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Dynamic cerebral autoregulation during step-wise increases in blood pressure during anaesthesia: A nonrandomised interventional trial. Eur J Anaesthesiol 2023; 40:407-417. [PMID: 36655712 PMCID: PMC10155696 DOI: 10.1097/eja.0000000000001798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Classically, cerebral autoregulation (CA) entails cerebral blood flow (CBF) remaining constant by cerebrovascular tone adapting to fluctuations in mean arterial pressure (MAP) between ∼60 and ∼150 mmHg. However, this is not an on-off mechanism; previous work has suggested that vasomotor tone is proportionally related to CA function. During propofol-based anaesthesia, there is cerebrovascular vasoconstriction, and static CA remains intact. Sevoflurane-based anaesthesia induces cerebral vasodilation and attenuates CA dose-dependently. It is unclear how this translates to dynamic CA across a range of blood pressures in the autoregulatory range. OBJECTIVE The aim of this study was to quantify the effect of step-wise increases in MAP between 60 and 100 mmHg, using phenylephrine, on dynamic CA during propofol- and sevoflurane-based anaesthesia. DESIGN A nonrandomised interventional trial. SETTING Single centre enrolment started on 11 January 2019 and ended on 23 September 2019. PATIENTS We studied American Society of Anesthesiologists (ASA) I/II patients undergoing noncardiothoracic, nonneurosurgical and nonlaparoscopic surgery under general anaesthesia. INTERVENTION In this study, cerebrovascular tone was manipulated in the autoregulatory range by increasing MAP step-wise using phenylephrine in patients receiving either propofol- or sevoflurane-based anaesthesia. MAP and mean middle cerebral artery blood velocity (MCA Vmean ) were measured in ASA I and II patients, anaesthetised with either propofol ( n = 26) or sevoflurane ( n = 28), during 10 mmHg step-wise increments of MAP between 60 and 100 mmHg. Static CA was determined by plotting 2-min averaged MCA Vmean versus MAP. Dynamic CA was determined using transfer function analysis and expressed as the phase lead (°) between MAP and MCA Vmean oscillations, created with positive pressure ventilation with a frequency of 6 min -1 . MAIN OUTCOMES The primary outcome of this study was the response of dynamic CA during step-wise increases in MAP during propofol- and sevoflurane-based anaesthesia. RESULTS MAP levels achieved per step-wise increments were comparable between anaesthesia regiment (63 ± 3, 72 ± 2, 80 ± 2, 90 ± 2, 100 ± 3 mmHg, and 61 ± 4, 71 ± 2, 80 ± 2, 89 ± 2, 98 ± 4 mmHg for propofol and sevoflurane, respectively). MCA Vmean increased more during step-wise MAP increments for sevoflurane compared to propofol ( P ≤0.001). Dynamic CA improved during propofol (0.73° mmHg -1 , 95% CI 0.51 to 0.95; P ≤ 0.001)) and less pronounced during sevoflurane-based anaesthesia (0.21° mmHg -1 (95% CI 0.01 to 0.42, P = 0.04). CONCLUSIONS During general anaesthesia, dynamic CA is dependent on MAP, also within the autoregulatory range. This phenomenon was more pronounced during propofol anaesthesia than during sevoflurane. TRIAL REGISTRATION NCT03816072 ( https://clinicaltrials.gov/ct2/show/NCT03816072 ).
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The Influence of Carbon Dioxide on Cerebral Autoregulation During Sevoflurane-based Anesthesia in Patients With Type 2 Diabetes. J Neurosurg Anesthesiol 2023; 35:65-73. [PMID: 34387283 DOI: 10.1097/ana.0000000000000794] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/06/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Cerebral autoregulation (CA) continuously adjusts cerebrovascular resistance to maintain cerebral blood flow (CBF) constant despite changes in blood pressure. Also, CBF is proportional to changes in arterial carbon dioxide (CO 2 ) (cerebrovascular CO 2 reactivity). Hypercapnia elicits cerebral vasodilation that attenuates CA efficacy, while hypocapnia produces cerebral vasoconstriction that enhances CA efficacy. In this study, we quantified the influence of sevoflurane anesthesia on CO 2 reactivity and the CA-CO 2 relationship. METHODS We studied patients with type 2 diabetes mellitus (DM), prone to cerebrovascular disease, and compared them to control subjects. In 33 patients (19 DM, 14 control), end-tidal CO 2 , blood pressure, and CBF velocity were monitored awake and during sevoflurane-based anesthesia. CA, calculated with transfer function analysis assessing phase lead (degrees) between low-frequency oscillations in CBF velocity and mean arterial blood pressure, was quantified during hypocapnia, normocapnia, and hypercapnia. RESULTS In both control and DM patients, awake CO 2 reactivity was smaller (2.8%/mm Hg CO 2 ) than during sevoflurane anesthesia (3.9%/mm Hg; P <0.005). Hyperventilation increased CA efficacy more (3 deg./mm Hg CO 2 ) in controls than in DM patients (1.8 deg./mm Hg CO 2 ; P <0.001) in both awake and sevoflurane-anesthetized states. CONCLUSIONS The CA-CO 2 relationship is impaired in awake patients with type 2 DM. Sevoflurane-based anesthesia does not further impair this relationship. In patients with DM, hypocapnia induces cerebral vasoconstriction, but CA efficacy does not improve as observed in healthy subjects.
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Cerebral oxygenation changes in response to post-hemodialysis standing. J Artif Organs 2022:10.1007/s10047-022-01343-2. [PMID: 35776247 DOI: 10.1007/s10047-022-01343-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 06/05/2022] [Indexed: 10/17/2022]
Abstract
Few reports have examined the association between changes in cerebral oxygenation and clinical factors, including blood pressure (BP), upon standing after hemodialysis (HD). This study aimed to clarify the factors affecting the changes in cerebral regional oxygen saturation (rSO2) upon standing after HD and monitor the differences in cerebral rSO2 changes that occur upon standing after HD in patients with and without diabetes mellitus (DM). Changes in mean BP and cerebral rSO2 were tracked in 43 HD patients during 120 s of standing after HD using an INVOS 5100c oxygen saturation monitor. The post-HD cerebral rSO2 at rest was 55.8 ± 10.2%, while that at 120 s of standing decreased to 51.9 ± 9.6%; therefore, the percentage change in cerebral rSO2 at 120 s of standing was - 6.8 ± 6.4%, which was significantly lower than before HD (p < 0.001). This change was significantly correlated with the presence of DM, HD duration, mean BP at 120 s of standing, and percentage change in mean BP at 120 s of standing. A multivariable linear regression analysis showed that percentage change in cerebral rSO2 at 120 s of standing was independently associated with the percentage change in mean BP at 120 s of standing (standardized coefficient: 0.432; p = 0.004). Furthermore, there were significant decreases in percentage changes in cerebral rSO2 throughout the standing period in HD patients with versus without DM. Therefore, cerebral oxygenation deterioration upon standing after HD should receive attention, particularly in HD patients with DM.
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Vidyashree M, Deepeshwar S, Nagarathna R, Manjunath NK, Kaligal C, Kanthi A, Nagendra HR, Bathala L, Sharma VK. Transcranial Doppler studies in Type 2 diabetes mellitus: A systematic review. Diabetes Res Clin Pract 2022; 186:109808. [PMID: 35247526 DOI: 10.1016/j.diabres.2022.109808] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 02/15/2022] [Accepted: 02/28/2022] [Indexed: 12/20/2022]
Abstract
BACKGROUND Type II Diabetes mellitus (T2DM) patients are at the risk of developing cerebrovascular diseases, often contributed by altered cerebral haemodynamics. We present a systematic review of studies on cerebral haemodynamics assessment using transcranial Doppler (TCD) in T2DM. REVIEW METHOD A systematic review of the published articles in the English language between 1991 to 2021. DATA SOURCES Articles were retrieved via Pubmed and Cochrane library. We included Cross-sectional, prospective, retrospective, randomized controlled, and cross-over studies for this review. RESULTS A total of 25 articles met the inclusion criteria, which provided data for 3212 patients. CONCLUSION Cerebral autoregulation is often impaired among patients with T2DM. The risk increased with the duration of T2DM, related complications and presence of comorbidities.
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Affiliation(s)
- Mahadevappa Vidyashree
- Yoga and Life Sciences, Swami Vivekananda Yoga Anusandana Samsthana(S-VYASA), Bangalore, India.
| | - Singh Deepeshwar
- Yoga and Life Sciences, Swami Vivekananda Yoga Anusandana Samsthana(S-VYASA), Bangalore, India.
| | - Raghuram Nagarathna
- Yoga and Life Sciences, Swami Vivekananda Yoga Anusandana Samsthana(S-VYASA), Bangalore, India
| | | | - Chidananda Kaligal
- Yoga and Life Sciences, Swami Vivekananda Yoga Anusandana Samsthana(S-VYASA), Bangalore, India
| | - Amit Kanthi
- Yoga and Life Sciences, Swami Vivekananda Yoga Anusandana Samsthana(S-VYASA), Bangalore, India
| | | | | | - Vijay K Sharma
- Yong Loo Lin School of Medicine, National University of Singapore and Division of Neurology, National University Hospital, Singapore
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Marzolini S, Wu C, Hussein R, Xiong LY, Kangatharan S, Peni A, Cooper CR, Lau KS, Nzodjou Makhdoom G, Pakosh M, Zaban SA, Nguyen MM, Banihashemi MA, Swardfager W. Associations Between Time After Stroke and Exercise Training Outcomes: A Meta-Regression Analysis. J Am Heart Assoc 2021; 10:e022588. [PMID: 34913357 PMCID: PMC9075264 DOI: 10.1161/jaha.121.022588] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Background Knowledge gaps exist regarding the effect of time elapsed after stroke on the effectiveness of exercise training interventions, offering incomplete guidance to clinicians. Methods and Results To determine the associations between time after stroke and 6-minute walk distance, 10-meter walk time, cardiorespiratory fitness and balance (Berg Balance Scale score [BBS]) in exercise training interventions, relevant studies in post-stroke populations were identified by systematic review. Time after stroke as continuous or dichotomized (≤3 months versus >3 months, and ≤6 months versus >6 months) variables and weighted mean differences in postintervention outcomes were examined in meta-regression analyses adjusted for study baseline mean values (pre-post comparisons) or baseline mean values and baseline control-intervention differences (controlled comparisons). Secondary models were adjusted additionally for mean age, sex, and aerobic exercise intensity, dose, and modality. We included 148 studies. Earlier exercise training initiation was associated with larger pre-post differences in mobility; studies initiated ≤3 months versus >3 months after stroke were associated with larger differences (weighted mean differences [95% confidence interval]) in 6-minute walk distance (36.3 meters; 95% CI, 14.2-58.5), comfortable 10-meter walk time (0.13 m/s; 95% CI, 0.06-0.19) and fast 10-meter walk time (0.16 m/s; 95% CI, 0.03-0.3), in fully adjusted models. Initiation ≤3 months versus >3 months was not associated with cardiorespiratory fitness but was associated with a higher but not clinically important Berg Balance Scale score difference (2.9 points; 95% CI, 0.41-5.5). In exercise training versus control studies, initiation ≤3 months was associated with a greater difference in only postintervention 6-minute walk distance (baseline-adjusted 27.3 meters; 95% CI, 6.1-48.5; fully adjusted, 24.9 meters; 95% CI, 0.82-49.1; a similar association was seen for ≤6 months versus >6 months after stroke (fully adjusted, 26.6 meters; 95% CI, 2.6-50.6). Conclusions There may be a clinically meaningful benefit to mobility outcomes when exercise is initiated within 3 months and up to 6 months after stroke.
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Affiliation(s)
- Susan Marzolini
- KITE Research Institute, Toronto Rehabilitation Institute ‐ University Health NetworkTorontoONCanada
- Healthy Living for Pandemic Event Protection (HL–PIVOT) NetworkTorontoONCanada
- Rehabilitation Sciences InstituteUniversity of TorontoONCanada
- Faculty of Kinesiology and Physical EducationUniversity of TorontoONCanada
| | - Che‐Yuan Wu
- Department of Pharmacology and ToxicologyUniversity of TorontoONCanada
- Hurvitz Brain Sciences ProgramSunnybrook Research InstituteTorontoONCanada
| | | | - Lisa Y. Xiong
- Department of Pharmacology and ToxicologyUniversity of TorontoONCanada
- Hurvitz Brain Sciences ProgramSunnybrook Research InstituteTorontoONCanada
| | - Suban Kangatharan
- KITE Research Institute, Toronto Rehabilitation Institute ‐ University Health NetworkTorontoONCanada
| | - Ardit Peni
- KITE Research Institute, Toronto Rehabilitation Institute ‐ University Health NetworkTorontoONCanada
| | | | - Kylie S.K. Lau
- Department of Human BiologyUniversity of TorontoONCanada
| | | | - Maureen Pakosh
- Library & Information ServicesUniversity Health NetworkToronto Rehabilitation InstituteTorontoONCanada
| | - Stephanie A. Zaban
- Faculty of Kinesiology and Physical EducationUniversity of TorontoONCanada
| | - Michelle M. Nguyen
- Department of Pharmacology and ToxicologyUniversity of TorontoONCanada
- Hurvitz Brain Sciences ProgramSunnybrook Research InstituteTorontoONCanada
| | - Mohammad Amin Banihashemi
- Hurvitz Brain Sciences ProgramSunnybrook Research InstituteTorontoONCanada
- Institute of Medical ScienceUniversity of TorontoTorontoONCanada
| | - Walter Swardfager
- KITE Research Institute, Toronto Rehabilitation Institute ‐ University Health NetworkTorontoONCanada
- Department of Pharmacology and ToxicologyUniversity of TorontoONCanada
- Hurvitz Brain Sciences ProgramSunnybrook Research InstituteTorontoONCanada
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Nogueira RC, Beishon L, Bor-Seng-Shu E, Panerai RB, Robinson TG. Cerebral Autoregulation in Ischemic Stroke: From Pathophysiology to Clinical Concepts. Brain Sci 2021; 11:511. [PMID: 33923721 PMCID: PMC8073938 DOI: 10.3390/brainsci11040511] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/02/2021] [Accepted: 04/09/2021] [Indexed: 11/17/2022] Open
Abstract
Ischemic stroke (IS) is one of the most impacting diseases in the world. In the last decades, new therapies have been introduced to improve outcomes after IS, most of them aiming for recanalization of the occluded vessel. However, despite this advance, there are still a large number of patients that remain disabled. One interesting possible therapeutic approach would be interventions guided by cerebral hemodynamic parameters such as dynamic cerebral autoregulation (dCA). Supportive hemodynamic therapies aiming to optimize perfusion in the ischemic area could protect the brain and may even extend the therapeutic window for reperfusion therapies. However, the knowledge of how to implement these therapies in the complex pathophysiology of brain ischemia is challenging and still not fully understood. This comprehensive review will focus on the state of the art in this promising area with emphasis on the following aspects: (1) pathophysiology of CA in the ischemic process; (2) methodology used to evaluate CA in IS; (3) CA studies in IS patients; (4) potential non-reperfusion therapies for IS patients based on the CA concept; and (5) the impact of common IS-associated comorbidities and phenotype on CA status. The review also points to the gaps existing in the current research to be further explored in future trials.
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Affiliation(s)
- Ricardo C. Nogueira
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo 01246-904, Brazil;
- Department of Neurology, Hospital Nove de Julho, São Paulo 01409-002, Brazil
| | - Lucy Beishon
- Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; (L.B.); (R.B.P.); (T.G.R.)
| | - Edson Bor-Seng-Shu
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo 01246-904, Brazil;
| | - Ronney B. Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; (L.B.); (R.B.P.); (T.G.R.)
- National Institute for Health Research (NIHR) Leicester Biomedical Research Centre, University of Leicester, Leicester LE5 4PW, UK
| | - Thompson G. Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; (L.B.); (R.B.P.); (T.G.R.)
- National Institute for Health Research (NIHR) Leicester Biomedical Research Centre, University of Leicester, Leicester LE5 4PW, UK
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Guo Z, Wu X, Fan W. Clarifying the effects of diabetes on the cerebral circulation: Implications for stroke recovery and beyond. Brain Res Bull 2021; 171:67-74. [PMID: 33662495 DOI: 10.1016/j.brainresbull.2021.02.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 02/21/2021] [Accepted: 02/26/2021] [Indexed: 02/07/2023]
Abstract
Given the sheer increased number of victims per year and the availability of only one effective treatment, acute ischemic stroke (AIS) remains to be one of the most under-treated serious diseases. Diabetes not only increases the incidence of ischemic stroke, but amplifies the ischemic damage, upon which if patients with diabetes suffer from stroke, he/she will confront increased risks of long-term functional deficits. The grim reality makes it a pressing need to intensify efforts at the basic science level to understand how diabetes impairs stroke recovery. This review retrospects the clinical and experimental studies in order to elucidate the detrimental effect of diabetes on cerebrovascular circulation including the major arteries/arterioles, collateral circulation, and neovascularization to shed light on further exploration of novel strategies for cerebral circulation protection before and after AIS in patients with diabetes.
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Affiliation(s)
- Zhihui Guo
- Department of Neurology, Zhongshan Hospital, Fudan University, 200032, Shanghai, China
| | - Xuqing Wu
- Department of Neurology, Zhongshan Hospital, Fudan University, 200032, Shanghai, China
| | - Wei Fan
- Department of Neurology, Zhongshan Hospital, Fudan University, 200032, Shanghai, China.
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Kim YS, van der Ster BJP, Brassard P, Secher NH, van Lieshout JJ. Cerebral vs. Cardiovascular Responses to Exercise in Type 2 Diabetic Patients. Front Physiol 2021; 11:583155. [PMID: 33519500 PMCID: PMC7844205 DOI: 10.3389/fphys.2020.583155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/23/2020] [Indexed: 12/17/2022] Open
Abstract
The human brain is constantly active and even small limitations to cerebral blood flow (CBF) may be critical for preserving oxygen and substrate supply, e.g., during exercise and hypoxia. Exhaustive exercise evokes a competition for the supply of oxygenated blood between the brain and the working muscles, and inability to increase cardiac output sufficiently during exercise may jeopardize cerebral perfusion of relevance for diabetic patients. The challenge in diabetes care is to optimize metabolic control to slow progression of vascular disease, but likely because of a limited ability to increase cardiac output, these patients perceive aerobic exercise to be more strenuous than healthy subjects and that limits the possibility to apply physical activity as a preventive lifestyle intervention. In this review, we consider the effects of functional activation by exercise on the brain and how it contributes to understanding the control of CBF with the limited exercise tolerance experienced by type 2 diabetic patients. Whether a decline in cerebral oxygenation and thereby reduced neural drive to working muscles plays a role for "central" fatigue during exhaustive exercise is addressed in relation to brain's attenuated vascular response to exercise in type 2 diabetic subjects.
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Affiliation(s)
- Yu-Sok Kim
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Department of Internal Medicine, Medisch Centrum Leeuwarden, Leeuwarden, Netherlands
| | - Björn J. P. van der Ster
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Department of Anesthesiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Niels H. Secher
- Department of Anesthesia, The Copenhagen Muscle Research Center, University of Copenhagen, Copenhagen, Denmark
| | - Johannes J. van Lieshout
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School, Queen’s Medical Centre, Nottingham, United Kingdom
- Department of Internal Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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Delay of cerebral autoregulation in traumatic brain injury patients. Clin Neurol Neurosurg 2021; 202:106478. [PMID: 33454499 DOI: 10.1016/j.clineuro.2021.106478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Adequate cerebral perfusion prevents secondary insult after traumatic brain injury (TBI). Cerebral autoregulation (CAR) keeps cerebral blood flow (CBF) constant when arterial blood pressure (ABP) changes. Aim of the study was to evaluate the existence of delayed CAR in TBI patients and its possible association with outcome. METHODS We retrospectively analysed TBI patients. Flow velocity (FV) in middle cerebral artery, invasive intra-cranial pressure (ICP) and ABP were recorded. Cerebral perfusion pressure (CPP) was calculated as ABP - ICP. Mean flow index (Mx) > 0.3 defined altered CAR. Samples from patients with altered CAR were further analysed: FV signal was shifted backward relative to CPP; Mx was calculated after each shift (MxD). Mx > 0.3 plus MxD ≤ 0.3 defined delayed CAR. Favourable outcome (FO) at 6 months was defined as Glasgow Outcome Scale 4-5. RESULTS 154 patients were included. GCS was 6 [4-9], ICP was 14 [9-20] mmHg. Data on 6 months outcome were available for 131 patients: 104/131 patients (79 %) were alive; GOS was 4 [3-5]; 70/131 (53 %) had FO. Mx was 0.07 [-0.19 to 0.28] overall. Mx was lower in patients with FO compared others (0.00 [-0.21 to 0.20] vs 0.17 [-0.12 to 0.37], p = 0.02). 118 (77 %) patients had intact CAR and 36 (23 %) patients had altered CAR; 23 patients - 15 % of the general cohort and 64 % of patients with altered CAR - had delayed CAR. Delay in the autoregulatory response was 2 [1-4] seconds. 80/98 (82 %) of patients with intact CAR survived, compared to 16/21 (76 %) with delayed and 8/12 (67 %) with altered CAR (p = 0.20). 80/98 (58 %) patients with intact, 10/21 (48 %) patients with delayed and 3/12 (25 %) patients with altered CAR had FO (p = 0.03). CONCLUSION A subgroup of TBI patients with delayed CAR was identified. Delayed CAR was associated with better neurological outcome than altered CAR.
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Does uncontrolled diabetes mellitus affect cerebral hemodynamics in heart surgery? TURK GOGUS KALP DAMAR CERRAHISI DERGISI-TURKISH JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY 2020; 28:84-91. [PMID: 32175147 DOI: 10.5606/tgkdc.dergisi.2020.18685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 11/20/2019] [Indexed: 01/08/2023]
Abstract
Background In this study, we aimed to investigate the effects of poor blood glucose control on the intraoperative cerebral system in patients undergoing coronary artery bypass grafting using various neuromonitors. Methods Between January 2011 and December 2011, a total of 40 adult patients (31 males, 9 females; mean age 58.8±9.2 years; range, 38 to 78 years) who were scheduled for elective coronary artery bypass grafting were included in the study. The patients were divided into four groups according to hemoglobin A1c levels as follows: Group 1 including non-diabetic controls (n=11); Group 2 including those with a hemoglobin A1c value of <7% (n=10); Group 3 including those with a hemoglobin A1c value of 7 to 10% (n=11); and Group 4 including those with a hemoglobin A1c value of ≥10% (n=8). Cerebral monitoring was performed with near-infrared spectroscopy and transcranial Doppler. Measurement periods were defined as follows: Before anesthesia induction (period 1), 10 min after anesthesia induction (period 2), during cannulation (period 3), 10 min after cardiopulmonary bypass (period 4), at 32°C temperature during cardiopulmonary bypass (period 5), at 36°C temperature during cardiopulmonary bypass (period 6), and at the end of the operation (period 7). Results There was a significant difference in the near-infrared spectroscopy values in the cannulation period for both right (p<0.001) and left (p=0.002) sides and the mean transcranial Doppler flow velocity (p=0.002) in Group 4, compared to Group 1. The heart rate was found to be significantly lower in Group 4 in the cannulation period. The near-infrared spectroscopy values and transcranial Doppler blood flow velocity decreased in Group 4 in all measurement periods. Conclusion The results of our study show that, in patients with severe diabetes undergoing open heart surgery, heart rate decreases in the cannulation period due to possible autonomic neuropathy, and cerebral blood flow and oxygenation decrease. For these patients, particularly in the cannulation period, perfusion of both cerebral and other organs should be closely monitored and necessary interventions should be performed.
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Vranish JR, Holwerda SW, Kaur J, Fadel PJ. Augmented pressor and sympathoexcitatory responses to the onset of isometric handgrip in patients with type 2 diabetes. Am J Physiol Regul Integr Comp Physiol 2019; 318:R311-R319. [PMID: 31823673 DOI: 10.1152/ajpregu.00109.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Patients with type 2 diabetes (T2D) exhibit greater daytime blood pressure (BP) variability, increasing their cardiovascular risk. Given the number of daily activities that incorporate short-duration isometric muscle contractions (e.g., carrying groceries), herein we investigated BP and muscle sympathetic nerve activity (MSNA) responses at the onset of isometric handgrip (HG). We tested the hypothesis that, relative to control subjects, patients with T2D would exhibit exaggerated pressor and MSNA responses to the immediate onset of HG. Mean arterial pressure (MAP) and MSNA were quantified during the first 30 s of isometric HG at 30% and 40% of maximal voluntary contraction (MVC) and during a cold pressor test (CPT), a nonexercise sympathoexcitatory stimulus. The onset of 30% MVC HG evoked similar increases in MAP between groups (P = 0.17); however, the increase in MSNA was significantly greater in patients with T2D versus control subjects with the largest group difference at 20 s (P < 0.001). At the onset of 40% MVC HG, patients with T2D demonstrated greater increases in MAP (e.g., 10 s, T2D: 9 ± 1 mmHg, controls: 5 ± 2 mmHg; P = 0.04). MSNA was also greater in patients with T2D at 40% MVC onset but differences were only significant at the 20-30 s timepoint (T2D: 15 ± 3 bursts/min, controls: -2 ± 4 bursts/min; P < 0.001). Similarly, MAP and MSNA responses were augmented during the onset of CPT in T2D patients. These findings demonstrate exaggerated pressor and MSNA reactivity in patients with T2D, with rapid and robust responses to both isometric contractions and cold stress. This hyper-responsiveness may contribute to daily surges in BP in patients with T2D, increasing their short-term and long-term cardiovascular risk.
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Affiliation(s)
- Jennifer R Vranish
- Department of Integrative Physiology and Health Science, Alma College, Alma, Michigan
| | - Seth W Holwerda
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa
| | - Jasdeep Kaur
- Department of Kinesiology, University of Texas at Arlington, Texas
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Texas
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Marzolini S, Robertson AD, Oh P, Goodman JM, Corbett D, Du X, MacIntosh BJ. Aerobic Training and Mobilization Early Post-stroke: Cautions and Considerations. Front Neurol 2019; 10:1187. [PMID: 31803129 PMCID: PMC6872678 DOI: 10.3389/fneur.2019.01187] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 10/25/2019] [Indexed: 12/14/2022] Open
Abstract
Knowledge gaps exist in how we implement aerobic exercise programs during the early phases post-stroke. Therefore, the objective of this review was to provide evidence-based guidelines for pre-participation screening, mobilization, and aerobic exercise training in the hyper-acute and acute phases post-stroke. In reviewing the literature to determine safe timelines of when to initiate exercise and mobilization we considered the following factors: arterial blood pressure dysregulation, cardiac complications, blood-brain barrier disruption, hemorrhagic stroke transformation, and ischemic penumbra viability. These stroke-related impairments could intensify with inappropriate mobilization/aerobic exercise, hence we deemed the integrity of cerebral autoregulation to be an essential physiological consideration to protect the brain when progressing exercise intensity. Pre-participation screening criteria are proposed and countermeasures to protect the brain from potentially adverse circulatory effects before, during, and following mobilization/exercise sessions are introduced. For example, prolonged periods of standing and static postures before and after mobilization/aerobic exercise may elicit blood pooling and/or trigger coagulation cascades and/or cerebral hypoperfusion. Countermeasures such as avoiding prolonged standing or incorporating periodic lower limb movement to activate the venous muscle pump could counteract blood pooling after an exercise session, minimize activation of the coagulation cascade, and mitigate potential cerebral hypoperfusion. We discuss patient safety in light of the complex nature of stroke presentations (i.e., type, severity, and etiology), medical history, comorbidities such as diabetes, cardiac manifestations, medications, and complications such as anemia and dehydration. The guidelines are easily incorporated into the care model, are low-risk, and use minimal resources. These and other strategies represent opportunities for improving the safety of the activity regimen offered to those in the early phases post-stroke. The timeline for initiating and progressing exercise/mobilization parameters are contingent on recovery stages both from neurobiological and cardiovascular perspectives, which to this point have not been specifically considered in practice. This review includes tailored exercise and mobilization prescription strategies and precautions that are not resource intensive and prioritize safety in stroke recovery.
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Affiliation(s)
- Susan Marzolini
- KITE, Toronto Rehab-University Health Network, Toronto, ON, Canada
- Department of Exercise Sciences, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
- Canadian Partnership for Stroke Recovery, Toronto, ON, Canada
| | - Andrew D. Robertson
- Schlegel-University of Waterloo Research Institute for Aging, University of Waterloo, Waterloo, ON, Canada
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada
| | - Paul Oh
- KITE, Toronto Rehab-University Health Network, Toronto, ON, Canada
- Department of Exercise Sciences, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
- Canadian Partnership for Stroke Recovery, Toronto, ON, Canada
| | - Jack M. Goodman
- KITE, Toronto Rehab-University Health Network, Toronto, ON, Canada
- Department of Exercise Sciences, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | - Dale Corbett
- Canadian Partnership for Stroke Recovery, Toronto, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Xiaowei Du
- KITE, Toronto Rehab-University Health Network, Toronto, ON, Canada
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | - Bradley J. MacIntosh
- Canadian Partnership for Stroke Recovery, Toronto, ON, Canada
- Sunnybrook Health Sciences Center, Toronto, ON, Canada
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13
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Drapeau A, Labrecque L, Imhoff S, Paquette M, Le Blanc O, Malenfant S, Brassard P. Six weeks of high-intensity interval training to exhaustion attenuates dynamic cerebral autoregulation without influencing resting cerebral blood velocity in young fit men. Physiol Rep 2019; 7:e14185. [PMID: 31373166 PMCID: PMC6675921 DOI: 10.14814/phy2.14185] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 06/12/2019] [Accepted: 06/30/2019] [Indexed: 12/22/2022] Open
Abstract
Elevated cardiorespiratory fitness (CRF) is associated with reduced dynamic cerebral autoregulation (dCA), but the impact of exercise training per se on dCA remains equivocal. In addition, resting cerebral blood flow (CBF) and dCA after high-intensity interval training (HIIT) in individuals with already high CRF remains unknown. We examined to what extent 6 weeks of HIIT affect resting CBF and dCA in cardiorespiratory fit men and explored if potential changes are intensity-dependent. Endurance-trained men were assigned to group HIIT85 (85% of maximal aerobic power, 1-7 min effort bouts, n = 8) and HIIT115 (115% of maximal aerobic power, 30 sec to 1 min effort bouts, n = 9). Training sessions were completed until exhaustion 3 times/week over 6 weeks. Mean arterial pressure (MAP) and middle cerebral artery mean blood velocity (MCAvmean ) were measured continuously at rest and during repeated squat-stands (0.05 and 0.10 Hz). Transfer function analysis (TFA) was used to characterize dCA on driven blood pressure oscillations during repeated squat-stands. Neither training nor intensity had an effect on resting MAP and MCAvmean (both P > 0.05). TFA phase during 0.10 Hz squat-stands decreased after HIIT irrespective of intensity (HIIT85 : 0.77 ± 0.22 vs. 0.67 ± 0.18 radians; HIIT115 : pre: 0.62 ± 0.19 vs. post: 0.59 ± 0.13 radians, time effect P = 0.048). These results suggest that HIIT over 6 weeks have no apparent benefits on resting CBF, but a subtle attenuation in dCA is seen posttraining irrespective of intensity training in endurance-trained men.
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Affiliation(s)
- Audrey Drapeau
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébecCanada
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébecCanada
| | - Sarah Imhoff
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébecCanada
| | - Myriam Paquette
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébecCanada
| | - Olivier Le Blanc
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébecCanada
| | - Simon Malenfant
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébecCanada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébecCanada
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14
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Sperna Weiland NH, Hermanides J, Hollmann MW, Preckel B, Stok WJ, van Lieshout JJ, Immink RV. Novel method for intraoperative assessment of cerebral autoregulation by paced breathing. Br J Anaesth 2019; 119:1141-1149. [PMID: 29028933 DOI: 10.1093/bja/aex333] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2017] [Indexed: 11/14/2022] Open
Abstract
Background Cerebral autoregulation (CA) is the mechanism that maintains constancy of cerebral blood flow (CBF) despite variations in blood pressure (BP). Patients with attenuated CA have been shown to have an increased incidence of peri-operative stroke. Studies of CA in anaesthetized subjects are rare, because a simple and non-invasive method to quantify the integrity of CA is not available. In this study, we set out to improve non-invasive quantification of CA during surgery. For this purpose, we introduce a novel method to amplify spontaneous BP fluctuations during surgery by imposing mechanical positive pressure ventilation at three different frequencies and quantify CA from the resulting BP oscillations. Methods Fourteen patients undergoing sevoflurane anaesthesia were included in the study. Continuous non-invasive BP and transcranial Doppler-derived CBF velocity (CBF V ) were obtained before surgery during 3 min of paced breathing at 6, 10, and 15 bpm and during surgery from mechanical positive pressure ventilation at identical frequencies. Data were analysed using frequency domain analysis to obtain CBF V -to-BP phase lead as a continuous measure of CA efficacy. Group averages were calculated. Values are means ( sd ), and P <0.05 was used to indicate statistical significance. Results Preoperative vs intraoperative CBF V -to-BP phase lead was 43 (9) vs 45 (8)°, 25 (8) vs 24 (10)°, and 4 (6) vs -2 (12)° during 6, 10, and 15 bpm, respectively (all P =NS). Conclusions During surgery, cerebral autoregulation indices were similar to values determined before surgery. This indicates that CA can be quantified reliably and non-invasively using this novel method and confirms earlier evidence that CA is unaffected by sevoflurane anaesthesia. Clinical trial registration NCT03071432.
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Affiliation(s)
- N H Sperna Weiland
- Department of Anaesthesiology.,Department of Medical Biology, Laboratory for Clinical Cardiovascular Physiology
| | | | | | | | - W J Stok
- Department of Medical Biology, Laboratory for Clinical Cardiovascular Physiology
| | - J J van Lieshout
- Department of Medical Biology, Laboratory for Clinical Cardiovascular Physiology.,Department of Internal Medicine, Academic Medical Centre AMC Amsterdam, University of Amsterdam, PO Box 22660, 1100DD Amsterdam, The Netherlands.,MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK
| | - R V Immink
- Department of Anaesthesiology.,Department of Medical Biology, Laboratory for Clinical Cardiovascular Physiology
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15
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Zheng G, Chen B, Fang Q, Lin Q, Tao J, Chen L. Baduanjin exercise intervention for community adults at risk of ischamic stroke: A randomized controlled trial. Sci Rep 2019; 9:1240. [PMID: 30718622 PMCID: PMC6362011 DOI: 10.1038/s41598-018-37544-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 12/10/2018] [Indexed: 01/01/2023] Open
Abstract
The aim of current study was to assess the effects of Baduanjin exercise on cerebrovascular function, cardiac structure and cardiac function, static pulmonary function, traditional risk factors of CVD and the related psychological outcomes in older community adults at risk for ischaemic stroke. A randomized controlled trial was conducted in three community between November 2013 and October 2015. Older community-dwelling adults (N = 170) were randomly allocated into either a Baduanjin training (5 × 60 min/weekly) or control group who kept their unaltered lifestyle during a 12-week intervention period. Primary (cerebral haemodynamic parameters) and secondary outcomes (cardiac structure, cardiac function, static pulmonary function, traditional risk factors and the related psychological outcomes) were measured at baseline, after a 12-week intervention period and after an additional 12-week follow-up period. After the 12-week intervention period and additional 12-week follow-up period, the Baduanjin exercise group displayed significant changes in most cerebral haemodynamic parameters compared to the control group: lower systolic blood pressure, diastolic blood pressure, plasma total cholesterol levels, waist circumference, hip circumference and waist/hip ratio; and improved mood, self-confidence, self-esteem, quality of life and sleep quality. A supervised 12-week Baduanjin exercise intervention was effective and safe in modulating cerebral haemodynamics, reducing blood pressure and improving anthropometric parameters and related psychological outcomes in older community adults at risk for ischaemic stroke.
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Affiliation(s)
- Guohua Zheng
- College of Nursing and Health Management, Shanghai University of Medicine & Health Sciences, Shanghai, 201318, China.,College of Rehabilitation Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Bai Chen
- College of Rehabilitation Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Qianying Fang
- College of Rehabilitation Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Qiu Lin
- Department of Physical Education, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Jing Tao
- Fujian Key Laboratory of Rehabilitation Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Lidian Chen
- Collaborative Innovation Center for Rehabilitation Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China.
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16
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Sperna Weiland NH, Hermanides J, van der Ster BJP, Hollmann MW, Preckel B, Stok WJ, van Lieshout JJ, Immink RV. Sevoflurane based anaesthesia does not affect already impaired cerebral autoregulation in patients with type 2 diabetes mellitus. Br J Anaesth 2018; 121:1298-1307. [PMID: 30442257 DOI: 10.1016/j.bja.2018.07.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 06/11/2018] [Accepted: 07/09/2018] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The baroreflex regulates arterial blood pressure (BP). During periods when blood pressure changes, cerebral blood flow (CBF) is kept constant by cerebral autoregulation (CA). In patients with diabetes mellitus (DM), low baroreflex sensitivity (BRS) is associated with impaired CA. As sevoflurane-based anaesthesia obliterates BRS, we hypothesised that this could aggravate the already impaired CA in patients with DM resulting in a 'double-hit' on cerebral perfusion leading to increased fluctuations in blood pressure and cerebral perfusion. METHODS On the day before surgery, we measured CBF velocity (CBFV), heart rate, and BP to determine BRS and CA efficacy (CBFVmean-to-BPmean-phase lead) in 25 patients with DM and in 14 controls. During the operation, BRS and CA efficacy were determined during sevoflurane-based anaesthesia. Patients with DM were divided into a group with high BRS (DMBRS↑) and a group with low BRS (DMBRS↓). Values presented are median (inter-quartile range). RESULTS Preoperative vs intraoperative BRS was 6.2 (4.5-8.5) vs 1.9 (1.1-2.5, P<0.001) ms mm Hg-1 for controls, 5.8 (4.9-7.6) vs 2.7 (1.5-3.9, P<0.001) ms mm Hg-1 for patients with DMBRS↑, and 1.9 (1.5-2.8) vs 1.1 (0.6-2.5, P=0.31) ms mm Hg-1 for patients with DMBRS↓. Preoperative vs intraoperative CA efficacy was 43° (38-46) vs 43° (38-51, P=0.30), 44° (36-49) vs 41° (32-49, P=0.52), and 34° (28-40) vs 30° (27-38, P=0.64) for controls, DMBRS↑, and DMBRS↓ patients, respectively. CONCLUSIONS In diabetic patients with low preoperative BRS, preoperative CA efficacy was also impaired. In controls and diabetic patients, CA was unaffected by sevoflurane-based anaesthesia. We therefore conclude that sevoflurane-based anaesthesia does not contribute to a 'double-hit' phenomenon on cerebral perfusion. CLINICAL TRIAL REGISTRATION NCT 03071432.
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Affiliation(s)
- N H Sperna Weiland
- Amsterdam UMC, University of Amsterdam, Anaesthesiology, Amsterdam, The Netherlands; Amsterdam UMC, University of Amsterdam, Laboratory for Clinical Cardiovascular Physiology, Department of Medical Biology, Amsterdam, The Netherlands
| | - J Hermanides
- Amsterdam UMC, University of Amsterdam, Anaesthesiology, Amsterdam, The Netherlands.
| | - B J P van der Ster
- Amsterdam UMC, University of Amsterdam, Laboratory for Clinical Cardiovascular Physiology, Department of Medical Biology, Amsterdam, The Netherlands; Amsterdam UMC, University of Amsterdam, Internal Medicine, Amsterdam, The Netherlands
| | - M W Hollmann
- Amsterdam UMC, University of Amsterdam, Anaesthesiology, Amsterdam, The Netherlands
| | - B Preckel
- Amsterdam UMC, University of Amsterdam, Anaesthesiology, Amsterdam, The Netherlands
| | - W J Stok
- Amsterdam UMC, University of Amsterdam, Laboratory for Clinical Cardiovascular Physiology, Department of Medical Biology, Amsterdam, The Netherlands
| | - J J van Lieshout
- Amsterdam UMC, University of Amsterdam, Laboratory for Clinical Cardiovascular Physiology, Department of Medical Biology, Amsterdam, The Netherlands; Amsterdam UMC, University of Amsterdam, Internal Medicine, Amsterdam, The Netherlands; MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK
| | - R V Immink
- Amsterdam UMC, University of Amsterdam, Anaesthesiology, Amsterdam, The Netherlands; Amsterdam UMC, University of Amsterdam, Laboratory for Clinical Cardiovascular Physiology, Department of Medical Biology, Amsterdam, The Netherlands
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17
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Coucha M, Abdelsaid M, Ward R, Abdul Y, Ergul A. Impact of Metabolic Diseases on Cerebral Circulation: Structural and Functional Consequences. Compr Physiol 2018; 8:773-799. [PMID: 29687902 DOI: 10.1002/cphy.c170019] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Metabolic diseases including obesity, insulin resistance, and diabetes have profound effects on cerebral circulation. These diseases not only affect the architecture of cerebral blood arteries causing adverse remodeling, pathological neovascularization, and vasoregression but also alter the physiology of blood vessels resulting in compromised myogenic reactivity, neurovascular uncoupling, and endothelial dysfunction. Coupled with the disruption of blood brain barrier (BBB) integrity, changes in blood flow and microbleeds into the brain rapidly occur. This overview is organized into sections describing cerebrovascular architecture, physiology, and BBB in these diseases. In each section, we review these properties starting with larger arteries moving into smaller vessels. Where information is available, we review in the order of obesity, insulin resistance, and diabetes. We also tried to include information on biological variables such as the sex of the animal models noted since most of the information summarized was obtained using male animals. © 2018 American Physiological Society. Compr Physiol 8:773-799, 2018.
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Affiliation(s)
- Maha Coucha
- South University, School of Pharmacy, Savannah, Georgia, USA
| | | | - Rebecca Ward
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Yasir Abdul
- Charlie Norwood VA Medical Center, Augusta, Georgia, USA.,Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Adviye Ergul
- Charlie Norwood VA Medical Center, Augusta, Georgia, USA.,Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
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18
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de Jong DLK, Tarumi T, Liu J, Zhang R, Claassen JAHR. Lack of linear correlation between dynamic and steady-state cerebral autoregulation. J Physiol 2017; 595:5623-5636. [PMID: 28597991 PMCID: PMC5556173 DOI: 10.1113/jp274304] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/06/2017] [Indexed: 01/15/2023] Open
Abstract
Key points For correct application and interpretation of cerebral autoregulation (CA) measurements in research and in clinical care, it is essential to understand differences and similarities between dynamic and steady‐state CA. The present study found no correlation between dynamic and steady‐state CA indices in healthy older adults. There was variability between individuals in all (steady‐state and dynamic) autoregulatory indices, ranging from low (almost absent) to highly efficient CA in this healthy population. These findings challenge the assumption that assessment of a single CA parameter or a single set of parameters can be generalized to overall CA functioning. Therefore, depending on specific research purposes, the choice for either steady‐state or dynamic measures or both should be weighed carefully.
Abstract The present study aimed to investigate the relationship between dynamic (dCA) and steady‐state cerebral autoregulation (sCA). In 28 healthy older adults, sCA was quantified by a linear regression slope of proportionate (%) changes in cerebrovascular resistance (CVR) in response to proportionate (%) changes in mean blood pressure (BP) induced by stepwise sodium nitroprusside (SNP) and phenylephrine (PhE) infusion. Cerebral blood flow (CBF) was measured at the internal carotid artery (ICA) and vertebral artery (VA) and CBF velocity at the middle cerebral artery (MCA). With CVR = BP/CBF, Slope‐CVRICA, Slope‐CVRVA and Slope‐CVRiMCA were derived. dCA was assessed (i) in supine rest, analysed with transfer function analysis (gain and phase) and autoregulatory index (ARI) fit from spontaneous oscillations (ARIBaseline), and (ii) with transient changes in BP using a bolus injection of SNP (ARISNP) and PhE (ARIPhE). Comparison of sCA and dCA parameters (using Pearson's r for continuous and Spearman's ρ for ordinal parameters) demonstrated a lack of linear correlations between sCA and dCA measures. However, comparisons of parameters within dCA and within sCA were correlated. For sCA slope‐CVRVA with Slope‐CVRiMCA (r = 0.45, P < 0.03); for dCA ARISNP with ARIPhE (ρ = 0.50, P = 0.03), ARIBaseline (ρ = 0.57, P = 0.03) and PhaseLF (ρ = 0.48, P = 0.03); and for GainVLF with GainLF (r = 0.51, P = 0.01). By contrast to the commonly held assumption based on an earlier study, there were no linear correlations between sCA and dCA. As an additional observation, there was strong inter‐individual variability, both in dCA and sCA, in this healthy group of elderly, in a range from low to high CA efficiency. For correct application and interpretation of cerebral autoregulation (CA) measurements in research and in clinical care, it is essential to understand differences and similarities between dynamic and steady‐state CA. The present study found no correlation between dynamic and steady‐state CA indices in healthy older adults. There was variability between individuals in all (steady‐state and dynamic) autoregulatory indices, ranging from low (almost absent) to highly efficient CA in this healthy population. These findings challenge the assumption that assessment of a single CA parameter or a single set of parameters can be generalized to overall CA functioning. Therefore, depending on specific research purposes, the choice for either steady‐state or dynamic measures or both should be weighed carefully.
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Affiliation(s)
- Daan L K de Jong
- Donders Institute for Brain, Cognition and Behavior, Radboud Alzheimer Center, and Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Takashi Tarumi
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas, USA.,Department of Internal Medicine
| | - Jie Liu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas, USA.,Department of Internal Medicine
| | - Rong Zhang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas, USA.,Department of Internal Medicine.,Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Texas, USA
| | - Jurgen A H R Claassen
- Donders Institute for Brain, Cognition and Behavior, Radboud Alzheimer Center, and Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
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19
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Tamura Y, Kimbara Y, Yamaoka T, Sato K, Tsuboi Y, Kodera R, Chiba Y, Mori S, Fujiwara Y, Tokumaru AM, Ito H, Sakurai T, Araki A. White Matter Hyperintensity in Elderly Patients with Diabetes Mellitus Is Associated with Cognitive Impairment, Functional Disability, and a High Glycoalbumin/Glycohemoglobin Ratio. Front Aging Neurosci 2017; 9:220. [PMID: 28729834 PMCID: PMC5498506 DOI: 10.3389/fnagi.2017.00220] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 06/23/2017] [Indexed: 01/07/2023] Open
Abstract
Aims: Although evidence has accumulated that white matter hyperintensity (WMH) is associated with the deterioration of cognitive function and impairment of activities of daily living (ADL), the clinical relevance of WMH in elderly patients with diabetes mellitus (DM) is not still clear. The aim of this study was to examine whether WMH volume is associated with ADL and cognitive function and whether glucose control and glucose variability can affect WMH volume in these patients. Methods: This cross-sectional study investigated the associations of WMH with cognitive function and instrumental ADL (IADL), as well as metabolic and vascular risk factors in a total of 178 elderly patients with diabetes. The study assessed WMH volumes and the functional status of cognition and IADL. WMH volumes were evaluated by obtaining axial T2-weighted and fluid-attenuated inversion recovery sequence images on brain magnetic resonance imaging and assessing the images using Software for Neuro-Image Processing in Experimental Research. Results: We found a significant association between WMH volumes and Mini-Mental State Examination (MMSE) scores (p = 0.039) and between WMH and IADL status (p = 0.006). Furthermore, we found significant relations of large WMH volumes with a high glycoalbumin/glycohemoglobin ratio (GA/HbA1c) (p < 0.001). Large WMH volumes were also found to be associated with a low body mass index (p = 0.014) and a low diastolic blood pressure (p = 0.024), but not with HbA1c. Multiple regression analysis showed that high GA/HbA1c, which reflects high glucose variability, was a significant determining factor for large WMH volumes. We also found that GA/HbA1c was negatively associated with both MMSE (p = 0.036) and IADL (p < 0.001). Conclusion: GA/HbA1c, which is a marker of glucose variability, was independently associated with WMH volumes, which could lead to the decline of cognition and IADL in elderly patients with DM.
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Affiliation(s)
- Yoshiaki Tamura
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Yoshiyuki Kimbara
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Takuya Yamaoka
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Ken Sato
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Yuki Tsuboi
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Remi Kodera
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Yuko Chiba
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Seijiro Mori
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Yoshinori Fujiwara
- Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of GerontologyTokyo, Japan
| | - Aya M Tokumaru
- Department of Diagnostic Radiology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Hideki Ito
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
| | - Takashi Sakurai
- Center for Comprehensive Care and Research on Memory Disorders, National Center for Geriatrics and GerontologyAichi, Japan
| | - Atsushi Araki
- Departments of Diabetes, Metabolism, and Endocrinology, Tokyo Metropolitan Geriatric HospitalTokyo, Japan
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20
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Bettermann K, Slocomb J, Shivkumar V, Quillen D, Gardner TW, Lott ME. Impaired Retinal Vasoreactivity: An Early Marker of Stroke Risk in Diabetes. J Neuroimaging 2016; 27:78-84. [PMID: 27892636 DOI: 10.1111/jon.12412] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/25/2016] [Accepted: 10/30/2016] [Indexed: 12/01/2022] Open
Abstract
Diabetes is a common cause of small vessel disease leading to stroke and vascular dementia. While the function and structure of large cerebral vessels can be easily studied, the brain's microvasculature remains difficult to assess. Previous studies have demonstrated that structural changes in the retinal vessel architecture predict stroke risk, but these changes occur at late disease stages. Our goal was to examine whether retinal vascular status can predict cerebral small vessel dysfunction during early stages of diabetes. Retinal vasoreactivity and cerebral vascular function were measured in 78 subjects (19 healthy controls, 22 subjects with prediabetes, and 37 with type-2 diabetes) using a new noninvasive retinal imaging device (Dynamic Vessel Analyzer) and transcranial Doppler studies, respectively. Cerebral blood vessel responsiveness worsened with disease progression of diabetes. Similarly, retinal vascular reactivity was significantly attenuated in subjects with prediabetes and diabetes compared to healthy controls. Subjects with prediabetes and diabetes with impaired cerebral vasoreactivity showed mainly attenuation of the retinal venous flicker response. This is the first study to explore the relationship between retinal and cerebral vascular function in diabetes. Impairment of venous retinal responsiveness may be one of the earliest markers of vascular dysfunction in diabetes possibly indicating subsequent risk of stroke and vascular dementia.
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Affiliation(s)
| | - Julia Slocomb
- Department of Biology, Johns Hopkins University, Baltimore, MD
| | | | - David Quillen
- Penn State Hershey Medical Center, Department of Ophthalmology, Hershey, PA
| | | | - Mary E Lott
- Penn State Hershey Medical Center, Heart and Vascular Institute, Hershey, PA
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21
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Sperna Weiland NH, Brevoord D, Jöbsis DA, de Beaumont EMFH, Evers V, Preckel B, Hollmann MW, van Dieren S, de Mol BAJM, Immink RV. Cerebral oxygenation during changes in vascular resistance and flow in patients on cardiopulmonary bypass - a physiological proof of concept study. Anaesthesia 2016; 72:49-56. [DOI: 10.1111/anae.13631] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2016] [Indexed: 12/17/2022]
Affiliation(s)
- N. H. Sperna Weiland
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - D. Brevoord
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - D. A. Jöbsis
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | | | - V. Evers
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - B. Preckel
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - M. W. Hollmann
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - S. van Dieren
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - B. A. J. M. de Mol
- Department of Cardiothoracic Surgery; Academic Medical Center; Amsterdam The Netherlands
| | - R. V. Immink
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
- Laboratory for Clinical Cardiovascular Physiology; Department of Anatomy and Embryology; Academic Medical Center; Amsterdam The Netherlands
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22
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Patel N, Panerai RB, Haunton V, Katsogridakis E, Saeed NP, Salinet A, Brodie F, Syed N, D'Sa S, Robinson TG. The Leicester cerebral haemodynamics database: normative values and the influence of age and sex. Physiol Meas 2016; 37:1485-98. [PMID: 27511128 DOI: 10.1088/0967-3334/37/9/1485] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Normative values of physiological parameters hold significance in modern day clinical decision-making. Lack of such normative values has been a major hurdle in the translation of research into clinical practice. A large database containing uniform recordings was constructed to allow more robust estimates of normative ranges and also assess the influence of age and sex. Doppler recordings were performed on healthy volunteers in the same laboratory, using similar protocols and equipment. Beat-to-beat blood pressure, heart-rate, electrocardiogram, and end-tidal CO2 were measured continuously. Bilateral insonation of the middle cerebral arteries (MCAs) was performed using TCD following a 15 min stabilisation, and a 5 min baseline recording. Good quality Doppler recordings for both MCAs were obtained in 129 participants (57 female) with a median age of 57 years (range 20-82). Age was found to influence baseline haemodynamic and transfer function analysis parameters. Cerebral blood flow velocity and critical closing pressure were the only sex-related differences found, which was significantly higher in females than males. Normative values for cerebral haemodynamic parameters have been defined in a large, healthy population. Such age/sex-defined normal values can be used to reduce the burden of collecting additional control data in future studies, as well as to identify disease-associated changes.
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Affiliation(s)
- Nikil Patel
- Department of Cardiovascular Sciences, Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, University of Leicester, Leicester, LE2 7LX, UK. NIHR Biomedical Research Unit for Cardiovascular Sciences, University of Leicester, Leicester, UK
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23
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Veloudi P, Blizzard L, Srikanth VK, McCartney P, Lukoshkova EV, Hughes AD, Head GA, Sharman JE. Associations of blood pressure variability and retinal arteriolar diameter in participants with type 2 diabetes. Diab Vasc Dis Res 2016; 13:299-302. [PMID: 27056406 PMCID: PMC4905517 DOI: 10.1177/1479164116633424] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Blood pressure variability is associated with macrovascular complications and stroke, but its association with the microcirculation in type II diabetes has not been assessed. This study aimed to determine the relationship between blood pressure variability indices and retinal arteriolar diameter in non-diabetic and type II diabetes participants. Digitized retinal images were analysed to quantify arteriolar diameters in 35 non-diabetic (aged 52 ± 11 years; 49% male) and 28 type II diabetes (aged 61 ± 9 years; 50% male) participants. Blood pressure variability was derived from 24-h ambulatory blood pressure. Arteriolar diameter was positively associated with daytime rate of systolic blood pressure variation (p = 0.04) among type II diabetes participants and negatively among non-diabetics (p = 0.008; interaction p = 0.001). This finding was maintained after adjusting for age, sex, body mass index and mean daytime systolic blood pressure. These findings suggest that the blood pressure variability-related mechanisms underlying retinal vascular disease may differ between people with and without type II diabetes.
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Affiliation(s)
- Panagiota Veloudi
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | - Leigh Blizzard
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | - Velandai K Srikanth
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia Department of Medicine, School of Clinical Sciences at Monash Health, Monash Medical Centre, Melbourne, VIC, Australia
| | - Paul McCartney
- Hobart Eye Surgeons, Royal Hobart Hospital, Hobart, TAS, Australia
| | | | - Alun D Hughes
- UCL Institute of Cardiovascular Science, University College London, London, UK
| | - Geoffrey A Head
- Baker IDI Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - James E Sharman
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
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24
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Hardigan T, Yasir A, Abdelsaid M, Coucha M, El-Shaffey S, Li W, Johnson MH, Ergul A. Linagliptin treatment improves cerebrovascular function and remodeling and restores reduced cerebral perfusion in Type 2 diabetes. Am J Physiol Regul Integr Comp Physiol 2016; 311:R466-77. [PMID: 27357799 DOI: 10.1152/ajpregu.00057.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/24/2016] [Indexed: 12/20/2022]
Abstract
The antihyperglycemic agent linagliptin, a dipeptidyl peptidase-4 (DPP-IV) inhibitor, has been shown to reduce inflammation and improve endothelial cell function. In this study, we hypothesized that DPP-IV inhibition with linagliptin would improve impaired cerebral perfusion in diabetic rats, as well as improve insulin-induced cerebrovascular relaxation and reverse pathological cerebrovascular remodeling. We further postulated that these changes would lead to a subsequent improvement of cognitive function. Male Type-2 diabetic and nondiabetic Goto-Kakizaki rats were treated with linagliptin for 4 wk, and blood glucose and DPP-IV plasma levels were assessed. Cerebral perfusion was assessed after treatment using laser-Doppler imaging, and dose response to insulin (10(-13) M-10(-6) M) in middle cerebral arteries was tested on a pressurized arteriograph. The impact of DPP-IV inhibition on diabetic cerebrovascular remodeling was assessed over a physiologically relevant pressure range, and changes in short-term hippocampus-dependent learning were observed using a novel object recognition test. Linagliptin lowered DPP-IV activity but did not change blood glucose or insulin levels in diabetes. Insulin-mediated vascular relaxation and cerebral perfusion were improved in the diabetic rats with linagliptin treatment. Indices of diabetic vascular remodeling, such as increased cross-sectional area, media thickness, and wall-to-lumen ratio, were also ameliorated; however, improvements in short-term hippocampal-dependent learning were not observed. The present study provides evidence that linagliptin treatment improves cerebrovascular dysfunction and remodeling in a Type 2 model of diabetes independent of glycemic control. This has important implications in diabetic patients who are predisposed to the development of cerebrovascular complications, such as stroke and cognitive impairment.
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Affiliation(s)
- Trevor Hardigan
- Department of Physiology, Medical College of Georgia, Augusta, Georgia; and
| | - Abdul Yasir
- Department of Physiology, Medical College of Georgia, Augusta, Georgia; and
| | - Mohammed Abdelsaid
- Charlie Norwood Veterans Administration Medical Center, Augusta, Georgia; Department of Physiology, Medical College of Georgia, Augusta, Georgia; and
| | - Maha Coucha
- Charlie Norwood Veterans Administration Medical Center, Augusta, Georgia; Department of Physiology, Medical College of Georgia, Augusta, Georgia; and
| | - Sally El-Shaffey
- Department of Physiology, Medical College of Georgia, Augusta, Georgia; and
| | - Weiguo Li
- Charlie Norwood Veterans Administration Medical Center, Augusta, Georgia; Department of Physiology, Medical College of Georgia, Augusta, Georgia; and
| | - Maribeth H Johnson
- Department of Biostatistics, The Graduate School at Augusta University, Augusta, Georgia
| | - Adviye Ergul
- Charlie Norwood Veterans Administration Medical Center, Augusta, Georgia; Department of Physiology, Medical College of Georgia, Augusta, Georgia; and
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25
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Nogueira RC, Saeed NP, Bor-Seng-Shu E, Teixeira MJ, Robinson TG, Panerai RB. The carotid artery as an alternative site for dynamic autoregulation measurement: an inter-observer reproducibility study. Med Eng Phys 2016; 38:690-694. [PMID: 27134150 DOI: 10.1016/j.medengphy.2016.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 02/02/2016] [Accepted: 03/19/2016] [Indexed: 11/19/2022]
Abstract
The internal carotid artery (ICA) has been proposed as an alternative site to the middle cerebral artery (MCA) to measure dynamic cerebral autoregulation (dCA) using transcranial Doppler ultrasound (TCD). Our aim was to test the inter-operator reproducibility of dCA assessment in the ICA and the effect of interaction amongst different variables (artery source × operator × intra-subject variability). Two operators measured blood flow velocity using TCD at the ICA and MCA simultaneously on each side in 12 healthy volunteers. The autoregulation index (ARI) was estimated by transfer function analysis. A two-way repeated measurements ANOVA with post-hoc Tukey tested the difference between ARI by different operators and interaction effects were analysed based on the generalized linear model. In this healthy population, no significant differences between operator and no interaction effects were identified amongst the different variables. This study reinforced the validity of using the ICA as an alternative site for the assessment of dCA. Further work is needed to confirm and extend our findings, particularly to disease populations.
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Affiliation(s)
- R C Nogueira
- Department of Neurology, Hospital das Clinicas, University of São Paulo School of Medicine, São Paulo, Brazil.
| | - N P Saeed
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK
| | - E Bor-Seng-Shu
- Department of Neurosurgery, Hospital das Clinicas, University of São Paulo School of Medicine, São Paulo, Brazil
| | - M J Teixeira
- Department of Neurosurgery, Hospital das Clinicas, University of São Paulo School of Medicine, São Paulo, Brazil
| | - T G Robinson
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; NIHR Biomedical Research Unit in Cardiovascular Science, Glenfield Hospital, Leicester LE3 9QP, UK
| | - R B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; NIHR Biomedical Research Unit in Cardiovascular Science, Glenfield Hospital, Leicester LE3 9QP, UK
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26
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Lucas SJE, Helge JW, Schütz UHW, Goldman RF, Cotter JD. Moving in extreme environments: extreme loading; carriage versus distance. EXTREME PHYSIOLOGY & MEDICINE 2016; 5:6. [PMID: 27110357 PMCID: PMC4840901 DOI: 10.1186/s13728-016-0047-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 04/01/2016] [Indexed: 12/17/2022]
Abstract
This review addresses human capacity for movement in the context of extreme loading and with it the combined effects of metabolic, biomechanical and gravitational stress on the human body. This topic encompasses extreme duration, as occurs in ultra-endurance competitions (e.g. adventure racing and transcontinental races) and expeditions (e.g. polar crossings), to the more gravitationally limited load carriage (e.g. in the military context). Juxtaposed to these circumstances is the extreme metabolic and mechanical unloading associated with space travel, prolonged bedrest and sedentary lifestyle, which may be at least as problematic, and are therefore included as a reference, e.g. when considering exposure, dangers and (mal)adaptations. As per the other reviews in this series, we describe the nature of the stress and the associated consequences; illustrate relevant regulations, including why and how they are set; present the pros and cons for self versus prescribed acute and chronic exposure; describe humans' (mal)adaptations; and finally suggest future directions for practice and research. In summary, we describe adaptation patterns that are often U or J shaped and that over time minimal or no load carriage decreases the global load carrying capacity and eventually leads to severe adverse effects and manifest disease under minimal absolute but high relative loads. We advocate that further understanding of load carrying capacity and the inherent mechanisms leading to adverse effects may advantageously be studied in this perspective. With improved access to insightful and portable technologies, there are some exciting possibilities to explore these questions in this context.
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Affiliation(s)
- Samuel J. E. Lucas
- />School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT UK
- />Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Jørn W. Helge
- />Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Uwe H. W. Schütz
- />Department of Diagnostic and Interventional Radiology, University Hospital of Ulm, Ulm, Germany
- />Orthopaedic Consulting Office at the Green Tower and Medical Pain Centre Lake Constance–Upper Swabia, Ravensburg, Germany
| | | | - James D. Cotter
- />School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
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27
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Brozovich FV, Nicholson CJ, Degen CV, Gao YZ, Aggarwal M, Morgan KG. Mechanisms of Vascular Smooth Muscle Contraction and the Basis for Pharmacologic Treatment of Smooth Muscle Disorders. Pharmacol Rev 2016; 68:476-532. [PMID: 27037223 PMCID: PMC4819215 DOI: 10.1124/pr.115.010652] [Citation(s) in RCA: 298] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The smooth muscle cell directly drives the contraction of the vascular wall and hence regulates the size of the blood vessel lumen. We review here the current understanding of the molecular mechanisms by which agonists, therapeutics, and diseases regulate contractility of the vascular smooth muscle cell and we place this within the context of whole body function. We also discuss the implications for personalized medicine and highlight specific potential target molecules that may provide opportunities for the future development of new therapeutics to regulate vascular function.
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Affiliation(s)
- F V Brozovich
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - C J Nicholson
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - C V Degen
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - Yuan Z Gao
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - M Aggarwal
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - K G Morgan
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
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28
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Amelioration of Metabolic Syndrome-Associated Cognitive Impairments in Mice via a Reduction in Dietary Fat Content or Infusion of Non-Diabetic Plasma. EBioMedicine 2015; 3:26-42. [PMID: 26870815 PMCID: PMC4739422 DOI: 10.1016/j.ebiom.2015.12.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/26/2015] [Accepted: 12/11/2015] [Indexed: 12/25/2022] Open
Abstract
Obesity, metabolic syndrome (MetS) and type 2 diabetes (T2D) are associated with decreased cognitive function. While weight loss and T2D remission result in improvements in metabolism and vascular function, it is less clear if these benefits extend to cognitive performance. Here, we highlight the malleable nature of MetS-associated cognitive dysfunction using a mouse model of high fat diet (HFD)-induced MetS. While learning and memory was generally unaffected in mice with type 1 diabetes (T1D), multiple cognitive impairments were associated with MetS, including deficits in novel object recognition, cued fear memory, and spatial learning and memory. However, a brief reduction in dietary fat content in chronic HFD-fed mice led to a complete rescue of cognitive function. Cerebral blood volume (CBV), a measure of vascular perfusion, was decreased during MetS, was associated with long term memory, and recovered following the intervention. Finally, repeated infusion of plasma collected from age-matched, low fat diet-fed mice improved memory in HFD mice, and was associated with a distinct metabolic profile. Thus, the cognitive dysfunction accompanying MetS appears to be amenable to treatment, related to cerebrovascular function, and mitigated by systemic factors.
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Key Words
- ADMA, Asymmetric dimethylarginine
- BDNF, Brain-derived neurotrophic factor
- BW, Body weight
- Br Fat, Brown adipose tissue
- Brain
- C-X-C motif, Chemokine
- CBV, Cerebral blood volume
- CH, Cholesterol
- Cerebrovascular
- Cognitive
- Cxcl1, Ligand 1
- DG, Diacylglycerol
- Diabetes
- FFA, Free fatty acids
- GL, Glycerolipid
- GLP-1, Glucagon-like peptide 1
- GPL, Glycerophospholipid
- GlcCer, Glucosylceramide
- HFD, High fat diet
- IFNγ, Interferon-γ
- IL-10, Interleukin-10
- IL-12p70, Interleukin-12p70
- IL-6, Interleukin-6
- IR, Insulin resistance
- ITT, Insulin tolerance test
- Il-1b, Interleukin-1β
- KB, Total ketone bodies
- LFD, Low fat diet
- LPA, Lysophosphatidic acid
- MetS, Metabolic syndrome
- Metabolic syndrome
- OGTT, Oral glucose tolerance test
- Obesity
- PC, Phosphatidylcholine
- PE, Phosphatidylethanolamine
- PG, Phosphatidylglycerol
- PGP, Phosphatidylglycerolphosphate
- PI, Phosphatidylinositol
- PS, Phosphatidylserine
- Plasma
- SC Fat, Subcutaneous adipose tissue
- T1D, Type 1 Diabetes
- T2D, Type 2 Diabetes
- TG, Triglycerides
- TNFα, Tumor necrosis factor-α
- V Fat, Visceral adipose tissue
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30
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van Veen TR, Panerai RB, Haeri S, van den Berg PP, Zeeman GG, Belfort MA. Cerebral autoregulation in pregnancies complicated by diabetes and overweight. Diab Vasc Dis Res 2015; 12:377-80. [PMID: 26092823 DOI: 10.1177/1479164115588547] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
AIM The aim of this study was to estimate the impact of diabetes and obesity on cerebral autoregulation in pregnancy. METHODS Cerebral autoregulation was evaluated in women with gestational diabetes, type 2 diabetes mellitus and/or overweight (body mass index ⩾ 25 kg m(-2)) and compared to a cohort of euglycaemic pregnant women. The autoregulation index was calculated using simultaneously recorded cerebral blood flow velocity in the middle cerebral artery and blood pressure. Autoregulation index values of 0 and 9 indicate absent and perfect autoregulation, respectively. RESULTS Autoregulation index in women with either diabetes (n = 33, 6.6 ± 1.1) or overweight (n = 21, 6.7 ± 0.6) was not significantly different to that in control patients (n = 23, 6.6 ± 0.8, p = 0.96). CONCLUSION Cerebral autoregulation is not impaired in pregnant women who have non-vasculopathic diabetes or overweight. This suggests that the increased risk of pre-eclampsia in diabetic and overweight women is not associated with early impaired cerebral autoregulation.
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Affiliation(s)
- Teelkien R van Veen
- Department of Obstetrics and Gynaecology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX, USA
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK NIHR Biomedical Research Unit in Cardiovascular Sciences, Glenfield Hospital, Leicester, UK
| | - Sina Haeri
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX, USA St. David's Women's Center of Texas, North Austin Maternal-Fetal Medicine, Austin, TX, USA
| | - Paul P van den Berg
- Department of Obstetrics and Gynaecology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Gerda G Zeeman
- Department of Obstetrics and Gynaecology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Michael A Belfort
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX, USA
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31
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Spauwen PJJ, van Boxtel MPJ, Verhey FRJ, Köhler S, Sep SJS, Koster A, Dagnelie PC, Henry RMA, Schaper NC, van der Kallen CJH, Schram MT, Kroon AA, Stehouwer CDA. Both Low and High 24-Hour Diastolic Blood Pressure Are Associated With Worse Cognitive Performance in Type 2 Diabetes: The Maastricht Study. Diabetes Care 2015; 38:1473-80. [PMID: 26016842 DOI: 10.2337/dc14-2502] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 05/07/2015] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Hypertension and diabetes are both risk factors for cognitive decline, and individuals with both might have an especially high risk. We therefore examined linear and nonlinear (quadratic) associations of 24-h blood pressure (BP) with cognitive performance in participants with and without type 2 diabetes. We also tested the association of nocturnal dipping status with cognitive performance. RESEARCH DESIGN AND METHODS This study was performed as part of the Maastricht Study, an ongoing population-based cohort study. Cross-sectional associations of 24-h BP (n = 713, of whom 201 had type 2 diabetes) and nocturnal dipping status (n = 686, of whom 196 had type 2 diabetes) with performance on tests for global cognitive functioning, information processing speed, verbal memory (immediate and delayed word recall), and response inhibition were tested using linear regression analysis and adjusted for demographics, vascular risk factors, cardiovascular disease, depression, and lipid-modifying and antihypertensive medication use. RESULTS After full adjustment, we found quadratic (inverted U-shaped) associations of 24-h diastolic blood pressure (DBP) with information processing speed (b for quadratic term = -0.0267, P < 0.01) and memory (immediate word recall: b = -0.0180, P < 0.05; delayed word recall: b = -0.0076, P < 0.01) in participants with diabetes, but not in those without. No clear pattern was found for dipping status. CONCLUSIONS This study shows that both low and high 24-h DBP are associated with poorer performance on tests of information processing speed and memory in individuals with type 2 diabetes.
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Affiliation(s)
- Peggy J J Spauwen
- Department of Psychiatry and Neuropsychology, Maastricht University Medical Centre, Maastricht, the Netherlands School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Martin P J van Boxtel
- Department of Psychiatry and Neuropsychology, Maastricht University Medical Centre, Maastricht, the Netherlands School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Frans R J Verhey
- Department of Psychiatry and Neuropsychology, Maastricht University Medical Centre, Maastricht, the Netherlands School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Sebastian Köhler
- Department of Psychiatry and Neuropsychology, Maastricht University Medical Centre, Maastricht, the Netherlands School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Simone J S Sep
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
| | - Annemarie Koster
- Department of Social Medicine, Maastricht University, Maastricht, the Netherlands School for Public Health and Primary Care, Maastricht University, Maastricht, the Netherlands
| | - Pieter C Dagnelie
- Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands School for Public Health and Primary Care, Maastricht University, Maastricht, the Netherlands Department of Epidemiology, Maastricht University, Maastricht, the Netherlands
| | - Ronald M A Henry
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
| | - Nicolaas C Schaper
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
| | - Carla J H van der Kallen
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
| | - Miranda T Schram
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
| | - Abraham A Kroon
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
| | - Coen D A Stehouwer
- Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands
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32
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Rolfe AJ. Re: cerebral autoregulation in different hypertensive disorders of pregnancy. Am J Obstet Gynecol 2015; 212:832. [PMID: 25637850 DOI: 10.1016/j.ajog.2015.01.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 01/24/2015] [Indexed: 11/16/2022]
Affiliation(s)
- Alyssa J Rolfe
- Florida State University, College of Medicine, Biomedical Sciences, Tallahassee, FL.
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33
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Lucas SJE, Cotter JD, Brassard P, Bailey DM. High-intensity interval exercise and cerebrovascular health: curiosity, cause, and consequence. J Cereb Blood Flow Metab 2015; 35:902-11. [PMID: 25833341 PMCID: PMC4640257 DOI: 10.1038/jcbfm.2015.49] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 01/25/2015] [Accepted: 03/01/2015] [Indexed: 12/14/2022]
Abstract
Exercise is a uniquely effective and pluripotent medicine against several noncommunicable diseases of westernised lifestyles, including protection against neurodegenerative disorders. High-intensity interval exercise training (HIT) is emerging as an effective alternative to current health-related exercise guidelines. Compared with traditional moderate-intensity continuous exercise training, HIT confers equivalent if not indeed superior metabolic, cardiac, and systemic vascular adaptation. Consequently, HIT is being promoted as a more time-efficient and practical approach to optimize health thereby reducing the burden of disease associated with physical inactivity. However, no studies to date have examined the impact of HIT on the cerebrovasculature and corresponding implications for cognitive function. This review critiques the implications of HIT for cerebrovascular function, with a focus on the mechanisms and translational impact for patient health and well-being. It also introduces similarly novel interventions currently under investigation as alternative means of accelerating exercise-induced cerebrovascular adaptation. We highlight a need for studies of the mechanisms and thereby also the optimal dose-response strategies to guide exercise prescription, and for studies to explore alternative approaches to optimize exercise outcomes in brain-related health and disease prevention. From a clinical perspective, interventions that selectively target the aging brain have the potential to prevent stroke and associated neurovascular diseases.
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Affiliation(s)
- Samuel J E Lucas
- 1] School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK [2] Department of Physiology, University of Otago, Dunedin, New Zealand
| | - James D Cotter
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Patrice Brassard
- 1] Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada [2] Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Damian M Bailey
- 1] Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, South Wales, UK [2] Université de Provence Marseille, Sondes Moléculaires en Biologie, Laboratoire Chimie Provence UMR 6264 CNRS, Marseille, France
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Ito K, Ookawara S, Ueda Y, Goto S, Miyazawa H, Yamada H, Kitano T, Shindo M, Kaku Y, Hirai K, Yoshida M, Hoshino T, Nabata A, Mori H, Yoshida I, Kakei M, Tabei K. Factors affecting cerebral oxygenation in hemodialysis patients: cerebral oxygenation associates with pH, hemodialysis duration, serum albumin concentration, and diabetes mellitus. PLoS One 2015; 10:e0117474. [PMID: 25706868 PMCID: PMC4338103 DOI: 10.1371/journal.pone.0117474] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 12/24/2014] [Indexed: 01/13/2023] Open
Abstract
Background Patients undergoing hemodialysis (HD) often develop cerebral disease complications. Furthermore, cerebral regional saturation of oxygen (rSO2) was previously reported to be significantly lower in HD patients than in healthy subjects. We aimed to identify the factors affecting the cerebral rSO2 in HD patients. Methods Fifty-four HD patients (38 men and 16 women; mean age, 67.7 ± 1.2 years, HD duration, 6.5 ± 1.9 years) were recruited. Cerebral rSO2 was monitored at the forehead before HD using an INVOS 5100C (Covidien Japan, Tokyo, Japan). Results The rSO2 levels were significantly lower in HD patients compared with healthy controls (49.5 ± 1.7% vs. 68.9 ± 1.6%, p <0.001). Multiple regression analysis showed that cerebral rSO2 independently associated with pH (standardized coefficient: -0.35), HD duration (standardized coefficient: -0.33), and serum albumin concentration (standardized coefficient: 0.28). Furthermore, the rSO2 was significantly lower in HD patients with diabetes mellitus (DM), compared with patients without DM (46.8 ± 1.7% vs. 52.1 ± 1.8%, p <0.05). Conclusions In HD patients, cerebral rSO2 was affected by multiple factors, including pH, HD duration, and serum albumin concentration. Furthermore, this is the first report describing significantly lower levels of rSO2 in HD patients with DM than in those without DM.
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Affiliation(s)
- Kiyonori Ito
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Susumu Ookawara
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
- Department of Internal Medicine, Nishikawa Town Hospital, Yamagata, Japan
- * E-mail:
| | - Yuichiro Ueda
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Sawako Goto
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Haruhisa Miyazawa
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Hodaka Yamada
- Division of Endocrinology and Metabolism, Department of Integrated Medicine Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Taisuke Kitano
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Mitsunobu Shindo
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Yoshio Kaku
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Keiji Hirai
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Masashi Yoshida
- Division of Endocrinology and Metabolism, Department of Integrated Medicine Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Taro Hoshino
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Aoi Nabata
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Honami Mori
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Izumi Yoshida
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Masafumi Kakei
- Division of Endocrinology and Metabolism, Department of Integrated Medicine Saitama Medical Center, Jichi Medical University, Saitama, Japan
| | - Kaoru Tabei
- Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
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Vianna LC, Deo SH, Jensen AK, Holwerda SW, Zimmerman MC, Fadel PJ. Impaired dynamic cerebral autoregulation at rest and during isometric exercise in type 2 diabetes patients. Am J Physiol Heart Circ Physiol 2015; 308:H681-7. [PMID: 25599569 DOI: 10.1152/ajpheart.00343.2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 01/15/2015] [Indexed: 12/21/2022]
Abstract
Type 2 diabetes mellitus patients (T2D) have elevated risk of stroke, suggesting that cerebrovascular function is impaired. Herein, we examined dynamic cerebral autoregulation (CA) at rest and during exercise in T2D patients and determined whether underlying systemic oxidative stress is associated with impairments in CA. Middle cerebral artery blood velocity and arterial blood pressure (BP) were measured at rest and during 2-min bouts of low- and high-intensity isometric handgrip performed at 20% and 40% maximum voluntary contraction, respectively, in seven normotensive and eight hypertensive T2D patients and eight healthy controls. Dynamic CA was estimated using the rate of regulation (RoR). Total reactive oxygen species (ROS) and superoxide levels were measured at rest. There were no differences in RoR at rest or during exercise between normotensive and hypertensive T2D patients. However, when compared with controls, T2D patients exhibited lower RoR at rest and during low-intensity handgrip indicating impaired dynamic CA. Moreover, the RoR was further reduced by 29 ± 4% during high-intensity handgrip in T2D patients (0.307 ± 0.012/s rest vs. 0.220 ± 0.014/s high intensity; P < 0.01), although well maintained in controls. T2D patients demonstrated greater baseline total ROS and superoxide compared with controls, both of which were negatively related to RoR during handgrip (e.g., total ROS: r = -0.71, P < 0.05; 40% maximum voluntary contraction). Collectively, these data demonstrate impaired dynamic CA at rest and during isometric handgrip in T2D patients, which may be, in part, related to greater underlying systemic oxidative stress. Additionally, dynamic CA is blunted further with high intensity isometric contractions potentially placing T2D patients at greater risk for cerebral events during such activities.
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Affiliation(s)
- Lauro C Vianna
- Faculty of Physical Education, University of Brasília, DF, Brazil; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Shekhar H Deo
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Areum K Jensen
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Seth W Holwerda
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Matthew C Zimmerman
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Paul J Fadel
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; and
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Abd-Elrahman KS, Walsh MP, Cole WC. Abnormal Rho-associated kinase activity contributes to the dysfunctional myogenic response of cerebral arteries in type 2 diabetes. Can J Physiol Pharmacol 2015; 93:177-84. [PMID: 25660561 DOI: 10.1139/cjpp-2014-0437] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The structural and functional integrity of the brain, and therefore, cognition, are critically dependent on the appropriate control of blood flow within the cerebral circulation. Inadequate flow leads to ischemia, whereas excessive flow causes small vessel rupture and (or) blood-brain-barrier disruption. Cerebral blood flow is controlled through the interplay of several physiological mechanisms that regulate the contractile state of vascular smooth muscle cells (VSMCs) within the walls of cerebral resistance arteries and arterioles. The myogenic response of cerebral VSMCs is a key mechanism that is responsible for maintaining constant blood flow during variations in systemic pressure, i.e., flow autoregulation. Inappropriate myogenic control of cerebral blood flow is associated with, and prognostic of, neurological deterioration and poor outcome in patients with several conditions, including type 2 diabetes. Here, we review recent advances in our understanding of the role of inappropriate Rho-associated kinase activity as a cause of impaired myogenic regulation of cerebral arterial diameter in type 2 diabetes.
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Affiliation(s)
- Khaled S Abd-Elrahman
- The Smooth Muscle Research Group, Libin Cardiovascular Institute, Hotchkiss Brain Institute, and the Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
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Abstract
SIGNIFICANCE The brain has high energetic requirements and is therefore highly dependent on adequate cerebral blood supply. To compensate for dangerous fluctuations in cerebral perfusion, the circulation of the brain has evolved intrinsic safeguarding measures. RECENT ADVANCES AND CRITICAL ISSUES The vascular network of the brain incorporates a high degree of redundancy, allowing the redirection and redistribution of blood flow in the event of vascular occlusion. Furthermore, active responses such as cerebral autoregulation, which acts to maintain constant cerebral blood flow in response to changing blood pressure, and functional hyperemia, which couples blood supply with synaptic activity, allow the brain to maintain adequate cerebral perfusion in the face of varying supply or demand. In the presence of stroke risk factors, such as hypertension and diabetes, these protective processes are impaired and the susceptibility of the brain to ischemic injury is increased. One potential mechanism for the increased injury is that collateral flow arising from the normally perfused brain and supplying blood flow to the ischemic region is suppressed, resulting in more severe ischemia. FUTURE DIRECTIONS Approaches to support collateral flow may ameliorate the outcome of focal cerebral ischemia by rescuing cerebral perfusion in potentially viable regions of the ischemic territory.
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Affiliation(s)
- Katherine Jackman
- Brain and Mind Research Institute, Weill Cornell Medical College , New York, New York
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Global brain blood-oxygen level responses to autonomic challenges in obstructive sleep apnea. PLoS One 2014; 9:e105261. [PMID: 25166862 PMCID: PMC4148259 DOI: 10.1371/journal.pone.0105261] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 07/22/2014] [Indexed: 01/18/2023] Open
Abstract
Obstructive sleep apnea (OSA) is accompanied by brain injury, perhaps resulting from apnea-related hypoxia or periods of impaired cerebral perfusion. Perfusion changes can be determined indirectly by evaluation of cerebral blood volume and oxygenation alterations, which can be measured rapidly and non-invasively with the global blood oxygen level dependent (BOLD) signal, a magnetic resonance imaging procedure. We assessed acute BOLD responses in OSA subjects to pressor challenges that elicit cerebral blood flow changes, using a two-group comparative design with healthy subjects as a reference. We separately assessed female and male patterns, since OSA characteristics and brain injury differ between sexes. We studied 94 subjects, 37 with newly-diagnosed, untreated OSA (6 female (age mean ± std: 52.1±8.1 yrs; apnea/hypopnea index [AHI]: 27.7±15.6 events/hr and 31 male 54.3±8.4 yrs; AHI: 37.4±19.6 events/hr), and 20 female (age 50.5±8.1 yrs) and 37 male (age 45.6±9.2 yrs) healthy control subjects. We measured brain BOLD responses every 2 s while subjects underwent cold pressor, hand grip, and Valsalva maneuver challenges. The global BOLD signal rapidly changed after the first 2 s of each challenge, and differed in magnitude between groups to two challenges (cold pressor, hand grip), but not to the Valsalva maneuver (repeated measures ANOVA, p<0.05). OSA females showed greater differences from males in response magnitude and pattern, relative to healthy counterparts. Cold pressor BOLD signal increases (mean ± adjusted standard error) at the 8 s peak were: OSA 0.14±0.08% vs. Control 0.31±0.06%, and hand grip at 6 s were: OSA 0.08±0.03% vs. Control at 0.30±0.02%. These findings, indicative of reduced cerebral blood flow changes to autonomic challenges in OSA, complement earlier reports of altered resting blood flow and reduced cerebral artery responsiveness. Females are more affected than males, an outcome which may contribute to the sex-specific brain injury in the syndrome.
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Moreno-Domínguez A, El-Yazbi AF, Zhu HL, Colinas O, Zhong XZ, Walsh EJ, Cole DM, Kargacin GJ, Walsh MP, Cole WC. Cytoskeletal reorganization evoked by Rho-associated kinase- and protein kinase C-catalyzed phosphorylation of cofilin and heat shock protein 27, respectively, contributes to myogenic constriction of rat cerebral arteries. J Biol Chem 2014; 289:20939-52. [PMID: 24914207 PMCID: PMC4110300 DOI: 10.1074/jbc.m114.553743] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 06/03/2014] [Indexed: 12/31/2022] Open
Abstract
Our understanding of the molecular events contributing to myogenic control of diameter in cerebral resistance arteries in response to changes in intravascular pressure, a fundamental mechanism regulating blood flow to the brain, is incomplete. Myosin light chain kinase and phosphatase activities are known to be increased and decreased, respectively, to augment phosphorylation of the 20-kDa regulatory light chain subunits (LC20) of myosin II, which permits cross-bridge cycling and force development. Here, we assessed the contribution of dynamic reorganization of the actin cytoskeleton and thin filament regulation to the myogenic response and serotonin-evoked constriction of pressurized rat middle cerebral arteries. Arterial diameter and the levels of phosphorylated LC(20), calponin, caldesmon, cofilin, and HSP27, as well as G-actin content, were determined. A decline in G-actin content was observed following pressurization from 10 mm Hg to between 40 and 120 mm Hg and in three conditions in which myogenic or agonist-evoked constriction occurred in the absence of a detectable change in LC20 phosphorylation. No changes in thin filament protein phosphorylation were evident. Pressurization reduced G-actin content and elevated the levels of cofilin and HSP27 phosphorylation. Inhibitors of Rho-associated kinase and PKC prevented the decline in G-actin; reduced cofilin and HSP27 phosphoprotein content, respectively; and blocked the myogenic response. Furthermore, phosphorylation modulators of HSP27 and cofilin induced significant changes in arterial diameter and G-actin content of myogenically active arteries. Taken together, our findings suggest that dynamic reorganization of the cytoskeleton involving increased actin polymerization in response to Rho-associated kinase and PKC signaling contributes significantly to force generation in myogenic constriction of cerebral resistance arteries.
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Affiliation(s)
| | - Ahmed F. El-Yazbi
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Hai-Lei Zhu
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Olaia Colinas
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - X. Zoë Zhong
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Emma J. Walsh
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Dylan M. Cole
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Gary J. Kargacin
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Michael P. Walsh
- Biochemistry & Molecular Biology, Libin Cardiovascular Institute and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - William C. Cole
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
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Brassard P, Pelletier C, Martin M, Gagné N, Poirier P, Ainslie PN, Caouette M, Bussières JS. Influence of Norepinephrine and Phenylephrine on Frontal Lobe Oxygenation During Cardiopulmonary Bypass in Patients with Diabetes. J Cardiothorac Vasc Anesth 2014; 28:608-17. [DOI: 10.1053/j.jvca.2013.09.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Indexed: 11/11/2022]
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Paquette M, Brassard P. Regarding "The effects of an exercise and lifestyle intervention program on cardiovascular, metabolic factors and cognitive performance in middle-aged adults with type 2 diabetes: a pilot study. Can J Diabetes 2013;37:214-9". Can J Diabetes 2014; 38:221. [PMID: 24797493 DOI: 10.1016/j.jcjd.2013.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 12/12/2013] [Indexed: 10/25/2022]
Affiliation(s)
- Myriam Paquette
- Department of Kinesiology, Faculty of Medicine, Université Laval Research Centre of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Québec, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval Research Centre of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Québec, Canada
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Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow. Med Eng Phys 2014; 36:563-75. [DOI: 10.1016/j.medengphy.2014.02.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
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Bronzwaer ASGT, Stok WJ, Westerhof BE, van Lieshout JJ. Arterial pressure variations as parameters of brain perfusion in response to central blood volume depletion and repletion. Front Physiol 2014; 5:157. [PMID: 24795652 PMCID: PMC4006039 DOI: 10.3389/fphys.2014.00157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 04/03/2014] [Indexed: 01/08/2023] Open
Abstract
Rationale: A critical reduction in central blood volume (CBV) is often characterized by hemodynamic instability. Restoration of a volume deficit may be established by goal-directed fluid therapy guided by respiration-related variation in systolic- and pulse pressure (SPV and PPV). Stroke volume index (SVI) serves as a surrogate end-point of a fluid challenge but tissue perfusion itself has not been addressed. Objective: To delineate the relationship between arterial pressure variations, SVI and regional brain perfusion during CBV depletion and repletion in spontaneously breathing volunteers. Methods: This study quantified in 14 healthy subjects (11 male) the effects of CBV depletion [by 30 and 70 degrees passive head-up tilt (HUT)] and a fluid challenge (by tilt back) on CBV (thoracic admittance), mean middle cerebral artery (MCA) blood flow velocity (Vmean), SVI, cardiac index (CI), PPV, and SPV. Results: PPV (103 ± 89%, p < 0.05) and SPV (136 ± 117%, p < 0.05) increased with progression of central hypovolemia manifested by a reduction in thoracic admittance (11 ± 5%, p < 0.001), SVI (28 ± 6%, p < 0.001), CI (6 ± 8%, p < 0.001), and MCAVmean (17 ± 7%, p < 0.05) but not in arterial pressure. The reduction in MCAVmean correlated to the fall in SVI (R2 = 0.52, p < 0.0001) and inversely to PPV and SPV [R2 = 0.46 (p < 0.0001) and R2 = 0.45 (p < 0.0001), respectively]. PPV and SPV predicted a ≥15% reduction in MCAVmean and SVI with comparable sensitivity (67/67% vs. 63/68%, respectively) and specificity (89/94 vs. 89/94%, respectively). A rapid fluid challenge by tilt-back restored all parameters to baseline values within 1 min. Conclusion: In spontaneously breathing subjects, a reduction in MCAVmean was related to an increase in PPV and SPV during graded CBV depletion and repletion. Specifically, PPV and SPV predicted changes in both SVI and MCAVmean with comparable sensitivity and specificity, however the predictive value is limited in spontaneously breathing subjects.
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Affiliation(s)
- Anne-Sophie G T Bronzwaer
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands ; Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center Amsterdam, Netherlands
| | - Wim J Stok
- Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center Amsterdam, Netherlands ; Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Berend E Westerhof
- Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center Amsterdam, Netherlands ; Edwards Lifesciences BMEYE Amsterdam, Netherlands
| | - Johannes J van Lieshout
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands ; Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center Amsterdam, Netherlands ; MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Queen's Medical Centre, School of Life Sciences, University of Nottingham Medical School Nottingham, UK
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Improvement of mild retinopathy in type 2 diabetic patients correlates with narrowing of retinal arterioles. A prospective observational study. Graefes Arch Clin Exp Ophthalmol 2014; 252:1561-7. [PMID: 24687143 DOI: 10.1007/s00417-014-2614-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 02/27/2014] [Accepted: 03/05/2014] [Indexed: 10/25/2022] Open
Abstract
PURPOSE Diabetic retinopathy is one of the leading causes of blindness in the Western world. The disease is characterized by morphological lesions secondary to disturbances in retinal blood flow assumed to be related to disturbances in retinal autoregulation. However, there is a need for elucidating the relation between disturbances in diameter regulation of retinal vessels and the development of diabetic retinopathy in longitudinal studies. METHODS Sixty-four patients with type 2 diabetes mellitus were subjected to measurement of pressure autoregulation of retinal arterioles using the Dynamic Vessel Analyzer (DVA) and measurement of retinal thickness using OCT scanning, and after a mean of 6.8 years, 42 of the patients were re-examined. The vascular response was compared in patients in whom retinopathy had disappeared, was unchanged, or had worsened. RESULTS At baseline, hemoglobin A1c (HbA1c) was significantly higher in the patients who would later experience worsening of diabetic retinopathy than in the other groups, but had been reduced at the follow-up examination. During the follow-up period, the resting diameter of retinal arterioles decreased significantly in the patients who experienced improvement in diabetic retinopathy but was unchanged in the other groups, whereas both the diameter response of retinal arterioles to isometric exercise and retinal thickness increased non-significantly with worsening of retinopathy. CONCLUSIONS The development of diabetic retinopathy is related to the diameter of retinal arterioles. Future clinical intervention studies should aim at investigating the effects of normalizing arteriolar diameters in diabetic retinopathy.
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Ainslie PN, Brassard P. Why is the neural control of cerebral autoregulation so controversial? F1000PRIME REPORTS 2014; 6:14. [PMID: 24669295 PMCID: PMC3944747 DOI: 10.12703/p6-14] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cerebral autoregulation refers to the mechanisms that act to keep cerebral blood flow (CBF) constant during changes in blood pressure. The mechanisms of cerebral autoregulation, especially in humans, are poorly understood but are undoubtedly multifactorial and likely reflect many redundant pathways that potentially differ between species. Whether sympathetic nervous activity influences CBF and/or cerebral autoregulation in humans remains controversial. Following a brief introduction to cerebral autoregulation, this review highlights the likely reasons behind the controversy of the neural control of cerebral autoregulation. Finally, suggestions are provided for further studies to improve the understanding of the neural control of CBF regulation.
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Affiliation(s)
- Philip N. Ainslie
- Center for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia – OkanaganKelowna, British ColumbiaCanada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université LavalQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébecCanada
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Lee JF, Harrison ML, Christmas KM, Kim K, Hurr C, Brothers RM. Elevated resting heart rate and reduced orthostatic tolerance in obese humans. Clin Auton Res 2013; 24:39-46. [PMID: 24292891 DOI: 10.1007/s10286-013-0222-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 11/15/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Obesity is linked with numerous physiological impairments; however, its impact on orthostatic tolerance (OT) remains unknown. This study tested the hypothesis that OT is reduced in obese individuals, and that reduced heart rate (HR) reserve and impaired cerebral autoregulation contribute to impaired OT. METHODS Eleven obese (8 females) and 22 non-obese (10 females) individuals were exposed to incremental lower body negative pressure (LBNP) to presyncope while HR, arterial blood pressure, and cerebral perfusion (middle cerebral artery blood velocity; MCA V mean) were measured. OT was quantified with a cumulative stress index (CSI). RESULTS OT was reduced in obese subjects, and there was an inverse relationship between body mass index (BMI) and OT (R = -0.47). HR was higher at rest and during each level of LBNP completed by all subjects. Similar peak HR (HRpeak) during LBNP between obese and non-obese subjects resulted in obese having a higher %peak HR at rest and at each stage of LBNP compared. Relationships existed for BMI and resting %HRpeak (R = 0.45) and resting %HRpeak and CSI (R = -0.52). Despite lower CSI in obese, MCA V mean and indices of cerebral autoregulation were similar between groups at all time points. CONCLUSIONS These data suggest that OT is reduced in obese and a higher resting HR, but not impaired regulation of cerebral perfusion, may contribute to this reduction.
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Affiliation(s)
- Joshua F Lee
- Environmental and Autonomic Physiology Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, 1 University Station: D-3700, Austin, TX, 78712, USA
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Immink RV, Pott FC, Secher NH, van Lieshout JJ. Hyperventilation, cerebral perfusion, and syncope. J Appl Physiol (1985) 2013; 116:844-51. [PMID: 24265279 DOI: 10.1152/japplphysiol.00637.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review summarizes evidence in humans for an association between hyperventilation (HV)-induced hypocapnia and a reduction in cerebral perfusion leading to syncope defined as transient loss of consciousness (TLOC). The cerebral vasculature is sensitive to changes in both the arterial carbon dioxide (PaCO2) and oxygen (PaO2) partial pressures so that hypercapnia/hypoxia increases and hypocapnia/hyperoxia reduces global cerebral blood flow. Cerebral hypoperfusion and TLOC have been associated with hypocapnia related to HV. Notwithstanding pronounced cerebrovascular effects of PaCO2 the contribution of a low PaCO2 to the early postural reduction in middle cerebral artery blood velocity is transient. HV together with postural stress does not reduce cerebral perfusion to such an extent that TLOC develops. However when HV is combined with cardiovascular stressors like cold immersion or reduced cardiac output brain perfusion becomes jeopardized. Whether, in patients with cardiovascular disease and/or defect, cerebral blood flow cerebral control HV-induced hypocapnia elicits cerebral hypoperfusion, leading to TLOC, remains to be established.
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Affiliation(s)
- R V Immink
- Laboratory for Clinical Cardiovascular Physiology, Department of Anatomy, Embryology, and Physiology, AMC Center for Heart Failure Research, Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
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Abstract
Vascular cognitive impairment defines alterations in cognition, ranging from subtle deficits to full-blown dementia, attributable to cerebrovascular causes. Often coexisting with Alzheimer's disease, mixed vascular and neurodegenerative dementia has emerged as the leading cause of age-related cognitive impairment. Central to the disease mechanism is the crucial role that cerebral blood vessels play in brain health, not only for the delivery of oxygen and nutrients, but also for the trophic signaling that inextricably links the well-being of neurons and glia to that of cerebrovascular cells. This review will examine how vascular damage disrupts these vital homeostatic interactions, focusing on the hemispheric white matter, a region at heightened risk for vascular damage, and on the interplay between vascular factors and Alzheimer's disease. Finally, preventative and therapeutic prospects will be examined, highlighting the importance of midlife vascular risk factor control in the prevention of late-life dementia.
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Affiliation(s)
- Costantino Iadecola
- Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10021, USA.
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Prakash K, Chandran DS, Khadgawat R, Jaryal AK, Deepak KK. Correction for blood pressure improves correlation between cerebrovascular reactivity assessed by breath holding and 6% CO(2) breathing. J Stroke Cerebrovasc Dis 2013; 23:630-5. [PMID: 23830954 DOI: 10.1016/j.jstrokecerebrovasdis.2013.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 05/28/2013] [Accepted: 06/03/2013] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Changes in cerebral blood flow velocity to hypercapnia are associated with changes in systemic blood pressure (BP). These confounding BP-dependent changes in cerebral blood flow velocity cause misinterpretation of cerebrovascular reactivity (CVR) results. The objective of the study was to determine the relationship between CVR assessed by breath holding and 6% CO2 breathing after correcting for BP-dependent changes in cerebral blood flow velocity. METHODS In 33 patients of uncomplicated type 2 diabetes mellitus, CVR was assessed as percentage changes in cerebral blood flow velocity and cerebrovascular conductance index. RESULTS Percentage change in cerebral blood flow velocity during breath holding was positively correlated with that of during 6% CO2 breathing (r = .35; P = .0448). CVR during breath holding and 6% CO2 breathing were better correlated when expressed as percentage changes in cerebrovascular conductance index (r = .49; P = .0040). Similarly, breath-holding test results expressed as percentage changes in cerebral blood flow velocity correctly identified only 37.5% of the poor reactors to 6% CO2 breathing. However, when the breath-holding test results were expressed as percentage changes in cerebrovascular conductance index, 62.5% of the poor reactors to 6% CO2 breathing were correctly identified indicating a better agreement between the test results obtained by the 2 methods. CONCLUSION Cerebrovascular response to breath holding is better correlated with that of 6% CO2 breathing when changes in cerebral blood flow velocity were corrected for associated changes in BP.
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Affiliation(s)
- Kiran Prakash
- Department of Physiology, All India Institute of Medical Sciences, New Delhi, India
| | - Dinu S Chandran
- Department of Physiology, All India Institute of Medical Sciences, New Delhi, India
| | - Rajesh Khadgawat
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India
| | - Ashok Kumar Jaryal
- Department of Physiology, All India Institute of Medical Sciences, New Delhi, India.
| | - Kishore Kumar Deepak
- Department of Physiology, All India Institute of Medical Sciences, New Delhi, India
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Abstract
The myogenic response has a critical role in regulation of blood flow to the brain. Increased intraluminal pressure elicits vasoconstriction, whereas decreased intraluminal pressure induces vasodilatation, thereby maintaining flow constant over the normal physiologic blood pressure range. Improved understanding of the molecular mechanisms underlying the myogenic response is crucial to identify deficiencies with pathologic consequences, such as cerebral vasospasm, hypertension, and stroke, and to identify potential therapeutic targets. Three mechanisms have been suggested to be involved in the myogenic response: (1) membrane depolarization, which induces Ca(2+) entry, activation of myosin light chain kinase, phosphorylation of the myosin regulatory light chains (LC(20)), increased actomyosin MgATPase activity, cross-bridge cycling, and vasoconstriction; (2) activation of the RhoA/Rho-associated kinase (ROCK) pathway, leading to inhibition of myosin light chain phosphatase by phosphorylation of MYPT1, the myosin targeting regulatory subunit of the phosphatase, and increased LC(20) phosphorylation; and (3) activation of the ROCK and protein kinase C pathways, leading to actin polymerization and the formation of enhanced connections between the actin cytoskeleton, plasma membrane, and extracellular matrix to augment force transmission. This review describes these three mechanisms, emphasizing recent developments regarding the importance of dynamic actin polymerization in the myogenic response of the cerebral vasculature.
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