Introduction

The healthcare provider has a crucial role in preventing heat loss and providing a stable thermal environment for neonates and infants. The thermoneutral environment (TNE) has been defined as maintenance of the infant’s temperature with a stable metabolic state along with minimal oxygen and energy expenditure.  The TNE is best achieved when infants can maintain a core temperature at rest between 36.5°C and 37.5°C.

 Healthcare providers must maintain a thermoneutral environment for infants yet to develop the physiological measures required. Environment thermostability involves blocking avenues of heat loss, nursing infants in the correct cot for their size and care requirements, and applying/monitoring radiant warmth.

Aim

To provide information to healthcare workers on the equipment available to apply assisted thermoregulation support to premature, neonatal and infant patients. Ensuring the most appropriate device is selected for patients will improve delivery of thermostability and optimise outcomes.

This guideline may be used in conjunction with the Temperature Managment Nursing Guideline.

Definition of Terms

• Brown adipose tissue is a highly vascular type of fat around nape of neck, kidneys, between scapulas and axillas. Brown fat contains thermogenin, which is effective in generating heat during lipolysis by oxidation. This is activated when neonate’s temperature decreases below 36.5C.
  
• Cold stress is a cascade of physiological events caused by the infant’s use of chemically mediated thermogenesis in an attempt to increase core temperature. Two specific alterations to thermogenesis occur in the infant suffering cold stress; vasoconstriction of the peripheries, which allows heat to be drawn back to the core and metabolism of brown adipose tissue.
• HFOV: High frequency oscillated ventilation, may be delivered by SLE ^TM ventilator or Sensormedics ventilator. Sensormedics circuit consists of large, immobile and rigid tubing, necessitating consideration in cot choice.
• HFJV: High frequency Jet ventilation, which is specialised for neonates, and requires a specialised circuit and JET ventilation box to be placed in close proximity to endotracheal tube. Requires easy access and close monitoring of neonate at all times.
  
• Heat stress may also be incurred if an infant is exposed to high environmental temperatures, often associated with increased heart rate and decreasing stability. It is imperative to ensure frequent observation of probe placement when utilising a thermoregulatory device to avoid a false-low reading if probe becomes detached, that will result in high heater output.
• Open Care System: A thermoregulatory cot that is not enclosed, allowing easy access to the infant requiring frequent intervention as well as temperature support (also described as radiant warmer and hybrid cots).
• Servo control: Heat output by the warmer or incubator which is automatically and constantly adjusted according to the programmed set skin temperature, which is continuously measured from the skin temperature probe. This is the preferred mode of applying thermoregulatory assistance to most neonates, but requires close monitoring and assessment of probe site.
  
• Thermoregulation: The ability to regulate one’s core body temperature, even when environmental temperature is variable. Assisted thermoregulation is the application of controlled environmental temperature to maintain core body temperature within expected parameters.

Modes of Heat Loss

• Evaporation - Heat loss occurring during conversion of liquid to vapour
• Convection - Transfer of heat from the body surface to the surrounding air via air current
• Conduction - Transfer of heat from one solid object to another solid object in direct contact with it
• Radiation - Transfer of heat to cooler solid objects not in direct contact with the body
  

It is important to note that preterm infants are at a higher risk of heat loss via the 4 modes mentioned above.  Preterm infants possess a disproportionate body mass-to-surface area ratio, reduced thermal insulation in decreased brown adipose tissue (BAT), a thin epidermis that has increased permeability, poor vasomotor control and a naturally extended position that exposes a greater body surface area to the external environment.  For these infants, cold stress will trigger a cascade of physiological responses that further impedes their transition to extrauterine life.

Equipment to aid providing inpatient thermoneutral environment

• Forced air warming: A temperature management system based on forced-air warming to prevent and treat hypothermia in surgical patients. This system consists of warming units and disposable blankets that distribute warm air across the patient before, during and/or after surgery. If this system is to be used intraoperatively on inpatient unit Butterfly, it will be upon instruction and provision of the surgical team.
• Cosytherm Heated mattress: An electronic mattress system that provides conductive heat for neonates and can be placed in any of our cots. This is usually appropriate for use in surgery (in liaison with the surgical team), and may be used for hypothermic neonates in some instances, such as palliative care, to enable families to have close contact with their baby in an open/portable cot.
• Hybrid Cot: Cot that operates as an incubator, with the ability to raise the hood and function as an open-system radiant warmer. This cot is beneficial for premature infants who are best suited to being nursed in an incubator, where there is indication for frequent access or surgery that necessitates an ability to provide open-system care. Surgery may be performed in the hybrid cot, however alternative thermoregulatory devices (forced air warming) may be required, at the discretion of surgical team.
  
• Incubator or Isolette: Incubators are utilised to provide a controlled, enclosed heated environment to ensure neutral thermoregulation is provided, enabling the infant to be nursed unwrapped. Incubators are the optimal choice for preterm infants requiring TNE support with or without environmental humidification. The incubator is not effective if frequent access to the baby is required for procedures or surgery, as temperature stability cannot be maintained with open portholes or sides down. Can be operated in servo or environmental control settings.
  
• Radiant warmer: Radiant warmers are an open care cot system designed to provide thermal stability to infants while allowing for continuous direct observation and accessibility. As this is not an enclosed system the temperature will fluctuate depending on the surrounding environment. Delivery of humidification is very limited and unable to be accurately measured. Radiant warmers are most suitable for term neonates requiring TNE support, or for use during surgery and procedures on the unit. During surgery, alternative thermoregulation devices will be required, such as the Cosytherm mattress or forced air warming system, at discretion of surgical team.

Criteria for provision of thermoregulation assistance

• Less than or equal to 32 weeks gestation OR less than or equal to 1800 grams
  
• Immature epidermis requiring environmental humidity in the first 14 days of life
• Surgery
• Moderate to high sedation therapies
• Muscle relaxation
• Phototherapy
• Prolonged procedure
• Observations requiring exposure of chest or abdomen
• Temperature instability for any reason
• Isolation for Droplet and Contact  precautions*

*Infants under Droplet and Contact precautions may be nursed in an incubator to minimise environmental contamination in some circumstances. When incubator is used for reducing transmission of organisms consider that infant may not meet criteria for assisted thermoregulation  as per this guideline. Infants may be nursed in a low temperature environmental setting with light clothing and wraps.

Surgery on Butterfly: Thermoregulation should be discussed with theatre staff prior to commencement of surgery on the unit. The Cosytherm may be utilised to provide conductive heat to the neonate throughout surgery. Alternatively, the theatre team may bring the forced air warming device for the procedure.

Intrahospital transfer options: Moving neonates to another department within the hospital is often      necessary to perform medical imaging, investigations and surgery. Patients who are low birthweight are at a higher risk of temperature instability.

• To ensure neonates temperature remains within  the optimal range consider: prewarming the mattress of Babyleo® prior to departure, utilising bubblewrap and warmed blankets, ensure the neonate is wearing a hat and minimise exposure to reduce heat loss.
• If possible, theatre temperature should be increased for surgical neonates and temperature monitored continuously throughout the procedure with oesophageal or rectal probe.
• More information regarding temperature management in theatre see the Temperature Management Nursing Guideline.

Other considerations: Procedures can place neonates at a higher risk of temperature instability due to exposure to the environment and cold fluids. If a neonate is to be exposed to a large volume of fluid for procedures, the fluids should be warmed to an appropriate temperature. The radiant warmer should always be used for neonates during procedures where a large surface area is required to be exposed, and plastic drapes may provide further protection against heat loss.

Equipment Indications

• Draegar® Isolette:  The Draegar® isolette is the incubator used at RCH.  This is not suitable for neonates requiring HFJV or HFOV via the sensormedics due to limitations with space and inability to access the infant with ease in an emergency.

• ATOM radiant warmer: The ATOM radiant warmer is brand of open care cot available at RCH. The ATOM is compatible with all modes of ventilation and other critical care equipment, and may also be used for short-term procedures in otherwise thermally stable infants. The warming canopy can be swung to the side.
• The ATOM cots contain built-in scales to enable close monitoring of infant weight without removing from the bed. 
• The ATOM cot should be preheated for 15-20 minutes prior to receiving a patient, utilising the preheat mode. It is imperative that the ATOM cot does not remain in this continuous heat mode when a patient is on the warmer.

Please see Thermo attachment Atom user guide for more information.

• Babyleo® incuwarmer: The Draegar® Babyleo® incuwarmer is the brand of hybrid cot available on Butterfly unit, provides multiple functions to ensure optimised TNE.
  • Features include ‘touch time’ mode increasing airflow to minimise alternations with open portholes during cares, and the ability to turn on the mattress heating to ensure conductive heat is applied when necessary. 
  • These features may be particularly useful post-operatively, or for off-unit transport to prolong temperature stability. 
  • The mattress must be unplugged for surgery on the unit, as it is not compatible with the diathermy equipment. 
  • Kangaroo mode is also available to provide continuous temperature monitoring of the infant whilst they are out of the cot for kangaroo cuddles. This reduces the need to disrupt family time, and ensures the cot adjusts environmental temperature according to the infants' needs prior to returning to the cot. Please see Thermo attachment babyleo user guide for more information.

• Skin temperature probe: All devices have unique skin temperature probes.
  • The ATOM skin temperature probes are reusable, and are fixed to the device. ATOM reusable probes are to be cleaned of adhesives to prevent organism transfer between patient’s, and optimise monitoring function. 
  • The isolette and Babyleo® skin temperature probes are disposable. 
  • Occlusive heat reflective patches are required to adhere the probe firmly to the infant’s skin, with gel and foam patches available at RCH. 
  • The probe site should be changed every time that the infant is repositioned (4-6 hourly).
  • Niltac ™adhesive remover wipes will aid to maintain skin integrity upon removal.

• Please ensure staff using equipment are familiar with the instructions for use. 

Selecting appropriate warming device for patient

Management 

Probe placement: Optimal temperature probe placement is on the abdomen, axillae, back or flanks. It is imperative that the probe is not placed between the mattress and the infant, as this will create a false high reading, resulting in inadequate heat output, and also poses a risk for pressure area development. 

Re-siting of the temperature probe should occur with each set of cares (4-6 hourly) and correlation between temperature reading and axillary measurement should be assessed. It may be normal for a variance of skin probe temperature reading and axillary temperature of 0.5 – 1.0°C, and setting servo control should target appropriate skin temperature, not axillary temperature in the instance of a discrepancy.

Servo control is the preferred mode for all neonates and infants requiring assisted thermoregulation. Servo control maintains the infant’s temperature within a specific range by adjusting heat output to achieve pre-set skin probe temperature. 

• This method of control relies on appropriate placement of the skin probe with a reflective patch, and continuous observation to ensure the probe remains well adhered to the skin and that the device heat output is not widely fluctuating. 
  
• If there is a significant change in heat output from the device, carefully assess to ensure probe remains well adhered. 
  
• Increased thermoregulation requirements may be indicative of a deterioration and routine observations may need to be more frequent. 

Manual control is where a constant environmental temperature is set with continuous, unadjusted heat output. This mode may be used on all devices to pre-warm for an expected admission, when a temperature probe needs to be removed temporarily for a procedure, or when aiming to wean from an incubator to an open cot. 

• The temperature probe should remain in place to monitor infant temperature continuously, and accordingly adapt device environmental temperature settings. 
• Refer to chart below for recommended environmental temperatures by gestational age and weight. 
• If the measured temperature is outside of the range of 36.5-37.5 the environmental temperature may be adjusted by 0.5 degrees Celsius each hour, targeting a change in the skin temperature of 0.3 degrees Celsius per hour.
  

Neutral Thermal Environment

This data has been taken from GHS Neonatal Intensive Care Unit Resident Handbook 2018-2019, adapted from Scopes JW, et al: Minimal rates of oxygen consumption in sick and premature infants, Arch Dis Child 41: 407, 1966 

Assessment

Frequency of Axillary Temperature Assessment

Hourly until stable for 4 hours on:

• Admission
• Transfer to incubator, radiant warmer or open cot
• Commencement or cessation of phototherapy
• Commencement or cessation of humidity
• Commencement or cessation of servo control

When infant’s temperature is stable (for at least 4 hours prior):

• 4 - 6 hourly
• 6 – 8 hourly for preterm infants

Exceptions:

• 4 hourly for the first 24 hours when manual control is commenced, then 6-8 hourly
• 4 hourly for the first 24 hours when transferred to an open cot
• If temperature is outside normal range, commence hourly temperatures until 2 consecutive normothermic measurements (Refer below for Temperature outside of Normothermic Range)
• Infants on Neonatal Abstinence Syndrome (NAS) scoring charts require a temperature check a minimum 4 hourly or otherwise prior to each feed

Documentation

Within the flowsheets of EMR, temperatures are to be documented within the ‘observations’ section with the method of temperature selected from the drop-down options.  Furthermore, within ‘thermoregulation’, select either incubator or radiant warmer, and document the ‘skin temperature probe reading’, ‘skin temperature site’ and ‘set temperature/air temperature’ hourly.

Special Considerations

Environmental humidity may also be applied to preterm infants in incubator and hybrid cots. See environmental humidity guideline.

Device cleaning frequency: The incubator and hybrid cots need to be changed every 14 days. If humidity has been applied then they need to be changed every 7 days. If humidity is ceased, the cot should be changed immediately. The Babyleo® requires a comprehensive cleaning procedure if humidity has been in use. Please ensure the waterbag remains attached to the cot, and the laminated card in the drawer is placed on the mattress to ensure cleaning staff can easily identify the required process.

Companion Documents

RCH Nursing Guidelines

• Temperature Management
• Environmental humidity

RCH NICU Departmental Guidelines

• Transport guideline
• Surgical procedures in NICU
• Transwarmer use

Evidence Table

Please remember to read the disclaimer.

The development of this nursing guideline was coordinated by Sarah Gardner, CSN/CNS, Butterfly Ward, and approved by the Nursing Clinical Effectiveness Committee. Updated July 2025.