THE INFLUENCE OF THERMAL FACTORS UPON OXYGEN CONSUMPTION OF THE NEWBORN HUMAN INFANT

Neural cell-types and circuits linking thermoregulation and social behavior

Understanding how social and affective behavioral states are controlled by neural circuits is a fundamental challenge in neurobiology. Despite increasing understanding of central circuits governing prosocial and agonistic interactions, how bodily autonomic processes regulate these behaviors is less resolved. Thermoregulation is vital for maintaining homeostasis, but also associated with cognitive, physical, affective, and behavioral states. Here, we posit that adjusting body temperature may be integral to the appropriate expression of social behavior and argue that understanding neural links between behavior and thermoregulation is timely. First, changes in behavioral states-including social interaction-often accompany changes in body temperature. Second, recent work has uncovered neural populations controlling both thermoregulatory and social behavioral pathways. We identify additional neural populations that, in separate studies, control social behavior and thermoregulation, and highlight their relevance to human and animal studies. Third, dysregulation of body temperature is linked to human neuropsychiatric disorders. Although body temperature is a "hidden state" in many neurobiological studies, it likely plays an underappreciated role in regulating social and affective states.

Thresholds for Red Blood Cell Transfusion in Preterm Infants: Evidence to Practice

Rapid blood loss with circulatory shock is dangerous for the preterm infant as cardiac output and oxygen-carrying capacity are simultaneously imperilled. This requires prompt restoration of circulating blood volume with emergency transfusion. It is recommended that clinicians use both clinical and laboratory responses to guide transfusion requirements in this situation. For preterm infants with anemia of prematurity, it is recommended that clinicians use a restrictive algorithm from one of two recently published clinical trials. Transfusion outside these algorithms in very preterm infants is not evidence-based and is actively discouraged.

Temperature Monitoring and Thermal Support in Exotic Animal Critical Care

Body temperature measurement is one of the most important parameters to assess the health of a patient. In small exotic mammals, rectal temperature is obtained via a similar process as in dogs or cats, with a few specific differences. In reptiles and birds, measurement of body temperature can provide important information, albeit its accuracy may be limited. In most animals, temperature should be taken at the beginning of the examination to not artificially elevate the temperature during the physical exam. Heat support is typically indicated any time a patient's temperature is below the accepted core temperature range and cooling may be indicated whenever a patient's temperature exceeds a critical point.

Use of Vasopressors in Extremely Preterm Infants in First Week of Life

OBJECTIVE

 A significant variability exists for diagnosis and treatment of hypotension in extremely preterm infants. Benefits of the use of vasopressors remain unclear. We wanted to identify the risk factors associated with use of vasopressors in the first week of life and their impact on outcomes of extremely preterm infants.

STUDY DESIGN

 Retrospective review of all newborns ≤28 weeks of gestational age (GA) admitted in neonatal intensive care unit from October 1, 2012, to October 31, 2015, done. Data regarding antenatal and neonatal characteristics and outcomes were recorded. Study infants were divided into two cohorts and compared based on vasopressor use. Chi-square, t-test, and multiple logistic regression were performed as appropriate and significance set at p <0.05.

RESULTS

 Of 213 extremely preterm infants, 90 (42.3%) received vasopressors in first week of life. The mean arterial pressure (MAP) at admission in these infants was significantly lower than that of infants who did not require vasopressors (27 ± 8 vs. 30 ± 6 mm Hg, p < 0.05). Vasopressors were initiated within 24 hours in 91% of babies. After controlling for other variables, use of vasopressors was significantly higher in infants with lower birth weight (odds ratio [OR]: 3.2, 95% confidence interval [CI]: 1.6-8.3), 5-minute Apgar's score ≤5 (OR: 1.8, 95% CI: 1.2-3.12), and admission hypothermia (OR: 2.7, 95% CI: 1.3-4.9). The use of vasopressors was significantly associated with severe intraventricular hemorrhage (IVH), even after controlling for other significant variables (OR: 5.9, 95% CI: 1.6-9.3).

CONCLUSION

 Lower birth weight, low 5-minute Apgar's score, and admission hypothermia are characteristics associated with early use of vasopressors in extremely preterm infants. Infants treated with vasopressors are at a higher risk of developing severe IVH.

KEY POINTS

· Low systemic blood pressure is a very common problem in the extremely preterm population.. · In clinical practice, mean arterial blood pressure (BP) less than the infants GA in week is typically considered to be "low BP.". · About 50% of infants born at <29 weeks of GA received very preterm in the first week of life.. · Use of vasopressors is associated with a higher incidence of intraventricular hemorrhage in extremely preterm population..

Reducing intraventricular hemorrhage following the implementation of a prevention bundle for neonatal hypothermia

Introduction

In very low birth weight (VLBW) infants, hypothermia immediately following birth is common even in countries rich in medical resources. The purpose of this study is to design a standard prevention bundle that decreases the rate of hypothermia among infants after birth and to investigate efficacy of the bundle and short-term outcomes for VLBW infants.

Methods

This quality improvement project was conducted from February 2017 to July 2018 on all VLBW preterm infants admitted at a single referral level III neonatal intensive care unit. The infants were classified into the pre-intervention (February to September 2017) and post-intervention (October 2017 to July 2018) groups according to the time periods when they were recruited. During the pre-intervention period, we analyzed the primary causes of hypothermia, developed solutions corresponding to each cause, integrated all solutions into a prevention bundle, and applied the bundle during the post-intervention period. Afterwards, the incidence of neonatal hypothermia and short-term outcomes, such as intraventricular hemorrhage (IVH), acidosis, and shock requiring inotropic agents, in each group were compared.

Results

A total of 95 VLBW infants were enrolled in the study, including 37 pre-intervention, and 58 post-intervention cases. The incidence of hypothermia in preterm infants decreased significantly upon the implementation of our prevention bundle, both in the delivery room (from 45.9% to 8.6%) and on admission (59.5% to 15.5%). In addition, the short-term outcomes of VLBW infants improved significantly, especially with the decreased incidence of IVH (from 21.6% to 5.2%, P = 0.015).

Conclusions

Our standardized prevention bundle for preventing hypothermia in VLBW infants is effective and decreased the IVH rate in VLBW infants. We strongly believe that this prevention bundle is a simple, low-cost, replicable, and effective tool that hospitals can adopt to improve VLBW infant outcomes.

Hypothermia among neonates admitted to the neonatal unit at a tertiary hospital in South Africa

OBJECTIVES

To determine the prevalence of hypothermia on admission and at 24 h of life in very low birth weight infants (VLBWI) and associated morbidity and mortality.

STUDY DESIGN

Hospital records of VLBWI admitted to a neonatal unit were reviewed for information on patient's body temperature, clinical characteristics and mortality. Comparisons between normothermic and hypothermic VLBWI were performed.

RESULTS

Mean gestational age and birth weight of enrolled infants were 29 ± 3 weeks and 1140 ± 253 g, respectively. Prevalence of admission hypothermia was 46.1%, with 38% developing hypothermia within 24-h following admission. VLBWI with hypothermia were more likely to have been born vaginally [aOR 2.85 (1.37-5.91)], have a birth weight < 1000 g [aOR 2.28 (1.25-4.16)], required resuscitation at birth [aOR 2.20 (1.23-3.94)], develop metabolic acidosis [aOR 3.04 (1.35-6.84)] and die within the first week of life [aOR 4.79 (1.43-16.02)].

CONCLUSIONS

Prevalence of hypothermia in VLBWI is high and is associated with poor outcomes.

Interventions to prevent hypothermia at birth in preterm and/or low birth weight infants

BACKGROUND

Newborn admission temperature is a strong predictor of outcomes across all gestations. Hypothermia immediately after birth remains a worldwide issue and, if prolonged, is associated with harm. Keeping preterm infants warm is difficult even when recommended routine thermal care guidelines are followed in the delivery room.

OBJECTIVES

To assess the efficacy and safety of interventions designed for prevention of hypothermia in preterm and/or low birth weight infants applied within 10 minutes after birth in the delivery room, compared with routine thermal care or any other single/combination of intervention(s) also designed for prevention of hypothermia in preterm and/or low birth weight infants applied within 10 minutes after birth in the delivery room.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 5), MEDLINE via PubMed (1966 to 30 June 2016), Embase (1980 to 30 June 2016), and CINAHL (1982 to 30 June 2016). We also searched clinical trials databases, conference proceedings, and reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

Trials using randomised or quasi-randomised allocations to test interventions designed to prevent hypothermia (apart from 'routine' thermal care) applied within 10 minutes after birth in the delivery room for infants at < 37 weeks' gestation and/or birth weight ≤ 2500 grams.

DATA COLLECTION AND ANALYSIS

We used Cochrane Neonatal methods when performing data collection and analysis.

MAIN RESULTS

Twenty-five studies across 15 comparison groups met the inclusion criteria, categorised as: barriers to heat loss (18 studies); external heat sources (three studies); and combinations of interventions (four studies).Barriers to heat loss Plastic wrap or bag versus routine carePlastic wraps improved core body temperature on admission to the neonatal intensive care unit (NICU) or up to two hours after birth (mean difference (MD) 0.58°C, 95% confidence interval (CI) 0.50 to 0.66; 13 studies; 1633 infants), and fewer infants had hypothermia on admission to the NICU or up to two hours after birth (typical risk ratio (RR) 0.67, 95% CI 0.62 to 0.72; typical risk reduction (RD) -0.25, 95% CI -0.29 to -0.20; number needed to treat for an additional beneficial outcome (NNTB) 4, 95% CI 4 to 5; 10 studies; 1417 infants). Risk of hyperthermia on admission to the NICU or up to two hours after birth was increased in infants in the wrapped group (typical RR 3.91, 95% CI 2.05 to 7.44; typical RD 0.04, 95% CI 0.02 to 0.06; number needed to treat for an additional harmful outcome (NNTH) 25, 95% CI 17 to 50; 12 studies; 1523 infants), but overall, fewer infants receiving plastic wrap were outside the normothermic range (typical RR 0.75, 95% CI 0.69 to 0.81; typical RD -0.20, 95% CI -0.26 to -0.15; NNTH 5, 95% CI 4 to 7; five studies; 1048 infants).Evidence was insufficient to suggest that plastic wraps or bags significantly reduce risk of death during hospital stay or other major morbidities, with the exception of reducing risk of pulmonary haemorrhage.Evidence of practices regarding permutations on this general approach is still emerging and has been based on the findings of only one or two small studies.External heat sourcesEvidence is emerging on the efficacy of external heat sources, including skin-to-skin care (SSC) versus routine care (one study; 31 infants) and thermal mattress versus routine care (two studies; 126 infants).SSC was shown to be effective in reducing risk of hypothermia when compared with conventional incubator care for infants with birth weight ≥ 1200 and ≤ 2199 grams (RR 0.09, 95% CI 0.01 to 0.64; RD -0.56, 95% CI -0.84 to -0.27; NNTB 2, 95% CI 1 to 4). Thermal (transwarmer) mattress significantly kept infants ≤ 1500 grams warmer (MD 0.65°C, 95% CI 0.36 to 0.94) and reduced the incidence of hypothermia on admission to the NICU, with no significant difference in hyperthermia risk.Combinations of interventionsTwo studies (77 infants) compared thermal mattresses versus plastic wraps or bags for infants at ≤ 28 weeks' gestation. Investigators reported no significant differences in core body temperature nor in the incidence of hypothermia, hyperthermia, or core body temperature outside the normothermic range on admission to the NICU.Two additional studies (119 infants) compared plastic bags and thermal mattresses versus plastic bags alone for infants at < 31 weeks' gestation. Meta-analysis of these two studies showed improvement in core body temperature on admission to the NICU or up to two hours after birth, but an increase in hyperthermia. Data show no significant difference in the risk of having a core body temperature outside the normothermic range on admission to the NICU nor in the risk of other reported morbidities.

AUTHORS' CONCLUSIONS

Evidence of moderate quality shows that use of plastic wraps or bags compared with routine care led to higher temperatures on admission to NICUs with less hypothermia, particularly for extremely preterm infants. Thermal mattresses and SSC also reduced hypothermia risk when compared with routine care, but findings are based on two or fewer small studies. Caution must be taken to avoid iatrogenic hyperthermia, particularly when multiple interventions are used simultaneously. Limited evidence suggests benefit and no evidence of harm for most short-term morbidity outcomes known to be associated with hypothermia, including major brain injury, bronchopulmonary dysplasia, retinopathy of prematurity, necrotising enterocolitis, and nosocomial infection. Many observational studies have shown increased mortality among preterm hypothermic infants compared with those who maintain normothermia, yet evidence is insufficient to suggest that these interventions reduce risk of in-hospital mortality across all comparison groups. Hypothermia may be a marker for illness and poorer outcomes by association rather than by causality. Limitations of this review include small numbers of identified studies; small sample sizes; and variations in methods and definitions used for hypothermia, hyperthermia, normothermia, routine care, and morbidity, along with lack of power to detect effects on morbidity and mortality across most comparison groups. Future studies should: be adequately powered to detect rarer outcomes; apply standardised morbidity definitions; focus on longer-term outcomes, particularly neurodevelopmental outcomes.

A Theoretical and Practical Approach to Defining "Adequate Oxygenation" in the Preterm Newborn

John Scott Haldane recognized that the administration of supplemental oxygen required titration in the individual. Although he made this observation in adults, it is equally applicable to the preterm newborn. But how, in practice, can the oxygen requirements in the preterm newborn be determined to avoid the consequences of too little and too much oxygen? Unfortunately, the current generation of oxygen saturation trials in preterm newborns guides saturation thresholds rather than individual oxygen requirements. For this reason, we propose an alternate model for the description of oxygen sufficiency. This model considers the adequacy of oxygen delivery relative to simultaneous consumption. We describe how measuring oxygen extraction or the venous oxygen reservoir could define a physiologically based definition of adequate oxygen. This definition would provide a clinically useful reference value while making irrelevant the absolute values of both oxygen delivery and consumption. Additional trials to test adjunctive, noninvasive measurements of oxygen status in high-risk preterm newborns are needed to minimize the effects of both insufficient and excessive oxygen exposure.

Innate hypothermia after hypoxic ischaemic delivery

The focus of this review is to collate the literature on the phenomenon of impaired thermal adaptation after hypoxic ischaemic (HI) delivery often culminating in hypothermia. This phenomenon appears different in severity and duration to a spontaneous postnatal fall in temperature observed after normal delivery. The original observation and contemporary descriptions of the temperature response to HI are described and a mechanism of action is proposed that may be utilised as a novel biomarker for HI.

Quantifying temperature and relative humidity of medical gases used for newborn resuscitation

AIM

The gases used to stabilise infants during resuscitation are usually unconditioned air and oxygen, often described as 'cold and dry', in comparison with the heated, humidified gases used for ongoing ventilation in neonatal intensive care units. The aim of this study was to determine exactly how 'cold and dry' these unconditioned gases are.

METHOD

Multiple measurements of temperature and relative humidity (RH) of piped gases were recorded at different sites, and at different times of day, across The Royal Women's Hospital, Melbourne. Ambient temperature and relative humidities were also recorded.

RESULTS

Eighty paired air and oxygen measurements of temperature and RH were recorded. Mean temperatures of piped oxygen and air were 23.3 (0.9) and 23.4 (0.9) °C respectively. Mean RH of piped air was 5.4 (0.7) %; piped oxygen was significantly drier, mean RH 2.1 (1.1) %.

CONCLUSION

Piped gases were delivered at room temperature and were extremely dry. This highlights the importance of research assessing the practicality of heating and humidifying resuscitation gases, and assessing the impact of their use on clinically important neonatal outcomes.

Clinical issues in the management of late preterm infants

Prematurity is defined as birth before 37 weeks of gestation and is the major determinant of morbidity and mortality in newborns. The gestational ages known as near term or late preterm represent about 75% of preterm births and are the fastest growing subgroups of premature infants. These infants range in gestational age from 34 0/7 to 36 6/7 weeks and are at greater risk of morbidity, such as respiratory complications, temperature instability, hypoglycemia, kernicterus, feeding problems, neonatal intensive care unit admissions, and adverse neurological sequelae when compared with term infants. Long-term neurological and school-age outcomes of late preterm infants are concerns of major public health importance because even a minor increase in the rate of neurological disability and scholastic failure in this group can have a huge impact on the health care and educational systems. There is an urgent need to educate health care providers and parents about the vulnerability of late preterm infants, who are in need of diligent monitoring and care during the initial hospital stay and a comprehensive follow-up plan for post neonatal and long-term evaluations. Clinicians involved in the day-to-day care of late preterm infants, as well as those developing guidelines and recommendations, would benefit from having a clear understanding of the potential differences in risks faced by these infants, compared with their more mature counterparts.

Interventions to prevent hypothermia at birth in preterm and/or low birthweight infants

BACKGROUND

Keeping vulnerable preterm infants warm is problematic even when recommended routine thermal care guidelines are followed in the delivery suite.

OBJECTIVES

To assess efficacy and safety of interventions designed for prevention of hypothermia in preterm and/or low birthweight infants applied within 10 minutes after birth in the delivery suite compared with routine thermal care.

SEARCH STRATEGY

We used the standard search strategy of the Cochrane Neonatal Review Group (CNRG). The review was updated in October 2009.

SELECTION CRITERIA

Trials using randomised or quasi-randomised allocations to test a specific intervention designed to prevent hypothermia, (apart from 'routine' thermal care) applied within 10 minutes after birth in the delivery suite to infants of < 37 weeks' gestational age or birthweight </= 2500 g.

DATA COLLECTION AND ANALYSIS

We used the methods of the CNRG for data collection and analysis.

MAIN RESULTS

1) Barriers to heat loss [5 studies; plastic wrap or bag (3), plastic cap (1), stockinet cap (1)]:Plastic wraps or bags were effective in reducing heat losses in infants < 28 weeks' gestation (4 studies, n = 223; WMD 0.68 degrees C; 95% CI 0.45, 0.91), but not in infants between 28 to 31 week's gestation. Plastic caps were effective in reducing heat losses in infants < 29 weeks' gestation (1 study, n = 64; MD 0.80 degrees C; 95% CI 0.41, 1.19). There was insufficient evidence to suggest that either plastic wraps or plastic caps reduce the risk of death within hospital stay. There was no evidence of significant differences in other clinical outcomes for either the plastic wrap/bag or the plastic cap comparisons. Stockinet caps were not effective in reducing heat losses.2) External heat sources [2 studies; skin-to-skin (1), transwarmer mattress (1)]:Skin-to-skin care (SSC) was shown to be effective in reducing the risk of hypothermia when compared to conventional incubator care for infants (1 study, n = 31; RR 0.09; 95% CI 0.01, 0.64). The transwarmer mattress reduced the incidence of hypothermia on admission to NICU in VLBW infants (1 study, n = 24; RR 0.30; 95% CI 0.11, 0.83).

AUTHORS' CONCLUSIONS

Plastic wraps or bags, plastic caps, SSC and transwarmer mattresses all keep preterm infants warmer leading to higher temperatures on admission to neonatal units and less hypothermia. However, the small numbers of infants and studies and the absence of long-term follow-up mean that firm recommendations for clinical practice cannot be given.

[Heat exchanges and thermoregulation in the neonate]

The newborn's energy expenditure is used in order of priority for: (i) basic metabolism; (ii) body temperature regulation and (iii) body growth. Thermal regulation is an important part of energy expenditure, especially for low birth-weight infants or preterm newborns. The heat exchanges with the environment are greater in the infant than in the adult, explaining the increased risk of body hypo- or hyperthermia. The newborn infant is a homeotherm, but over a long period of time, he cannot maintain the thermal processes. Further developments are expected to improve the infant's thermal environment, with assessment of the various heat exchange mechanisms by conduction, convection, radiation and evaporation. The quantification of the respective parts of these exchanges would improve nursing care through clinical procedures or equipment used to ensure the control of the optimal thermohygrometric conditions in incubators, especially when the likelihood of excessive body cooling is high. The present review focuses on the various body heat exchange mechanisms, the thermoregulation processes of the newborn, and their implications in clinical usage and limitations in the neonatal intensive care unit.

Influence of thermal drive on central sleep apnea in the preterm neonate

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).

Increasing ambient operating theatre temperature and wrapping in polyethylene improves admission temperature in premature infants

AIM

To improve admission temperatures of preterm infants < or =31 weeks gestation by increasing the ambient temperature in the operating theatre and wrapping in polyethylene wrap at caesarean section.

METHODS

A review of admission temperature of infants with gestational age < or =31 weeks from January 2000 to July 2002 was performed. Between October 2002 and 2003 the ambient operating theatre temperature was increased to 26-28 degrees C for deliveries < or =27 weeks gestation and to 25 degrees C for deliveries > or =28 weeks gestation. From September 2004 to December 2005 the ambient theatre temperature was increased along with wrapping infants in polyethylene. A clinical audit cycle review of admission temperatures and early morbidity and mortality was undertaken.

RESULTS

156 premature infants were included, 42 <28 weeks and 114 28-31 weeks gestation. The mean admission temperature in <28 weeks infants prior to intervention was 35.3 degrees C, after increasing ambient theatre temperature 35.9 degrees C, and after increasing ambient temperature and using polyethylene wrap 37.0 degrees C (P < 0.0001). For infants 28-31 weeks the mean admission temperatures in the three epochs were 36.3 degrees C, 36.5 degrees C and 36.6 degrees C, respectively (P = 0.002). There was no statistically significant difference in: total days of ventilation or oxygen, definite necrotising enterocolitis, intraventricular haemorrhage grade 3 or 4 or survival.

CONCLUSIONS

Increasing the ambient temperature in the operating theatre and wrapping premature infants in polyethylene wrap improves admission temperature. Further studies are required to determine whether these interventions are associated with improved outcome in the premature neonate.

Keeping infants warm: challenges of hypothermia

Hypothermia is a major cause of morbidity and mortality in infants; therefore, maintaining normal body temperatures in the delivery room is crucial. An understanding of how infants produce heat and what can be done to maintain normal body temperatures in full-term and preterm infants is essential for the preservation of thermal stability in this population. This article reviews the consequences of hypothermia, mechanisms of heat exchange and heat production in full-term and low birth-weight infants, and discusses interventions in the delivery room to alleviate hypothermia.

Interventions to prevent hypothermia at birth in preterm and/or low birthweight infants

BACKGROUND

Hypothermia incurred during routine postnatal resuscitation is a world-wide issue (across all climates), associated with morbidity and mortality. Keeping vulnerable preterm infants warm is problematic even when recommended routine thermal care guidelines are followed in the delivery suite.

OBJECTIVES

To assess efficacy and safety of interventions designed for prevention of hypothermia in preterm and/or low birthweight infants applied within ten minutes after birth in the delivery suite compared with routine thermal care.

SEARCH STRATEGY

The standard search strategy of The Cochrane Collaboration was followed. Electronic databases were searched: MEDLINE (1966 to July Week 4 2007 ), CINAHL (1982 to July Week 4 2007), EMBASE (1974 to 01/08/2007), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2007), Database of Abstracts of Reviews of Effects (DARE 1994 to July 2007), conference/symposia proceedings using ZETOC (1993 to 17/08/2007), ISI proceedings (1990 to 17/08/2007) and OCLC WorldCat (July 2007). Identified articles were cross-referenced. No language restrictions were imposed.

SELECTION CRITERIA

All trials using randomised or quasi-randomised allocations to test a specific intervention designed to prevent hypothermia, (apart from 'routine' thermal care) applied within 10 minutes after birth in the delivery suite to infants of < 37 weeks' gestational age or birthweight </=2500 g.

DATA COLLECTION AND ANALYSIS

Methodological quality was assessed and data were extracted for important clinical outcomes including adverse effects of the intervention by at least three independent review authors. Authors were contacted for missing data. Data were analysed using RevMan 4.2.5. Relative risk (RR), risk difference (RD) and number needed to treat (NNT) with 95% confidence limits were calculated for each dichotomous outcome and mean differences (MD) with 95% confidence limits for continuous outcomes.

MAIN RESULTS

Six studies giving a total of 304 infants randomised and 295 completing the studies were included. Four comparisons to 'routine care' were undertaken within two categories:1) barriers to heat loss (four studies): plastic wrap or bag (three), stockinet caps (one) and2) external heat sources (two studies): skin-to-skin (one), transwarmer mattress (one). Plastic barriers were effective in reducing heat losses in infants < 28 weeks' gestation (three studies, n = 159; WMD 0.76 degrees C; 95% CI 0.49, 1.03), but not in infants between 28 to 31 week's gestation. There was insufficient evidence to suggest that plastic wrap reduces the risk of death within hospital stay (three studies, n = 161; typical RR 0.63; 95% CI 0.32, 1.22; typical RD -0.09; 95% CI -0.20, 0.03). There was no evidence of a significant difference in major brain injury, mean duration of oxygen therapy or hospitalisation for infants < 29 weeks' gestation. Stockinet caps were not effective (borderline significant for infants < 2000 g birthweight) in reducing heat losses.Skin-to-skin care was shown to be effective in reducing the risk of hypothermia when compared to conventional incubator care for infants 1200 to 2199 g birthweight (one study, n = 31; RR 0.09; 95% CI 0.01, 0.64; NNT 2; 2 to 4). The transwarmer mattress kept infants </=1500 g significantly warmer and reduced the incidence of hypothermia on admission to NICU(one study, n = 24; RR 0.30; 95% CI 0.11, 0.83; NNT 2 range 2 to 4).

AUTHORS' CONCLUSIONS

Plastic wraps or bags, skin-to-skin care and transwarmer mattresses all keep preterm infants warmer, leading to higher temperatures on admission to neonatal units and less hypothermia. Given the low NNT, consideration should be given to using these interventions in the delivery suite. However, the small numbers of infants and studies and the absence of long-term follow-up mean that firm recommendations for clinical practice cannot be given. There is a need to conduct large, high quality randomised controlled trials looking at long-term outcomes.

Admission temperature of low birth weight infants: predictors and associated morbidities

BACKGROUND

There is a paucity of information on the maintenance of body temperature at birth for low birth weight infants.

OBJECTIVES

We examined the distribution of temperatures in low birth weight infants on admission to the NICUs in the Neonatal Research Network centers and determined whether admission temperature was associated with antepartum and birth variables and selected morbidities and mortality.

METHODS

Infants without major congenital anomalies born during 2002 and 2003 with birth weights of 401 to 1499 g who were admitted directly from the delivery room to the NICU were included. Bivariate associations between antepartum/birth variables and admission temperature and selected morbidities/mortality and admission temperature were examined, followed by multivariable linear or logistic regressions to detect independent associations.

RESULTS

There were 5277 study infants and the mean (+/-SD) birth weight and gestational age were 1036 +/- 286 g and 28 +/- 3 weeks, respectively. The distribution of admission temperatures was 14.3% at < 35 degrees C, 32.6% between 35 and 35.9 degrees C, 42.3% between 36 and 36.9 degrees C, and 10.8% at > or = 37 degrees C. The estimate of birth weight on admission temperature with and without intubation was +0.13 degrees C and +0.04 degrees C per 100-g increase in birth weight, respectively. The mean admission temperature for each center varied from 1.5 degrees C below to 0.3 degrees C above a reference center. On adjusted analyses, admission temperature was inversely related to mortality (28% increase per 1 degrees C decrease) and late-onset sepsis (11% increase per 1 degrees C decrease) but not to intraventricular hemorrhage, necrotizing enterocolitis, or duration of conventional ventilation.

CONCLUSIONS

Preventing decreases in temperature at birth among low birth weight infants remains a challenge. Associations with intubation and center of birth suggest that assessment of temperature control for infants intubated in the delivery room may be beneficial. Whether the admission temperature is part of the casual path or a marker of mortality needs additional study.

Polyethylene skin wrapping accelerates recovery from hypothermia in very low-birthweight infants

BACKGROUND

Thermal management of the very low-birthweight (VLBW) infant is a cornerstone of neonatology because thermal stress is an important determinant of survival. This prospective study was designed to determine the effects of polyethylene occlusive skin wrapping on heat loss in VLBW infants admitted to the neonatal intensive care unit (NICU) promptly after birth.

METHODS

Thirty consecutively inborn infants weighing <1500 g were allocated to a wrap or non-wrap group within an incubator after admission to the NICU. Axillary and incubator temperatures were taken on arrival at 1 and 2 h.

RESULTS

Infants in the wrap group reached a normal axillary temperature faster then non-wrap infants and required lower incubator temperatures.

CONCLUSIONS

Polyethylene film wrapping effectively helps to correct hypothermia in VLBW infants admitted to the NICU.

Cold stress and hypoglycemia in the late preterm ("near-term") infant: impact on nursery of admission

Late preterm infants (34-37 weeks gestation) pose unique challenges to physicians and nurses involved in their care after birth. They may be cared for in different units within hospitals after birth, including Neonatal Intensive Care Units, Newborn Nurseries, or rooming in with the mother. As a result of their gestational age and birth weight, the late preterm infant is often assessed quickly and triaged identical to term infants. Such practice can potentially result in a lack of attention to important components for successful transition after birth. Cold stress and hypoglycemia are the two important problems in late preterm infants which require immediate treatment. Thus, surveillance of these and other physiological variables is needed to insure that they do not affect successful adaptation during the early hours and days after birth.

Temperature variation in newborn babies: importance of physical contact with the mother

BACKGROUND

Hypothermia is a major cause of deterioration and death in the neonatal period. Temperature deviations are key signs of illness.

OBJECTIVE

To determine normal patterns of temperature variation in newborn babies and the influence of external factors.

METHODS

Abdominal and foot skin temperature were continuously recorded in 27 healthy full term babies during the first two days of life and related to the care situation-that is, whether the baby was with the mother or in its cot. The recordings were made using no wires to avoid interference with the care of the neonate. Ambient temperature was close to 23 degrees C during the study period.

RESULTS

Mean rectal and abdominal and foot skin temperature were lower on day 1 than day 2. The foot skin temperature was directly related to the care situation, being significantly higher when the baby was with the mother. The abdominal skin temperature was much less influenced by external factors. When the neonates were with their mothers, the mean difference between rectal temperature and abdominal skin temperature was 0.2 degrees C compared with a mean difference between rectal temperature and foot skin temperature of 1.5 degrees C, indicating a positive heat balance. In the cot the corresponding temperature differences were 0.7 degrees C and 7.5 degrees C. A temperature difference between rectal and foot skin temperature of 7-8 degrees C indicates a heat loss close to the maximum for which a neonate can compensate (about 70 W/m2).

CONCLUSION

This study emphasises the importance of close physical contact with the mothers for temperature regulation during the first few postnatal days.

Interventions to prevent hypothermia at birth in preterm and/or low birthweight babies

BACKGROUND

Hypothermia incurred during routine postnatal resuscitation is a world-wide issue (across all climates), with associated morbidity and mortality. Keeping vulnerable preterm infants warm is problematic even when recommended routine thermal care guidelines are followed in the delivery suite.

OBJECTIVES

To assess efficacy and safety of interventions, designed for prevention of hypothermia in preterm and/or low birthweight infants, applied within 10 minutes after birth in the delivery suite compared with routine thermal care.

SEARCH STRATEGY

The standard search strategy of The Cochrane Collaboration was followed. Electronic databases were searched: MEDLINE (1966 to May Week 4 2004 ), CINAHL (1982 to May Week 4 2004), EMBASE (1974 to 09/07/04), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2004), Database of Abstracts of Reviews of Effects (DARE 1994 to July 2004), conference/symposia proceedings using ZETOC (1993 to July 2004), ISI proceedings (1990 to 09/07/2004) and OCLC WorldCat (July 2004). Identified articles were cross-referenced. No language restrictions were imposed.

SELECTION CRITERIA

All trials using randomised or quasi-randomised allocations to test a specific intervention designed to prevent hypothermia, (apart from 'routine' thermal care) applied within 10 minutes after birth in the delivery suite to infants of < 37 weeks' gestational age or birthweight </=2500 g.

DATA COLLECTION AND ANALYSIS

Methodological quality was assessed and data were extracted for important clinical outcomes including adverse effects of the intervention by at least three independent reviewers. Authors were contacted for missing data. Data were analysed using RevMan 4.2.5. Relative risk (RR), risk difference (RD) and number needed to treat (NNT) with 95% confidence limits were calculated for each dichotomous outcome and mean differences (MD) with 95% confidence limits for continuous outcomes.

MAIN RESULTS

Six studies giving a total of 304 infants randomised and 295 completing the studies were included. Four comparisons to 'routine care' were undertaken within two categories: 1) barriers to heat loss (four studies): plastic wrap or bag (three), stockinet caps (one) and 2) external heat sources (two studies): skin-to-skin (one), transwarmer mattress (one). Plastic barriers were effective in reducing heat losses in infants < 28 weeks' gestation (three studies, n = 159; WMD 0.76 degrees C; 95% CI 0.49, 1.03) but not in the 28 to 31 week group. There was insufficient evidence to suggest that plastic wrap reduces the risk of death within hospital stay (three studies, n = 161; typical RR 0.63; 95% CI 0.32, 1.22; typical RD -0.09; 95% CI -0.20, 0.03). There was no evidence of a significant difference in major brain injury, mean duration of oxygen therapy or hospitalisation for infants < 29 weeks' gestation. Stockinet caps were not effective (borderline significant for infants < 2000 g birthweight) in reducing heat losses.Skin-to-skin care was shown to be effective in reducing the risk of hypothermia when compared to conventional incubator care for infants 1200 to 2199 g birthweight (one study, n = 31; RR 0.09; 95% CI 0.01, 0.64; NNT 2; 2 to 4). The transwarmer mattress significantly kept infants </=1500 g warmer and reduced the incidence of hypothermia on admission to NICU (one study, n = 24; RR 0.30; 95% CI 0.11, 0.83; NNT 2 range 2 to 4).

AUTHORS' CONCLUSIONS

Plastic wraps or bags, skin-to-skin care and transwarmer mattresses all keep preterm infants warmer, leading to higher temperatures on admission to neonatal units and less hypothermia. Given the low NNT, consideration should be given to using these interventions in the delivery suite. However, the small numbers of infants and studies and the absence of long term follow-up mean that firm recommendations for clinical practice cannot be given. There is a need to conduct large, high quality randomised controlled trials looking at long-term outcomes.

Peripheral chemoreceptor activity in sleeping neonates exposed to warm environments

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.

The impact of two transfer techniques used during skin-to-skin care on the physiologic and behavioral responses of preterm infants

BACKGROUND

Conservation of energy assumes an important role in the care of infants requiring assisted ventilation, yet little research has been conducted on this group of infants in terms of thermoregulation, oxygenation, heart rate, or sleep states during skin-to-skin care.

OBJECTIVES

To compare the impact of two different transfer techniques used in skin-to-skin care (nurse transfer and parent transfer) on physiologic stability and other descriptive measures of physiologic stability related to energy conservation in ventilated preterm infants during and after skin-to-skin care.

METHOD

Fifteen ventilated preterm infants weighing a mean of 1,094 g were randomly assigned to receive either parent or nurse-to-parent transfer on the first of 2 consecutive days and the alternate method the following day. Temperature was taken before and after skin-to-skin care. Oxygen saturation and heart rate were recorded minute by minute, and the Assessment of Behavioral Systems Observation (ABSO) scale scores was used to measure physiologic organization, motor organization, self-regulation, and need for caregiver facilitation during transfer to and from the parent and during pre, post, and skin-to-skin periods.

RESULTS

Temperature remained stable. Oxygen saturation decreased and heart rate increased when the infant was transferred to and from the parent, but returned to baseline levels during and after skin-to-skin care regardless of the transfer method. Infants showed more physiologic and motor disorganization, less self-regulation, and more need for caregiver facilitation during transfers to and from the parent than during the pre, post, and skin-to-skin care periods.

CONCLUSIONS

Both transfer methods resulted in physiologic disorganization. However, during and after skin-to-skin care, infants exhibited no signs of energy depletion.

Nonmalignant hyperthermia on induction of anesthesia in a pediatric patient undergoing bidirectional Glenn procedure

We report a case of severe hyperthermia in a 6-month-old boy with a single ventricle, dextrocardia, asplenia, and transposition of the great arteries, during induction of anesthesia on three separate occasions. To our knowledge, this is the first case reported of repeated intraoperative hyperthermia not related to malignant hyperthermia, infection, neuroendocrine tumor, or iatrogenic causes (e.g., anticholinergic blockade or warming devices). The severe hyperthermia may be secondary to the medications given before and during induction and/or the stress of the induction. Among the induction medications given during the three episodes, fentanyl is the most likely contributing drug. Human data indicate that opioids increase the sweating threshold and decrease the vasoconstriction and shivering thresholds. The medications could cause a widening in the thermoregulation interthreshold and the stress could induce nonshivering thermogenesis.

Neonatal cardiopulmonary resuscitation: the good news and the bad

Many health care professionals all over the world have been taught neonatal cardiopulmonary resuscitation (CPR) using the neonatal CPR course based upon the work of Bloom and Cropley. The purpose of this article is to provide a retrospective review of the development of some of the neonatal CPR techniques, to discuss current techniques and to complement the dedication of this issue to Dr. Ronald Brown and Catherine Copley, MN, RN.

Spectral analysis of heart rate fluctuations and optimum thermal management for low birth weight infants

Spectral analysis of heart rate variability is studied in 10 healthy growing premature infants to investigate the changes in autonomic balance achieved as a function of changes in skin temperature. Heart rate is obtained from ECG recordings and the power spectrum of beat-to-beat heart rate fluctuations is computed. The infants maintain mean rectal temperature within 36.3-37.2 degrees C, while skin temperature changes. The respiratory rate does not change at the different servocontrol set points. Heart rate is found to increase slightly, but consistently. The low-frequency band (0.02-0.2 Hz), reflecting the interplay of the sympathetic and parasympathetic tone and known to be maximum at the thermoneutral zone, is maximum at 35.5 and 36 degrees C and decreases gradually to a lower level at a servocontrol temperature of 36.5-37 degrees C. The high-frequency band (0.2-2.0 Hz), coinciding with the respiratory peak and reflecting parasympathetic activity, is significantly elevated at 36 degrees C (p < 0.01). The minimum low: high ratio, indicating the minimum sympathetic-parasympathetic balance and possibly reflecting the most comfortable conditions, occurs at 36 degrees C, although the differences are not statistically significant. Servocontrol skin temperature may thus be adapted, and possibly selected at 36 degrees C for growing premature infants in an attempt to achieve thermal comfort and more balanced autonomic activity.

Consequences of a small decrease of air temperature from thermal equilibrium on thermoregulation in sleeping neonates

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.

Skin derivative control of thermal environment in a closed incubator

Defining a thermoneutral environment remains difficult because thermoneutrality depends on both physical and physiological factors. A servocontrolled skin temperature derivative (SCS) heating device has been designed to control the thermal environment in closed incubators without the necessity of setting an air or skin reference temperature. The thermal environment obtained with the SCS program is controlled only by the neonate's skin temperature changes. For each neonate, the program allows the attainment of a specific individual thermal equilibrium (Teq). Although the mean value of the thermal equilibrium level measured on 29 neonates does not differ significantly from the neutral air temperature defined from the charts of other researchers, individual values of Teq differed greatly among neonates of similar birthweight and postnatal age. When compared with on/off heating programs, the SCS system permits greater quiet sleep occurrence and seems to provide an optimal thermal environment. The results suggest that the skin temperature derivative heating program takes into account both the ambient and physiological factors affecting body temperature regulation of each neonate.

Body temperature regulation in the newborn infant: interaction with sleep and clinical implications

Thermoregulation in newborn infant differs from that of adult. Comparisons between sleep stages show that, during rapid eye movements (REM) sleep, the impairment of thermoregulatory responses in adult is not observed in newborn. Both behavioral and autonomic temperature regulations are always operative in the range of air temperatures usually imposed. The interaction between sleep and thermoregulation seems to be less important in newborns than in adults, suggesting that sleep processes are well protected, reducing the probability of occurrence of central dysfunction. According to the model describing thermoregulation during sleep on the basis of changes in the hierarchical dominance of brain structures, either the influence of diencephalic structures is never depressed in REM sleep or the functional autonomy of the rhombencephalon is still relevant in the immature encephalon of the newborn. The thermoregulatory model also allows understanding of inter-individual differences in thermoregulation and levels of thermoneutrality. An attempt has also been made to learn the role of heat stroke in the production of sudden infant death syndrome when body heat loss is hampered.

Effect of insulated skin probes to increase skin-to-environmental temperature gradients of preterm infants cared for in convective incubators

Thermal support systems for premature infants that are based on skin servocontrol depend on accurate measurement of skin surface temperature. We examined prospectively the effect of probe insulation to alter measured skin temperature in 10 preterm infants. The use of insulated probes resulted in significant alteration in incubator servocontrol, with lower incubator air temperatures and higher skin-to-environment temperature gradients.

Ontogeny of water sorption-desorption in the perinatal rat

In mammals, birth marks a transition to a cold and gaseous environment that requires rapid physiologic adaptations limiting heat and water loss. In this study, the perinatal Sprague-Dawley rat was utilized as a model to study the behavior of water binding to the external body surface following birth. Water sorption and desorption were quantified by measurement of skin surface capacitance following water loading using a dry ring electrode system. The results indicate that the external body surface of the newborn rat is highly hydrophobic. This hydrophobicity is manifested by the rapid desorption of water (amniotic fluid) following birth as well as marked limitation of water sorption after birth. Post-natally, this hydrophobic effect is gradually lost over the first 3 d of life. Somatic growth retardation results in retention of this surface property, whereas extraction of the skin surface with acetone abolishes it. Morphologic and functional (water binding) studies performed after stripping the stratum corneum with acrylic adhesive strongly suggest a physiologic role for the periderm in determining this postnatal hydrophobic effect. These data are interpreted as evidence for a novel thermoregulatory mechanism in the rat during adaptation to post-natal life.

Thermal responses and heart rates of low-birth-weight premature babies during daily care on a heated, water-filled mattress

Body temperatures, heart rates and resting oxygen consumptions were examined during routine nursing care in 12 premature babies treated alternately in incubators or on a heated, water-filled mattress (HWM). The mean temperatures were significantly higher in the axilla (0.3 degree C; p less than or equal to 0.05) and the foot (1.4 degrees C; p less than 0.001) during HWM care. The degree of maximal fall in various body temperatures during routine nursing procedures was the same for both treatments, whereas the time taken for the foot temperature to fall was 13 min shorter during HWM care (p less than 0.001). The proportion of heart rates below 160 bpm when the babies were not disturbed was 7.4% greater during HWM treatment (p less than 0.01). The resting oxygen consumption in babies treated on HWM was slightly lower (6.2 +/- 0.4 vs 6.4 +/- 0.5 ml/kg/min; p less than 0.05). Treatment on the HWM seems to promote calm and comfort, since it reduces the amount of thermal stress and prolongs quiet resting periods.

Measuring the severity of surgical stress in newborn infants

Measurement of the severity of surgery would greatly facilitate the design and interpretation of studies in neonates undergoing surgery. A scoring method, based on the amount of blood loss, superficial dissection, and visceral trauma, the site and duration of surgery, cardiac surgical factors, and associated stress factors for surgical neonates, was formulated and applied to 94 neonates undergoing surgery. Perioperative management was standardized for all patients and hormonal-metabolic variables were measured in blood samples drawn preoperatively at the end of the operation, and at six, 12, and 24 hours after operation. The stress scores were correlated significantly with the plasma epinephrine (P less than .0001), norepinephrine (P less than .0001), insulin (P less than .001), glucagon (P less than .005), and cortisol (P less than .02) responses, and with changes in blood glucose (P less than .0001), lactate (P less than .0001), pyruvate (P less than .0001), and alanine (P less than .005) during and after operation. Discriminant function analysis was used for further validation and this scoring method was found to predict accurately the severity of surgical stress in 89.4% cases. Discrepancies in the remaining cases were found to be related to specific clinical factors. On comparison of the hormonal and metabolic responses of neonates in the minor (N = 71), moderate (N = 12), and severe (N = 11) stress groups, increasing severity of surgical stress was found to be associated with greater and more prolonged changes in plasma catecholamines, blood glucose, and gluconeogenic substrates during and after operation. Clinical outcome following operation was also significantly different between the three stress groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Improving pulmonary function does not decrease oxygen consumption in infants with bronchopulmonary dysplasia

To determine whether the high oxygen consumption VO2 in infants with bronchopulmonary dysplasia (BPD) is caused by increased mechanical power of breathing, and if improvement of pulmonary mechanics would reduce mechanical power of breathing and VO2 we gave 16 infants with oxygen-dependent BPD at 19.5 +/- 10.7 (mean +/- SD) weeks of age placebo, theophylline, and orally administered diuretics or theophylline plus diuretics. Pulmonary mechanics, mechanical power of breathing, and VO2 were measured at the beginning and end of each study period. In the placebo group, all infants had elevated VO2 (7.4 +/- 1.4 mL/kg/min) and carbon dioxide production (6.6 +/- 1.2 mL/kg/min), increased airway resistance (59 +/- 30 cm H2O/L/sec), decreased dynamic compliance (0.073 +/- 0.024 mL/cm H2O/cm), increase respiratory rate (52 +/- 11), and increased mechanical power of breathing (2.22 +/- 1.05 kg.cm/kg/min). Treatment with theophylline, diuretics, and theophylline plus diuretics resulted in a significant improvement in pulmonary mechanics and mechanical power of breathing, but not in VO2. These results suggest that the increased VO2 in infants with BPD is not secondary to increased mechanical power of breathing.

Temperature regulation in healthy and resuscitated newborns immediately after birth

Oxygen consumption (VO2) is a sensitive and reliable indicator of any disturbances of thermoregulatory adaptation in the newborn. This study has been carried out in a attempt to find out, if there is any difference between the thermoregulatory processes of healthy and resuscitated neonates. To this end, both VO2 and rectal temperature (RT) were continuously measured in 31 healthy and 13 resuscitated neonates respectively, within the first 140 postnatal minutes and during 30 minutes from the second until the fifth day of their lives. In the healthy neonates, the VO2 used to decrease over the study period. The high initial VO2 observed postnatally is due to mechanisms of thermoregulation beginning immediately after delivery as soon as the newborn child is exposed to chilly environmental temperatures. The brown adipose tissue (BAT) is supposed to be the essential site of non-shivering thermogenesis (NST). The thermogenetic function of this tissue may be shown by local measuring of temperature. In the resuscitated neonates, VO2 was lower than in the healthy children. Hypoxia results in an ineffective capillary blood supply of the BAT owing to a redistribution of circulating blood volume, thus leading to a disturbance of thermoregulation. Since the activity of the BAT is dependent on oxygen supply hypoxia might be regarded as the limiting factor. In the presence of an isothermal environment, the RT measured in the healthy children differed from those determined in the resuscitated neonates. This clearly shows that thermoregulatory processes may be impaired by a difficult birth.(ABSTRACT TRUNCATED AT 250 WORDS)

Techniques for warming red blood cells packaged in different containers for neonatal use

Essential to the management of the sick, low birth weight infant is maintenance of a neutral thermal environment by use of convection incubators and radiant warmers. Manipulation of the infant in preparation for transfusion and the transfusion of cold blood could theoretically lower the infant's body temperature, subsequently contribute to cold stress, and concomitantly increase metabolic demands and oxygen requirements. The authors evaluated different pretransfusion manipulations of syringe aliquots and bags of blood in an effort to provide a clinically acceptable product for transfusion to sick, very low birth weight infants.