Skin blood flow oscillations respond more effectively to rhythmic thermal stimulation than to continuous or periodic breathing in newborn infants.

Effect of continuous (n = 30) and periodic (n = 5) breathing on forehead skin blood flow (SBF) oscillations was studied in healthy 3-day-old preterm and term infants. Femoral SBF was measured in 10 of the term infants during continuous breathing. Respiratory and SBF signals were analysed by power spectrum during the control period. The signal analysis was repeated during rhythmic thermal stimulation which was applied to the skin of each infant in order to synchronise spontaneous SBF oscillations. During the control period, the forehead and femoral SBF of all the studied infants oscillated at frequencies corresponding to the frequency of regular continuous breathing. External thermal stimulation decreased these high-frequency oscillations of forehead SBF in both preterm and term infants. Oscillations in femoral SBF of term infants remained unchanged. During periodic breathing, the spontaneous forehead SBF oscillation was synchronised to the frequency of respiratory amplitude variation. Despite periodic breathing, thermal stimulation was able to resynchronise the SBF oscillation to the stimulation frequency in 4/5 infants. Forehead SBF oscillates at the frequency of both continuous and periodic breathing in preterm as well as in term infants on postnatal day 3. Rhythmic thermal stimulation synchronises SBF and affects SBF more effectively than continuous or periodic breathing. These results suggest functional neural control of cutaneous vasculature at birth.