Challenges of Minimizing Heat Loss at Birth: A Narrative Overview of Evidence-Based Thermal Care Interventions

Early detection of cold stress to prevent hypothermia: A narrative review

Temperature monitoring is essential for assessing neonates and providing appropriate neonatal thermal care. Thermoneutrality is defined as the environmental temperature range within which the oxygen and metabolic consumptions are minimum to maintain normal body temperature. When neonates are in an environment below thermoneutral temperature, they respond by vasoconstriction to minimise heat losses, followed by a rise in metabolic rate to increase heat production. This condition, physiologically termed cold stress, usually occurs before hypothermia. In addition to standard axillary or rectal temperature monitoring by a thermometer, cold stress can be detected by monitoring peripheral hand or foot temperature, even by hand-touch. However, this simple method remains undervalued and generally recommended only as a second and lesser choice in clinical practice. This review presents the concepts of thermoneutrality and cold stress and highlights the importance of early detection of cold stress before hypothermia occurs. The authors suggest systematic clinical determination of hand and foot temperatures by hand-touch for early detection of physiological cold stress, in addition to monitoring core temperature for detection of established hypothermia, particularly in low-resource settings.

Clinical detection of 'cold stress' is overlooked: an online survey of healthcare workers to explore the gap in neonatal thermal care in low-resource settings

BACKGROUND

Neonatal hypothermia has been widely regarded as a major contributory factor to neonatal mortality and morbidity in low-resource settings. The high prevalence of potentially preventable hypothermia today urges an investigation into why neonates still become hypothermic despite awareness of the problem and established thermal care guidelines. This study aimed to explore the gaps in knowledge and practices of neonatal thermal care among healthcare workers in low-resource settings.

METHODS

A cross-sectional, questionnaire-based survey was performed online among healthcare workers in low-resource settings. We applied a purposive and snowballing sampling method to recruit participants through a two-round international online survey. Questionnaires were developed using themes of neonatal thermal care extracted from existing neonatal care guidelines.

RESULTS

55 neonatal care professionals participated in the first-round survey and 33 in the second. Almost all participants (n=44-54/55) acknowledged the importance of the WHO's warm chain to keep a neonate warm. However, fewer participants (n=34-46/55) responded to practice them. When asked about cold stress, defined as a condition in which neonates are below optimum environmental temperature and using more oxygen and energy while maintaining normal body temperature, 15 out of 55 participants answered that checking extremity temperatures by hand touch was useless. Some participants reported concern about the extremity temperature's inaccuracy compared with core temperature. Opinions and preferences for rewarming methods differed among participants, and so did the availability of warming equipment at their institutions.

CONCLUSION

An inadequate understanding of cold stress underestimates the potential benefits of extremity temperatures and leads to missed opportunities for the timely prevention of hypothermia. The current thermal care guidelines fail to highlight the importance of monitoring cold stress and intervening before hypothermia occurs. Therefore, we urge introducing the concept of cold stress in any neonatal thermal care guidelines.

The effect of thermoregulation quality improvement initiatives on the admission temperature of premature/very low birth-weight infants in neonatal intensive care units: A systematic review

PURPOSE

The purpose of this review was to ascertain the impact of thermoregulation quality improvement initiatives (QIs) on the admission temperatures of premature/very-low-birth-weight infants in neonatal intensive care units (NICUs).

METHODS

A systematic search of databases Cumulative Index to Nursing and Allied Health Literature, Medline, Embase, and the Cochrane library was carried out. Specific inclusion and exclusion criteria were adhered to, with no publication date limitations added. The chosen studies were examined for quality, data were extracted and analysed, before a narrative synthesis was performed. The last search occurred on January 7, 2019, with PRISMA flow diagrams completed for identified studies.

RESULTS

Ten studies of varying methodology design were included in this review. Variations of thermoregulation interventions were included in the 10 studies. Nevertheless, all of them demonstrated that admission temperature rates can be significantly improved by implementing a thermoregulation QI. The multidisciplinary team and ongoing education were seen as much needed components to the overall sustainability, and continuing success of the QI's.

PRACTICAL IMPLICATIONS

This systematic review determines that thermoregulation QIs can positively impact the admission temperatures of premature/very-low-birth-weight infants in the NICU. Prevention of hypothermia is aimed at reducing the risks of developing major neonatal morbidities. The pooling of the results from the 10 studies helps in the sharing of outcome measures and thus, improving quantitative synthesis. More frequent monitoring of the axillary temperature would help in preventing hypothermia and hyperthermia occurring. Ongoing education and staff training are essential for managing thermoregulation successfully. Examining the compliance rates to such quality initiatives, and the variations in interventions would benefit from further research to ensure better standardisation of clinical practice.

Do transport factors increase the risk of severe brain injury in outborn infants <33 weeks gestational age?

OBJECTIVE

We evaluated transport factors and postnatal practices to identify modifiable risk factors for SBI.

STUDY DESIGN

Retrospective review of Canadian Neonatal Transport Network data linked to Canadian Neonatal Network data for outborns <33 weeks gestational age (GA), during January 2014 to December 2015. SBI was defined as grade 3 or 4 intraventricular hemorrhage or parenchymal echogenicity, including hemorrhagic and/or ischemic lesions.

RESULT

Among 781 infants, 115 (14.7%) had SBI with range 5.6-40% among transport teams. In multivariable analysis, SBI was associated with GA [0.77 (0.71, 0.85)] per week, receipt of chest compressions and/or epinephrine at delivery [1.81 (1.08, 3.05)] and receipt of fluid boluses [1.61 (1.00, 2.58)].

CONCLUSIONS

Risk factors for SBI were related to the condition at birth and immediate postnatal management and not related to transport factors. These results highlight the importance of maternal transfer to perinatal centers to allow optimization of perinatal management.

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.

Comparison of the Effect of Plastic Cover and Blanket on Body Temperature of Preterm Infants Hospitalized in NICU: Randomized Clinical Trial

Introduction: Preterm infants are unable to regulate their body temperature and there are insufficient research evidences on different kinds of covers for hospitalized preterm infants; therefore, the present study was conducted with the aim of comparing the effects of plastic and blanket covers on the body temperature of preterm infants under radiant warmer.

Methods: This randomized cross-over clinical trial was carried out upon 80 infants with the gestational age of 28-30 weeks and birth weight of 800- 1250 gr who were in Neonatal Intensive Care Unit on the second day of their hospitalization. The study lasted for two days. In group 1, the plastic cover was used during the first day of the study while the blankets were used during the second day. Infants’ heads were kept out of the cover and coated with a hat. In group 2, the plastic cover was used during the first day of the study while the blanket was used during second day. Digital thermometer was used to measure infants’ axillary temperature. The data was analyzed using SPSS ver 13 and MiniTab software. Descriptive statistics, (Mean (SE), 95%CI) and inferential statistics (Repeated measurement and ANCOVA tests) were used.

Results: The mean body temperature of the infants in the group covered with the plastic was calculated to be higher and the warmer was set on low temperature.

Conclusion: Using plastic cover during the first few days of hospitalization in NICU resulted in regulation of preterm infants’ body temperature.