For a better understanding of thermoregulation in premature infants≤28 weeks of gestation: infrared thermography (IRT) and photoplethysmography imaging (PPGI) in a hybrid camera model as non-contact measuring methods.

BACKGROUND

Infrared thermography (IRT) reveals significant temperature differences between central and peripheral body regions in preterm infants, despite stable core temperature. This suggests active thermoregulation. Photoplethysmography imaging (PPGI) enables contactless, spatially resolved perfusion measurement.

METHODS

Ten preterm infants [GA at birth: 26 weeks (24-28); postnatal age: 35 days (12-62); weight: 960 g (670-1290)] were examined in prone (PR) and supine (SU) positions in the incubator. PPGI (amplitude) and IRT were recorded from arm, head, and thorax every 10 s for 5 min per position, with a 10 min washout. Heart rate (ECG) was monitored. Lin's concordance correlation coefficient was calculated.

RESULTS

Central regions were ~1°C warmer than peripheral regions (p<0.05), independent of position. PPGI amplitude remained constant (< 1.0; p>0.05) in all regions, with no correlation between IRT and PPGI (p>0.05).

CONCLUSION

In preterm infants, local perfusion remains stable despite regional temperature differences, suggesting that skin temperature is influenced more by passive heat diffusion than by perfusion changes.