In this section
Temperature control in the infant is a critical physiological function that is strongly influenced by physical immaturity, illness and environmental factors. Both hypothermia and hyperthermia should be avoided as they can have severe adverse outcomes and can increase morbidity and mortality. Maintaining correct body temperature maximizes metabolic efficiency, decreases oxygen use, protects enzyme function and decreases caloric expenditure.
The aim of this guideline is to provide staff with knowledge regarding thermoregulation in the preterm infant. This will optimise health and wellbeing outcomes by providing care that is research based, clinically effective and safe.
Modes of Heat Loss:
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.Cold Stress:Cold Stress is a cascade of physiological events caused by the infant’s use of chemically mediated thermogenesis in 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 BAT, which is described here.Metabolism of Brown Adipose Tissue:Within the metabolism of BAT during states of cold stress, a cascade of metabolic and chemical reactions are initiated and maintained, which result in a number of detrimental physiological changes (depicted below).
Environmental Humidity: Infants born at <30 weeks gestation have an immature epidermis and stratum corneum and are at an increased risk of transepidermal water loss (TEWL). The use of environmental humidity assists to reduce TEWL and in turn supports temperature regulation, fluid and electrolyte management and skin integrity (See Environmental Humidity Guideline).
Perspex cots are preferential in the preterm infant to prevent heat loss due to their enclosed design. However, limitations pertaining to access and procedures do exist and in this case the patient may need to remain in an incubator at low temperature for longer if they cannot maintain their temperature in a regular paediatric metal cot.
Axilla Temperature is taken thereafter the initial rectal temperature.
Skin Probe Temperature measures the infant’s skin temperature when utilising servo control and assists the incubator in adjusting heat output based on the ‘set’ skin temperature and the ‘actual’ skin temperature.
Temperature Outside of Normothermic Range
Within the flowsheets of EMR, temperatures can be documented within the ‘observations’ section with the method of temperature selected from the drop down options below. 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.
Manual Control:This requires one constant environmental temperature to be set. This mode is used in the more stable late preterm infant where minute adjustments are not required. Servo Control:This is the preferred setting used to nurse preterm infants as it automatically and constantly adjusts the incubator heat output according to the skin temperature set and the skin temperature measured from the skin temperature probe. The infant’s skin temperature is continuously monitored via the temperature skin probe. Cessation of servo control can be considered when the infant:
When transferring an infant from servo to manual control, set the air temperature at the same temperature that was delivered over the previous 24 hours. If there have been significant fluctuations, consider if the infant is ready to be transitioned to manual control.Weaning Incubator Temperature:Weaning of the incubator temperature may take place under a number of circumstances and is to be considered by the bedside nurse when an infant is being nursed with the Manual Control setting. Circumstances may include environmental, physiological and maturity.
Transfer to an Open Cot:Preterm infants can be transferred to an open cot once they have met the following criteria:
Once the preterm infant meets the above criteria and discussion has taken place between the bedside nurse, medical team & AUM, the infant may be transferred to an open cot by using the following steps as a guide:
The evidence table for this guideline can be viewed here.
Please remember to read the disclaimer.
The development of this nursing guideline was coordinated by Alanah Crowle, RN, Butterfly Ward, and approved by the Nursing Clinical Effectiveness Committee. Updated November 2016.