E 8 Radiant Warmer

This equipment is mainly important for Hypothermia as decribed in Prevention and Management of Hypothermia.

Subsection of this chapter:

  1. Clinical Problem
  2. Assessment
  3. Management
  4. Infection Prevention
  5. Complications
  6. Care & Maintenance
  7. Troubleshooting & Repair

NEST360°. Newborn Essential Solutions and Technologies-Education – Clinical Modules: Radiant Warmer. (June 2020). License: CC BY-NC-SA 4.0.

Clinical Problem

Temperature less than 36°C at birth has been recognised as an independent risk factor for death in preterm infants. 1,2

Radiant warmers may be used on any neonatal patient admitted to the nursery ward, but especially for:

OBSTETRIC & LABOUR NOTE

In stable newborns priority should always be given to skin-to-skin and KMC over artificial warming devices. Unstable babies and any requiring resuscitation need an area post-delivery to prevent hypothermia. Using pre-warmed towels, neonatal patients should immediately be dried, with one towel that is then discarded and replaced by another dry one, wrapped and placed under a radiant warmer following delivery. Newborn babies can drop their body temperature very quickly, even within minutes. They must be kept warm from the moment of birth, during their time in the labour ward and when transferred to the nursery. Even small drops in temperature increase the likelihood of mortality.2–4

Extremely premature babies can be placed in a clean plastic bag immediately after birth, without prior drying and ensuring the head is kept free from the plastic.4 (1.1) The head is covered with a hat. This assists prevention of heat loss. A baby in a plastic bag must be monitored very frequently to prevent overheating.

Regardless of location, it is preferential to start patients on Kangaroo Mother Care if it is clinically appropriate and the patient is stable.

Assessment

However warm a room may feel to an adult, a neonate can lose heat. This heat loss in neonatal patients is rapid, with hypothermia directly contributing to mortality.2–4 Radiant warmers (2.1) use overhead heating elements to provide radiating heat ensuring maintenance of normothermia.

Newborn babies lose heat through four main mechanisms.5

Radiant warmers provide radiating heat to minimise metabolic requirements for heat production, decreasing the risks of hypoglycaemia and respiratory distress associated with hypothermia. Radiant warmers provide an area where resuscitations, procedures, and short-term observation can take place while keeping the baby warm. Warmers may vary in complexity, including only heating functionality or heating functionality with resuscitation and oxygen equipment. All warmers include a temperature probe that provides information on the patient’s temperature. (2.2)

Radiant warmers heat in various modes, the names of which may vary based on device: (2.3)

Normothermic axillary temperature in neonates ranges from 36.5oC to 37.5oC.4,5 Every effort must be made to keep a baby's temperature within the normal range as temperature below 36oC is an independent risk factor for death in newborns.1,2

Management

Management covers how to use the radiant warmer, including set up for a patient, patient preparation & commencement, care whilst on the device & removal of the patient from the device

SETTING UP FOR A PATIENT

  1. Plug power cable into the radiant warmer. (3.1) Plug power cable into a wall socket & surge protector if available and switch on the power. (3.2)
  2. Select manual setting at 25% or Prewarm setting (if available on model). (3.3)
  3. Plug temperature probe into the infant temperature probe port. (3.4) Hold temperature probe in hand and move hand directly under overhead heating elements to check for heat. (3.5) You should be able to feel heat emitting from the heating elements. (3.6) Allow bedding to grow warm while waiting for the baby to arrive in the nursery, be transferred to the radiant warmer, or be delivered in the labour ward.

PREPARING A PATIENT

  1. Collect:
  2. Always explain the purpose, risks, and benefits of a procedure to guardians BEFORE performing the procedure.
  3. Follow handwashing protocol.
  4. Ensure patient is dry from any birth fluids or bodily secretions and is wearing a hat to prevent excess heat loss from the head.

STARTING A PATIENT

  1. Ensure radiant heater has been prewarmed. If the radiant warmer has not been prewarmed, then take steps to do so. Prewarming is essential in order to prevent infant from losing heat to the mattress when initially placed on the warmer.
  2. Change the radiant warmer from Pre-Warm to select Servo/Automatic mode. (3.7)
  3. Position infant in middle of radiant warmer cot, maintaining additional treatment tubing (e.g., CPAP tubing, IV lines) in place. (3.8)
  4. Use gauze and 70% alcohol to clean temperature probe.
  5. Place temperature probe directly above infant’s liver and secure with tape or elastic bandage. (3.9) If a child with myelomeningocele needs to be cared for prone, then place the probe over the infant’s flank. The probe should be secured firmly enough that it will not fall off the patient, but not so firmly that it is pressing into the infant’s skin.
  6. If used in servo mode, the goal temperature for the baby is usually set to a default 36.50C. The user may change the goal temperature depending on patient’s clinical status.
  7. Ideally, each radiant warmer should be used for one baby with a temperature probe dedicated for that patient. Sharing of a radiant warmer and temperature probe poses a risk for temperature regulation and infection control. If multiple patients are sharing one warmer, regular temperature monitoring must be conducted using a temperature probe or thermometer. If the radiant heater is used in manual mode, the baby must be constantly attended as there is a real danger of overheating.

CARING FOR A PATIENT

  1. Monitor the patient’s temperature 5 minutes after starting on radiant warmer, and then 4 hourly (if in servo mode) or every 30 minutes (if in manual mode).
  2. Pay close attention to any alarms:

REMOVING A PATIENT

  1. Collect:
  2. Gently remove tape/bandage holding temperature probe from patient. (3.15)
  3. Disinfect probe site on patient and temperature probe with gauze and 70% alcohol.
  4. Turn off warmer using switch and unplug.
  5. Check the patient’s temperature after 30 minutes off the warmer, to ensure normal body temperature is maintained.
  6. Disinfect the cot before reuse.

Infection Prevention

Routine and adequate cleaning of medical devices is critical to prevent hospital-acquired infections in newborn care units.

GENERAL INFECTION PREVENTION

  1. Clean hands with soap and water or 70% alcohol before and after placing a patient in a radiant warmer or handling any consumables that will be used on a patient (e.g., temperature probe).
  2. Ensure that all patient-related consumables (including probes) are new or have been cleaned thoroughly before use. Any patient-related consumables must be cleaned before they are used to assess another patient on the radiant warmer.
  3. All patient-related consumables should be stored in a clean, dry location. Any cables should be loosely wrapped and secured, preventing sharp bends or kinks, which will decrease the lifetime of the cables. Do not pinch or bend the cables.
  4. As mentioned in Radiant Warmer: Management, each radiant warmer should be used for one baby with a temperature probe dedicated for that patient. Sharing of a radiant warmer and temperature probe poses a high risk for infection transmission between patients. If the patient probe and surfaces are not cleaned thoroughly before use, infection can also be transmitted.

DISINFECTION AFTER USE

  1. Turn off and unplug the radiant warmer, if not using with another patient. Allow to cool.
  2. After every use, use gauze and 70% alcohol or diluted chlorine (Alert 4.1) to thoroughly wipe:
  3. Housing of the radiant warmer should be cleaned according to ward guidelines for disinfecting surfaces.
! ALERT 4.1
Disinfection of equipment should always comply with manufacturer guidelines. General guidance on environmental cleaning and disinfection of equipment was taken from the Infection Prevention and Control: Reference Manual for Health Care Facilities with Limited Resources, Jhpiego, Module 66 which lists isopropyl alcohol (70-90%), sodium hypochlorite (0.05% or >100ppm available chlorine) quaternary ammonium, and Iodophor germicidal detergent as appropriate for low level disinfection. Phenolic germicidal detergent is also listed in this category but should not be used in neonatal wards since affordable, effective alternatives are available; and, there are concerns it may cause hyperbilirubinemia and/or neurotoxicity in neonates.7 When utilising re-processed devices meant for single-use (like temperature probes), careful attention must always be paid to assure that devices are continuing to function properly.

Complications

Introduction of equipment in newborn care units poses clinical and device Ethics application 3463complications for patients. Awareness of potential complications is critical to maximise patient safety.

CLINICAL COMPLICATIONS

? ALERT 5.1 Contextualising Hyperthermia
There are two ways that an infant might have an elevated core temperature: (1) infection (2) environmental.
  1. Infection: In the case that an elevated temperature is generated by infection, there is no temperature which is considered “dangerous” and would require additional alarms. Fever, regulated by the hypothalamus, is the body’s normal response to infection or inflammation which is induced by cytokine activation.
  2. Environmental overheating:
    • Device overheating: A device overheating an infant can lead to a number of potentially dangerous outcomes that may result in serious harm. Environmental overheating is not a body’s normal response to an illness (as seen in fever) but rather a mismatch between environmental heat and the ability of the infant’s body to dissipate heat. Environmental overheating may result in serious heat related illness including damage to the central nervous system.8,9 Compared to older individuals, babies are at particularly high risk of environmental overheating since they have higher heat production (metabolic rates), higher surface area to mass ratios (i.e., higher absorption of heat from environment), less ability to dissipate heat and no ability to independently access fluids.10-12
    • Maternal heat transference: Immediately following delivery hyperthermia can be caused by maternal fever during labour and delivery as foetal temperature is up to 1°C higher than maternal temperature.13
Note on special circumstances: CNS injury, in which it is critical to avoid hyperthermia in the first 72 hours following birth, may affect the newborn’s temperature. However, CNS damage will typically result in temperature instability rather than hyperthermia.13

DEVICE COMPLICATIONS

Care & Maintenance

Users are responsible for basic first-line care and maintenance to ensure equipment lasts to their potential lifetime.

POWER SOURCE

Radiant warmers are powered with mains/socket power. Radiant warmers are typically the largest consumers of power in a nursery and should be plugged into their own socket and surge protector if available. (6.1 & 6.2) Radiant warmers typically draw too much power to be used with small-scale solar systems. In most cases, the cost (both financially and energetically) to run radiant warmers during a power cut prevents them from being used with backup power.

WARD LOCATION

Radiant warmers should be placed against a wall with the power cable/stand facing the wall and control panel facing the middle of the nursery room. (6.3) Warmers should be away from any windows to avoid air currents disrupting heat radiation. Windows are preferably kept closed.

USER PREVENTIVE MAINTENANCE

Preventive maintenance should be conducted weekly and should include:

  1. Test the heating elements and temperature probe:
  2. Test the power loss alarm: while the radiant warmer is plugged in and turned on, turn off the power at the wall socket. An alarm should sound. If it does not sound, contact your maintenance department.

Troubleshooting & Repair

Although users are not responsible for repairing their devices, there are steps that may be taken to troubleshoot first-line errors that may occur before contacting maintenance or engineering support.

1 The radiant warmer does not turn on
  • Check that the power cable is firmly plugged in to the back of the device. Check that the power switch on the back of the device is turned on.
  • If the power switch is turned on and the power cable is firmly plugged in but the device is still not turning on, try replacing the power cable.
  • Should the radiant warmer still not turn on, contact your maintenance department.

2 The radiant warmer is turning on, but is not heating
  • Check the radiant warmer settings to ensure that heating is turned on: If in manual, the heating settings may be set to 0%.(7.1a) Make sure that the heater output is set to a number above 0%.(7.1b)
  • If the power switch is turned on and the power cable is firmly plugged in but the device is still not turning on, try replacing the power cable.
  • If the heating settings are turned on & the radiant warmer is still not heating, contact your maintenance department.


3 The radiant warmer is turning on, but the temperature probe is not reading the patient’s temperature
  • Hold the temperature probe in the palm of the hand and watch temperature reading on control panel to see if the temperature changes to a reasonable body temperature.
  • If the temperature does not change or there is a “Probe alarm” displayed, replace the probe with a spare or contact your maintenance department.

References

  1. Mullany, L. C. et al. Hypothermia and associated risk factors among newborns of southern Nepal. BMC Pediatrics 8, 13 (2010).
  2. Laptook, A. R. et al. Admission Temperature and Associated Mortality and Morbidity among Moderately and Extremely Preterm Infants. The Journal of Pediatrics 192, 53-59.e2 (2018).
  3. Miller, S. S., Lee, H. C. & Gould, J. B. Hypothermia in very low birth weight infants: distribution, risk factors and outcomes. Journal of Perinatology 31, S49–S56 (2011).
  4. Perlman, J. M. et al. Part 7: Neonatal Resuscitation: 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations (Reprint). PEDIATRICS 136, S120–S166 (2015).
  5. Essential elements of obstetric care at first referral level. (World Health Organization, 1991).
  6. Curless MS, Ruparelia CS, Thompson E, and Trexler PA, eds. 2018. Infection Prevention and Control: Reference Manual for Health Care Facilities with Limited Resources. Jhpiego: Baltimore, MD.
  7. Sharma, G. Infection Prevention and Control at Neonatal Intensive Care Units. 134.
  8. Bouchama, A. & Knochel, J. P. Heat stroke. N. Engl. J. Med. 346, 1978–1988 (2002).
  9. Bynum, G. D. et al. Induced hyperthermia in sedated humans and the concept of critical thermal maximum. Am. J. Physiol. 235, R228-236 (1978).
  10. Bytomski, J. R. & Squire, D. L. Heat illness in children. Curr Sports Med Rep 2, 320–324 (2003).
  11. Naughton, G. A. & Carlson, J. S. Reducing the risk of heat-related decrements to physical activity in young people. J Sci Med Sport 11, 58–65 (2008).
  12. Falk, B. Effects of thermal stress during rest and exercise in the paediatric population. Sports Med 25, 221–240 (1998).
  13. Ringer, S. A. Core Concepts: Thermoregulation in the Newborn, Part II: Prevention of Aberrant Body Temperature. NeoReviews 14, e221 (2013).