Temperature measurement and thermoregulation in the term and preterm infant

Background Prevention of hypothermia is one of the basic tenets of effective neonatal care. Concerns about cold stress and its link to increased morbidity and mortality in neonates were first documented in 1907 (Budin 1907), but it was not until 1958 that Silverman et al. (1958) demonstrated the association between more effective temperature regulation and decreased mortality. Cold stress, or hypothermia, is known to result in complications such as an increased need for oxygen, difficult resuscitation, an increased incidence of disseminated intravascular coagulation (DIC), post delivery acidosis, delayed adjustment from foetal to newborn circulation, worsening respiratory distress syndrome, and increase morbidity from infection (Soll, 2008; Knobel, 2007). Unfortunately, hypothermia (temperature <36.5°C) remains a common finding in premature neonates following delivery, resuscitation, stabilisation and admission to the neonatal intensive care unit (NICU). During this period, body temperature is highly dependent on the environmental temperature and its surroundings. Predisposing factors for hypothermia, especially in the premature infant, include a large surface area to body mass ratio, wet at birth, skin immaturity, and prematurity. Evaporation, convection, conduction and radiation all participate in the frequently rapid fall in body temperature. Heat loss is the greatest in the first few minutes of life as infants are born wet into a relatively cool environment when compared to the uterus (Cramer et al., 2005; Soll, 2008). Given that the Townsville Hospital neonatal unit is set in a regional, tropical area that includes a high proportion of Indigenous Australians prone to preterm birth, and as preterm and low birth weight are more likely in rural and regional areas than in urban environments (AIHW, 2010), the need for an intervention to help improve admission temperature to the NICU and decrease heat loss at birth was considered important. The measurement of temperature is also an important part of the care of the neonate admitted to the NICU. Accurate temperature assessment enables early intervention and/or treatment as a change in body temperature can indicate the presence of infection or disorders of the thermoregulatory system. The necessity for regular observations such as temperature measurement does however require prolonged handling and disturbance. Finding ways to reduce the need to disturb the preterm neonate are essential. Study 1: In an attempt to decrease hypothermia at birth and on admission to the NICU the use of the plastic wrap in infants less than 30 weeks gestation was trialled. A randomised controlled trial was conducted. The study enrolled 92 infants < 30 weeks gestation. Randomisation concealment was by the use of sealed opaque envelopes. The infants' temperatures were assessed for two hours following admission to the NICU. Study 2: In order to try to reduce handling time in the neonatal population a study was conducted to assess the concordance of two alternative thermometers to the BD Digital thermometer, currently the thermometer of choice at The Townsville Hospital. Results study 1: The results of the study indicate an increase in admission temperature between intervention and control group (36.26°C versus 35.79°C), confirming that the application of the plastic wrap at birth increases admission temperature in infants born less than 30 weeks gestation. Results study 2: This study found that the BD digital and the SureTemp®Plus model 692 measurements showed moderately good agreement. The results confirm that the SureTemp®Plus model 692 thermometers can be used safely instead of the BD digital thermometer in term and preterm neonates. Non-thesis components of degree During the course of the degree a number of coursework requirements were completed. These subjects included literature review and research statistics subjects. In addition, a number of teaching and learning modules were developed on areas of neonatal specialist content. The four distance learning modules, currently in use at James Cook University and The College of Nursing, were written as part of the Doctoral Specialisation subjects (1 & 2) (see Appendix VIII and VIIII for an overview of the subjects). These subjects will be used to enhance the knowledge and skills of neonatal nurses, especially when hypothermia and hyperthermia are evident. Education opportunities for nurses working in specialised areas, such as the NICU, is important to ensure evidence based care is delivered in the area. Other work that contributes towards this portfolio is also included. During the course of the professional doctorate I gave five conference presentations and three local seminars, and presented four conference posters related to the neonatal specialty area. Copies of some of this work are also included in the Appendices.