Variations in incubator temperature and humidity management: a survey of current practice

Preterm Infant Incubator Humidity Levels: A Systematic Review

BACKGROUND

Numerous scholars have reported that inconsistent levels of incubator humidity in the neonatal intensive care unit (NICU) require attention. Evidence synthesis was needed to identify optimal incubator humidity levels and duration to decrease transepidermal water loss (TEWL) and the potential for infection.

PURPOSE

The purpose of this systematic review was to appraise and synthesize the evidence of preterm outcomes related to incubator humidity. The primary aim of this study was to determine how patient outcomes were impacted by incubator humidity levels and duration in premature infants born before 320/7 weeks cared for in the NICU.

METHODS/SEARCH STRATEGY

The foundation of this systematic review was the Joanna Briggs Institute method for systematic reviews. Mefford's theory of health promotion for the preterm infant was used to address the wholeness of the preterm infant's body system. Evidence was classified using the Johns Hopkins evidence-based practice levels and quality of evidence.

FINDINGS

Twelve studies met inclusion criteria. The evidence demonstrated that the practice of incubator humidity is warranted; however, it does not come without risks. Microbial growth was increased in high levels of incubator humidity. Unnecessary TEWL was prevented by lowering high levels of incubator humidity after the first week of life, improving skin barrier formation.

IMPLICATIONS FOR PRACTICE

Incubator humidity of 60% to 70% in the first week of life was effective in preventing TEWL in infants born 26 weeks or more.

IMPLICATIONS FOR RESEARCH

Future incubator humidity research is needed for infants born before 26 weeks.Video Abstract available athttps://journals.lww.com/advancesinneonatalcare/Pages/videogallery.aspx?autoPlay=false&videoId=39.

The Association Between Very Premature Infant Body Temperatures Over Time and Respiratory Care

BACKGROUND

Due to global immaturity, very low birthweight (VLBW) infants (<1,500 g) require auxiliary thermal and respiratory care. However, the impact of respiratory care on infant thermal stability remains unclear.

AIMS

Examine the association between VLBW infant body temperatures over time and respiratory support type (mechanical ventilation (MV), continuous positive airway pressure (CPAP), room air (RA)), respiratory care interventions, and nursing care.

DESIGN

Exploratory, longitudinal, and correlational design.

SUBJECTS

12 infants <29 weeks' gestation (median = 27.1, 25.9-27.9) and <1,200 g (median = 865 g, 660-1,050 g).

MEASUREMENTS

Minute-to-minute body temperatures and continuous video data were collected over the first 5 days of life. Video data was coded with Noldus Observer®XT software. Respiratory support was retrieved from the electronic health record. Hierarchical multi-level, mixed-effects models for intensive longitudinal data examined the associations.

RESULTS

Body temperatures were associated with respiratory support type, respiratory care, and care events (all p < .0001). Pairwise comparison found significant differences in body temperatures between all respiratory support types (all p < .0001). The covariate-adjusted risk of hypothermia (<36.5 °C) was significantly greater during MV vs. RA (aOR = 2.6); CPAP vs. MV (aOR = 1.2); CPAP vs RA (aOR = 3.1); respiratory care vs. other types of care (aOR = 1.5); care event vs. closed portholes (aOR = 2.6).

CONCLUSION

Our results found an association between VLBW infant thermal instability and respiratory support type, respiratory care, and care events. Larger studies with advanced longitudinal analysis are needed to assess the causal impact of these interventions on infant temperatures over time, as well as the implications of longitudinal thermal instability on infant outcomes.

Measurement and Control of an Incubator Temperature by Using Conventional Methods and Fiber Bragg Grating (FBG) Based Temperature Sensors

Incubator is a medical device that provide a climatic environment for a newborn and a preterm infant. In the incubator environment, especially, the temperature significantly increases the survival rate of infants. In this study, the incubator air temperature, temperature uniformity and infant skin temperature were measured and controlled with conventional methods and FBG based temperature sensors, and their results and related literature results were compared among them. To this end, in addition to classical sensors, six FBG sensors were used during the measurements, and very close results were obtained between them (R² = 0.9989). In addition, since real time monitoring of the FBG bands were ensured with a user-friendly interface, measurement processes have been made more ergonomic. In this way, the insulation required for the measurements is also provided perfectly. Measurement errors caused by conventional sensors' properties, which are different for each of them, change over/with time, and also change with different values, have been minimized by using this method. Moreover, in case of increasing the number of sensors for multi-point, continuous and real time temperature measurement in conventional methods, some of the problems such as monitoring of these sensors, obstructing or changing the air flow due to the confusions of these sensors and their cables in the incubator cabinet, and following these, control errors caused by these reasons, and difficulties that may be happened during the infant care and resuscitation procedures have been eliminated. Thus, thermoneutrality in closed incubators were also able to validated and assessed fast and more accurately for preterm and neonates.

Target Body Temperature in Very Low Birth Weight Infants: Clinical Consensus in Place of Scientific Evidence

Background: Although thermal care is part of the daily routine in Neonatal Intensive Care Units (NICUs), scientific evidence on what is the appropriate body temperature for very low birth weight infants (VLBWI) is largely lacking. Aim: To find out to what extent the standards of thermal care vary among high-level NICUs, especially with respect to the target body temperature in VLBWI. Methods: An online survey with 21 questions on thermal care in three categories of VLBWI was sent to 149 NICUs in Germany, Switzerland, and Austria. Results and discussion: Out of 112 (75%) returned questionnaires, 87 (58%) were included into analysis. A significant increase in incubator settings (air temperature/relative humidity) with decreasing gestational age and birth weight was reported, according to common textbook recommendations. However, a uniform target body temperature of 36.99 ± 0.19°C was chosen for all VLBWI categories. Likewise, the cut-off points for hypo- and hyperthermia were defined very similarly and showed low inter-center variability. This is a remarkable finding in view of the fact that the body temperature of mammalian fetuses in utero is 0.5-1.0°C higher than that of the mother. Conclusion: Despite lacking scientific evidence, there is a tacit consensus among high-level NICUs that 37.0°C is the appropriate body temperature in VLBWI, regardless of gestational age and birth weight. As this is below the intrauterine "breeding temperature" of the fetus, further research on this topic is warranted.

Failing to meet relative humidity targets for incubated neonates causes higher heat loss and metabolic costs in the first week of life

AIM

Frequent nursing procedures can modify a newborn infant's thermal environment when their incubator is opened. This study evaluated the impact of relative humidity (RH) on preterm infants in closed incubators and calculated their heat loss and additional metabolic cost.

METHODS

We studied 45 preterm infants born before 32 + 0 weeks, nursed at the neonatal intensive care unit at Amiens University Hospital, France from January 2009 to November 2011. Their body, skin and air temperatures and the incubator's RH were continuously recorded from day 1 to 8 of life, and the differences between the measured and target RH were calculated. Body heat loss (BHL) was also calculated.

RESULTS

On day one, the measured RH (68.7 ± 1.0%) was significantly lower than the target RH (75%, p < 0.05), but this difference, together with BHL (p < 0.001) and evaporative heat loss (p < 0.001), fell significantly over time (p < 0.05). The additional metabolic cost correlated with the difference between measured and target RH (p < 0.001).

CONCLUSION

RH from day 1 to 8 was below the recommended target value for preterm infants and resulted in high evaporative and greater total BHL and additional metabolic cost. The findings pose numerous challenges, including nursing care and incubator design.

Thermal management in closed incubators: New software for assessing the impact of humidity on the optimal incubator air temperature

BACKGROUND

Low-birth-weight (LBW) neonates are nursed in closed incubators to prevent transcutaneous water loss. The RH's impact on the optimal incubator air temperature setting has not been studied.

METHODS

On the basis of a clinical cohort study, we modelled all the ambient parameters influencing body heat losses and gains. The algorithm quantifies the change in RH on the air temperature, to maintain optimal thermal conditions in the incubator.

RESULTS

Twenty-three neonates (gestational age (GA): 30.0 [28.9-31.6] weeks) were included. A 20% increase and a 20% decrease in the RH induced a change in air temperature of between -1.51 and +1.85°C for a simulated 650g neonate (GA: 26 weeks), between -1.66 and +1.87°C for a 1000g neonate (GA: 31 weeks), and between -1.77 and +1.97°C for a 2000g neonate (GA: 33 weeks) (p<0.001). According to regression analyses, the optimal incubator air temperature=a+b relative humidity +c age +d weight (p<0.001).

CONCLUSIONS

We have developed new mathematical equations for calculating the optimal temperature for the incubator air as a function of the latter's relative humidity. The software constitutes a decision support tool for improving patient care in routine clinical practice.

Dynamics and complexity of body temperature in preterm infants nursed in incubators

BACKGROUND

Poor control of body temperature is associated with mortality and major morbidity in preterm infants. We aimed to quantify its dynamics and complexity to evaluate whether indices from fluctuation analyses of temperature time series obtained within the first five days of life are associated with gestational age (GA) and body size at birth, and presence and severity of typical comorbidities of preterm birth.

METHODS

We recorded 3h-time series of body temperature using a skin electrode in incubator-nursed preterm infants. We calculated mean and coefficient of variation of body temperature, scaling exponent alpha (Talpha) derived from detrended fluctuation analysis, and sample entropy (TSampEn) of temperature fluctuations. Data were analysed by multilevel multivariable linear regression.

RESULTS

Data of satisfactory technical quality were obtained from 285/357 measurements (80%) in 73/90 infants (81%) with a mean (range) GA of 30.1 (24.0-34.0) weeks. We found a positive association of Talpha with increasing levels of respiratory support after adjusting for GA and birth weight z-score (p<0.001; R2 = 0.38).

CONCLUSION

Dynamics and complexity of body temperature in incubator-nursed preterm infants show considerable associations with GA and respiratory morbidity. Talpha may be a useful marker of autonomic maturity and severity of disease in preterm infants.

Conhecimentos e práticas de manuseio de incubadoras neonatais por profissionais de enfermagem

Resumo Objetivo Comparar conhecimentos e práticas de manuseio de incubadoras neonatais por enfermeiras e técnicas/auxiliares de enfermagem. Métodos Estudo transversal, realizado em unidade neonatal de hospital de referência, com dados obtidos por questionário sobre conhecimentos e observação direta, estruturada e não participante, das práticas da equipe de enfermagem no manuseio de incubadoras. Criou-se escore de adequação de práticas realizadas. Resultados Não houve diferença entre os dois grupos estudados, quanto aos conhecimentos sobre manuseio de incubadoras, exceto para o benefício de umidificação, mais citado entre enfermeiras (p=0,040). Comparando-se escores de práticas obtidos isoladamente e considerando o escore total, também não se constatou diferença (p=0,723). Técnicas/auxiliares de enfermagem e enfermeiras realizaram 70% de práticas adequadas ao manusearem a incubadora, proporção baixa, visto tratar-se de hospital de alta complexidade. Conclusão Em geral, não houve diferença entre os componentes da equipe de enfermagem com relação aos conhecimentos e práticas estudadas.

Effects of Handling and Environment on Preterm Newborns Sleeping in Incubators

OBJECTIVE

To describe the total sleep time, stages of sleep, and wakefulness of preterm newborns and correlate them to levels of sound pressure, light, temperature, relative air humidity, and handling inside incubators.

DESIGN

Observational, correlational study.

SETTING

A neonatal intermediate care unit.

PARTICIPANTS

Twelve preterm newborns, who were 32.2 ± 4.2 weeks gestational age and weighed 1,606 ± 317 g.

METHODS

Sleep records were assessed by polysomnograph. Environmental variables were measured with a noise dosimeter, light meter, and thermohygrometer. To record time and frequency of handling, a video camera was used. All recordings were made for an uninterrupted 24-hour period.

RESULTS

Mean total sleep time in 24 hours was 899 ± 71.8 minutes (daytime = 446 ± 45.3 and nighttime = 448 ± 60.2). Mean wakefulness was 552 ± 94.0 minutes. The predominant stage was quiet sleep. A significant correlation was identified only between the levels of light and wakefulness (r = 0.65 and p = .041).

CONCLUSION

The environmental conditions and care provided to hospitalized preterm newborns did not influence sleep except for high light levels, which increased wakefulness. Nurses in clinical practice should implement strategies to promote and protect sleep by decreasing newborns' exposure to excessive light.

Toward Incorporating the Infant Weight Into Incubator's Automatic Temperature Control

A premature infant needs a stable thermal environment. This paper studies if the infant weight can be employed in the standard heat regulation system in incubators. This was done in two stages. First, a weight sensor was designed by means of using strain gauge in order to provide weight measurement. Later, a heat regulation circuit was designed and implemented by means of using a microcontroller. The humidity, environmental and skin temperature, and infant's weight are measured and used as inputs. The experiments showed that infant's weight can be successfully added to the control circuit in the incubator instrument. The results showed that infant's weight can productively contribute in temperature control with good confidence. The average standard error was equal to 0.48 °C. The results reveal that the infant's weight can contribute to increase quality assurance of incubators.

A mean body temperature of 37°C for incubated preterm infants is associated with lower energy costs in the first 11 days of life

AIM

This randomised trial compared the energy costs of providing incubated preterm infants born before 32 weeks of gestation with homeothermia using either air temperature control (ATC) or skin servocontrol (SSC).

METHODS

We studied 38 incubated preterm infants for the first 11 days of life, calculating the frequency of hypothermia (<36.0°C), hyperthermia (>37.5°C) and thermal challenge, together with energy costs, based on a change in incubator air temperature of 2°C above or below thermoneutrality.

RESULTS

The daily mean incubator air temperature was higher in ATC than SSC (p < 0.05) for the first 6 days, and the mean body temperature was higher in ATC (37.0 ± 0.03°C) than SSC (36.8 ± 0.02; p < 0.01) over the whole study period. The frequency of moderate hyperthermia was higher in ATC (p < 0.001), whereas warm and cold thermal challenges were higher in SSC (p < 0.001). The two groups did not differ in terms of energy costs. The time to recover birthweight was shorter in ATC (p < 0.05).

CONCLUSION

In incubators using ATC, a body temperature of 37°C was associated with lower energy costs and greater weight gain at 11 days of life for preterm infants. Future studies should test SSC shielded abdominal skin temperature set to 37°C.

A laminar flow unit for the care of critically ill newborn infants

INTRODUCTION

Medical and nursing care of newborns is predicated on the delicate control and balance of several vital parameters. Closed incubators and open radiant warmers are the most widely used devices for the care of neonates in intensive care; however, several well-known limitations of these devises have not been resolved. The use of laminar flow is widely used in many fields of medicine, and may have applications in neonatal care.

OBJECTIVE

To describe the neonatal laminar flow unit, a new equipment we designed for care of ill newborns.

METHODS

The idea, design, and development of this device was completed in Sao Paulo, Brazil. The unit is an open mobile bed designed with the objective of maintaining the advantages of the incubator and radiant warmer, while overcoming some of their inherent shortcomings; these shortcomings include noise, magnetic fields and acrylic barriers in incubators, and lack of isolation and water loss through skin in radiant warmers. The unit has a pump that aspirates environmental air which is warmed by electrical resistance and decontaminated with High Efficiency Particulate Air Filter (HEPA) filters (laminar flow). The flow is directed by an air flow directioner. The unit has an embedded humidifier to increase humidity in the infant's microenvironment and a servo control mechanism for regulation of skin temperature.

RESULTS

The laminar flow unit is open and facilitates access of care providers and family, which is not the case in incubators. It provides warming by convection at an air velocity of 0.45 m/s, much faster than an incubator (0.1 m/s). The system provides isolation 1000 class (less than 1,000 particles higher than 0.3 micron per cubic feet at all times). This is much more protection than an incubator provides and more than radiant warmers, which have no isolation whatsoever. Additionally, it provides humidification of the newborn's microenvironment (about 60% relative humidity), which is impossible with a radiant warmer, which produces high water body loss. It has no mechanical barriers like acrylic walls, its magnetic field is lower than an incubator (0.25 μt versus 1.2 μt), and the noise is minimal compared to incubators. The unit is also able to provide controlled total body hypothermia, which is not possible with either of the other two units.

CONCLUSION

The laminar flow unit for neonatal care is a novel device which we recently developed. The introduction of laminar flow technology represents a real innovation in the neonatal field. We have described the various components of the unit and the potential advantages for management of ill neonates. This will hopefully lead to improved clinical outcomes and more effective neonatal management and safety.