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 forehe ad 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 analy sis was repeated during rhythmic thermal stimulation which was applied to the skin of each infant in order to synchronise spontaneous SBF os cillations. During the control period, the forehead and femoral SBF of all the studied infants oscillated at frequencies corresponding to th e frequency of regular continuous breathing. External thermal stimulat ion decreased these high-frequency oscillations of forehead SBF in bot h preterm and term infants. Oscillations in femoral SBF of term infant s remained unchanged. During periodic breathing, the spontaneous foreh ead SBF oscillation was synchronised to the frequency of respiratory a mplitude variation. Despite periodic breathing, thermal stimulation wa s able to resynchronise the SBF oscillation to the stimulation frequen cy in 4/5 infants. Forehead SBF oscillates at the frequency of both co ntinuous 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. Th ese results suggest functional neural control of cutaneous vasculature at birth.