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Stéphan-Blanchard E, Chardon K, Léké A, Delanaud S, Bach V, Telliez F. Heart rate variability in sleeping preterm neonates exposed to cool and warm thermal conditions. PLoS One 2013; 8:e68211. [PMID: 23840888 PMCID: PMC3698119 DOI: 10.1371/journal.pone.0068211] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 05/27/2013] [Indexed: 11/18/2022] Open
Abstract
Sudden infant death syndrome (SIDS) remains the main cause of postneonatal infant death. Thermal stress is a major risk factor and makes infants more vulnerable to SIDS. Although it has been suggested that thermal stress could lead to SIDS by disrupting autonomic functions, clinical and physiopathological data on this hypothesis are scarce. We evaluated the influence of ambient temperature on autonomic nervous activity during sleep in thirty-four preterm neonates (mean ± SD gestational age: 31.4±1.5 weeks, postmenstrual age: 36.2±0.9 weeks). Heart rate variability was assessed as a function of the sleep stage at three different ambient temperatures (thermoneutrality and warm and cool thermal conditions). An elevated ambient temperature was associated with a higher basal heart rate and lower short- and long-term variability in all sleep stages, together with higher sympathetic activity and lower parasympathetic activity. Our study results showed that modification of the ambient temperature led to significant changes in autonomic nervous system control in sleeping preterm neonates. The latter changes are very similar to those observed in infants at risk of SIDS. Our findings may provide greater insight into the thermally-induced disease mechanisms related to SIDS and may help improve prevention strategies.
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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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Antonucci R, Porcella A, Fanos V. The infant incubator in the neonatal intensive care unit: unresolved issues and future developments. J Perinat Med 2010; 37:587-98. [PMID: 19591569 DOI: 10.1515/jpm.2009.109] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Since the 19th century, devices termed incubators were developed to maintain thermal stability in low birth weight (LBW) and sick newborns, thus improving their chances of survival. Remarkable progress has been made in the production of infant incubators, which are currently highly technological devices. However, they still need to be improved in many aspects. Regarding the temperature and humidity control, future incubators should minimize heat loss from the neonate and eddies around him/her. An unresolved issue is exposure to high noise levels in the Neonatal Intensive Care Unit (NICU). Strategies aimed at modifying the behavior of NICU personnel, along with structural improvements in incubator design, are required to reduce noise exposure. Light environment should be taken into consideration in designing new models of incubators. In fact, ambient NICU illumination may cause visual pathway sequelae or possibly retinopathy of prematurity (ROP), while premature exposure to continuous lighting may adversely affect the rest-activity patterns of the newborn. Accordingly, both the use of incubator covers and circadian lighting in the NICU might attenuate these effects. The impact of electromagnetic fields (EMFs) on infant health is still unclear. However, future incubators should be designed to minimize the EMF exposure of the newborn.
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Affiliation(s)
- Roberto Antonucci
- Neonatal Intensive Care Unit, Department of Pediatrics and Clinical Medicine, University of Cagliari, Cagliari, Italy.
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Tourneux P, Léké A, Kongolo G, Cardot V, Dégrugilliers L, Chardon K, Storme L, Krim G, Libert JP, Bach V. Relationship between functional residual capacity and oxygen desaturation during short central apneic events during sleep in "late preterm" infants. Pediatr Res 2008; 64:171-6. [PMID: 18414144 DOI: 10.1203/pdr.0b013e318179951d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Apneic episodes are frequent in the preterm neonate and particularly in active sleep (AS), when functional residual capacity (FRC) can be decreased. Furthermore, FRC may be inversely correlated with the speed of blood-O(2)-desaturation. We evaluated the potential involvement of FRC in the mechanisms responsible for blood-O(2)-desaturation during short central apneic events (>3 s) in "late-preterm" infants and analyzed the specific influence of sleep state. Apneic events were scored in 29 neonates (postmenstrual age: 36.1 +/- 1.2 wk) during AS and quiet sleep (QS). FRC was measured during well-established periods of regular breathing. Apneas with blood-O(2)-desaturation (drop in SpO(2) >5% from the baseline, lowest SpO(2) during apnea: 91.4 +/- 1.8%) were more frequent in AS than in QS, whereas no difference was seen for apneas without desaturation. The magnitude of the FRC did not depend on the sleep state. In AS only, there was a negative relationship between FRC and the proportion of apneas with desaturation. Even in late preterm infants who do not experience long-lasting apnea, blood-O(2)-desaturation during short apneic events is related (in AS but not QS) to a low baseline FRC. Sleep stage differences argue for a major role of AS-related mechanisms in the occurrence of these apneas.
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Affiliation(s)
- Pierre Tourneux
- PériTox (EA 3901-INERIS), University of Picardy, Amiens, France.
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Tourneux P, Cardot V, Museux N, Chardon K, Léké A, Telliez F, Libert JP, Bach V. Influence of thermal drive on central sleep apnea in the preterm neonate. Sleep 2008; 31:549-56. [PMID: 18457243 DOI: 10.1093/sleep/31.4.549] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The incidence of apnea in neonates depends on a number of factors, including sleep state and thermoregulation. OBJECTIVE To assess the role of thermal drive (body heat loss [BHL]) in the mechanisms underlying short episodes of central apnea during active and quiet sleep in neonates. MATERIAL AND METHOD Twenty-two neonates (postconceptional age: 36.3 +/- 0.9 weeks) were exposed at thermoneutral (incubator temperature: 32.5 degrees C), warm (34.2 degrees C), and cool (30.4 degrees C) conditions during 3 consecutive morning naps. Oxygen consumption (VO2), skin and rectal temperatures, and central apnea were scored during active sleep and quiet sleep. The thermal drive was expressed as BHL calculated using indirect partitional calorimetry. RESULTS As expected, apnea occurred more frequently in active sleep than in quiet sleep (P < 0.001). The frequency of apnea in active sleep was higher in the warm condition (P < 0.05). In contrast, apnea episodes were less frequent (P < 0.05) and shorter (P < 0.05) for cool exposure, during which VO2 and rectal temperature increased. The frequency (P < 0.001, r2 = 0.31), mean (P < 0.05, r2 = 0.06), and maximum (P < 0.001, r2 = 0.19) durations of apnea were correlated with the BHL: the greater the BHL (body cooling), the less frequent and the shorter the apnea episodes. In contrast, no relationship between apnea and mean skin or rectal temperature was observed. CONCLUSION Apneic events were more closely related to BHL than to body temperatures. In cool exposure, the decreases in the duration and frequency of apneic episodes suggest that these events depend on the metabolic drive (which is proportional to energy expenditure).
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Affiliation(s)
- Pierre Tourneux
- PériTox (EA 3901-UM INERIS), Faculty of Medicine, Jules Verne University of Picardy, Amiens, France.
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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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Chardon K, Telliez F, Bach V, Leke A, Delanaud S, Bouferrache B, Libert JP, Gaultier C. Effects of warm and cool thermal conditions on ventilatory responses to hyperoxic test in neonates. Respir Physiol Neurobiol 2004; 140:145-53. [PMID: 15134662 DOI: 10.1016/j.resp.2003.11.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2003] [Indexed: 11/22/2022]
Abstract
Body temperature interacts with respiratory control, but it is unclear what sites or mechanisms mediate those interactions. We hypothesized that warm and cool thermal conditions affect the decrease in ventilation (VE) seen during the hyperoxic test (HT), a breathing response believed to reflect the strength of the peripheral chemoreceptor drive. A breath-by-breath analysis during a 30 s HT was performed in eight premature neonates (postconceptional age: 36 +/- 1 weeks) under neutral, warm, and cool thermal conditions. Quiet sleep (QS) and active sleep (AS) were scored by neurophysiological criteria. The VE fall was higher in AS than in QS, and warm and cool conditions significantly enhanced the response only in AS (-24.2 +/- 6.0, -39.1 +/- 9.1, and -37.5 +/- 14.1% in neutral, warm, and cool conditions, respectively). Central control mechanisms of the respiratory chemoreflex may explain the increase in peripheral chemoreceptor drive during AS in response to thermal challenges, which may produce increased breathing instability leading to apnea in early life.
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Affiliation(s)
- Karen Chardon
- Environnement Toxique Périnatal et Adaptations Physiologiques et Comportementales (EA2088), School of Medicine, 3 rue des Louvels, Amiens 80036, France.
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Chardon K, Bach V, Telliez F, Cardot V, Tourneux P, Leke A, Libert JP. Effect of caffeine on peripheral chemoreceptor activity in premature neonates: interaction with sleep stages. J Appl Physiol (1985) 2004; 96:2161-6. [PMID: 14966021 DOI: 10.1152/japplphysiol.01160.2003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Caffeine is widely used for the treatment of apnea in premature neonates. However, the localization of caffeine's target site (central nervous system and/or peripheral chemoreceptors) is not well defined, especially for sleeping neonates whose sleep stages interact with respiratory control. The aim of this study was to assess the activity of the peripheral chemoreceptors in relation to sleep stages in premature neonates treated (or not) with caffeine for idiopathic apnea. Peripheral chemoreceptor activity was assessed in 22 neonates (postconceptional age of 36 +/- 1 wk with birth weights ranging from 790 to 1,910 g) by performing a 30-s hyperoxic test during active and quiet sleep. Eleven neonates received caffeine treatment (4.0 +/- 0.5 mg.kg(-1).day(-1)) and 11 served as controls. For all neonates, the decrease in minute ventilation observed during hyperoxia was greater during active than during quiet sleep. Neonates receiving caffeine showed a significantly greater decrease in ventilation during hyperoxia in both sleep stages, compared with controls (caffeine; -29.7 +/- 12.8% vs. control; -22.0 +/- 7.4%; F(1,15) = 4.6, P = 0.04). We conclude that caffeine administration increases the effectiveness of chemoreceptor activity. Because sleep stage durations were not affected by the treatment, it is likely that the decrease in apneic episodes typically observed with caffeine therapy is only related to respiratory processes and is independent of the sleep stage organization.
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Affiliation(s)
- Karen Chardon
- Laboratoire d'Environnement Toxique Périnatal et Adaptations Physiologiques et Comportementales (EA2088), Faculté deMédecine, Université de Picardie Jules Verne, 3 rue des Louvels, F-80036 Amiens cedex, France.
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Chardon K, Bach V, Telliez F, Tourneux P, Elabbassi EB, Cardot V, Gaultier C, Libert JP. Peripheral chemoreceptor activity in sleeping neonates exposed to warm environments. Neurophysiol Clin 2003; 33:196-202. [PMID: 14519548 DOI: 10.1016/s0987-7053(03)00052-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
In neonates, it is often assumed that ventilatory control and heat stress interact. Thus the two factors have been implicated in various pathologies (apnoea, sudden infant death syndrome). However, little is known about the mechanisms of this interaction, and the influence of sleep is still debated. This study aimed at determining the influence of warm exposure on the decrease in ventilation during a hyperoxic test (HT), which is considered to be a measure of peripheral chemoreceptor activity. The test was performed in active (AS) and quiet sleep (QS) in 12 neonates exposed to thermoneutral or warm environments. The HT consisted of 30 s of inspired, 100% O(2). The ventilatory response was assessed in terms of a response time, defined as the time elapsing between HT onset and the first significant change in V(E). Our results show that, in both thermal conditions, the fall in V(E) was higher in AS than in QS. Warm exposure significantly enhanced the ventilatory response in AS (-27.5 +/- 8.7% vs. -38.3 +/- 8.8%, P < 0.01) but not in QS. A thermometabolic drive or inputs from thermoreceptors could be involved in the reinforcement of peripheral chemoreceptor activity in AS in warmer environments, which could contribute to an increasing risk of apnoea in neonates with altered chemoreceptor function. Since hypothalamic structures are involved in thermoregulatory, sleep processes and (probably) in respiratory control, it could well be the principal site where this interaction occurs.
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Affiliation(s)
- K Chardon
- Laboratoire d'environnement toxique périnatal et adaptations physiologiques et comportementales, (EA 2088), Faculté de Médecine, 3, rue des Louvels, 80036 Amiens cedex, France.
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Bach V, Telliez F, Libert JP. The interaction between sleep and thermoregulation in adults and neonates. Sleep Med Rev 2002; 6:481-92. [PMID: 12505480 DOI: 10.1053/smrv.2001.0177] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The interaction between sleep and thermoregulation leads to different thermoregulatory responses depending on the sleep stage and alterations in sleep when in a cool or warm environment. In the human adult, differences in thermoregulatory efficiency during rapid eye movement (REM) sleep and slow wave sleep (SWS) are less pronounced compared to other mammals: although thermoregulatory processes persist in REM sleep, they are less efficient than during SWS. Cold and warm loads disturb the efficiency and structure of sleep. The duration of REM sleep and (to a lesser extent) of SWS decreases. In contrast, pre-sleep warm loads enhance SWS and improve sleep continuity. This procedure may promote and maintain sleep in depressed patients, whose sleep and body temperature rhythms are modified. In contrast to adults, homeothermic processes in neonates are maintained or even enhanced during active sleep (AS) when compared to quiet sleep (QS). Sleeping in a cool environment increases the duration of AS at the expense of QS. As a result, the thermoregulatory function overcomes the need to conserve energy that would otherwise lead to increased QS. An interaction between sleep, respiration, and thermoregulation may be involved in Sudden Infant Death Syndrome: an alteration in the thermal balance may perhaps induce respiration instability, especially during AS.
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Affiliation(s)
- Veronique Bach
- Unité de Recherches sur les Adaptations Physiologiques et Comportementales, Faculté de Médecine, Université de Picardie Jules Verne, 3 rue des Louvels, F- 80 036 Amiens, France.
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Kim YH, Kwon CH, Yoo SC. Experimental and numerical studies on convective heat transfer in a neonatal incubator. Med Biol Eng Comput 2002; 40:114-21. [PMID: 11954698 DOI: 10.1007/bf02347704] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Thermo-neutrality is one of the major environmental factors affecting a premature or low-birth-weight neonate inside an incubator. Severe temperature differences inside an incubator lead to neonate heat loss, hypothermia and apnoea, which are closely related to air flow and air velocity. In the study, flow visualisations, hot-wire velocity measurements and computational fluid dynamics simulate the airflow inside a neonatal incubator. An anatomically correct neonate model is designed using a three-dimensional laser scanner system and a rapid prototyping machine. Flow visualisations demonstrate that large-scale rotating airflow is produced inside the chamber, and a number of small, stationary eddies are found in regions between the air inlet and the neonate. Hot-wire measurements show that air velocities along the long inlets are not uniform. Computational fluid dynamics show relatively uniform temperatures of about 34 degrees C on the neonate's anterior aspect and the highest temperature of 36.1 degrees C at the right armpit and the crotch. Flow fields from airflow visualisations, hot-wire measurements and computational fluid dynamics are very similar, both qualitatively and quantitatively. The small eddies produced between the neonate and the mattress could interfere with convective and evaporative heat transfers from the neonate. Therefore it is important to eliminate eddies around the neonate in future designs of neonatal incubators.
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Affiliation(s)
- Y H Kim
- Department of Biomedical Engineering, College of Health Science, Yonsei University, South Korea Research Institute for Medical Instrumentation & Rehabilitation Engineering, Yonsei University.
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Bach V, Telliez F, Leke A, Libert JP. Gender-related sleep differences in neonates in thermoneutral and cool environments. J Sleep Res 2000; 9:249-54. [PMID: 11012863 DOI: 10.1046/j.1365-2869.2000.00206.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Although thermoregulation and sleep exhibit gender differences in adults, the question is still debated in neonates. The aim of this study was to examine the relationship between gender-related sleep differences and cool defence mechanisms in neonates. Sleep and thermoregulation were recorded in healthy preterm neonates (21 boys and 17 girls, 37 +/- 2 weeks post-conceptional age) exposed to thermoneutral and cool conditions. Sleep was analysed for continuity and structure. Although the cool exposure did not strongly impair body homeothermia, sleep was altered but without any significant gender difference. However, when data recorded under each of the thermal conditions were pooled, some gender differences emerged: boys slept less, with more wakefulness after sleep onset, more active sleep and less quiet sleep than girls. In contrast to sleep architecture, most of the sleep continuity parameters exhibited greater variability in boys than in girls. This variability may bias the statistical analyses and probably explains the varying conclusions reported in the literature regarding gender-specific sleep-related differences.
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Affiliation(s)
- V Bach
- Unité de Recherches sur les Adaptations Physiologiques et Comportementales, Université de Picardie Jules Verne, Amiens, France
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Bach V, Telliez F, Makki M, Farges G, Zoccoli G, Krim G, Libert J. Contrôle de l'environnement thermique dans les incubateurs pour nouveau-nés prématurés. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0222-0776(99)80041-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Telliez F, Bach V, Dewasmes G, Leke A, Libert JP. Sleep modifications during cool acclimation in human neonates. Neurosci Lett 1998; 245:25-8. [PMID: 9596347 DOI: 10.1016/s0304-3940(98)00169-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The present study aimed at testing in human neonates whether the thermal acclimation could reduce the sleep disturbances induced by brief cool exposure. Six neonates were exposed in incubator to a standardised cool thermal load of 75 h duration. The results show an increase of the metabolic heat production (VO2: +25% reaching 5.68 ml/min per kg) during cool acclimation which is not associated with a reduction of the sleep modifications observed on the first cool exposure: the increase of active sleep (+15%, +2 min) and the decrease of quiet sleep (-15%, -11 min) persist and wakefulness after sleep onset increases (+12%, +10 min). In conclusion, there is no sleep adaptation as cool acclimation progressed.
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Affiliation(s)
- F Telliez
- Laboratoire des Techniques d'Explorations Fonctionnelles, Faculté de Médecine, Université de Picardie Jules Verne, Amiens, France
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Telliez F, Bach V, Krim G, Libert JP. Consequences of a small decrease of air temperature from thermal equilibrium on thermoregulation in sleeping neonates. Med Biol Eng Comput 1997; 35:516-20. [PMID: 9374057 DOI: 10.1007/bf02525533] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A new heating unit (servocontrolled skin temperature derivative system) has been designed to control the thermal environment in closed incubators. This type of control acts to attain and closely maintain a thermal equilibrium between a neonate's skin temperature and the environment. The present study aims to discover if thermal equilibrium is located within a thermoneutral range defined from oxygen consumption VO2 and body temperature, and whether it is more appropriate to define an optimal thermal environment. As regards VO2 and body temperature, results show that the air temperature reached at thermal equilibrium fulfils the definition of thermoneutrality. According to these criteria, a small decrease (1:5 degrees C) from thermal equilibrium also provides a near thermoneutral environment to the neonate but induces sleep disturbances and an increase in body movements. These two additional parameters delineate a narrower thermoneutral zone than does minimal metabolic rate because VO2 can stay constant even when air and body temperatures decrease. The results suggest that thermal equilibrium might be assimilated with a thermal comfort zone.
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Affiliation(s)
- F Telliez
- Physiological & Behavioural Research Unit (EA 2088), Medical Faculty, University of Picardy, Jules Verne, Amiens, France
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