasive, high-resolution assessment of internal carotid shear and dilation may provide novel insights into the function and health of the clinically important extracranial arteries in humans.
Collapse
Affiliation(s)
- Howard H. Carter
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| | - Ceri L. Atkinson
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| | - Ilkka H.A. Heinonen
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| | - Andrew Haynes
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| | - Elisa Robey
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| | - Kurt J. Smith
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| | - Philip N. Ainslie
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| | - Ryan L. Hoiland
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| | - Daniel J. Green
- From the School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia (H.H.C., C.L.A., I.H.A.H., A.H., E.R., K.J.S., R.L.H., D.J.G.); Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark (H.H.C.); Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada (K.J.S., P.N.A., R.L.H.); and Research Institute for Sport and Exercise Science, Liverpool John Moores University
| |
Collapse
|
292
|
Smirl JD, Wright AD, Bryk K, van Donkelaar P. Where ’ s Waldo ? The utility of a complicated visual search paradigm for transcranial Doppler-based assessments of neurovascular coupling. J Neurosci Methods 2016; 270:92-101. [DOI: 10.1016/j.jneumeth.2016.06.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 06/07/2016] [Accepted: 06/08/2016] [Indexed: 01/22/2023]
|
293
|
Oldag A, Neumann J, Goertler M, Hinrichs H, Heinze HJ, Kupsch A, Sweeney-Reed CM, Kopitzki K. Near-infrared spectroscopy and transcranial sonography to evaluate cerebral autoregulation in middle cerebral artery steno-occlusive disease. J Neurol 2016; 263:2296-2301. [PMID: 27544503 DOI: 10.1007/s00415-016-8262-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 08/06/2016] [Accepted: 08/08/2016] [Indexed: 10/21/2022]
Abstract
The measurement of autoregulatory delay by near-infrared spectroscopy (NIRS) has been proposed as an alternative technique to assess cerebral autoregulation, which is routinely assessed via transcranial Doppler sonography (TCD) in most centers. Comparitive studies of NIRS and TCD, however, are largely missing. We investigated whether cerebrovascular reserve (CVR), as assessed via TCD, correlates with the delay of the autoregulatory response to changes in arterial blood pressure (ABP) as assessed by NIRS, i.e., if impaired upstream vasomotor reactivity is reflected by downstream cortical autoregulation. Twenty patients with unilateral high-grade steno-occlusion of the middle cerebral artery (MCA) underwent bilateral multichannel NIRS of the cortical MCA distributions over a period of 6 min while breathing at a constant rate of 6 cycles/min to induce stable oscillations in ABP. The phase shift φ between ABP and cortical blood oxygenation was calculated as a measure of autoregulatory latency. In a subgroup of 13 patients, CO2 reactivity of the MCAs was determined by TCD to assess CVR in terms of normalized autoregulatory response (NAR). Mean phase shift between ABP and blood oxygenation was significantly increased over the hemisphere ipsilateral to the steno-occlusion (n = 20, p = 0.042). The interhemispheric difference Δφ in phase shift was significantly larger in patients with markedly diminished or exhausted CVR (NAR < 10) than in patients with normal NAR values (NAR ≥ 10) (p = 0.007). Within the MCA core distribution territory, a strong correlation existed between Δφ and CO2 reactivity of the affected MCA (n = 13, r = -0.78, p = 0.011). NIRS may provide an alternative or supplementary approach to evaluate cerebral autoregulation in risk assessment of ischemic events in steno-occlusive disease of cerebral arteries, especially in patients with insufficient bone windows for TCD.
Collapse
Affiliation(s)
- Andreas Oldag
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Jens Neumann
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Michael Goertler
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany.,Leibniz Institute for Neurobiology, Brenneckestrasse 6, 39118, Magdeburg, Germany
| | - Hermann Hinrichs
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany.,Leibniz Institute for Neurobiology, Brenneckestrasse 6, 39118, Magdeburg, Germany
| | - Hans-Jochen Heinze
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany.,Leibniz Institute for Neurobiology, Brenneckestrasse 6, 39118, Magdeburg, Germany.,German Center for Neurodegenerative Diseases (DZNE), Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Andreas Kupsch
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Catherine M Sweeney-Reed
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Klaus Kopitzki
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany. .,Leibniz Institute for Neurobiology, Brenneckestrasse 6, 39118, Magdeburg, Germany.
| |
Collapse
|
294
|
Addison PS, Antunes A, Montgomery D, Borg UR. Gradient adjustment method for better discriminating correlating and non-correlating regions of physiological signals: application to the partitioning of impaired and intact zones of cerebral autoregulation. J Clin Monit Comput 2016; 31:727-737. [PMID: 27496051 PMCID: PMC5500687 DOI: 10.1007/s10877-016-9913-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 07/25/2016] [Indexed: 11/10/2022]
Abstract
Cerebral blood flow (CBF) is regulated over a range of systemic blood pressures by the cerebral autoregulation (CA) control mechanism. This range lies within the lower and upper limits of autoregulation (LLA, ULA), beyond which blood pressure drives CBF, and CA function is considered impaired. A standard method to determine autoregulation limits noninvasively using NIRS technology is via the COx measure: a moving correlation index between mean arterial pressure and regional oxygen saturation. In the intact region, there should be no correlation between these variables whereas in the impaired region, the correlation index should approximate unity. In practice, however, the data may be noisy and/or the intact region may often exhibit a slightly positive relationship. This positive relationship may render traditional autoregulation limit calculations difficult to perform, resulting in the need for manual interpretation of the data using arbitrary thresholds. Further, the underlying mathematics of the technique are asymmetric in terms of the results produced for impaired and intact regions and are, in fact, not computable for the ideal case within the intact region. In this work, we propose a novel gradient adjustment method (GACOx) to enhance the differences in COx values observed in the intact and impaired regions. Results from a porcine model (N = 8) are used to demonstrate that GACOx is successful in determining LLA values where traditional methods fail. It is shown that the derived GACOx indices exhibit a mean difference between the intact/impaired regions of 1.54 ± 0.26 (mean ± SD), compared to 0.14 ± 0.10 for the traditional COx method. The GACOx effectively polarizes the COx data in order to better differentiate the intact and impaired zones and, in doing so, makes the determination of the LLA and ULA points a simpler and more consistent task. The method lends itself to the automation of the robust determination of autoregulation zone limits.
Collapse
Affiliation(s)
- Paul S Addison
- Medtronic Respiratory and Monitoring Solutions, Edinburgh, Scotland, UK.
| | - André Antunes
- Medtronic Respiratory and Monitoring Solutions, Edinburgh, Scotland, UK
| | - Dean Montgomery
- Medtronic Respiratory and Monitoring Solutions, Edinburgh, Scotland, UK
| | - Ulf R Borg
- Medtronic Respiratory and Monitoring Solutions, Boulder, CO, USA
| |
Collapse
|
295
|
Abstract
Cerebral blood flow (CBF) regulation is an indicator of cerebrovascular health increasingly recognized as being influenced by physical activity. Although regular exercise is recommended during healthy pregnancy, the effects of exercise on CBF regulation during this critical period of important blood flow increase and redistribution remain incompletely understood. Moreover, only a few studies have evaluated the effects of human pregnancy on CBF regulation. The present work summarizes current knowledge on CBF regulation in humans at rest and during aerobic exercise in relation to healthy pregnancy. Important gaps in the literature are highlighted, emphasizing the need to conduct well-designed studies assessing cerebrovascular function before, during and after this crucial life period to evaluate the potential cerebrovascular risks and benefits of exercise during pregnancy.
Collapse
|
296
|
Exercise training reduces the frequency of menopausal hot flushes by improving thermoregulatory control. Menopause 2016; 23:708-18. [DOI: 10.1097/gme.0000000000000625] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
297
|
Boulet LM, Tymko MM, Jamieson AN, Ainslie PN, Skow RJ, Day TA. Influence of prior hyperventilation duration on respiratory chemosensitivity and cerebrovascular reactivity during modified hyperoxic rebreathing. Exp Physiol 2016; 101:821-35. [DOI: 10.1113/ep085706] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/16/2016] [Indexed: 12/30/2022]
Affiliation(s)
- Lindsey M. Boulet
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Michael M. Tymko
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Alenna N. Jamieson
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Philip N. Ainslie
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Rachel J. Skow
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Trevor A. Day
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| |
Collapse
|
298
|
Peng B, Li J, Wang J, Liang X, Zheng Z, Mai J. Changes in cerebral hemodynamics during a sleep-deprived video-electroencephalogram in healthy children. Physiol Meas 2016; 37:981-9. [DOI: 10.1088/0967-3334/37/7/981] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
|
299
|
Donnelly J, Budohoski KP, Smielewski P, Czosnyka M. Regulation of the cerebral circulation: bedside assessment and clinical implications. Crit Care 2016; 20:129. [PMID: 27145751 PMCID: PMC4857376 DOI: 10.1186/s13054-016-1293-6] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Regulation of the cerebral circulation relies on the complex interplay between cardiovascular, respiratory, and neural physiology. In health, these physiologic systems act to maintain an adequate cerebral blood flow (CBF) through modulation of hydrodynamic parameters; the resistance of cerebral vessels, and the arterial, intracranial, and venous pressures. In critical illness, however, one or more of these parameters can be compromised, raising the possibility of disturbed CBF regulation and its pathophysiologic sequelae. Rigorous assessment of the cerebral circulation requires not only measuring CBF and its hydrodynamic determinants but also assessing the stability of CBF in response to changes in arterial pressure (cerebral autoregulation), the reactivity of CBF to a vasodilator (carbon dioxide reactivity, for example), and the dynamic regulation of arterial pressure (baroreceptor sensitivity). Ideally, cerebral circulation monitors in critical care should be continuous, physically robust, allow for both regional and global CBF assessment, and be conducive to application at the bedside. Regulation of the cerebral circulation is impaired not only in primary neurologic conditions that affect the vasculature such as subarachnoid haemorrhage and stroke, but also in conditions that affect the regulation of intracranial pressure (such as traumatic brain injury and hydrocephalus) or arterial blood pressure (sepsis or cardiac dysfunction). Importantly, this impairment is often associated with poor patient outcome. At present, assessment of the cerebral circulation is primarily used as a research tool to elucidate pathophysiology or prognosis. However, when combined with other physiologic signals and online analytical techniques, cerebral circulation monitoring has the appealing potential to not only prognosticate patients, but also direct critical care management.
Collapse
Affiliation(s)
- Joseph Donnelly
- />Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Hills Road, Cambridge, CB2 0QQ UK
| | - Karol P. Budohoski
- />Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Hills Road, Cambridge, CB2 0QQ UK
| | - Peter Smielewski
- />Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Hills Road, Cambridge, CB2 0QQ UK
| | - Marek Czosnyka
- />Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Hills Road, Cambridge, CB2 0QQ UK
- />Institute of Electronic Systems, Warsaw University of Technology, ul. Nowowiejska 15/19, 00-665 Warsaw, Poland
| |
Collapse
|
300
|
Hoiland RL, Ainslie PN, Bain AR, MacLeod DB, Stembridge M, Drvis I, Madden D, Barak O, MacLeod DM, Dujic Z. β 1-Blockade increases maximal apnea duration in elite breath-hold divers. J Appl Physiol (1985) 2016; 122:899-906. [PMID: 27125844 DOI: 10.1152/japplphysiol.00127.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 04/04/2016] [Accepted: 04/26/2016] [Indexed: 11/22/2022] Open
Abstract
We hypothesized that the cardioselective β1-adrenoreceptor antagonist esmolol would improve maximal apnea duration in elite breath-hold divers. In elite national-level divers (n = 9), maximal apneas were performed in a randomized and counterbalanced order while receiving either iv esmolol (150 μg·kg-1·min-1) or volume-matched saline (placebo). During apnea, heart rate (ECG), beat-by-beat blood pressure, stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) were measured (finger photoplethysmography). Myocardial oxygen consumption (MV̇o2) was estimated from rate pressure product. Cerebral blood flow through the internal carotid (ICA) and vertebral arteries (VA) was assessed using Duplex ultrasound. Apnea duration improved in the esmolol trial when compared with placebo (356 ± 57 vs. 323 ± 61 s, P < 0.01) despite similar end-apnea peripheral oxyhemoglobin saturation (71.8 ± 10.3 vs. 74.9 ± 9.5%, P = 0.10). The HR response to apnea was reduced by esmolol at 10-30% of apnea duration, whereas MAP was unaffected. Esmolol reduced SV (main effect, P < 0.05) and CO (main effect; P < 0.05) and increased TPR (main effect, P < 0.05) throughout apnea. Esmolol also reduced MV̇o2 throughout apnea (main effect, P < 0.05). Cerebral blood flow through the ICA and VA was unchanged by esmolol at baseline and the last 30 s of apnea; however, global cerebral blood flow was reduced in the esmolol trial at end-apnea (P < 0.05). Our findings demonstrate that, in elite breath-hold divers, apnea breakpoint is improved by β1-blockade, likely owing to an improved total body oxygen sparring through increased centralization of blood volume (↑TPR) and reduced MV̇o2NEW & NOTEWORTHY The governing bodies for international apnea competition, the Association Internationale pour le Développment de l'Apnée and La Confédération Mondaile des Activités Subaquatiques, have banned the use of β-blockers based on anecdotal reports that they improve apnea duration. Using a randomized placebo-controlled trial, we are the first to empirically confirm that β-blockade improves apnea duration. This improvement in apnea duration coincided with a reduced myocardial oxygen consumption.
Collapse
Affiliation(s)
- Ryan L Hoiland
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada;
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Anthony R Bain
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - David B MacLeod
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina
| | - Mike Stembridge
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Ivan Drvis
- University of Zagreb School of Kinesiology, Zagreb, Croatia
| | - Dennis Madden
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Otto Barak
- Department of Physiology, University of Novi Sad School of Medicine, Novi Sad, Serbia; and
| | | | - Zeljko Dujic
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| |
Collapse
|