Features of autonomic circulatory regulation in newborns during early neonatal adaptation

Objective: to compare the features of autonomic regulation of blood circulation in newborns of different gestational ages on the basis of heart rate variability (HRV) and photoplethysmographic waveform (PPWF). Material and methods. Fifty neonates were included in the study: group 1 (n=20; gestational age 37-42 weeks) — with physiological course of early neonatal adaptation period; group 2 (n=30; 34-42 weeks) with pathological course of early neonatal adaptation period: 2a (n=15; 37-42 weeks) — infants with birth weight >2500, and 2b (n=15; 34-36.6 weeks) — infants with birth weight <2500 g. All infants underwent synchronous recording of electrocardiography, pho-toplethysmography, and respiration signals using a Reacor-T multichannel biological signal recorder. Spectral analysis of HRV and PPWF was performed, and the strength of synchronization between low-frequency oscillations in HRV and PPWF (S-index) was assessed. Results. Infants in subgroup 2b had higher values of HR (p=0.004) and two HRV indices in the time domain: RMSSD — 26.6 (p=0.005) and PNN50 — 7.65 (p=0.002), relative to infants in the other groups. S-index was low in all infants (14.4-18.5). Conclusion. Newborns are characterized by functional immaturity of sympathetic autonomic regulation of blood circulation and predominance of sympathetic and baroreflex influences on cardiac function. In the regulation of peripheral blood flow in newborns of group 1, respiratory influences over sympathetic influences prevail, and in infants of group 2 — sympathetic influences.