Mathematical modelling of thermoregulation processes for premature infants in closed convectively heated incubators

The low-weight newborns and especially the premature infants have difficulty in maintaining their temperature in the range considered to be normal. Several studies revealed the importance of thermal environment and moisture to increase the survival rate of newborns. This work models the process of heat exchange and energy balance in premature newborns during the first hours of life in a closed incubator. In addition, a control problem was proposed and solved in order to maintain thermal stability of premature newborns to increase their rate of survival and weight. For this purpose, we propose an algorithm to control the temperature inside the incubator. It takes into account the measurements of the body temperature of a premature newborn which are recorded continuously. We show that using this model the temperature of a premature newborn inside the incubator can be kept in a thermal stability range

Considerations for Measuring and Monitoring Thermal Stress During Infancy

The present thesis builds upon existing evidence and public-facing recommendations in the field of infant thermoregulation, specifically in scenarios where infants are nursed under radiant warmers in the neonatal intensive care unit (NICU), and in outdoor settings, where infants can be exposed to heat stress when transported in strollers during hot summer weather. The experimental study presented in Chapter 3 aimed to compare the suitability and level of agreement of using skin temperature measured on the neck over the carotid artery (Tneck), with the traditional method used currently (Tfeedback), as a surrogate non-invasive measure of core (rectal) temperature (Trec) in infants nursed under a radiant warmer. The aim of the experimental study described in Chapter 4 was to further optimize the non-invasive measurement of core temperature in NICU settings. Specially, the aim was to compare the suitability and level of agreement of potential zero heat flux skin contact temperature sites – specifically the lower back region (Tback) when an infant is lying in supine, and on the chest (Tchest) when an infant is lying in prone – with the traditional method used currently (Tfeedback) as a surrogate measure of core temperature measured rectally (Trec) in infants nursed under a radiant warmer. Finally, the experimental investigation in Chapter 5 sought to empirically determine the cooling efficacy of several low-cost stroller configurations to alleviate heat stress experienced within an infant stroller carriage in hot and moderately humid weather conditions. Together, the experimental chapters of this thesis provide empirical data which may help inform the development of improved evidence-based guidance and policy to help protect potentially vulnerable infants against the effects of thermal stress during the earliest stages of life