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Besset D, Selmaoui B, Delanaud S, Bessarion L, Chardon K, de Seze R, Leke A, Stéphan-Blanchard E. Influence of radiofrequency electromagnetic fields exposure on sleep patterns in preterm neonates. Int J Radiat Biol 2023; 100:427-432. [PMID: 37972294 DOI: 10.1080/09553002.2023.2277365] [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: 05/24/2023] [Accepted: 09/29/2023] [Indexed: 11/19/2023]
Abstract
PURPOSE The study objective was to assess the influence of radiofrequency electromagnetic fields (RF-EMF) exposure on sleep patterns in preterm newborns. We hypothesized that an increase in RF-EMF exposure levels would alter infants' sleep structure parameters. MATERIALS AND METHODS Individual, continuous measurements of RF-EMF levels were performed in 29 hospitalized preterm newborns throughout the first 21 days after birth. The last day, overnight sleep structure was recorded by polysomnography. Relationships between both chronic (three-week period) and acute (polysomnographic period) RF-EMF levels with sleep parameters were computed. RESULTS At median levels, the main chronic effect was an increase in indeterminate sleep with RF-EMF exposure. At the highest exposure levels found in our study, an increase in RF-EMF levels increased sleep fragmentation. No significant relationship was found between acute RF-EMF levels and sleep parameters. CONCLUSIONS Despite no consolidated disruption in sleep structure, this study is the first to show that some sleep parameters seem to have a certain sensitivity to chronic - but not acute - RF-EMF exposure in preterm newborns. Further studies are needed to confirm our results and examine possible mid- to long-term, sleep-related cardiorespiratory and neurodevelopmental outcomes.
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Affiliation(s)
- Dimitri Besset
- PériTox (UMR_I 01), UPJV/INERIS, Jules Verne University of Picardy, Amiens, France
| | - Brahim Selmaoui
- PériTox (UMR_I 01), INERIS/UPJV, INERIS, Verneuil en Halatte, France
| | - Stéphane Delanaud
- PériTox (UMR_I 01), UPJV/INERIS, Jules Verne University of Picardy, Amiens, France
| | - Lisa Bessarion
- PériTox (UMR_I 01), UPJV/INERIS, Jules Verne University of Picardy, Amiens, France
- Neonatal Intensive Care Unit, CHU Amiens-Picardie, Amiens, France
| | - Karen Chardon
- PériTox (UMR_I 01), UPJV/INERIS, Jules Verne University of Picardy, Amiens, France
| | - René de Seze
- PériTox (UMR_I 01), INERIS/UPJV, INERIS, Verneuil en Halatte, France
| | - André Leke
- PériTox (UMR_I 01), UPJV/INERIS, Jules Verne University of Picardy, Amiens, France
- Neonatal Intensive Care Unit, CHU Amiens-Picardie, Amiens, France
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Bach V, Libert JP. Hyperthermia and Heat Stress as Risk Factors for Sudden Infant Death Syndrome: A Narrative Review. Front Pediatr 2022; 10:816136. [PMID: 35498814 PMCID: PMC9051231 DOI: 10.3389/fped.2022.816136] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 03/24/2022] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Heat stress and hyperthermia are common findings in sudden infant death syndrome (SIDS) victims. It has been suggested that thermal stress can increase the risk of SIDS directly via lethal hyperthermia or indirectly by altering autonomic functions. Major changes in sleep, thermoregulation, cardiovascular function, and the emergence of circadian functions occur at the age at which the risk of SIDS peaks-explaining the greater vulnerability at this stage of development. Here, we review the literature data on (i) heat stress and hyperthermia as direct risk factors for SIDS, and (ii) the indirect effects of thermal loads on vital physiological functions. RESULTS Various situations leading to thermal stress (i.e., outdoors temperatures, thermal insulation from clothing and bedding, the prone position, bed-sharing, and head covering) have been analyzed. Hyperthermia mainly results from excessive clothing and bedding insulation with regard to the ambient thermal conditions. The appropriate amount of clothing and bedding thermal insulation for homeothermia requires further research. The prone position and bed-sharing do not have major thermal impacts; the elevated risk of SIDS in these situations cannot be explained solely by thermal factors. Special attention should be given to brain overheating because of the head's major role in body heat losses, heat production, and autonomic functions. Thermal stress can alter cardiovascular and respiratory functions, which in turn can lead to life-threatening events (e.g., bradycardia, apnea with blood desaturation, and glottal closure). Unfortunately, thermal load impairs the responses to these challenges by reducing chemosensitivity, arousability, and autoresuscitation. As a result, thermal load (even when not lethal directly) can interact detrimentally with vital physiological functions. CONCLUSIONS With the exception of excessive thermal insulation (which can lead to lethal hyperthermia), the major risk factors for SIDS appears to be associated with impairments of vital physiological functions when the infant is exposed to thermal stress.
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Affiliation(s)
- Véronique Bach
- PeriTox, UMR_I 01, UPJV/INERIS, Jules Verne University of Picardy, Amiens, France
| | - Jean-Pierre Libert
- PeriTox, UMR_I 01, UPJV/INERIS, Jules Verne University of Picardy, Amiens, France
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Neubauer J, Forst AL, Warth R, Both CP, Haas C, Thomas J. Genetic variants in eleven central and peripheral chemoreceptor genes in sudden infant death syndrome. Pediatr Res 2022; 92:1026-1033. [PMID: 35102300 PMCID: PMC9586864 DOI: 10.1038/s41390-021-01899-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 07/14/2021] [Accepted: 08/16/2021] [Indexed: 12/15/2022]
Abstract
BACKGROUND Sudden infant death syndrome (SIDS) is still one of the leading causes of postnatal infant death in developed countries. The occurrence of SIDS is described by a multifactorial etiology that involves the respiratory control system including chemoreception. It is still unclear whether genetic variants in genes involved in respiratory chemoreception might play a role in SIDS. METHODS The exome data of 155 SIDS cases were screened for variants within 11 genes described in chemoreception. Pathogenicity of variants was assigned based on the assessment of variant types and in silico protein predictions according to the current recommendations of the American College of Medical Genetics and Genomics. RESULTS Potential pathogenic variants in genes encoding proteins involved in respiratory chemoreception could be identified in 5 (3%) SIDS cases. Two of the variants (R137S/A188S) were found in the KNCJ16 gene, which encodes for the potassium channel Kir5.1, presumably involved in central chemoreception. Electrophysiologic analysis of these KCNJ16 variants revealed a loss-of-function for the R137S variant but no obvious impairment for the A188S variant. CONCLUSIONS Genetic variants in genes involved in respiratory chemoreception may be a risk factor in a fraction of SIDS cases and may thereby contribute to the multifactorial etiology of SIDS. IMPACT What is the key message of your article? Gene variants encoding proteins involved in respiratory chemoreception may play a role in a minority of SIDS cases. What does it add to the existing literature? Although impaired respiratory chemoreception has been suggested as an important risk factor for SIDS, genetic variants in single genes seem to play a minor role. What is the impact? This study supports previous findings, which indicate that genetic variants in single genes involved in respiratory control do not have a dominant role in SIDS.
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Affiliation(s)
- Jacqueline Neubauer
- grid.7400.30000 0004 1937 0650Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
| | - Anna-Lena Forst
- grid.7727.50000 0001 2190 5763Medical Cell Biology, Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Richard Warth
- grid.7727.50000 0001 2190 5763Medical Cell Biology, Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Christian Peter Both
- grid.412341.10000 0001 0726 4330Department of Anesthesiology, University Children’s Hospital Zurich, Zurich, Switzerland
| | - Cordula Haas
- grid.7400.30000 0004 1937 0650Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
| | - Jörg Thomas
- Department of Anesthesiology, University Children's Hospital Zurich, Zurich, Switzerland.
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Marullo AL, Bird JD, Ciorogariu-Ivan AM, Boulet LM, Strzalkowski NDJ, Day TA. Acute hyperglycemia does not affect central respiratory chemoreflex responsiveness to CO 2 in healthy humans. Respir Physiol Neurobiol 2021; 296:103803. [PMID: 34653661 DOI: 10.1016/j.resp.2021.103803] [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: 08/29/2021] [Revised: 10/05/2021] [Accepted: 10/10/2021] [Indexed: 11/17/2022]
Abstract
The central respiratory chemoreceptor complex (CCRC) is comprised of brainstem neurons and surrounding interoceptors, which collectively increase ventilation in response to elevated brainstem tissue CO2/[H+] (i.e., central chemoreflex; CCR). The extent that the CCRC detects/responds to other metabolically related chemostimuli is unknown. We aimed to test the effects of acute oral glucose ingestion on CCR reactivity in heathy human participants (n = 38). We instrumented participants with a pneumotachometer (minute ventilation) and a gas sample line connected to a dual gas analyzer (pressure of end-tidal CO2). Following a baseline (BL) period and capillary blood [glucose] (BG) sample, fasted (F) participants underwent a modified hyperoxic rebreathing test to assess CCR reactivity. Participants then consumed a 75 g standard glucose beverage (glucose loaded; GL). Following 30-min, they underwent a second BL, BG sample and hyperoxic rebreathing test. BG and metabolic rate were higher in GL, confirming the metabolic stimulus. However, the ventilatory recruitment threshold and the CCR responses were unchanged between F and GL states.
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Affiliation(s)
- Anthony L Marullo
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Jordan D Bird
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Anna-Maria Ciorogariu-Ivan
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Colombia Okanagan, Kelowna, BC, Canada
| | - Nicholas D J Strzalkowski
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada.
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Li HP, Wang HQ, Li N, Zhang L, Li SQ, Yan YR, Lu HH, Wang Y, Sun XW, Lin YN, Zhou JP, Li QY. Model for Identifying High Carotid Body Chemosensitivity in Patients with Obstructive Sleep Apnea. Nat Sci Sleep 2021; 13:493-501. [PMID: 33911906 PMCID: PMC8071699 DOI: 10.2147/nss.s299646] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 04/07/2021] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVE The carotid body (CB) is a major peripheral respiratory chemoreceptor. In patients with obstructive sleep apnea (OSA), high CB chemosensitivity (CBC) is associated with refractory hypertension and insulin resistance and known to further aggravate OSA. Thus, the identification of high CB (hCBC) among OSA patients is of clinical significance, but detection methods are still limited. Therefore, this study aimed to explore the association of CBC with OSA severity and to develop a simplified model that can identify patients with hCBC. METHODS In this cross-sectional study of subjects who underwent polysomnography (PSG), CBC was measured using the Dejours test. We defined hCBC as a decrease of >12% in respiratory rate (RR) after breathing of pure O2. The association of CBC with OSA severity was explored by logistic regression, and a model for identifying hCBC was constructed and confirmed using receiver operating characteristic analysis. RESULTS Patients with OSA (n=142) and individuals without OSA (n=38) were enrolled. CBC was higher in patients with OSA than in those without OSA (% decrease in RR, 15.2%±13.3% vs 9.1%±7.5%, P<0.05). Apnea-hypopnea index (AHI), fraction of apnea-hypopnea events in rapid-eye-movement sleep (Fevents-in-REM), and longest time of apnea (LTA) were associated with hCBC independently (odds ratio [OR]=1.048, OR=1.082, and OR=1.024 respectively; all P<0.05). The model for identifying hCBC allocated a score to each criterion according to its OR values, ie, 1 (LTA >48.4 s), 2 (AHI >15.7 events/hour), and 3 (Fevents-in-REM >12.7%). A score of 3 or greater indicated hCBC with a sensitivity of 79.4% and specificity of 88.2%. CONCLUSION High CBC is associated with the severity of OSA. A simplified scoring system based on clinical variables from PSG can be used to identify hCBC.
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Affiliation(s)
- Hong Peng Li
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Hai Qin Wang
- Xietu Community Health Service Center of Xuhui District, Shanghai, 200231, People's Republic of China
| | - Ning Li
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Liu Zhang
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Shi Qi Li
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Ya Ru Yan
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Huan Huan Lu
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Yi Wang
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Xian Wen Sun
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Ying Ni Lin
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Jian Ping Zhou
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Qing Yun Li
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
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Fujii N, Kashihara M, Kenny GP, Honda Y, Fujimoto T, Cao Y, Nishiyasu T. Carotid chemoreceptors have a limited role in mediating the hyperthermia-induced hyperventilation in exercising humans. J Appl Physiol (1985) 2019; 126:305-313. [PMID: 30382804 DOI: 10.1152/japplphysiol.00562.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Hyperthermia causes hyperventilation at rest and during exercise. We previously reported that carotid chemoreceptors partly contribute to the hyperthermia-induced hyperventilation at rest. However, given that a hyperthermia-induced hyperventilation markedly differs between rest and exercise, the results obtained at rest may not be representative of the response in exercise. Therefore, we evaluated whether carotid chemoreceptors contribute to hyperthermia-induced hyperventilation in exercising humans. Eleven healthy young men (23 ± 2 yr) cycled in the heat (37°C) at a fixed submaximal workload equal to ~55% of the individual's predetermined peak oxygen uptake (moderate intensity). To suppress carotid chemoreceptor activity, 30-s hyperoxia breathing (100% O2) was performed at rest (before exercise) and during exercise at increasing levels of hyperthermia as defined by an increase in esophageal temperature of 0.5°C (low), 1.0°C (moderate), 1.5°C (high), and 2.0°C (severe) above resting levels. Ventilation during exercise gradually increased as esophageal temperature increased (all P ≤ 0.05), indicating that hyperthermia-induced hyperventilation occurred. Hyperoxia breathing suppressed ventilation in a greater manner during exercise (-9 to -13 l/min) than at rest (-2 ± 1 l/min); however, the magnitude of reduction during exercise did not differ at low (0.5°C) to severe (2.0°C) increases in esophageal temperature (all P > 0.05). Similarly, hyperoxia-induced changes in ventilation during exercise as assessed by percent change from prehyperoxic levels were not different at all levels of hyperthermia (~15-20%, all P > 0.05). We show that in young men carotid chemoreceptor contribution to hyperthermia-induced hyperventilation is relatively small at low-to-severe increases in body core temperature induced by moderate-intensity exercise in the heat. NEW & NOTEWORTHY Exercise-induced increases in hyperthermia cause a progressive increase in ventilation in humans. However, the mechanisms underpinning this response remain unresolved. We showed that in young men hyperventilation associated with exercise-induced hyperthermia is not predominantly mediated by carotid chemoreceptors. This study provides important new insights into the mechanism(s) underpinning the regulation of hyperthermia-induced hyperventilation in humans and suggests that factor(s) other than carotid chemoreceptors play a more important role in mediating this response.
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Affiliation(s)
- Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba , Japan
| | - Miki Kashihara
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba , Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa , Ottawa Ontario , Canada
| | - Yasushi Honda
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba , Japan
| | - Tomomi Fujimoto
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba , Japan
| | - Yinhang Cao
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba , Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba , Japan
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7
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Poncin W, Lebecque P. [Lung clearance index in cystic fibrosis]. Rev Mal Respir 2019; 36:377-395. [PMID: 30686561 DOI: 10.1016/j.rmr.2018.03.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 03/28/2018] [Indexed: 01/03/2023]
Abstract
INTRODUCTION Small airways' involvement in cystic fibrosis (CF) pulmonary disease is a very early event, which can progress sub-clinically and insidiously since it is poorly reflected by commonly used lung function tests. STATE OF ART Sensitive and discriminative tools are available to investigate small airways function. However their complexity and/or invasiveness has confined their use to research purposes and to some specialized research teams. By contrast, the multiple breath washout (MBW) test is more affordable and non-invasive. Lung clearance index (LCI), which is the most used derived parameter, is reproducible and much more sensitive than spirometry in detecting small airways disease. However, MBW is operator dependent. PERSPECTIVES The recent commercialization of devices assessing LCI launches MBW as a potential tool in routine clinical care, although its use currently remains mostly dedicated to research purposes. However, important differences in LCI between various equipment settings raise a number of theoretical questions. Specific algorithms should be refined and more transparent. Standardization of MBW is still an ongoing process. Whether other MBW derived indices can prove superior over LCI deserves further study. CONCLUSIONS In CF, LCI is now a well-established outcome in research settings to detect early lung function abnormalities and new treatment effects, especially in patients with mild lung disease. In these patients, LCI seems an attractive tool for clinicians too. Yet, further investigation is needed to define clinically significant changes in LCI and to which extent this index can be useful in guiding clinical decisions remains to be studied.
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Affiliation(s)
- W Poncin
- Pôle de pneumologie, ORL et dermatologie, université Catholique de Louvain, institut de recherche expérimentale et clinique (IREC), 1200 Bruxelles, Belgique; Service de médecine physique et réadaptation, cliniques universitaires Saint-Luc, 1200 Bruxelles, Belgique.
| | - P Lebecque
- Pneumologie pédiatrique & centre de référence pour la mucoviscidose, cliniques universitaires Saint-Luc, 1200 Bruxelles, Belgique
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Bain AR, Nybo L, Ainslie PN. Cerebral Vascular Control and Metabolism in Heat Stress. Compr Physiol 2016; 5:1345-80. [PMID: 26140721 DOI: 10.1002/cphy.c140066] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review provides an in-depth update on the impact of heat stress on cerebrovascular functioning. The regulation of cerebral temperature, blood flow, and metabolism are discussed. We further provide an overview of vascular permeability, the neurocognitive changes, and the key clinical implications and pathologies known to confound cerebral functioning during hyperthermia. A reduction in cerebral blood flow (CBF), derived primarily from a respiratory-induced alkalosis, underscores the cerebrovascular changes to hyperthermia. Arterial pressures may also become compromised because of reduced peripheral resistance secondary to skin vasodilatation. Therefore, when hyperthermia is combined with conditions that increase cardiovascular strain, for example, orthostasis or dehydration, the inability to preserve cerebral perfusion pressure further reduces CBF. A reduced cerebral perfusion pressure is in turn the primary mechanism for impaired tolerance to orthostatic challenges. Any reduction in CBF attenuates the brain's convective heat loss, while the hyperthermic-induced increase in metabolic rate increases the cerebral heat gain. This paradoxical uncoupling of CBF to metabolism increases brain temperature, and potentiates a condition whereby cerebral oxygenation may be compromised. With levels of experimentally viable passive hyperthermia (up to 39.5-40.0 °C core temperature), the associated reduction in CBF (∼ 30%) and increase in cerebral metabolic demand (∼ 10%) is likely compensated by increases in cerebral oxygen extraction. However, severe increases in whole-body and brain temperature may increase blood-brain barrier permeability, potentially leading to cerebral vasogenic edema. The cerebrovascular challenges associated with hyperthermia are of paramount importance for populations with compromised thermoregulatory control--for example, spinal cord injury, elderly, and those with preexisting cardiovascular diseases.
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Affiliation(s)
- Anthony R Bain
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, Canada
| | - Lars Nybo
- Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Philip N Ainslie
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, Canada
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Decima PFF, Fyfe KL, Odoi A, Wong FY, Horne RSC. The longitudinal effects of persistent periodic breathing on cerebral oxygenation in preterm infants. Sleep Med 2015; 16:729-35. [PMID: 25959095 DOI: 10.1016/j.sleep.2015.02.537] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 01/14/2015] [Accepted: 02/13/2015] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Periodic breathing is common in preterm infants, but is thought to be benign. The aim of our study was to assess the incidence and impact of periodic breathing on heart rate (HR), oxygen saturation (SpO2), and brain tissue oxygenation index (TOI) over the first six months after term-equivalent age. STUDY DESIGN Twenty-four preterm infants (27-36 weeks gestational age) were studied with daytime polysomnography in quiet sleep (QS) and active sleep (AS) and in both the prone and supine positions at 2-4 weeks, 2-3 months, and 5-6 months post-term corrected age. HR, SpO2, and TOI (NIRO-200 spectrophotometer) were recorded. Periodic breathing episodes were defined as greater than or equal to three sequential apneas each lasting ≥3 s. RESULTS A total 164 individual episodes of periodic breathing were recorded in 19 infants at 2-4 weeks, 62 in 12 infants at 2-3 months, and 35 in 10 infants at 5-6 months. There was no effect of gestational age on periodic breathing frequency or duration. Falls in HR (-21.9 ± 2.7%) and TOI (-13.1 ± 1.5%) were significantly greater at 2-3 months of age compared to 2-4 weeks of age. CONCLUSIONS The majority of preterm infants discharged home without clinical respiratory problems had persistent periodic breathing. Although in most infants periodic breathing was not associated with significant falls in SpO2 or TOI, several infants had significant desaturations and reduced cerebral oxygenation especially during AS. The clinical significance of this on neurodevelopmental outcome is unknown and warrants further investigations.
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MESH Headings
- Brain/physiopathology
- Cross-Sectional Studies
- Female
- Follow-Up Studies
- Gestational Age
- Heart Rate/physiology
- Humans
- Hypoxia, Brain/diagnosis
- Hypoxia, Brain/epidemiology
- Hypoxia, Brain/physiopathology
- Infant
- Infant, Newborn
- Infant, Premature, Diseases/diagnosis
- Infant, Premature, Diseases/epidemiology
- Infant, Premature, Diseases/physiopathology
- Longitudinal Studies
- Male
- Oxygen/blood
- Oxygen Consumption/physiology
- Polysomnography
- Sleep Apnea, Central/diagnosis
- Sleep Apnea, Central/epidemiology
- Sleep Apnea, Central/physiopathology
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Affiliation(s)
- Pauline F F Decima
- The Ritchie Centre, Monash Institute of Medical Research and Prince Henry's Institute, Monash University, Melbourne, VIC, Australia; Laboratoire PériTox, UMR-I 01 INERIS, Faculté de Médecine, Université de Picardie Jules Verne, Amiens, France
| | - Karinna L Fyfe
- The Ritchie Centre, Monash Institute of Medical Research and Prince Henry's Institute, Monash University, Melbourne, VIC, Australia; Department of Paediatrics, Monash University, Melbourne, VIC, Australia
| | - Alexsandria Odoi
- The Ritchie Centre, Monash Institute of Medical Research and Prince Henry's Institute, Monash University, Melbourne, VIC, Australia
| | - Flora Y Wong
- The Ritchie Centre, Monash Institute of Medical Research and Prince Henry's Institute, Monash University, Melbourne, VIC, Australia; Department of Paediatrics, Monash University, Melbourne, VIC, Australia
| | - Rosemary S C Horne
- The Ritchie Centre, Monash Institute of Medical Research and Prince Henry's Institute, Monash University, Melbourne, VIC, Australia; Department of Paediatrics, Monash University, Melbourne, VIC, Australia.
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Singer F, Yammine S, Schmidt A, Proietti E, Kieninger E, Barben J, Casaulta C, Regamey N, Gustafsson P, Frey U, Latzin P. Ventilatory response to nitrogen multiple-breath washout in infants. Pediatr Pulmonol 2014; 49:342-7. [PMID: 23853006 DOI: 10.1002/ppul.22841] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 05/31/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND Nitrogen multiple-breath washout (N2 MBW) using 100% oxygen (O2) has regained interest to assess efficiency of tracer gas clearance in, for example, children with Cystic Fibrosis (CF). However, the influence of hyperoxia on the infants' respiratory control is unclear. We assessed safety and impact on breathing pattern from hyperoxia, and if exposure to 40% O2 first induces tolerance to subsequent 100% O2 for N2 MBW. METHODS We prospectively enrolled 39 infants aged 3-57 weeks: 15 infants with CF (8 sedated for testing) and 24 healthy controls. Infants were consecutively allocated to the protocols comprising of 100% O2 or 40/100% O2 administered for 30 breaths. Lung function was measured using an ultrasonic flowmeter setup. Primary outcome was tidal volume (VT). RESULTS None of the infants experienced apnea, desaturation, or bradycardia. Both protocols initially induced hypoventilation. VT temporarily declined in 33/39 infants across 10-25 breaths. Hypoventilation occurred independent of age, disease, and sedation. In the new 40/100% O2 protocol, VT returned to baseline during 40% O2 and remained stable during 100% O2 exposure. End-tidal carbon dioxide monitored online did not change. CONCLUSION The classical N2 MBW protocol with 100% O2 may change breathing patterns of the infants. The new protocol with 40% O2 induces hyperoxia-tolerance and does not lead to changes in breathing patterns during later N2 washout using 100% O2. Both protocols are safe, the new protocol seems an attractive option for N2 MBW in infants.
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Affiliation(s)
- Florian Singer
- Department of Paediatrics, University Hospital of Bern, Bern, Switzerland; University Children's Hospital of Zurich, Zurich, Switzerland
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11
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Ghyselen L, Fontaine C, Dégrugilliers L, Degorre C, Léké A, Tourneux P. Polyethylene bag wrapping to prevent hypothermia during percutaneous central venous catheter insertion in the preterm newborn under 32 weeks of gestation. J Matern Fetal Neonatal Med 2014; 27:1922-5. [DOI: 10.3109/14767058.2014.885498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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12
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Garcia AJ, Koschnitzky JE, Dashevskiy T, Ramirez JM. Cardiorespiratory coupling in health and disease. Auton Neurosci 2013; 175:26-37. [PMID: 23497744 DOI: 10.1016/j.autneu.2013.02.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 01/21/2013] [Accepted: 02/08/2013] [Indexed: 10/27/2022]
Abstract
Cardiac and respiratory activities are intricately linked both functionally as well as anatomically through highly overlapping brainstem networks controlling these autonomic physiologies that are essential for survival. Cardiorespiratory coupling (CRC) has many potential benefits creating synergies that promote healthy physiology. However, when such coupling deteriorates autonomic dysautonomia may ensue. Unfortunately there is still an incomplete mechanistic understanding of both normal and pathophysiological interactions that respectively give rise to CRC and cardiorespiratory dysautonomia. Moreover, there is also a need for better quantitative methods to assess CRC. This review addresses the current understanding of CRC by discussing: (1) the neurobiological basis of respiratory sinus arrhythmia (RSA); (2) various disease states involving cardiorespiratory dysautonomia; and (3) methodologies measuring heart rate variability and RSA.
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Affiliation(s)
- Alfredo J Garcia
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
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13
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Edwards BA, Sands SA, Berger PJ. Postnatal maturation of breathing stability and loop gain: the role of carotid chemoreceptor development. Respir Physiol Neurobiol 2012; 185:144-55. [PMID: 22705011 DOI: 10.1016/j.resp.2012.06.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/16/2012] [Accepted: 06/01/2012] [Indexed: 11/17/2022]
Abstract
Any general model of respiratory control must explain a puzzling array of breathing patterns that are observed during the course of a lifetime. Particular challenges are to understand why periodic breathing is rarely seen in the first few days after birth, reaches a peak at 2-4 weeks postnatal age, and disappears by 6 months, why it is prevalent in preterm infants, and why it reappears in adults at altitude or with heart failure. In this review we use the concept of loop gain to obtain quantitative insight into the genesis of unstable breathing patterns with a particular focus on how changes in carotid body function could underlie the age-related dependence of periodic breathing.
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Affiliation(s)
- Bradley A Edwards
- Division of Sleep Medicine, Brigham and Women's Hospital & Harvard Medical School, Boston, MA, USA.
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14
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Abstract
Most abnormalities of ventilatory control in infants are due to immaturity or abnormal development of ventilatory control. This includes a broad range, from rare disorders like congenital central hypoventilation syndrome to common problems such as apnoea of prematurity. Development of the ventilatory control system, including central respiratory rhythmogenesis and central and peripheral chemoreception, begins early in gestation and continues for weeks or months after birth. Development of the neural components of central rhythmogenesis and their highly complex interconnectivity results from complex, timing-sensitive interactions between patterning and other genes, transcription factors and neurotrophic factors. At birth, nearly all aspects of ventilatory control remain immature, especially in preterm infants; and postnatal maturation can be altered by hypoxia, toxins and other stressors. Clinical care may be greatly enhanced by increased awareness of ventilatory control maturation and related disorders.
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Affiliation(s)
- John L Carroll
- University of Arkansas for Medical Sciences, Department of Pediatrics, Division of Pulmonary Medicine, Arkansas Children's Hospital, Little Rock, Arkansas 72212, USA.
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15
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Stéphan-Blanchard E, Chardon K, Léké A, Delanaud S, Djeddi D, Libert JP, Bach V, Telliez F. In utero exposure to smoking and peripheral chemoreceptor function in preterm neonates. Pediatrics 2010; 125:e592-9. [PMID: 20176675 DOI: 10.1542/peds.2008-2976] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE We aimed to assess the involvement of peripheral chemoreceptor tonic activity in the ventilatory pattern during sleep in preterm neonates exposed in utero to maternal smoking. PATIENTS AND METHODS Peripheral chemoreceptor activity was measured at thermoneutrality in neonates (postmenstrual age: 36.1 +/- 1.2 weeks) born to nonsmoking (n = 21) or smoking (n = 16) mothers by performing a 30-second hyperoxic test during active and quiet sleep. Blood oxygen saturation, baseline ventilatory parameters, and central apnea were monitored. RESULTS Prenatal smoking exposure did not modify baseline ventilation. It was interesting to note that prenatal smoking exposure decreased the peripheral chemoreceptor tonic activity during active sleep and increased the response time during quiet sleep. These changes could explain the increase in the time spent in apnea (both with and without blood oxygen desaturation) and in the mean duration of apneic episodes with desaturation found in neonates exposed to smoking in utero. The involvement of a change in the chemoreceptor function is supported by the fact that the peripheral chemoreceptor tonic activity was negatively correlated with the mean duration of apneic episodes with desaturation in the control group only. CONCLUSIONS To our knowledge, this is the first study to reveal that prenatal smoking exposure does not directly modify baseline ventilatory parameters in the neonate but has a negative impact on peripheral chemoreceptor tonic activity. These alterations may increase the risk of sleep respiratory disorders, especially via apnea with desaturation.
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Affiliation(s)
- Erwan Stéphan-Blanchard
- Jules Verne University of Picardy, Faculté de Médecine, 3 Rue des Louvels, 80036 Amiens Cedex, France.
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Stern G, Beel J, Suki B, Silverman M, Westaway J, Cernelc M, Baldwin D, Frey U. Long-range correlations in rectal temperature fluctuations of healthy infants during maturation. PLoS One 2009; 4:e6431. [PMID: 19641615 PMCID: PMC2713399 DOI: 10.1371/journal.pone.0006431] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 05/22/2009] [Indexed: 11/20/2022] Open
Abstract
Background Control of breathing, heart rate, and body temperature are interdependent in infants, where instabilities in thermoregulation can contribute to apneas or even life-threatening events. Identifying abnormalities in thermoregulation is particularly important in the first 6 months of life, where autonomic regulation undergoes critical development. Fluctuations in body temperature have been shown to be sensitive to maturational stage as well as system failure in critically ill patients. We thus aimed to investigate the existence of fractal-like long-range correlations, indicative of temperature control, in night time rectal temperature (Trec) patterns in maturing infants. Methodology/Principal Findings We measured Trec fluctuations in infants every 4 weeks from 4 to 20 weeks of age and before and after immunization. Long-range correlations in the temperature series were quantified by the correlation exponent, α using detrended fluctuation analysis. The effects of maturation, room temperature, and immunization on the strength of correlation were investigated. We found that Trec fluctuations exhibit fractal long-range correlations with a mean (SD) α of 1.51 (0.11), indicating that Trec is regulated in a highly correlated and hence deterministic manner. A significant increase in α with age from 1.42 (0.07) at 4 weeks to 1.58 (0.04) at 20 weeks reflects a change in long-range correlation behavior with maturation towards a smoother and more deterministic temperature regulation, potentially due to the decrease in surface area to body weight ratio in the maturing infant. α was not associated with mean room temperature or influenced by immunization Conclusions This study shows that the quantification of long-range correlations using α derived from detrended fluctuation analysis is an observer-independent tool which can distinguish developmental stages of night time Trec pattern in young infants, reflective of maturation of the autonomic system. Detrended fluctuation analysis may prove useful for characterizing thermoregulation in premature and other infants at risk for life-threatening events.
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Affiliation(s)
- Georgette Stern
- Division of Respiratory Medicine, Department of Pediatrics, Inselspital and University of Bern, Bern, Switzerland.
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17
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Bollen B, Bouslama M, Matrot B, Rotrou Y, Vardon G, Lofaso F, Van den Bergh O, D'Hooge R, Gallego J. Cold stimulates the behavioral response to hypoxia in newborn mice. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1503-11. [DOI: 10.1152/ajpregu.90582.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In newborns, hypoxia elicits increased ventilation, arousal followed by defensive movements, and cries. Cold is known to affect the ventilatory response to hypoxia, but whether it affects the arousal response remains unknown. The aim of the present study was to assess the effects of cold on the ventilatory and arousal responses to hypoxia in newborn mice. We designed an original platform measuring noninvasively and simultaneously the breathing pattern by whole body plethysmography, body temperature by infrared thermography, as well as motor and ultrasonic vocal (USV) responses. Six-day-old mice were exposed twice to 10% O2 for 3 min at either cold temperature (26°C) or thermoneutrality (33°C). At 33°C, hypoxia elicited a marked increase in ventilation followed by a small ventilatory decline, small motor response, and almost no USVs. Body temperature was not influenced by hypoxia, and oxygen consumption (V̇o2) displayed minimal changes. At 26°C, hypoxia elicited a slight increase in ventilation with a large ventilatory decline and a large drop of V̇o2. This response was accompanied by marked USV and motor responses. Hypoxia elicited a small decrease in temperature after the return to normoxia, thus precluding any causal influence on the motor and USV responses to hypoxia. In conclusion, cold stimulated arousal and stress responses to hypoxia, while depressing hypoxic hyperpnea. Arousal is an important defense mechanism against sleep-disordered breathing. The dissociation between ventilatory and behavioral responses to hypoxia suggests that deficits in the arousal response associated with sleep breathing disorders cannot be attributed to a depressed hypoxic response.
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18
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Fujii N, Honda Y, Hayashi K, Kondo N, Koga S, Nishiyasu T. Effects of chemoreflexes on hyperthermic hyperventilation and cerebral blood velocity in resting heated humans. Exp Physiol 2008; 93:994-1001. [PMID: 18403444 DOI: 10.1113/expphysiol.2008.042143] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We tested the hypothesis that hyperthermic hyperventilation in part reflects enhanced chemoreceptor ventilatory O(2) drive, and that the resultant hypocapnia attenuates ventilatory responses and/or middle cerebral artery mean blood velocity (MCAV(mean)) in resting humans. Eleven healthy subjects were passively heated for 50-80 min, causing oesophageal temperature (T(oes)) to increase by 1.6 degrees C. During heating, minute ventilation increased (P < 0.05), while end-tidal CO(2) pressure (P(ET,CO(2))) and MCAV(mean) declined. A hyperoxia test in which three breaths of hyperoxic air were inspired was performed once before heating and three times during the heating. When we observed hypocapnia (P(ET,CO(2)) below 40 mmHg), P(ET,CO(2)) was restored to the eucapnic level by adding 100% CO(2) to the inspired air immediately before the last two tests. Minute ventilation was significantly reduced by hyperoxia, and that reduction gradually increased with increasing T(oes). However, the percentage decrease in from the normoxic level was small (20-29%) and unchanged during heating. When P(ET,CO(2)) was restored to eucapnic levels, was unchanged, but MCAV(mean) was partly restored to the level seen prior to heating (28.1% restoration at T(oes) 37.6 degrees C and 38.1% restoration at T(oes) 38.0 degrees C). These findings suggest that although hyperthermia increases chemoreceptor ventilatory O(2) drive in resting humans, the relative contribution of the chemoreceptor ventilatory O(2) drive to hyperthermic hyperventilation is small ( approximately 20%) and unaffected by increasing core temperature. Moreover, hypocapnia induced by hyperthermic hyperventilation reduces cerebral blood flow but not ventilatory responses.
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Affiliation(s)
- Naoto Fujii
- Institute of Health and Sports Science, University of Tsukuba, Tsukuba City, Ibaraki 305-8574, Japan
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19
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Cardot V, Chardon K, Tourneux P, Micallef S, Stéphan E, Léké A, Bach V, Libert JP, Telliez F. Ventilatory response to a hyperoxic test is related to the frequency of short apneic episodes in late preterm neonates. Pediatr Res 2007; 62:591-6. [PMID: 17805205 DOI: 10.1203/pdr.0b013e318155868e] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Chemoreception is frequently involved in the processes underlying apnea in premature infants. Apnea could result from a decrease in carotid body effectiveness. However, increased carotid body activity could also initiate apnea through hypocapnia following hyperventilation when the receptors are stimulated. The aim of this study was to analyze the relationship between carotid body effectiveness and short apneic episodes in older preterm neonates. Carotid body effectiveness was assessed at thermoneutrality in 36 premature neonates (2.07 +/- 0.26 kg) by performing a 30-s hyperoxic test during sleep, the oxygen inhalation involving a ventilation decrease. Blood O(2) saturation (Sp(o2)) and ventilatory parameters were monitored before and during the hyperoxic test. Short episodes of apnea (frequency and mean duration) were recorded during the morning's 3-h interfeeding interval. Pretest Sp(o2) was not related to any of the measured respiratory parameters. A higher frequency of short apneic episodes was linked to a greater ventilation decrease in response to the hyperoxic test (rho = -0.32; p = 0.01). Increased carotid body response is correlated with greater apneic episodes frequency, even in the absence of concomitant oxygen desaturation. Fetal or early postnatal hypoxemia could have increased peripheral chemoreceptor activity, which could initiate a "overshoot/undershoot" situation, which in turn could induce a critical P(o2)/P(co2) combination and apnea.
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Affiliation(s)
- Virginie Cardot
- Dysrégulations Métaboliques Acquises et Génétiques (EA3901), Medical Faculty, University of Picardy, 80036 Amiens, France.
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20
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Baldwin DN, Pillow JJ, Stocks J, Frey U. Lung-function tests in neonates and infants with chronic lung disease: tidal breathing and respiratory control. Pediatr Pulmonol 2006; 41:391-419. [PMID: 16555264 DOI: 10.1002/ppul.20400] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This paper is the fourth in a series of reviews that will summarize available data and critically discuss the potential role of lung-function testing in infants with acute neonatal respiratory disorders and chronic lung disease of infancy. The current paper addresses information derived from tidal breathing measurements within the framework outlined in the introductory paper of this series, with particular reference to how these measurements inform on control of breathing. Infants with acute and chronic respiratory illness demonstrate differences in tidal breathing and its control that are of clinical consequence and can be measured objectively. The increased incidence of significant apnea in preterm infants and infants with chronic lung disease, together with the reportedly increased risk of sudden unexplained death within the latter group, suggests that control of breathing is affected by both maturation and disease. Clinical observations are supported by formal comparison of tidal breathing parameters and control of breathing indices in the research setting.
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Affiliation(s)
- David N Baldwin
- Centre for Child Health Research and Telethon Institute for Child Health Research, University of Western Australia, Perth, Western Australia, Australia.
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21
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Gaultier C, Gallego J. Development of respiratory control: Evolving concepts and perspectives. Respir Physiol Neurobiol 2005; 149:3-15. [PMID: 15941676 DOI: 10.1016/j.resp.2005.04.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 04/22/2005] [Accepted: 04/25/2005] [Indexed: 10/25/2022]
Abstract
The mechanisms underlying respiratory system immaturity in newborns have been investigated, both in vivo and in vitro, in humans and in animals. Immaturity affects breathing rhythmicity and its modulation by suprapontine influences and by afferents from central and peripheral chemoreceptors. Recent research has moved from bedside tools to sophisticated technologies, bringing new insights into the plasticity and genetics of respiratory control development. Genetic research has benefited from investigations of newborn mice having targeted deletions of genes involved in respiratory control. Genetic variability may govern the normal programming of development and the processes underlying adaptation to homeostasis disturbances induced by prenatal and postnatal insults. Studies of plasticity have emphasized the role of neurotrophic factors. Improvements in our understanding of the mechanistic effects of these factors should lead to new neuroprotective strategies for infants at risk for early respiratory control disturbances, such as apnoeas of prematurity, sudden infant death syndrome and congenital central hypoventilation syndrome.
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Affiliation(s)
- Claude Gaultier
- Service de Physiologie, Hôpital Robert Debré, 48 Boulevard Serurier, 75019 Paris, France.
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22
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Mortola JP. Influence of temperature on metabolism and breathing during mammalian ontogenesis. Respir Physiol Neurobiol 2005; 149:155-64. [PMID: 16126013 DOI: 10.1016/j.resp.2005.01.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Revised: 01/17/2005] [Accepted: 01/24/2005] [Indexed: 11/21/2022]
Abstract
A literature survey of the ventilatory responses to changes in ambient temperature (T) in neonatal mammals reveals that, as in adults, the metabolic response to T is the major determining factor. In fact, the newborn's metabolic response to changes in T determines not only the pulmonary ventilation and the breathing pattern, but also the magnitude of the ventilatory responses to chemical stimuli and the intensity of the pulmonary reflexes at different T. The important difference from the adult is that in many neonatal mammals the control of body temperature (T(b)) is poorly developed. Hence, the metabolic response can be more similar to that of an ectothermic, rather than endothermic, animal, and T(b) can vary substantially with T. When hypoxia occurs in cold, T(b) can decrease greatly, because of the hypoxic drop in the thermoregulatory set-point, and this lowers pulmonary ventilation. Hence, in addition to the metabolic response, also the changes in T(b) are a factor modulating the ventilatory responses to T. Artificial warming of the newborn during hypoxia causes heat-dissipation responses that can be counterproductive. During ontogenesis, with prolonged cold conditions, the sustained alterations in metabolic rate and body growth do not modify the postnatal development of the respiratory control mechanisms. Presumably, this indicates that respiratory regulation develops independently from the individual's metabolic history.
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Affiliation(s)
- Jacopo P Mortola
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Que., Canada H3G 1Y6.
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Abstract
The genetic approach to respiratory control is opening up new paths for research into developmental respiratory control disorders. Despite the identification of numerous genes involved in respiratory control, none of the genetically engineered mice developed to date fully replicate the human respiratory phenotype of human developmental respiratory disorders. However, combining studies in humans and studies in mouse models has proved useful in identifying candidate genes for human developmental respiratory control disorders and providing pathogenic information. In clinical practice, the development of databases that incorporate clinical phenotypes and genetic samples from patients would facilitate further genetic studies. International multicentre studies would advance the area of respiratory control research.
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Affiliation(s)
- Claude Gaultier
- Department of Physiology, INSERM 9935, Hôpital Robert, Faculté de Médecine Lariboisière, Université Paris VII, France.
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