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Patural H, Franco P, Pichot V, Giraud A. Heart Rate Variability Analysis to Evaluate Autonomic Nervous System Maturation in Neonates: An Expert Opinion. Front Pediatr 2022; 10:860145. [PMID: 35529337 PMCID: PMC9069105 DOI: 10.3389/fped.2022.860145] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 03/15/2022] [Indexed: 02/03/2023] Open
Abstract
While heart rate variability (HRV) is a relevant non-invasive tool to assess the autonomic nervous system (ANS) functioning with recognized diagnostic and therapeutic implications, the lack of knowledge on its interest in neonatal medicine is certain. This review aims to briefly describe the algorithms used to decompose variations in the length of the RR interval and better understand the physiological autonomic maturation data of the newborn. Assessing newborns' autonomous reactivity can identify dysautonomia situations and discriminate children with a high risk of life-threatening events, which should benefit from cardiorespiratory monitoring at home. Targeted monitoring of HRV should provide an objective reflection of the newborn's intrinsic capacity for cardiorespiratory self-regulation.
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Affiliation(s)
- Hugues Patural
- Neonatal and Pediatric Intensive Care Department, Centre Hospitalier Universitaire de Saint-Étienne, Saint-Étienne, France.,INSERM, U1059, SAINBIOSE, Université de Lyon, Université Jean-Monnet, Saint-Étienne, France
| | - Patricia Franco
- Sleep and Neurological Functional Explorations, Hôpital Femme Mère Enfant, Hospices Civils de Lyon, Lyon, France
| | - Vincent Pichot
- INSERM, U1059, SAINBIOSE, Université de Lyon, Université Jean-Monnet, Saint-Étienne, France
| | - Antoine Giraud
- Neonatal and Pediatric Intensive Care Department, Centre Hospitalier Universitaire de Saint-Étienne, Saint-Étienne, France.,INSERM, U1059, SAINBIOSE, Université de Lyon, Université Jean-Monnet, Saint-Étienne, France
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Autonomic maturation from birth to 2 years: normative values. Heliyon 2019; 5:e01300. [PMID: 30899829 PMCID: PMC6407160 DOI: 10.1016/j.heliyon.2019.e01300] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 02/03/2019] [Accepted: 02/27/2019] [Indexed: 01/11/2023] Open
Abstract
Background While heart rate variability (HRV) constitutes a relevant non-invasive tool to assess the autonomic nervous system (ANS) function with recognized diagnostic or therapeutic implications, there is still a lack of established data on maturation of autonomic control of heart rate during the first months of life. The Autonomic Baby Evaluation (AuBE) cohort was built to establish, the normal autonomic maturation profile from birth up to 2 years, in a healthy population of full-term newborns. Methods Heart rate variability analysis was carried out in 271 full-term newborns (mean gestational age 39 wGA + 5 days) from reliable polysomnographic recordings at 0 (n = 270) and 6 (n = 221) months and from a 24-hour ambulatory electrocardiogram (ECG) at 12 (n = 210), 18 (n = 197), and 24 (n = 190) months. Indices of HRV analysis were calculated through the ANSLabTools software. Results Indices are dissociated according a temporal, geometrical, frequency, Poincaré, empirical mode decomposition, fractal, Chaos and DC/AC and entropy analysis. Each index is presented for five different periods of time, 0, 6, 12, 18 and 24 months and with smoothed values in the 3rd, 10th, 50th, 90th and 97th percentiles. Data are also presented for the full cohort and individualized by sex to account for gender variability. Discussion & conclusion The physiological autonomic maturation profile from birth to 2 years in a healthy population of term neonates results in a fine-tuning autonomic maturation underlying progressively a new equilibrium and privileging the parasympathetic activity over the sympathetic activity.
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Rossor T, Ali K, Bhat R, Trenear R, Rafferty G, Greenough A. The effects of sleeping position, maternal smoking and substance misuse on the ventilatory response to hypoxia in the newborn period. Pediatr Res 2018; 84:411-418. [PMID: 29976971 DOI: 10.1038/s41390-018-0090-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/08/2018] [Accepted: 04/08/2018] [Indexed: 11/09/2022]
Abstract
BACKGROUND Maternal smoking, substance misuse in pregnancy and prone sleeping increase the risk of sudden infant death syndrome (SIDS). We examined the effect of maternal smoking, substance misuse and sleeping position on the newborn response to hypoxia. METHODS Infants born between 36 and 42 weeks of gestational age underwent respiratory monitoring in the prone and supine sleeping position before and during a hypoxic challenge. Minute ventilation (MV) and end-tidal carbon dioxide (ETCO2) levels were assessed. RESULTS Sixty-three infants were studied: 22 controls, 23 whose mothers smoked and 18 whose mothers substance-misused and smoked. In the supine position, baseline MV was higher and ETCO2 levels were lower in infants of substance-misusing mothers compared to controls (p = 0.015, p = 0.017, respectively). Infants of substance-misusing mothers had a lower baseline MV and higher ETCO2 levels in the prone position (p = 0.005, p = 0.004, respectively). When prone, the rate of decline in minute ventilation in response to hypoxia was greater in infants whose mothers substance-misused and smoked compared to controls (p = 0.002) and infants of smoking mothers (p = 0.016). CONCLUSION The altered response to hypoxia in the prone position of infants whose mothers substance-misused and smoked in pregnancy may explain their increased vulnerability to SIDS.
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Affiliation(s)
- Thomas Rossor
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK.,Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Kamal Ali
- Neonatal Intensive Care Centre, King's College Hospital NHS Foundation Trust, London, UK
| | - Ravindra Bhat
- Neonatal Intensive Care Centre, King's College Hospital NHS Foundation Trust, London, UK
| | - Rebecca Trenear
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK.,Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Gerrard Rafferty
- School of Basic and Medical Biosciences, King's College London, London, UK
| | - Anne Greenough
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK. .,Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK. .,NIHR Biomedical Centre at Guy's and St Thomas' NHS Foundation Trust, King's College London, London, UK.
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Rossor T, Bhat R, Ali K, Peacock J, Rafferty GF, Greenough A. The effect of caffeine on the ventilatory response to hypercarbia in preterm infants. Pediatr Res 2018; 83:1152-1157. [PMID: 29790869 DOI: 10.1038/pr.2018.48] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 02/15/2018] [Indexed: 11/09/2022]
Abstract
BackgroundWe tested the hypotheses that caffeine therapy would increase the ventilatory response to hypercarbia in infants above the effect of maturation and those with a weaker ventilatory response to hypercarbia would be more likely to subsequently develop apnea that required treatment.MethodsInfants born at less than 34 weeks of gestation underwent a steady-state hypercarbic challenge using 0, 2, and 4% carbon dioxide soon after birth that was repeated at weekly intervals. The results of the initial study were compared between infants who did or did not subsequently develop apnea requiring treatment with caffeine.ResultsTwenty-six infants born at a median gestation of 32 (range 31-33) weeks were assessed. Caffeine administration was associated with an increase in CO2 sensitivity, and the mean increase was 15.3 (95% CI: 1-30) ml/kg/min/% CO2. Fourteen infants subsequently developed apnea treated with caffeine. After controlling for gestational age and birth weight, they had significantly lower carbon dioxide sensitivity at their initial study compared with those who did not require treatment.ConclusionCaffeine administration was associated with an increase in the ventilatory response to hypercarbia. An initial weaker ventilatory response to hypercarbia was associated with the subsequent development of apnea requiring treatment with caffeine.
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Affiliation(s)
- Thomas Rossor
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Ravindra Bhat
- Neonatal Intensive Care Centre, King's College Hospital NHS Foundation Trust, London, UK
| | - Kamal Ali
- Neonatal Intensive Care Centre, King's College Hospital NHS Foundation Trust, London, UK
| | - Janet Peacock
- School of Population Sciences, School of Population Sciences and Health Services Research, King's College London, London, UK
| | - Gerrard F Rafferty
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Anne Greenough
- Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
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Potter M, Rosenkrantz T, Fitch RH. Behavioral and neuroanatomical outcomes in a rat model of preterm hypoxic-ischemic brain Injury: Effects of caffeine and hypothermia. Int J Dev Neurosci 2018; 70:46-55. [PMID: 29476789 DOI: 10.1016/j.ijdevneu.2018.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 02/13/2018] [Accepted: 02/15/2018] [Indexed: 01/10/2023] Open
Abstract
The current study investigated behavioral and post mortem neuroanatomical outcomes in Wistar rats with a neonatal hypoxic-ischemic (HI) brain injury induced on postnatal day 6 (P6; Rice-Vannucci HI method; Rice et al., 1981). This preparation models brain injury seen in premature infants (gestational age (GA) 32-35 weeks) based on shared neurodevelopmental markers at time of insult, coupled with similar neuropathologic sequelae (Rice et al., 1981; Workman et al., 2013). Clinically, HI insult during this window is associated with poor outcomes that include attention deficit hyperactivity disorder (ADHD), motor coordination deficits, spatial memory deficits, and language/learning disabilities. To assess therapies that might offer translational potential for improved outcomes, we used a P6 HI rat model to measure the behavioral and neuroanatomical effects of two prospective preterm neuroprotective treatments - hypothermia and caffeine. Hypothermia (aka "cooling") is an approved and moderately efficacious intervention therapy for fullterm infants with perinatal hypoxic-ischemic (HI) injury, but is not currently approved for preterm use. Caffeine is a respiratory stimulant used during removal of infants from ventilation but has shown surprising long-term benefits, leading to consideration as a therapy for HI of prematurity. Current findings support caffeine as a preterm neuroprotectant; treatment significantly improved some behavioral outcomes in a P6 HI rat model and partially rescued neuropathology. Hypothermia treatment (involving core temperature reduction by 4 °C for 5 h), conversely, was found to be largely ineffective and even deleterious for some measures in both HI and sham rats. These results have important implications for therapeutic intervention in at-risk preterm populations, and promote caution in the application of hypothermia protocols to at-risk premature infants without further research.
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Affiliation(s)
- Molly Potter
- University of Connecticut Health Center, School of Medicine, Farmington, CT, United States
| | - Ted Rosenkrantz
- University of Connecticut Health Center, Dept. of Pediatrics/Neonatology, Farmington, CT, United States
| | - R Holly Fitch
- University of Connecticut, Dept. of Psychological Sciences/Behavioral Neuroscience, Storrs, CT, United States.
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Ali K, Rossor T, Bhat R, Wolff K, Hannam S, Rafferty GF, Peacock JL, Greenough A. Antenatal substance misuse and smoking and newborn hypoxic challenge response. Arch Dis Child Fetal Neonatal Ed 2016; 101:F143-8. [PMID: 26290480 DOI: 10.1136/archdischild-2015-308491] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 07/28/2015] [Indexed: 11/04/2022]
Abstract
OBJECTIVES Infants of smoking (S) and substance misusing (SM) mothers have an increased risk of sudden infant death syndrome. The aim of this study was to test the hypothesis that infants of SM or S mothers compared with infants of non-SM, non-smoking mothers (controls) would have a poorer ventilatory response to hypoxia, which was particularly marked in the SM infants. DESIGN Physiological study. SETTING Tertiary perinatal centre. PATIENTS 21 SM; 21 S and 19 control infants. Infants were assessed before maternity/neonatal unit discharge. INTERVENTIONS Maternal and infant urine samples were tested for cotinine, cannabinoids, opiates, amphetamines, methadone, cocaine and benzodiazepines. MAIN OUTCOME MEASURES During quiet sleep, the infants were switched from breathing room air to 15% oxygen and changes in minute volume were assessed. RESULTS The SM infants had a greater mean increase (p=0.028, p=0.034, respectively) and a greater magnitude of decline (p<0.001, p=0.018, respectively) in minute volume than the S infants and the controls. The rate of decline in minute volume was greater in the SM infants (p=0.008) and the S infants (p=0.011) compared with the controls. CONCLUSIONS Antenatal substance misuse and smoking affect the infant's ventilatory response to a hypoxic challenge.
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Affiliation(s)
- Kamal Ali
- Division of Asthma, Allergy and Lung Biology, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK
| | - Thomas Rossor
- Division of Asthma, Allergy and Lung Biology, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK
| | - Ravindra Bhat
- Division of Asthma, Allergy and Lung Biology, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK
| | - Kim Wolff
- Addiction Sciences Unit, King's College London, London, UK
| | - Simon Hannam
- Division of Asthma, Allergy and Lung Biology, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK
| | - Gerrard F Rafferty
- Division of Asthma, Allergy and Lung Biology, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK
| | - Janet L Peacock
- National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK Division of Health and Social Care Research, King's College London, London, UK
| | - Anne Greenough
- Division of Asthma, Allergy and Lung Biology, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, UK National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK
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Patural H, Flori S, Pichot V, Barthelemy JC, Roche F. [Autonomic regulation and bradycardia during the neonatal period]. Arch Pediatr 2013; 21:226-30. [PMID: 24290181 DOI: 10.1016/j.arcped.2013.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Revised: 08/28/2013] [Accepted: 10/14/2013] [Indexed: 12/16/2022]
Abstract
The high frequency of bradycardia observed during the neonatal period requires cardiac monitoring but also understanding its intrinsic mechanisms, including responsiveness of the autonomic nervous system (ANS). Heart rate variability and spontaneous baroreflex analysis can help understand the autonomic dysregulation of cardiorespiratory control, possibly responsible for sudden infant death. In clinical neonatology practice, neonatal bradycardia does not warrant continuation of monitoring if it remains isolated, asymptomatic, and short (<10 s), followed by a rapid cardiac acceleration indicating an adapted sympathetic response. Further evaluation of ANS responsiveness is possible for newborns including analyzing the complexity of the heart rate and respiratory variability. This allows better targeting children with high risk after discharge. The real-time evaluation of autonomic regulation could become a valuable tool in clinical practice.
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Affiliation(s)
- H Patural
- Réanimation néonatale et pédiatrique, centre hospitalier universitaire de Saint-Étienne, 42005 Saint-Étienne, France; EA SNA-Epis 4607, université Jean-Monnet, 42023 Saint-Étienne, France.
| | - S Flori
- EA SNA-Epis 4607, université Jean-Monnet, 42023 Saint-Étienne, France
| | - V Pichot
- EA SNA-Epis 4607, université Jean-Monnet, 42023 Saint-Étienne, France
| | - J-C Barthelemy
- EA SNA-Epis 4607, université Jean-Monnet, 42023 Saint-Étienne, France
| | - F Roche
- EA SNA-Epis 4607, université Jean-Monnet, 42023 Saint-Étienne, France
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Duy PM, Xia L, Bartlett D, Leiter JC. An adenosine A(2A) agonist injected in the nucleus of the solitary tract prolongs the laryngeal chemoreflex by a GABAergic mechanism in decerebrate piglets. Exp Physiol 2010; 95:774-87. [PMID: 20418346 PMCID: PMC2889172 DOI: 10.1113/expphysiol.2010.052647] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hyperthermic prolongation of the laryngeal chemoreflex (LCR) in decerebrate piglets is prevented or reversed by GABA(A) receptor antagonists and adenosine A(2A) (Ad-A(2A)) receptor antagonists administered in the nucleus of the solitary tract (NTS). Therefore, we tested the hypothesis that enhanced GABA(A) activity and administration of the Ad-A(2A) agonist, CGS-21680, would prolong the LCR in normothermic conditions. We studied 46 decerebrate piglets ranging from 3 to 8 postnatal days of age. Focal injection into the NTS of 100 nl of 0.5 m nipecotic acid, a GABA reuptake inhibitor, significantly (P < 0.05) prolonged the LCR in normothermic conditions in 10 of 11 animals tested. Injecting 100 nl of 5-12.5 microm CGS-21680 unilaterally or bilaterally into the NTS also prolonged the LCR in normothermic conditions (n = 15), but the effect was smaller than that of unilateral injection of nipecotic acid. Systemic administration of the GABA(A) receptor antagonist, bicuculline, prevented the CGS-21680-dependent prolongation of the LCR in normothermic animals (n = 11). We conclude that thermal prolongation of the LCR depends on a thermally sensitive process or set of neurons in the NTS, which, when activated by elevated brain temperature, enhances adenosinergic and GABAergic function in the region of the NTS. These results emphasize the importance of a thermally sensitive integrative site in the dorsal medulla that, along with sites in the ventral medulla, determine the response to laryngeal chemoreflex stimulation.
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Affiliation(s)
- Philip M Duy
- Department of Physiology and Neuroscience, Dartmouth Medical School, Lebanon, NH 03756, USA
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Moriette G, Lescure S, El Ayoubi M, Lopez E. [Apnea of prematurity: what's new?]. Arch Pediatr 2009; 17:186-90. [PMID: 19944573 DOI: 10.1016/j.arcped.2009.09.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 09/11/2009] [Accepted: 09/22/2009] [Indexed: 10/20/2022]
Abstract
Prematurity apnea remains a major clinical problem that requires treatment choices which are sometimes difficult. Prematurity apnea occurs in most infants of gestational age at birth less than 33 weeks. It is a developmental disorder which usually reflects a "physiological" immaturity of respiratory control. However, neonatal diseases may be associated and play an additive role, resulting in an increased incidence of apnea. Careful screening should therefore be performed in order to make sure that no other factor than immaturity is involved in the occurrence of apnea. Short apnea (less than 10s, without hypoxemia and bradycardia), due to immaturity, are not clinically relevant. More prolonged apnea, that last for more than 15 or 20s, and / or apnea associated with bradycardia or oxygen desaturation, results in short-term disturbances of cerebral haemodynamics and oxygenation, which may negatively impact on neurodevelopmental outcome. Evaluating the immediate severity of apnea and the risks that apnea may affect long-term outcome remains a challenge. The choice of treatments is based on a few evidences. Caffeine citrate, which reduces the incidence of apnea, has been used for decades. However, a thorough evaluation of risks and benefits of this medication has been performed only recently. Caffeine citrate was found to be safe and resulted in unexpected benefits. In treated infants, compared with controls, indeed, a decreased incidence of the following complications was recorded: bronchopulmonary dysplasia at 36 weeks of conceptional age, patent ductus arteriosus, cerebral palsy at 18 months of age. Nasal CPAP can be used in association with caffeine citrate, when the latter is not effective enough.
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Affiliation(s)
- G Moriette
- Service de médecine néonatale, groupe hospitalier Cochin Saint-Vincent-de-Paul (AP-HP), université Paris-Descartes, 75014 Paris, France.
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Altered expression of adenosine A1 and A2A receptors in the carotid body and nucleus tractus solitarius of adult male and female rats following neonatal caffeine treatment. Brain Res 2009; 1287:74-83. [DOI: 10.1016/j.brainres.2009.06.064] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 06/12/2009] [Accepted: 06/19/2009] [Indexed: 12/26/2022]
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Abstract
Apnea of prematurity (AOP) remains a major clinical problem in present day neonatology that warrants frequent evaluations and imposes challenges in therapeutic strategies. Although the pathogenesis of AOP is poorly understood, it is probably a manifestation of physiologic immaturity of breathing control rather than a pathologic disorder. Immature breathing responses to hypoxia, hypercapnia and exaggerated inhibitory pulmonary reflexes in preterm infants might also contribute to the occurrence or severity of AOP. Recent data suggest a role for genetic predisposition. Although typically resolve with maturation, the role of bradycardia and desaturation episodes associated with AOP in the development of sleep disorder breathing and neurodevelopmental delay needs further clarification. Pharmacological treatment with methylxanthines and CPAP remain the mainstay for treatment of AOP. However, recent studies have implicated central inhibitory neuromodulators including prostaglandins, GABA and adenosine in its pathogenesis, the fact that might provide future specific targets for treatment. This review will summarize new insights involving these issues as well as others involving the pathogenesis, treatment strategies and consequences of apnea in premature infants.
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Affiliation(s)
- Jalal M Abu-Shaweesh
- Rainbow Babies & Children's Hospital, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106-6010, USA
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Xia L, Bartlett D, Leiter JC. An adenosine A(2A) antagonist injected in the NTS reverses thermal prolongation of the LCR in decerebrate piglets. Respir Physiol Neurobiol 2008; 164:358-65. [PMID: 18775519 DOI: 10.1016/j.resp.2008.08.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 08/09/2008] [Accepted: 08/11/2008] [Indexed: 10/21/2022]
Abstract
Hyperthermia prolongs the laryngeal chemoreflex (LCR). Under normothermic conditions, adenosine antagonists shorten and adenosine A(2A) (Ad-A(2A)) agonists prolong the LCR. Therefore, we tested the hypothesis that SCH-58261, an Ad-A(2A) receptor antagonist, would prevent thermal prolongation of the LCR when injected unilaterally within the nucleus of the solitary tract (NTS). We studied decerebrate piglets aged 4-13 days. We elicited the LCR by injecting 0.1ml of water into the larynx and recorded integrated phrenic nerve activity. The laryngeal chemoreflex was prolonged when the body temperature of each piglet was raised approximately 2.5 degrees C, and SCH-58261 reversed the thermal prolongation of the LCR when injected into the NTS (n=13), but not when injected in the nucleus ambiguus (n=9). Injections of vehicle alone into the NTS did not alter the thermal prolongation of the LCR (n=9). We conclude that activation of adenosine receptors, perhaps located on GABAergic neurons in the NTS, contributes to thermal prolongation of the LCR.
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Affiliation(s)
- Luxi Xia
- Department of Physiology, Dartmouth Medical School, Lebanon, NH 03756, United States
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Abstract
Apnea, the cessation of respiratory airflow, can begin in many preterm infants in the first week of life and can last until the day of discharge or beyond. This article provides an overview of the complex anatomic, physiological, and developmental mechanisms related to immaturity of both the central nervous system and musculature of the pulmonary system, that contribute to apnea of prematurity. Apnea of prematurity is a diagnosis of exclusion; an array of other conditions and stimuli can also cause apnea, including infections, pulmonary disease, and intracranial pathology. The standard clinical management of apnea, including cutaneous stimulation, methylxanthine therapy, and continuous positive airway pressure or ventilatory support, are discussed as well as newer investigational therapies, such as olfactory stimulation. Emerging evidence on the long-term neurodevelopmental impact of apnea is reviewed. Nursing measures to prevent and manage apnea are reviewed with an emphasis on parent education and preparation for discharge. Apnea resolves in most preterm infants as they approach term corrected gestational age; however, if it does not, options include continued hospitalization or, for infants with stable apnea, discharge with a home apnea monitor.
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MESH Headings
- Apnea/diagnosis
- Apnea/mortality
- Apnea/nursing
- Central Nervous System Stimulants/therapeutic use
- Combined Modality Therapy
- Continuity of Patient Care
- Drug Therapy, Combination
- Female
- Follow-Up Studies
- Gestational Age
- Home Nursing
- Humans
- Infant, Newborn
- Infant, Premature, Diseases/diagnosis
- Infant, Premature, Diseases/mortality
- Infant, Premature, Diseases/nursing
- Infant, Very Low Birth Weight
- Intensive Care Units, Neonatal
- Male
- Monitoring, Ambulatory/instrumentation
- Monitoring, Ambulatory/methods
- Neonatal Nursing/standards
- Neonatal Nursing/trends
- Nurse's Role
- Positive-Pressure Respiration
- Risk Assessment
- Severity of Illness Index
- Survival Rate
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