The present study was performed to measure the vasoregulatory reactions to dynamic changes in local skin temperature during open bed phototherapy. Periodic thermal stimulation using warm and cool air currents was applied to the skin of ten term infants with physiological jaundice, before and during open bed phototherapy. The reactivity of skin blood flow (SBF) and heart rate was measured using laser Doppler flowmetry and power spectral analysis. The baseline SBF increased significantly by 70% (P = 0.008) during phototherapy without any significant change in skin or rectal temperature. Before phototherapy, the rhythmic (0.08 Hz) thermal skin stimulation increased the oscillations of SBF (from 89 +/- 26 au to 213 +/- 37 au, P = 0.02) at the stimulation frequency band. This response was further increased (P = 0.03) during phototherapy (from 198 +/- 54 au to 658 +/- 115 au, P = 0.004). Phototherapy increased SBF in icteric otherwise healthy neonates. The cutaneous vasodilatation augments the cardiovascular responsiveness to thermal stimulation. These results suggest that open bed phototherapy does not inhibit the cardiovascular responsiveness to local thermal skin stimulation in healthy term infants.
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