Newborns have thermoregulatory mechanisms that differ from those of adults. Instead of producing heat through shivering, newborns primarily rely on non-shivering thermogenesis by the brown adipose tissue. The development of this thermogenic tissue starts around the 26th gestational week and continues until shortly before birth, after which no further growth occurs. As a result, premature infants, who have less developed brown fat, are more prone to reduced heat production and are at higher risk for hypothermia. There are few human studies examining the thermoregulatory differences and mechanisms between full-term and premature neonates, and the findings remain inconclusive.
In this study, the investigators aim to conduct a prospective, observational research. Researchers will compare body temperature, brown adipose tissue activity, and specific plasma markers between full-term and premature neonates in insensive care units and during elective surgeries.
For Substudy 1: Patients admitted to the Neonatal Intensive Care Unit at the University of Pécs, Department of Obstetrics and Gynaecology (premature infants or those in neonatal intensive care).
For Substudy 2: Patients under 2 years of age undergoing elective surgery lasting more than 30 minutes at the University of Pécs, Department of Paediatrics.
For both substudies: Written consent for participation in the study has been provided by the patient's parent, guardian, or legal representative.
For both substudies: If the patient cannot be mobilized (e.g., during the post-operative phase of abdominal or thoracic surgery; presence of chest tubes for pneumothorax or other reasons; hemodynamic instability; need for continuous electrocardiogram (ECG) monitoring; or use of an external pacemaker).
The patient's parent, guardian, or legal representative does not consent to the study or withdraws their consent at any point.
For Substudy 2: if the patient is older than 2 years.
Study population consist of randomly chosen preterm and full-term neonates.
Cohort
Prospective
Not listed
Temperature data from the back of neonates revealing brown adipose tissue activity
Primary objective (Primary endpoint): The thermogram analysis may reveal reduced brown adipose tissue activity in preterm infants, which could contribute to their increased susceptibility to hypothermia during surgeries and intensive care. The temperature values of the head, brown fat, and trunk will be recorded in degrees of Celsius (°C) with thermal imaging. Their difference (e.g., brown fat temperature minus trunk temperature) will be used as a measure of brown fat activity also expressed in °C.
Concentration and count of special laboratory parameters in connection with thermogenesis in neonates
Secondary objective (Secondary endpoint): Blood test parameters of the newborns will be determined by the accredited Medical Testing Laboratory at the Clinical Centre, University of Pecs. These include blood cell counts \[red blood cells (T/l), white blood cells (G/l), and platelets (G/l)\], hemoglobin (g/l), hematocrit (%), glucose (mmol/l), bilirubin (µmol/l), thyroid hormones (mIU/l), urea (µmol/l), creatinine (µmol/l), CRP (mg/l), AST (IU/l), ALT (IU/l), GGT (IU/l), LDH (IU/l), PCT (0,5 ng/ml). They will be used to assess correlations between brown fat activity (see Primary Outcome Measure) and blood levels of a given blood parameter.
Blood cell counts
Level of red blood cells in T/l, white blood cells in G/l, and platelets in G/l.
Hemoglobin level
Hemoglobin level in g/l
Hematocrit level
Hematocrit level in %.
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