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Lo YHJ, Graves C, Holland JL, Rogers AJ, Money N, Hashikawa AN, Ramgopal S. Temperature threshold in the screening of bacterial infections in young infants with hypothermia. Emerg Med J 2023; 40:189-194. [PMID: 36396347 DOI: 10.1136/emermed-2022-212575] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 11/07/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Young infants with hypothermia presenting to the emergency department (ED) are at risk for serious bacterial infections (SBI), however there is no consensus temperature to prompt evaluation for SBI among these children. We sought to statistically derive a temperature threshold to guide detection of SBI in young infants with hypothermia presenting to the ED. METHODS We performed a cross-sectional study of infants ≤90 days old presenting to four academic paediatric EDs in the United States of America from January 2015 through December 2019 with a rectal temperature of ≤36.4°C. Our primary outcomes were SBI, defined as urinary tract infection (UTI), bacteraemia and/or bacterial meningitis, and invasive bacterial infections (IBI, limited to bacteraemia and/or bacterial meningitis). We constructed receiver operating characteristic (ROC) curves to evaluate an optimally derived cutpoint for minimum ED temperature and presence of SBI or IBI. RESULTS We included 3376 infants, of whom SBI were found in 62 (1.8%) and IBI in 16 (0.5%). The most common infection identified was Escherichia coli UTI. Overall, cohort minimum median temperature was 36.2°C (IQR 36.0°C-36.4°C). Patients with SBI and IBI had lower median temperatures, 35.8°C (IQR 35.8°C-36.3°C) and 35.4°C (IQR 35.7°C-36.3°C), respectively, compared with those without corresponding infections (both p<0.05). Using an outcome of SBI, the area under the ROC curve (AUROC) was 61.0% (95% CI 54.1% to 67.9%). At a cutpoint of 36.2°C, sensitivity was 59.7% and specificity was 59.2%. When using an outcome of IBI, the AUROC was 65.9% (95% CI 51.1% to 80.6%). Using a cutpoint of 36.1°C in this model resulted in a sensitivity of 68.8% and specificity of 60.1%. CONCLUSION Young infants with SBI and IBI presented with lower temperatures than infants without infections. However, there was no temperature threshold to reliably identify SBI or IBI. Further research incorporating clinical and laboratory parameters, in addition to temperature, may help to improve risk stratification for these vulnerable patients.
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Affiliation(s)
- Yu Hsiang Johnny Lo
- Emergency Medicine, NewYork-Presbyterian Hospital/Weill Cornell Medicine, New York, New York, USA
| | - Christopher Graves
- Emergency Medicine, Pediatric Emergency Medicine Associates (PEMA), Atlanta, Georgia, USA
| | | | - Alexander Joseph Rogers
- Emergency Medicine and Pediatrics, University of Michigan, Michigan Medicine, Ann Arbor, Michigan, USA
| | - Nathan Money
- Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Andrew Nobuhide Hashikawa
- Emergency Medicine and Pediatrics, University of Michigan, Michigan Medicine, Ann Arbor, Michigan, USA
| | - Sriram Ramgopal
- Emergency Medicine, Ann and Robert H Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
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Baddock SA, Galland BC, Bolton DPG, Williams SM, Taylor BJ. Hypoxic and hypercapnic events in young infants during bed-sharing. Pediatrics 2012; 130:237-44. [PMID: 22802605 DOI: 10.1542/peds.2011-3390] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVES To identify desaturation events (arterial oxygen saturation [Sao(2)] <90%) and rebreathing events (inspired carbon dioxide (CO(2)) >3%), in bed-sharing (BS) versus cot-sleeping (CS) infants. METHODS Forty healthy, term infants, aged 0 to 6 months who regularly bed-shared with at least 1 parent >5 hours per night and 40 age-matched CS infants were recruited. Overnight parent and infant behavior (via infrared video), Sao(2), inspired CO(2) around the infant's face, and body temperature were recorded during sleep at home. RESULTS Desaturation events were more common in BS infants (risk ratio = 2.17 [95% confidence interval: 1.75 to 2.69]), associated partly with the warmer microenvironment during BS. More than 70% of desaturations in both groups were preceded by central apnea of 5 to 10 seconds with no accompanying bradycardia, usually in active sleep. Apnea >15 seconds was rare (BS infants: 3 events; CS infants: 6 events), as was desaturation <80% (BS infants: 3 events; CS infants: 4 events). Eighty episodes of rebreathing were identified from 22 BS infants and 1 CS infant, almost all preceded by head covering. During rebreathing, Sao(2) was maintained at the baseline of 97.6%. CONCLUSIONS BS infants experienced more oxygen desaturations preceded by central apnea, partly related to the warmer microenvironment. Rebreathing occurred mainly during bed-sharing. Infants were at low risk of sudden infant death syndrome and maintained normal oxygenation. The effect of repeated exposure to oxygen desaturation in vulnerable infants is unknown as is the ability of vulnerable infants to respond effectively to rebreathing caused by head covering.
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Affiliation(s)
- Sally A Baddock
- Department of Women’s and Children’s Health, University of Otago, Dunedin, New
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3
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Apnea of prematurity: What can observational studies tell us about pathophysiology? Sleep Med 2010; 11:701-7. [DOI: 10.1016/j.sleep.2009.11.016] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 10/30/2009] [Accepted: 11/04/2009] [Indexed: 11/21/2022]
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Abstract
AIM To review treatments for apnoea of prematurity (AOP). METHODS Literature Review and description of personal practice. RESULTS Provided that symptomatic apnoea has been ruled out, interventions to improve AOP can be viewed as directed at one of three underlying mechanisms: (i) a reduced work of breathing [e.g. prone positioning, nasal continuous positive airway pressure (CPAP)], (ii) an increased respiratory drive (e.g. caffeine), and (iii) an improved diaphragmatic function (e.g. branched-chain amino acids). Most options currently applied, however, have not yet been shown to be effective and/or safe, except for prone, head-elevated positioning, synchronized nasal ventilation/CPAP, and caffeine. CONCLUSION Treatment usually follows an incremental approach, starting with positioning, followed by caffeine (which should be started early, at least in infants <1250 g), and nasal ventilation or CPAP via variable flow systems that reduce work of breathing. From a research point of view, we most urgently need data on the frequency and severity of bradycardia and intermittent hypoxia that can yet be tolerated without putting an infant at risk of impaired development or retinopathy of prematurity.
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Affiliation(s)
- C F Poets
- Department of Neonatology, Tübingen University Hospital, Tübingen, Germany.
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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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Ludington-Hoe SM, Anderson GC, Swinth JY, Thompson C, Hadeed AJ. Randomized controlled trial of kangaroo care: cardiorespiratory and thermal effects on healthy preterm infants. Neonatal Netw 2004; 23:39-48. [PMID: 15182119 DOI: 10.1891/0730-0832.23.3.39] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
PURPOSE To determine the safety and effects on healthy preterm infants of three continuous hours of kangaroo care (KC) compared to standard NICU care by measuring cardiorespiratory and thermal responses. DESIGN Randomized controlled trial-pretest-test-posttest control group design. SAMPLE Twenty-four healthy preterm infants (33-35 weeks gestation at birth) nearing discharge. Eleven of the infants received KC; 13 received standard NICU care. MAIN OUTCOME VARIABLES Heart rate, respiratory rate, oxygen saturation, and abdominal skin temperature were manually recorded every minute. Apnea, bradycardia, periodic breathing, and regular breathing were captured continuously on a pneumocardiogram printout. Three consecutive interfeeding intervals (three hours each) on one day constituted the pretest, test, and posttest periods. RESULTS Mean cardiorespiratory and temperature outcomes remained within clinically acceptable ranges during KC. Apnea, bradycardia, and periodic breathing were absent during KC. Regular breathing increased for infants receiving KC compared to infants receiving standard NICU care.
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Jackson JA, Wailoo MP, Thompson JR, Petersen SA. Early physiological development of infants with intrauterine growth retardation. Arch Dis Child Fetal Neonatal Ed 2004; 89:F46-50. [PMID: 14711856 PMCID: PMC1721660 DOI: 10.1136/fn.89.1.f46] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES To assess the patterns of early postnatal physiological adaptation and maturation in intrauterine growth retarded (IUGR) infants by measuring changes in sleeping deep body temperature, heart rate, and concentrations of urinary cortisol. SETTING At home. PATIENTS Sixty five IUGR babies and 127 controls matched for sex, social class, and levels of parental smoking. RESULTS Night time sleeping deep body temperature, heart rate, and cortisol excretion fell with age, eventually establishing an adult type diurnal rhythm of physiological function. Minimum overnight temperature showed a linear decline with age (p < 0.001), but the IUGR infants and the controls had significant differences in intercept (p = 0.007) and slope (p = 0.02). The estimated rate of decline per week was 0.020 degrees C for IUGR infants and 0.031 degrees C for controls. Maximum temperature did not show similar changes. IUGR infants had a mean (SE) age adjusted minimum overnight heart rate that was 4.2 (1.5) beats/min (p = 0.005) higher than controls. Overnight cortisol/creatinine ratios declined with age at a rate of 4.1% per week (log ratio -0.421 (0.0165), p = 0.01), but the ratio for IUGR infants was on average 42% higher (log ratio 0.35 (0.11), p = 0.002) than for controls of the same age. Morning cortisol concentrations did not show a similar pattern. CONCLUSIONS Postnatal physiological adaptation and maturation of IUGR infants is slower than normal and therefore they remain in a physiologically immature state for longer. The higher heart rates and greater cortisol excretion in such infants may be precursors to hypertension and cardiovascular disease seen in adults.
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Affiliation(s)
- J A Jackson
- Department of Child Health, University of Leicester and University of Warwick, UK
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Tappin DM, Ford RPK, Price B, Macey PM, Larkin J. Central and peripheral temperature change in normal infants. Child Care Health Dev 2002; 28 Suppl 1:35-6. [PMID: 12515437 DOI: 10.1046/j.1365-2214.2002.00010.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The purpose was to explore the relationship between the fall in rectal temperature seen in normal infants after being put down to sleep and the concomitant rise in peripheral shin temperature. In this observational study 21 normal infants had continuous overnight peripheral shin and central rectal temperature recorded, for three nights at 2 weeks, 6 weeks, 3 months and 5 months of age. Parents documented the start and end of feed/nappy changing episodes during the night. All recordings were made in the infants' own home. A strong inverse linear correlation (median r2 = 0.95, lower quartile 0.92, upper quartile 0.97) was seen between rectal temperature and shin temperature on falling to sleep when put down on 106 (65%) of 161 nights. On many other nights a significant nonlinear association was present. It was not possible to exclude the process of being put down to sleep as a confounding variable in this strong association. However, a similar inverse relationship between shin and rectal temperature was seen overnight during 111 of 121 (92%) feed/nappy changing episodes. If causal, the development in early infancy of an inverse relationship between shin and rectal temperature may be important for cardiovascular homeostasis. Further sleep laboratory work including video recording is required to separate the peripheral and central temperature changes that take place on falling to sleep from those associated with removal of clothing during a nappy change.
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Affiliation(s)
- D M Tappin
- Community Paediatric Unit, HealthLink South, University of Canterbury, Christchurch, New Zealand.
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Abstract
The effects on infants of sleeping with their parents is currently the subject of much debate. One concern regarding infants who sleep in their parents' bed involves the possibility of overheating. Previous research reported a significantly greater core temperature of 0.1 degrees C among a cohort of bed-sharing infants compared with a matched cohort of infants sleeping alone. This paper presents a preliminary analysis of the overnight rectal temperature of 12 of the 20 infants who were monitored sleeping alone and with their parents on separate nights at the University of Durham Parent-Infant Sleep Lab. No significant differences were found in all night rectal temperature, or temperature from 2 h after sleep onset between bed-sharing and cot sleeping nights. These preliminary analyses suggest a night-time difference in rectal temperature between routine bed-sharers and routine cot sleepers, however, these findings will be further explored in the full analyses for this study.
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Affiliation(s)
- H L Ball
- Infancy and Childhood Research Group, Department of Anthropology, University of Durham, Durham, UK.
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10
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Thomas KA. Biological rhythm development in preterm infants: does health status influence body temperature circadian rhythm? Res Nurs Health 2001; 24:170-80. [PMID: 11526616 DOI: 10.1002/nur.1020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Twenty-six preterm infants, postconceptional age from 28 to 35 weeks and postnatal age approximately 14 days, were included in a study of the development of temperature circadian rhythm. Insulated abdominal skin temperature and incubator air temperature were recorded continuously at 1-min intervals for 24 hr. Using cosinor analysis, cycle mesor, amplitude, and acrophase were determined. Initial results from regression analysis did not confirm a predicted linear relationship between postconceptional age and amplitude; however, dividing the sample according to health status into sick (N = 15) and not sick (N = 11) groups revealed differing regression models. For not sick infants, amplitude increased with postconceptional age (R(2) =.405), whereas no relationship was found between postconceptional age and cycle amplitude in sick infants (R(2) =.069). These results indicate that healthy preterm infants demonstrate emergence of circadian temperature rhythm. Implications include potential time-based periods of vulnerability, overheating and hyperthermia, and management of incubator operation.
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Affiliation(s)
- K A Thomas
- University of Washington, Box 357262, Seattle, 98195-7262, USA
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11
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Abstract
Sudden infant death syndrome (SIDS) accounts for the largest number of deaths during the first year of life in developed countries. The possible causes of SIDS are numerous and, to date, there is no adequate unifying pathological explanation for SIDS. Epidemiological studies have played a key role in identifying risk factors, knowledge of which has underpinned successful preventive programmes. This review critically assesses information on the main risk factors and causal hypotheses put forward for SIDS, focusing on research published since 1994. The overall picture that emerges from this review is that affected infants are not completely normal in development, but possess some inherent weakness, which may only become obvious when the infant is subjected to stress. Initially there may be some minor impairment or delay in development of respiratory, cardiovascular or neuromuscular function. None of these is likely to be sufficient, in isolation, to cause death and, provided the infant survives the first year of life, may no longer be of any significance. However, when a compromised infant is confronted with one or more stressful situations, several of which are now clearly identified as risk factors, and from which the majority of infants would normally escape, the combination may prove fatal.
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Affiliation(s)
- F M Sullivan
- Division of Pharmacology and Toxicology, United Medical School, University of London, UK.
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12
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Abstract
AIM To demonstrate that skin-to-skin care (SSC) has no detrimental effects on the frequency of episodes of bradycardia and/or hypoxemia. METHODS Twenty-two spontaneously breathing preterm infants (median gestational age at birth, 29 weeks [range, 24-31 weeks]; age at study, 26 days [range, 7-72 days]; weight at study, 1310 g [range, 725-1890 g]) had three 2-hour recordings of breathing movements, nasal airflow, heart rate, and oxygen saturation as measured by pulse oximetry (SpO(2)) before, during, and after SSC. Rectal temperature was obtained every 2 hours. Recordings were analyzed for baseline heart and respiratory rates, bradycardia (heart rate < two thirds of baseline), and hypoxemia (SpO(2) < or =80%), as well as for breathing pattern (regular vs non-regular). RESULTS Baseline heart rate and respiratory rate increased during SSC (P <.01), as did the combined frequency of bradycardia and hypoxemia (from 1.5/h [0-8] before to 2.8/h [0-15] during SSC; P<.05). Rectal temperature increased from 36.9 degrees C (36.2 degrees -37.4 degrees C) to 37.3 degrees C (36.6 degrees -38.6 degrees C; P <.01). The proportion of regular breathing pattern decreased from 14% (2%-28%) to 7% (3%-26%) with SSC (P<.01). CONCLUSION SSC was associated with a significant increase in the combined frequency of bradycardia and hypoxemia and with less regular breathing. These changes were unexpected and may have been related to heat stress. Body temperature, heart rate, and oxygenation should be monitored during SSC.
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Affiliation(s)
- B Bohnhorst
- Department of Neonatology and Pediatric Pulmonology, Hannover Medical School, Hannover, Germany
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13
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Schluter PJ, Macey PM, Ford RP. The relationship between inside and outside ambient temperatures in Christchurch, New Zealand. Paediatr Perinat Epidemiol 2000; 14:275-82. [PMID: 10949221 DOI: 10.1046/j.1365-3016.2000.00264.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The objective of this study was to examine and identify relationships between hourly recorded meteorological temperature and ambient temperature, measured from within the home-sleeping environment of young infants' homes in Christchurch, New Zealand. From 1991 to 1994, home polysomnography recordings were conducted for up to 6 weeks on 32 infants aged between 2 and 24 weeks. One of the recorded signals was ambient room temperature. In total, 15735 hourly recordings of this temperature were available for analysis. The New Zealand Meteorological Service supplied hourly recordings of climatic temperature, collected over this time, from an exposed site that was considered to be representative of weather conditions for Christchurch. Temperature seasonality, hourly climatic temperature recordings and the interaction of these variables were found to be significantly related to the indoor ambient temperature recordings (all had P < 0.001). Fluctuations in hourly recorded indoor temperature appeared to lag outdoor temperature fluctuations by approximately 2 h; hence, a strong autocorrelation was identified in the regression residuals. The most parsimonious autoregression model accounted for 97% of the variability in the hourly indoor temperature measurements (r2 = 0.97). In Christchurch houses, which typically have poor thermal insulation properties, yet have no central heating capabilities, a very strong association between indoor and outdoor temperatures was clearly demonstrated.
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Affiliation(s)
- P J Schluter
- Department of Social and Preventative Medicine, The University of Queensland, Australia
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Abstract
BACKGROUND The mechanism of death in sudden infant death syndrome (SIDS) remains unclear. Progressive bradycardia is the pre-eminent terminal event, suggesting that circulatory failure might be a crucial factor. Vasomotor tone regulates the circulatory system by controlling blood volume distribution while maintaining venous return and blood pressure. AIM To examine whether prone sleeping, the most consistently identified risk factor for SIDS, has a measurable influence on vasomotor/circulatory control. METHODS 44 full term infants (mean age, 7.9 weeks) were studied during an overnight sleep. Recordings were made while the infants were horizontal and asleep in the supine and prone positions, and repeated after a head up tilt to 60 degrees, maintained for 30 minutes, while in both sleep positions. Blood pressure, heart rate, anterior shin, and anterior abdominal wall skin temperatures were measured. RESULTS Systolic blood pressure was lower, but peripheral skin temperature and heart rate were higher during sleep, while horizontal, in the prone rather than the supine position. After tilting, there was a greater reduction in blood pressure and a greater increase in peripheral skin temperature and heart rate when in the prone position. Anterior abdominal wall skin temperature did not vary in either sleeping positions while horizontal or tilted. CONCLUSION Prone sleeping has a measurable effect on circulatory control, with a reduction in vasomotor tone resulting in peripheral vasodilatation, a higher peripheral skin temperature, a lower blood pressure, and a higher resting heart rate. Because vasomotor tone is crucially important in circulatory control this could be a factor in increasing the risk of SIDS.
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Affiliation(s)
- A Chong
- Department of Paediatrics, Rotunda Hospital, Dublin 1, Republic of Ireland
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Lindsley G, Dowse HB, Burgoon PW, Kolka MA, Stephenson LA. A persistent circhoral ultradian rhythm is identified in human core temperature. Chronobiol Int 1999; 16:69-78. [PMID: 10023577 DOI: 10.3109/07420529908998713] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
There have been inconclusive reports of intermittent rhythmic fluctuations in human core temperature, with the fluctuations having a period of about an hour. However, there has been no definitive demonstration of the phenomenon. This is likely due to the intermittency and seeming instability of the events. They have been assumed to be secondary rather than autonomous phenomena, putatively arising from the oscillation between rapid eye movement (REM) and non-REM (NREM) sleep. In this study, we report identification of a clear, persistent circhoral ultradian rhythm in core temperature with a period for this study sample of 64 +/- 8 minutes. It appeared simultaneously with an intact circadian core temperature rhythm, persisted despite complex perturbations in core temperature brought about by the sequelae of 40 h of sleep deprivation, and could not be attributed to sleep stage alternation or other endogenous or exogenous factors. Analysis of power spectra using the maximum entropy spectral analysis (MESA) method, which can uncover hidden rhythmicities, demonstrated that the apparent intermittency of the rhythm is due to periodic interference of this rhythm by other rhythmic events. The persistence of this oscillation suggests that, in this system as in the endocrine system, circhoral regulation is an integral component of thermoregulatory control. Identifying the source and functional role of this novel rhythm warrants further work.
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Affiliation(s)
- G Lindsley
- U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
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16
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West C. Hypoxic responses in infants. Subjecting infants to low oxygen concentrations seems unethical. BMJ (CLINICAL RESEARCH ED.) 1998; 317:675; author reply 677-8. [PMID: 9728005 PMCID: PMC1113844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Parkins KJ, Poets CF, O'Brien LM, Stebbens VA, Southall DP. Effect of exposure to 15% oxygen on breathing patterns and oxygen saturation in infants: interventional study. BMJ (CLINICAL RESEARCH ED.) 1998; 316:887-91. [PMID: 9552835 PMCID: PMC28490 DOI: 10.1136/bmj.316.7135.887] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To assess the response of healthy infants to airway hypoxia (15% oxygen in nitrogen). DESIGN Interventional study. SETTINGS Infants' homes and paediatric ward. SUBJECTS 34 healthy infants (20 boys) born at term; mean age at study 3.1 months. 13 of the infants had siblings whose deaths had been ascribed to the sudden infant death syndrome. INTERVENTION Respiratory variables were measured in room air (pre-challenge), while infants were exposed to 15% oxygen (challenge), and after infants were returned to room air (post-challenge). MAIN OUTCOME MEASURES Baseline oxygen saturation as measured by pulse oximetry, frequency of isolated and periodic apnoea, and frequency of desaturation (oxygen saturation < or = 80% for > or = 4 s). Exposure to 15% oxygen was terminated if oxygen saturation fell to < or = 80% for > or = 1 min. RESULTS Mean duration of exposure to 15% oxygen was 6.3 (SD 2.9) hours. Baseline oxygen saturation fell from a median of 97.6% (range 94.0% to 100%) in room air to 92.8% (84.7% to 100%) in 15% oxygen. There was no correlation between baseline oxygen saturation in room air and the extent of the fall in baseline oxygen saturation on exposure to 15% oxygen. During exposure to 15% oxygen there was a reduction in the proportion of time spent in regular breathing pattern and a 3.5-fold increase in the proportion of time spent in periodic apnoea (P < 0.001). There was an increase in the frequency of desaturation from 0 episodes per hour (range 0 to 0.2) to 0.4 episodes per hour (0 to 35) (P < 0.001). In 4 infants exposure to hypoxic conditions was ended early because of prolonged and severe falls in oxygen saturation. CONCLUSIONS A proportion of infants had episodes of prolonged (< or = 80% for > or = 1 min) or recurrent shorter (< or = 80% for > or = 4 s) desaturation, or both, when exposed to airway hypoxia. The quality and quantity of this response was unpredictable. These findings may explain why some infants with airway hypoxia caused by respiratory infection develop more severe hypoxaemia than others. Exposure to airway hypoxia similar to that experienced during air travel or on holiday at high altitude may be harmful to some infants.
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Affiliation(s)
- K J Parkins
- Academic Department of Pediatrics, North Staffordshire Hospital Centre, Stoke on Trent
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Tappin DM, Ford RP, Nelson KP, Price B, Macey PM, Dove R. The febrile stress of routine vaccination does not increase central apnoea in normal infants. Acta Paediatr 1997; 86:873-80. [PMID: 9307170 DOI: 10.1111/j.1651-2227.1997.tb08614.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We tested the hypothesis that the febrile stress of routine vaccination would increase central apnoea in normal infants. Twenty-one normal infants had continuous overnight breathing and temperature recorded at home, before and after 58 routine vaccination episodes. Central apnoea, of at least 5 sec duration, was detected by computer algorithm and confirmed by human inspection. The longest recorded apnoea was 16 sec (n = 1) during 3629 h of sleep. Overnight rectal temperature increased after vaccination (median 0.52 degrees C, 95% CI 0.40, 0.65). Apnoea density reduced on 46/53 vaccination nights (median -29%, 95% CI -20, -37) followed by an increase on subsequent nights (median +10%, 95% CI +1%,+21%). Overall, apnoea density was similar during the 3 nights preceding and 4 nights following vaccination (median +1%, 95% CI +9,-6). The febrile stress of routine vaccination did not increase central apnoea in normal infants.
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Affiliation(s)
- D M Tappin
- Community Paediatric Unit, HealthLink South, University of Canterbury, Christchurch, New Zealand
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