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Chen Y, Zheng Y, Johnson S, Wiffen R, Yang B. A comparative study of accuracy in major adaptive filters for motion artifact removal in sleep apnea tests. Med Biol Eng Comput 2024; 62:829-842. [PMID: 38052880 PMCID: PMC10881614 DOI: 10.1007/s11517-023-02979-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 11/22/2023] [Indexed: 12/07/2023]
Abstract
Sleep apnea is probably the most common respiratory disorder; respiration and blood oxygen saturation (SpO2) are major concerns in sleep apnea and are also the two main parameters checked by polysomnography (PSG, the gold standard for diagnosing sleep apnea). In this study, we used a simple, non-invasive monitoring system based on photoplethysmography (PPG) to continuously monitor SpO2 and heart rate (HR) for individuals at home. Various breathing experiments were conducted to investigate the relationship between SpO2, HR, and apnea under different conditions, where two techniques (empirical formula and customized formula) for calculating SpO2 and two methods (resting HR and instantaneous HR) for assessing HR were compared. Various adaptive filters were implemented to compare the effectiveness in removing motion artifacts (MAs) during the tests. This study fills the gap in the literature by comparing the performance of different adaptive filters on estimating SpO2 and HR during apnea. The results showed that up-down finger motion introduced more MA than left-right motion, and the errors in SpO2 estimation were increased as the frequency of movement was increased; due to the low sampling frequency features of these tests, the insertion of adaptive filter increased the noise in the data instead of eliminating the MA for SpO2 estimation; the normal least mean squares (NLMS) filter is more effective in removing MA in HR estimation than other filters.
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Affiliation(s)
- Yongrui Chen
- Department of Physical, Mathematics and Engineering Sciences, University of Chester, Chester, CH1 4BJ, UK
| | - Yurui Zheng
- Department of Physical, Mathematics and Engineering Sciences, University of Chester, Chester, CH1 4BJ, UK
| | - Sam Johnson
- Passion for Life Healthcare (UK) Ltd, Chester, CH1 2NP, UK
| | - Richard Wiffen
- Passion for Life Healthcare (UK) Ltd, Chester, CH1 2NP, UK
| | - Bin Yang
- Department of Physical, Mathematics and Engineering Sciences, University of Chester, Chester, CH1 4BJ, UK.
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Wendi W, Dongzhe W, Hao W, Yongjin S, Xiaolin G. Effect of dry dynamic apnea on aerobic power in elite rugby athletes: a warm-up method. Front Physiol 2024; 14:1269656. [PMID: 38292448 PMCID: PMC10824898 DOI: 10.3389/fphys.2023.1269656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 12/28/2023] [Indexed: 02/01/2024] Open
Abstract
Objective: While long-term dynamic breath-holding training has been extensively studied to enhance cardiopulmonary function in athletes, limited research has explored the impact of a single breath-holding session on subsequent athletic capacity. In addition, Dry Dynamic Apnea (DA) has a more immediate physiological response than wet and static breath-holding. This study aims to assess the immediate effects of a single session of DA on the aerobic power and hematological parameters of elite athletes. Methods: Seventeen elite male rugby athletes (average age 23.5 ± 1.8) participated in this study. Two warm-up protocols were employed prior to incremental exercise: a standard warm-up (10 min of no-load pedaling) and a DA warm-up (10 min of no-load pedaling accompanied by six maximum capacity breath holds, with 30 s between each breath hold). Fingertip blood indicators were measured before and after warm-up. The incremental exercise test assessed aerobic parameters with self-regulation applied throughout the study. Results: Compared to the baseline warm-up, the DA warm-up resulted in a significant increase in VO2peak from 3.14 to 3.38 L/min (7.64% change, p < 0.05). HRmax increased from 170 to 183 bpm (7.34% change, p < 0.05), and HRpeak increased from 169 to 182 bpm (7.52% change, p < 0.05). Hematocrit and hemoglobin showed differential changes between the two warm-up methods (PHematocrit = 0.674; Phemoglobin = 0.707). Conclusion: This study investigates how DA influences physiological factors such as spleen contraction, oxygen uptake, and sympathetic nerve activation compared to traditional warm-up methods. Immediate improvements in aerobic power suggest reduced vagus nerve stimulation, heightened sympathetic activity, and alterations in respiratory metabolism induced by the voluntarily hypoxia-triggered warm-up. Further research is warranted to comprehensively understand these physiological responses and optimize warm-up strategies for elite athletic performance.
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Affiliation(s)
- Wang Wendi
- Sports Rehabilitation Research Center, China Institute of Sport Science, Beijing, China
| | - Wu Dongzhe
- Sports Rehabilitation Research Center, China Institute of Sport Science, Beijing, China
| | - Wang Hao
- Sports Rehabilitation Research Center, China Institute of Sport Science, Beijing, China
| | - Shi Yongjin
- Department of Sports and Arts, China Agricultural University, Beijing, China
| | - Gao Xiaolin
- Sports Rehabilitation Research Center, China Institute of Sport Science, Beijing, China
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Mišić NŽ, Ostojić M, Cvetković S, Miodragović P, Aničić Z, Kovačić Popović A, Stefanović Đ. Wavelet Analysis of Respiratory Muscle sEMG Signals during the Physiological Breakpoint of Static Dry End-Expiratory Breath-Holding in Naive Apneists: A Pilot Study. SENSORS (BASEL, SWITZERLAND) 2023; 23:7200. [PMID: 37631736 PMCID: PMC10459781 DOI: 10.3390/s23167200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023]
Abstract
The wavelet spectral characteristics of three respiratory muscle signals (scalenus (SC), parasternal intercostal (IC), and rectus abdominis (RA)) and one locomotor muscle (brachioradialis (BR)) were analyzed in the time-frequency (T-F) domain during voluntary breath-holding (BH), with a focus on the physiological breakpoint that is commonly considered the first involuntary breathing movement (IBM) that signals the end of the easy-going phase of BH. The study was performed for an end-expiratory BH physiological breaking point maneuver on twelve healthy, physically active, naive breath-holders/apneists (six professional athletes; six recreational athletes, and two individuals in the post-COVID-19 period) using surface electromyography (sEMG). We observed individual effects that were dependent on muscle oxygenation and each person's fitness, which were consistent with the mechanism of motor unit (MU) recruitment and the transition of slow-twitch oxidative (type 1) to fast-twitch glycolytic (type 2) muscle fibers. Professional athletes had longer BH durations (BHDs) and strong hypercapnic responses regarding the expiratory RA muscle, which is activated abruptly at higher BHDs in a person-specific range below 250 Hz and is dependent on the BHD. This is in contrast with recreational athletes, who had strong hypoxic responses regarding inspiratory IC muscle, which is activated faster and gradually in the frequency range of 250-450 Hz (independent of the person and BHD). This pilot study preliminarily indicates that it is possible to noninvasively assess the physiological characteristics of skeletal muscles, especially oxygenation, and improve physical fitness tests by determining the T-F features of elevated myoelectric IC and RA activity during BH.
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Affiliation(s)
- Nataša Ž. Mišić
- Division of Computational Bioengineering, Research & Development Institute Lola Ltd., 11030 Belgrade, Serbia; (M.O.); (S.C.)
| | - Mirko Ostojić
- Division of Computational Bioengineering, Research & Development Institute Lola Ltd., 11030 Belgrade, Serbia; (M.O.); (S.C.)
| | - Saša Cvetković
- Division of Computational Bioengineering, Research & Development Institute Lola Ltd., 11030 Belgrade, Serbia; (M.O.); (S.C.)
| | - Petar Miodragović
- Department of Physiology, Faculty of Medicine, University of Novi Sad, 21137 Novi Sad, Serbia;
| | - Zdravko Aničić
- Laboratory of Methodology and Research, Faculty of Sport and Physical Education, University of Belgrade, 11030 Belgrade, Serbia;
| | - Anita Kovačić Popović
- Department of Defectology and Clinical Psychology, Medika College for Vocational Studies in Healthcare, 11000 Belgrade, Serbia;
| | - Đorđe Stefanović
- Department for Basic Sports, Faculty of Sport and Physical Education, University of Belgrade, 11030 Belgrade, Serbia;
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Karunarathne LU, Amarasiri W, Fernando A. Respiratory function in healthy long-term meditators: A cross-sectional comparative study. Heliyon 2023; 9:e18585. [PMID: 37554788 PMCID: PMC10404977 DOI: 10.1016/j.heliyon.2023.e18585] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 07/13/2023] [Accepted: 07/21/2023] [Indexed: 08/10/2023] Open
Abstract
PURPOSE Respiratory function is thought to improve with long-term meditation. This study aimed to assess respiratory function in a cohort of healthy long-term meditators and non-meditators in Sri Lanka. METHODS Respiratory function of healthy, skilled long-term meditators (n = 20) practicing Buddhist meditation consistently >3 years, and age-sex matched non-meditators (n = 20) were assessed by assessing resting respiratory rate, spirometry, breath-holding time and six-minute-walk distance. Data were analyzed with SPSS-23 statistical software. RESULTS The long-term meditators; 45% male, mean (SD) total lifetime meditation experience 12.8 (6.5) years, aged 45.8 (8.74) years, BMI 23.68 (2.23) kgm-2, and non-meditators; 45% male, mean (SD) age 45.3 (8.05) years, BMI 23.68 (3.28) kgm-2, were comparable. Long-term meditators had slower resting respiratory rates [mean (SD); 13.35 (1.9) vs. 18.37 (2.31) breaths/minute; p < 0.001], higher peak expiratory flow rates [mean (SD); 9.89 (2.5) vs. 8.22 (2.3) L/s; p = 0.03], and higher inspiratory breath-holding times [mean (SD); 74 (29.84) vs. 53.61 (26.83) seconds, p = 0.038] compared to non-meditators. There was no significant difference in the six-minute-walk distance and estimated maximal oxygen consumption between the two groups.Resting respiratory rate of long-term meditators, showed a significant negative correlation with total lifetime meditation practice in years (r = -0.444, p = 0.049), and the average length of a meditation session per day (r = -0.65, p = 0.002). The long-term meditators with longer duration of retreat participation demonstrated lower resting respiratory rate (r = -0.522, p = 0.018) and higher tidal volumes (r = 0.474, p = 0.04). CONCLUSIONS Long-term meditators had significantly slower resting respiratory rates and longer breath-holding times, with better spirometry parameters than non-meditators. Greater practice duration and retreat experience appear to be associated with improved resting respiratory function in long-term meditators.
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Affiliation(s)
- L.J. Udani Karunarathne
- Department of Physiology, Faculty of Medicine, University of Colombo, Colombo, 00800, Sri Lanka
- Department of Physical Medicine, National Hospital of Colombo, Colombo, 00700, Sri Lanka
| | - W.A.D.L. Amarasiri
- Department of Physiology, Faculty of Medicine, University of Colombo, Colombo, 00800, Sri Lanka
| | - A.D.A. Fernando
- Department of Physiology, Faculty of Medicine, University of Colombo, Colombo, 00800, Sri Lanka
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Towell V, Gysen KV, Cross S, KK Low G. Efficacy of preoxygenation administration in volunteers, in extending the end-expiration breath-hold duration for application to abdominal radiotherapy. Tech Innov Patient Support Radiat Oncol 2023; 26:100208. [PMID: 37207259 PMCID: PMC10189463 DOI: 10.1016/j.tipsro.2023.100208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 04/02/2023] [Accepted: 04/18/2023] [Indexed: 05/21/2023] Open
Abstract
Background and purpose End expiration breath hold (EEBH) is the preferred motion management method for abdominal Stereotactic Ablative Body Radiotherapy (SABR) treatments. However, multiple short EEBHs are required to complete a single treatment session. The study aimed to determine the efficacy of preoxygenation with hyperventilation in extending an EEBH duration. Materials and methods We randomised 10 healthy participants into two arms, each included breathing room air and oxygen at a rate of 10 L per minute (l/min) without hyperventilation for four minutes, and normally for four minutes and with hyperventilation for one minute at a rate of 20 breaths/minute for hyperventilation. The type of gas was blinded from the participants for each test. EEBH durations were then recorded, as well as systolic blood pressure, SpO2 and heart rate. A discomfort rating was also recorded after each breath hold. Results A significant increase in duration of almost 50% was observed between normal breathing of room air and breathing oxygen normally followed by hyperventilation. Vital signs remained consistent between the 4 tests. The tests were well tolerated with 75% of participants recording none or minimal discomfort. Conclusion Preoxygenation with hyperventilation could be used to increase the EEBH duration for abdominal SABR patients which would assist in the accuracy of these treatments and possibly resulting in a reduction of overall treatment times.
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Affiliation(s)
- Vincent Towell
- Department of Radiation Oncology, Nepean Hospital Cancer Care Centre, Sydney, Australia
- Corresponding author.
| | - Kirsten Van Gysen
- Department of Radiation Oncology, Nepean Hospital Cancer Care Centre, Sydney, Australia
- Nepean Clinical School, University of Sydney, Sydney, Australia
| | - Shamira Cross
- Department of Radiation Oncology, Nepean Hospital Cancer Care Centre, Sydney, Australia
- Nepean Clinical School, University of Sydney, Sydney, Australia
| | - Gary KK Low
- Research Operations, Nepean Hospital, Sydney, Australia
- Sydney Medical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
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Muacevic A, Adler JR, Zidan M, Elgyoum A, Hassan H, Abdelrahman O. Estimation of Spleen Volume Using MRI Segmentation: Would One Slice Be Enough? Cureus 2022; 14:e32165. [PMID: 36601193 PMCID: PMC9806286 DOI: 10.7759/cureus.32165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2022] [Indexed: 12/07/2022] Open
Abstract
This study aimed to establish spleen volume in adult Sudanese using manual segmentation and the Cavalieri method with magnetic resonance images (MRI). A total of 345 abdominal MRI scans for adults were retrospectively studied for patients who underwent abdomen MRI between September to October 2016. The data were collected from two scanning centers in Khartoum, Sudan. For each series of sectional images, the spleen was manually segmented, and the volume was calculated using matrix laboratory (MATLAB) code. Furthermore, abdominal circumferences and diameters, in addition to L1 body dimension and spinal canal, were measured. The mean splenic volume in our study was 187.2 cm3, without a significant change with age (P = 0.269). The average volume in males was 223.5 cm3 while in females it was 170.27 cm3. The average coefficient error (CE) was 0.029. A positive significant correlation was found between the volume and spleen length (beta standardized coefficient = 0.781, P < 0.05). The mean length was 9.18 cm. Additionally, our data showed an insignificant correlation between the volume and the other measurements, except for the abdomen transverse diameter (beta standardized coefficient = 0.267, P < 0.05). The results of our study coincided with previous studies in the normal range of spleen volume and the strong correlation with length, regardless of the irregular shape of the spleen. In addition, manual segmentation was a reliable method to measure spleen volume objectively. However, our single-slice measurements were insufficient.
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Ciumas C, Rheims S, Ryvlin P. fMRI studies evaluating central respiratory control in humans. Front Neural Circuits 2022; 16:982963. [PMID: 36213203 PMCID: PMC9537466 DOI: 10.3389/fncir.2022.982963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/01/2022] [Indexed: 11/13/2022] Open
Abstract
A plethora of neural centers in the central nervous system control the fundamental respiratory pattern. This control is ensured by neurons that act as pacemakers, modulating activity through chemical control driven by changes in the O2/CO2 balance. Most of the respiratory neural centers are located in the brainstem, but difficult to localize on magnetic resonance imaging (MRI) due to their small size, lack of visually-detectable borders with neighboring areas, and significant physiological noise hampering detection of its activity with functional MRI (fMRI). Yet, several approaches make it possible to study the normal response to different abnormal stimuli or conditions such as CO2 inhalation, induced hypercapnia, volitional apnea, induced hypoxia etc. This review provides a comprehensive overview of the majority of available studies on central respiratory control in humans.
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Affiliation(s)
- Carolina Ciumas
- Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Lyon Neuroscience Research Center, Institut National de la Santé et de la Recherche Médicale U1028/CNRS UMR 5292 Lyon 1 University, Bron, France
- IDEE Epilepsy Institute, Lyon, France
- *Correspondence: Carolina Ciumas
| | - Sylvain Rheims
- Lyon Neuroscience Research Center, Institut National de la Santé et de la Recherche Médicale U1028/CNRS UMR 5292 Lyon 1 University, Bron, France
- IDEE Epilepsy Institute, Lyon, France
- Department of Functional Neurology and Epileptology, Hospices Civils de Lyon, Lyon, France
| | - Philippe Ryvlin
- Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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Marullo AL, Bruce CD, Pfoh JR, Chauhan UV, Abrosimova M, Berg ERV, Skow RJ, Davenport MH, Strzalkowski NDJ, Steinback CD, Day TA. Cerebrovascular and blood pressure responses during voluntary apneas are larger than rebreathing. Eur J Appl Physiol 2022; 122:735-743. [PMID: 34978604 DOI: 10.1007/s00421-021-04864-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/29/2021] [Indexed: 11/03/2022]
Abstract
Both voluntary rebreathing (RB) of expired air and voluntary apneas (VA) elicit changes in arterial carbon dioxide and oxygen (CO2 and O2) chemostimuli. These chemostimuli elicit synergistic increases in cerebral blood flow (CBF) and sympathetic nervous system activation, with the latter increasing systemic blood pressure. The extent that simultaneous and inverse changes in arterial CO2 and O2 and associated increases in blood pressure affect the CBF responses during RB versus VAs are unclear. We instrumented 21 healthy participants with a finometer (beat-by-beat mean arterial blood pressure; MAP), transcranial Doppler ultrasound (middle and posterior cerebral artery velocity; MCAv, PCAv) and a mouthpiece with sample line attached to a dual gas analyzer to assess pressure of end-tidal (PET)CO2 and PETO2. Participants performed two protocols: RB and a maximal end-inspiratory VA. A second-by-second stimulus index (SI) was calculated as PETCO2/PETO2 during RB. For VA, where PETCO2 and PETO2 could not be measured throughout, SI values were calculated using interpolated end-tidal gas values before and at the end of the apneas. MAP reactivity (MAPR) was calculated as the slope of the MAP/SI, and cerebrovascular reactivity (CVR) was calculated as the slope of MCAv or PCAv/SI. We found that compared to RB, VA elicited ~ fourfold increases in MAPR slope (P < 0.001), translating to larger anterior and posterior CVR (P ≤ 0.01). However, cerebrovascular conductance (MCAv or PCAv/MAP) was unchanged between interventions (P ≥ 0.2). MAP responses during VAs are larger than those during RB across similar chemostimuli, and differential CVR may be driven by increases in perfusion pressure.
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Affiliation(s)
- Anthony L Marullo
- Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, T3E 6K6, Canada
| | - Christina D Bruce
- Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, T3E 6K6, Canada
| | - Jamie R Pfoh
- Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, T3E 6K6, Canada
| | - Uday V Chauhan
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Maria Abrosimova
- Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, T3E 6K6, Canada
| | - Emily R Vanden Berg
- Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, T3E 6K6, Canada
| | - Rachel J Skow
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Margie H Davenport
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Nicholas D J Strzalkowski
- Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, T3E 6K6, Canada
| | - Craig D Steinback
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, T3E 6K6, Canada.
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Citherlet T, Crettaz von Roten F, Kayser B, Guex K. Acute Effects of the Wim Hof Breathing Method on Repeated Sprint Ability: A Pilot Study. Front Sports Act Living 2021; 3:700757. [PMID: 34514386 PMCID: PMC8424088 DOI: 10.3389/fspor.2021.700757] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 07/02/2021] [Indexed: 11/23/2022] Open
Abstract
The Wim Hof breathing method (WHBM) combines periods of hyperventilation (HV) followed by voluntary breath-holds (BH) at low lung volume. It has been increasingly adopted by coaches and their athletes to improve performance, but there was no published research on its effects. We determined the feasibility of implementing a single WHBM session before repeated sprinting performance and evaluated any acute ergogenic effects. Fifteen amateur runners performed a single WHBM session prior to a Repeated Ability Sprint Test (RAST) in comparison to voluntary HV or spontaneous breathing (SB) (control) in a randomized cross-over design. Gas exchange, heart rate, and finger pulse oxygen saturation (SpO2) were monitored. Despite large physiological effects in the SpO2 and expired carbon dioxide (VCO2) levels of both HV and WHBM, no significant positive or negative condition effects were found on RAST peak power, average power, or fatigue index. Finger SpO2 dropped to 60 ± 12% at the end of the BHs. Upon the last HV in the WHBM and HV conditions, end-tidal CO2 partial pressure (PETCO2) values were 19 ± 3 and 17 ± 3 mmHg, indicative of respiratory alkalosis with estimated arterial pH increases of +0.171 and of +0.181, respectively. Upon completion of RAST, 8 min cumulated expired carbon dioxide volumes in the WHBM and HV were greater than in SB, suggesting lingering carbon dioxide stores depletion. These findings indicate that despite large physiological effects, a single WHBM session does not improve anaerobic performance in repeated sprinting exercise.
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Affiliation(s)
- Tom Citherlet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | | | - Bengt Kayser
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Kenny Guex
- School of Health Sciences, University of Applied Sciences and Arts Western Switzerland, Lausanne, Switzerland
- Swiss Athletics, Haus des Sports, Ittigen, Switzerland
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Stavrou VT, Astara K, Karetsi E, Daniil Z, Gourgoulianis KI. Respiratory Muscle Strength as an Indicator of the Severity of the Apnea-Hypopnea Index: Stepping Towards the Distinction Between Sleep Apnea and Breath Holding. Cureus 2021; 13:e14015. [PMID: 33889460 PMCID: PMC8056360 DOI: 10.7759/cureus.14015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Background and objective The aim of this study was to investigate whether the maximum inspiratory and expiratory pressure are correlated with the apnea-hypopnea index (AHI) in patients with obstructive sleep apnea syndrome (OSAS). Methods Fifty-two patients with OSAS were divided into two groups (AHI, events/hours: <30, n=28, versus ≥30, n=24). For each patient, anthropometric characteristics, spirometry parameters, maximum inspiratory (MIP) and expiratory pressure (MEP), and cardiopulmonary function (CPF) parameters (oxygen uptake at rest (VO2), carbon dioxide output (VCO2), heart rate (HR), minute ventilation (VE), tidal volume at inspiratory (TVin) and expiratory (TVex), breath frequency (f β), end-tidal carbon dioxide pressure (PETCO2), end-tidal oxygen pressure (PETO2), and mean arterial pressure (MAP)) in sitting position for three minutes were recorded. The independent t-test was used to measure the differences between groups (events/hours <30 versus ≥30) and Pearson correlation analysis was used for statistical comparison between parameters. Results Results showed differences between groups (AHI, events/h ≥30 versus <30) in MIP (102.0±18.3 versus 91.1±12.1 % of predicted, p=0.013) and CPF parameters TVin (0.8±0.2 versus 0.7±0.1, L, p=0.047), PETCO2 (34.6±4.2 versus 31.4±3.7, mmHg, p=0.007), and MAP (88.4±6.5 versus 82.9±6.2, mmHg, p=0.003). Pearson correlation analysis between respiratory muscle strength (MIP and MEP) and polysomnography (PSG) parameters, MIP is related to AHI (r=.332, p=0.016) and desaturation index (r=.439, p=0.001), as well as MEP to percent of REM sleep stage (r=-.564, p<0.001). Conclusion The data from the present study support that maximal inspiratory pressure relates to the severity of AHI and intermittent breath-holding during sleep increases the inspiratory muscle strength.
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Affiliation(s)
- Vasileios T Stavrou
- Laboratory of Cardio-Pulmonary Testing and Pulmonary Rehabilitation, Respiratory Medicine Department, Faculty of Medicine, University of Thessaly, Larissa, GRC
| | - Kyriaki Astara
- Laboratory of Cardio-Pulmonary Testing and Pulmonary Rehabilitation, Respiratory Medicine Department, Faculty of Medicine, University of Thessaly, Larissa, GRC
| | - Eleni Karetsi
- Laboratory of Cardio-Pulmonary Testing and Pulmonary Rehabilitation, Respiratory Medicine Department, Faculty of Medicine, University of Thessaly, Larissa, GRC
| | - Zoe Daniil
- Laboratory of Cardio-Pulmonary Testing and Pulmonary Rehabilitation, Respiratory Medicine Department, Faculty of Medicine, University of Thessaly, Larissa, GRC
| | - Konstantinos I Gourgoulianis
- Laboratory of Cardio-Pulmonary Testing and Pulmonary Rehabilitation, Respiratory Medicine Department, Faculty of Medicine, University of Thessaly, Larissa, GRC
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11
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Laborde S, Allen MS, Borges U, Hosang TJ, Furley P, Mosley E, Dosseville F. The Influence of Slow-Paced Breathing on Executive Function. J PSYCHOPHYSIOL 2021. [DOI: 10.1027/0269-8803/a000279] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Abstract. The aim of this experiment was to test the immediate effects of slow-paced breathing on executive function. Slow-paced breathing is suggested to increase cardiac vagal activity, and the neurovisceral integration model predicts that higher cardiac vagal activity leads to better executive functioning. In total, 78 participants (41 men, 37 women; Mage = 23.22 years) took part in two counterbalanced experimental conditions: a 3 × 5 min slow-paced breathing condition and a television viewing control condition. After each condition, heart rate variability was measured and participants performed three executive function tasks: the color-word match Stroop (inhibition), the automated operation span task (working memory), and the modified card sorting task (cognitive flexibility). Results showed that performance on executive function tasks was better after slow-paced breathing compared to control, with higher scores observed for Stroop interference accuracy, automated operation span score, and perseverative errors, but not Stroop interference reaction times. This difference in executive function between experimental conditions was not mediated by cardiac vagal activity. Therefore, findings only partially align with predictions of the neurovisceral integration model. Slow-paced breathing appears a promising technique to improve immediate executive function performance. Further studies are recommended that address possible alternative underlying mechanisms and long-term effects.
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Affiliation(s)
- S. Laborde
- Department of Performance Psychology, Institute of Psychology, German Sport University Cologne, Germany
- UFR STAPS, EA 4260 CESAMS, University of Caen Normandy, Caen, France
| | - M. S. Allen
- School of Psychology, University of Wollongong, Australia
| | - U. Borges
- Department of Performance Psychology, Institute of Psychology, German Sport University Cologne, Germany
- Department of Health & Social Psychology, Institute of Psychology, German Sport University Cologne, Germany
| | - T. J. Hosang
- Experimental Psychology Unit, Helmut Schmidt University/University of the Federal Armed Forces, Hamburg, Germany
| | - P. Furley
- Institute for Training and Computer Science in Sport, German Sport University Cologne, Germany
| | - E. Mosley
- Department of Sport Science and Performance, Solent University, Southampton, UK
| | - F. Dosseville
- UMR-S 1075 COMETE, Caen, France
- INSERM, UMR-S 1075 COMETE, University of Caen Normandy, Caen, France
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12
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Bruce CD, Vanden Berg ER, Pfoh JR, Steinback CD, Day TA. Prior oxygenation, but not chemoreflex responsiveness, determines breath-hold duration during voluntary apnea. Physiol Rep 2021; 9:e14664. [PMID: 33393725 PMCID: PMC7780234 DOI: 10.14814/phy2.14664] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 11/05/2020] [Accepted: 11/11/2020] [Indexed: 01/24/2023] Open
Abstract
Central and peripheral respiratory chemoreceptors are stimulated during voluntary breath holding due to chemostimuli (i.e., hypoxia and hypercapnia) accumulating at the metabolic rate. We hypothesized that voluntary breath-hold duration (BHD) would be (a) positively related to the initial pressure of inspired oxygen prior to breath holding, and (b) negatively correlated with respiratory chemoreflex responsiveness. In 16 healthy participants, voluntary breath holds were performed under three conditions: hyperoxia (following five normal tidal breaths of 100% O2 ), normoxia (breathing room air), and hypoxia (following ~30-min of 13.5%-14% inspired O2 ). In addition, the hypoxic ventilatory response (HVR) was tested and steady-state chemoreflex drive (SS-CD) was calculated in room air and during steady-state hypoxia. We found that (a) voluntary BHD was positively related to initial oxygen status in a dose-dependent fashion, (b) the HVR was not correlated with BHD in any oxygen condition, and (c) SS-CD magnitude was not correlated with BHD in normoxia or hypoxia. Although chemoreceptors are likely stimulated during breath holding, they appear to contribute less to BHD compared to other factors such as volitional drive or lung volume.
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Affiliation(s)
- Christina D. Bruce
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
- School of Health and Exercise SciencesCentre for Heart, Lung and Vascular HealthFaculty of Health and Social DevelopmentUniversity of British ColumbiaKelownaBCCanada
| | - Emily R. Vanden Berg
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
- Department of BiologyFaculty of ScienceUniversity of VictoriaVictoriaBCCanada
- Faculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonABCanada
| | - Jamie R. Pfoh
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Craig D. Steinback
- Faculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonABCanada
| | - Trevor A. Day
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
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13
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McIntosh RC, Hoshi RA, Timpano KR. Take my breath away: Neural activation at breath-hold differentiates individuals with panic disorder from healthy controls. Respir Physiol Neurobiol 2020; 277:103427. [PMID: 32120012 DOI: 10.1016/j.resp.2020.103427] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 02/12/2020] [Accepted: 02/24/2020] [Indexed: 01/04/2023]
Abstract
There is neuroanatomical evidence of an "extended fear network" of brain structures involved in the etiology of panic disorder (PD). Although ventilatory distrubance is a primary symptom of PD these sensations may also trigger onset of a panic attack (PA). Here, a voluntary breath-holding paradigm was used to mimic the hypercapnia state in order to compare blood oxygen level-dependent (BOLD) response, at the peak of a series of 18 s breath-holds, of 21 individuals with PD to 21 low anxiety matched controls. Compared to the rest condition, BOLD activity at the peak (12 - 18 s) of the breath-hold was greater for PD versus controls within a number of structures implicated in the extended fear network, including hippocampus, thalamus, and brainstem. Activation was also observed in cortical structures that are shown to be involved in interoceptive and self-referential processing, such as right insula, middle frontal gyrus, and precuneus/posterior cingulate. In lieu of amygdala activation, our findings show elevated activity throughout an extended network of cortical and subcortical structures involved in contextual, interoceptive and self-referential processing when individuals with PD engage in voluntary breath-holding.
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Affiliation(s)
- R C McIntosh
- Department of Psychology, University of Miami, 1120 NW 14th Street, Miami, FL, 33136, United States.
| | - R A Hoshi
- Clinical and Epidemiological Research Center, Sao Paulo University. 2565 Professor Lineu Prestes Ave, Sao Paulo, 05508-000, Brazil
| | - K R Timpano
- Department of Psychology, University of Miami, 1120 NW 14th Street, Miami, FL, 33136, United States
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14
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Vestergaard MB, Larsson HB. Cerebral metabolism and vascular reactivity during breath-hold and hypoxic challenge in freedivers and healthy controls. J Cereb Blood Flow Metab 2019; 39:834-848. [PMID: 29099292 PMCID: PMC6498754 DOI: 10.1177/0271678x17737909] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The goal of the present study was to examine the cerebral metabolism and vascular reactivity during extended breath-holds (ranging from 2 min 32 s to 7 min 0 s) and during a hypoxic challenge in freedivers and non-diver controls. Magnetic resonance imaging was used to measure the global cerebral blood flow (CBF) and metabolic rate of oxygen (CMRO2), and magnetic resonance spectroscopy was used to measure the cerebral lactate, glutamate+glutamine, N-acetylaspartate and phosphocreatine+creatine concentrations in the occipital lobe. Fifteen freedivers and seventeen non-diver controls participated. The freedivers showed remarkable increases in CBF (107%) during the breath-holds, compensating for arterial desaturation, and sustained cerebral oxygen delivery (CDO2). CMRO2 was unaffected throughout the breath-holds. During the hypoxic challenge, the freedivers had larger increases in blood flow in the sagittal sinus than the non-divers, and could sustain normal CDO2. No differences were found in lactate production, global CBF or CMRO2. We conclude that the mechanism for sustaining brain function during breath-holding in freedivers involves an extraordinary increase in perfusion, and that freedivers present evidence for higher cerebrovascular reactivity, but not for higher lactate-producing glycolysis during a hypoxic challenge compared to controls.
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Affiliation(s)
- Mark B Vestergaard
- 1 Department of Clinical Physiology, Nuclear Medicine and PET, Functional Imaging Unit, Copenhagen University Hospital, Rigshospitalet Glostrup, Glostrup, Denmark
| | - Henrik Bw Larsson
- 1 Department of Clinical Physiology, Nuclear Medicine and PET, Functional Imaging Unit, Copenhagen University Hospital, Rigshospitalet Glostrup, Glostrup, Denmark.,2 Institute of Clinical Medicine, The Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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15
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Busch SA, Bruce CD, Skow RJ, Pfoh JR, Day TA, Davenport MH, Steinback CD. Mechanisms of sympathetic regulation during Apnea. Physiol Rep 2019; 7:e13991. [PMID: 30693670 PMCID: PMC6349657 DOI: 10.14814/phy2.13991] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 12/26/2018] [Indexed: 12/11/2022] Open
Abstract
Volitional Apnea produces a robust peak sympathetic response through several interacting mechanisms. However, the specific contribution of each mechanism has not been elucidated. Muscle sympathetic activity was collected in participants (n = 10; 24 ± 3 years) that performed four maximal volitional apneas aimed at isolating lung-stretch (mechanical) and chemoreflex drive: (Ainslie and Duffin ) end-expiratory breath-hold, (Ainslie et al. ) end-inspiratory breath-hold, (Alpher et al. ) prehyperventilation breath-hold, and (Andersson and Schagatay ) prehyperoxia breath-hold. A final repeated rebreathe breath-hold protocol was performed to measure the peak sympathetic response during successive breath-holds at increasing chemoreflex stress. Finally, the influence of dynamic ventilation was assessed through asphyxic rebreathe. Muscle sympathetic activity was calculated as the change in burst frequency (burst/min), burst incidence (burst/100 heart-beats), and amplitude (au) between baseline and prevolitional breakpoint. Rebreathe was analyzed at similar chemoreflex stress as inspiratory breath-hold. All maneuvers increased muscle sympathetic activity compared to baseline (P < 0.01). However, prehyperoxia exhibited a smaller increase (+22.18 ± 9.13 burst/min; +25.52 ± 11.7 burst/100 heart-beats) compared to inspiratory, expiratory, and prehyperventilation breath-holds. At similar chemoreflex strain, rebreathe sympathetic activity was blunted compared to inspiratory breath-hold (P < 0.01). Finally, muscle sympathetic activity was not different between the repeated rebreathe trials, despite elevated chemoreflex stress and lower breath-hold duration with each subsequent breath-hold. We have demonstrated an obligatory role of the peripheral, but not central, chemoreflex (prehyperventilation vs. prehyperoxia) in producing peak sympathetic responses. At similar chemoreflex stresses the act of dynamic ventilation, but not static lung stretch per se, blunts muscle sympathetic activity. Finally, similar peak sympathetic responses during successive repeated breath-holds suggest a sympathetic ceiling may exist.
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Affiliation(s)
- Stephen A. Busch
- Neurovascular Health LaboratoryFaculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonAlbertaCanada
| | - Christina D. Bruce
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Rachel J. Skow
- Neurovascular Health LaboratoryFaculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonAlbertaCanada
| | - Jaime R. Pfoh
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Trevor A. Day
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryAlbertaCanada
| | - Margie H. Davenport
- Neurovascular Health LaboratoryFaculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonAlbertaCanada
| | - Craig D. Steinback
- Neurovascular Health LaboratoryFaculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonAlbertaCanada
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16
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Tsuboyama T, Jost G, Kim T, Hori M, Onishi H, Pietsch H, Tomiyama N. Experimental studies on artifacts and tumor enhancement on gadoxetic acid-enhanced arterial phase liver MRI in a rabbit VX2 tumor model. Acta Radiol 2018; 59:1029-1037. [PMID: 29235879 DOI: 10.1177/0284185117747134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Background Rapid injection of gadoxetic acid is reported to produce more frequent artifacts and lower vascular enhancement on arterial phase liver magnetic resonance imaging (MRI). However, its effect on tumor enhancement and the mechanism of the artifacts remain unclear. Purpose To evaluate the effect of rapid injection of gadoxetic acid on artifacts and tumor enhancement during arterial phase liver MRI, and on arterial blood gases (ABGs) which may explain the cause of the artifacts. Material and Methods ABG analysis was performed in 13 free-breathing rabbits after rapid injection (1 mL/s; injection time = 0.6-0.8 s) of gadoxetic acid (0.025 mmol/kg). Dynamic liver MRI was performed in six anesthetized rabbits with VX2 tumors under a ventilation stoppage after rapid and slow injection (0.25 mL/s; injection time = 2.4-3.2 s) of gadoxetic acid. Artifacts and signal enhancement on arterial phase imaging were compared with those obtained after rapid injection of gadopentetic acid (Gd-DTPA, 0.1 mmol/kg) using a Friedman test or Kruskal-Wallis test. Results ABG analysis did not find any significant changes. Artifacts were not related to injection protocols ( P = 0.95). Aortic enhancement with slow injection of gadoxetic acid was significantly higher than that with rapid injection ( P < 0.05), and was comparable to that with Gd-DTPA injection. Tumor enhancement obtained with gadoxetic acid was not significantly different between rapid and slow injection, and was significantly lower than that with Gd-DTPA injection ( P < 0.05). Conclusion Rapid injection of gadoxetic acid did not affect ABGs and may not be the cause of the artifacts. It lowered vascular enhancement but not arterial tumor enhancement.
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Affiliation(s)
- Takahiro Tsuboyama
- Department of Radiology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Gregor Jost
- MR and CT Contrast Media Research, Bayer Pharma AG, Berlin, Germany
| | - Tonsok Kim
- Department of Radiology, Naniwa Ikuno Hospital, Osaka, Japan
| | - Masatoshi Hori
- Department of Radiology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hiromitsu Onishi
- Department of Radiology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hubertus Pietsch
- MR and CT Contrast Media Research, Bayer Pharma AG, Berlin, Germany
| | - Noriyuki Tomiyama
- Department of Radiology, Osaka University Graduate School of Medicine, Osaka, Japan
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17
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Trembach N, Zabolotskikh I. The Influence of Age on Interaction between Breath-Holding Test and Single-Breath Carbon Dioxide Test. BIOMED RESEARCH INTERNATIONAL 2017; 2017:1010289. [PMID: 28251147 PMCID: PMC5306978 DOI: 10.1155/2017/1010289] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 12/15/2016] [Accepted: 01/16/2017] [Indexed: 11/25/2022]
Abstract
Introduction. The aim of the study was to compare the breath-holding test and single-breath carbon dioxide test in evaluation of the peripheral chemoreflex sensitivity to carbon dioxide in healthy subjects of different age. Methods. The study involved 47 healthy volunteers between ages of 25 and 85 years. All participants were divided into 4 groups according to age: 25 to 44 years (n = 14), 45 to 60 years (n = 13), 60 to 75 years (n = 12), and older than 75 years (n = 8). Breath-holding test was performed in the morning before breakfast. The single-breath carbon dioxide (SB-CO2) test was performed the following day. Results. No correlation was found between age and duration of breath-holding (r = 0.13) and between age and peripheral chemoreflex sensitivity to CO2 (r = 0.07). In all age groups there were no significant differences in the mean values from the breath-holding test and peripheral chemoreflex sensitivity tests. In all groups there was a strong significant inverse correlation between breath-holding test and SB-CO2 test. Conclusion. A breath-holding test reflects the sensitivity of the peripheral chemoreflex to carbon dioxide in healthy elderly humans. Increasing age alone does not alter the peripheral ventilatory response to hypercapnia.
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Affiliation(s)
- Nikita Trembach
- Kuban State Medical University, Sedin Str. 4, Krasnodar 350012, Russia
| | - Igor Zabolotskikh
- Kuban State Medical University, Sedin Str. 4, Krasnodar 350012, Russia
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18
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Trembach N, Zabolotskikh I. Breath-holding test in evaluation of peripheral chemoreflex sensitivity in healthy subjects. Respir Physiol Neurobiol 2016; 235:79-82. [PMID: 27756650 DOI: 10.1016/j.resp.2016.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 10/04/2016] [Accepted: 10/09/2016] [Indexed: 11/19/2022]
Abstract
The aim of the study was to determine the feasibility of using a breath-holding test in assessing the sensitivity of the peripheral chemoreflex compared with the single-breath carbon dioxide test. The study involved 48 healthy volunteers between the ages of 18-29 years. The breath-holding test was performed followed by the single-breath carbon dioxide test on the next day. A month after the first tests, these tests were repeated to evaluate their reproducibility The coefficient of variability in the single-breath carbon dioxide test ranged from 0 to 32% with a mean of 10±7%. The mean coefficient of variability of the breath-holding test was 6±4% (0-19%). A significant inverse correlation between the results of the two tests was noted following analysis (r=-0.82, p<0.05). CONCLUSION A breath-holding test after deep inspiration reflects the sensitivity of the peripheral chemoreflex as defined by the single-breath carbon dioxide test in healthy subjects.
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Affiliation(s)
- Nikita Trembach
- Kuban State Medical University, 350012, Krasnodar, Sedin str., 4, Russian Federation.
| | - Igor Zabolotskikh
- Kuban State Medical University, 350012, Krasnodar, Sedin str., 4, Russian Federation
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19
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Pinto J, Jorge J, Sousa I, Vilela P, Figueiredo P. Fourier modeling of the BOLD response to a breath-hold task: Optimization and reproducibility. Neuroimage 2016; 135:223-31. [PMID: 26908316 DOI: 10.1016/j.neuroimage.2016.02.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/09/2016] [Accepted: 02/12/2016] [Indexed: 11/18/2022] Open
Abstract
Cerebrovascular reactivity (CVR) reflects the capacity of blood vessels to adjust their caliber in order to maintain a steady supply of brain perfusion, and it may provide a sensitive disease biomarker. Measurement of the blood oxygen level dependent (BOLD) response to a hypercapnia-inducing breath-hold (BH) task has been frequently used to map CVR noninvasively using functional magnetic resonance imaging (fMRI). However, the best modeling approach for the accurate quantification of CVR maps remains an open issue. Here, we compare and optimize Fourier models of the BOLD response to a BH task with a preparatory inspiration, and assess the test-retest reproducibility of the associated CVR measurements, in a group of 10 healthy volunteers studied over two fMRI sessions. Linear combinations of sine-cosine pairs at the BH task frequency and its successive harmonics were added sequentially in a nested models approach, and were compared in terms of the adjusted coefficient of determination and corresponding variance explained (VE) of the BOLD signal, as well as the number of voxels exhibiting significant BOLD responses, the estimated CVR values, and their test-retest reproducibility. The brain average VE increased significantly with the Fourier model order, up to the 3rd order. However, the number of responsive voxels increased significantly only up to the 2nd order, and started to decrease from the 3rd order onwards. Moreover, no significant relative underestimation of CVR values was observed beyond the 2nd order. Hence, the 2nd order model was concluded to be the optimal choice for the studied paradigm. This model also yielded the best test-retest reproducibility results, with intra-subject coefficients of variation of 12 and 16% and an intra-class correlation coefficient of 0.74. In conclusion, our results indicate that a Fourier series set consisting of a sine-cosine pair at the BH task frequency and its two harmonics is a suitable model for BOLD-fMRI CVR measurements based on a BH task with preparatory inspiration, yielding robust estimates of this important physiological parameter.
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Affiliation(s)
- Joana Pinto
- Institute for Systems and Robotics, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.
| | - João Jorge
- Institute for Systems and Robotics, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; Biomedical Imaging Research Center, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Inês Sousa
- Institute for Systems and Robotics, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; Healthcare Sector, Siemens, S.A., Portugal
| | - Pedro Vilela
- Imaging Department, Hospital da Luz, Lisbon, Portugal
| | - Patrícia Figueiredo
- Institute for Systems and Robotics, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
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