Time structures in the development of children

Objective: The study investigates circaseptan and circadian changes in blood pressure and heart rate of newborns. Materials and methods: Long-term oscillometric blood pressure and heart rate monitoring at 30-min intervals was applied using an automatic sphygmomanometer on 86 premature babies. All babies were cared for in the intensive care unit of the Teaching Hospital, Brno, Czech Republic. Babies were monitored in continuous light of 201.3 ± 35.6 (mean ± SD) Lux. They were fed every 3 hours through an esophageal tube or by continuous parenteral infusion for 6 weeks. The 86 premature babies (850 to 3250 g BW) were seriously ill; 27 died later; 12 of them were diagnosed as having intracranial hemorrhage. The values of systolic blood pressure (SBP), mean arterial pressure (MAP), diastolic blood pressure (DBP) and heart rate (HR) were processed by spectral analysis and Halberg's cosinor. Results: The autocorrelation functions and power spectral densities of blood pressure and heart rate, computed for each newborn baby, yielded statistically significant (p<0.05) oscillations with frequencies of one cycle in 5 to 10 days (in the circaseptan range) either for HR, SBP, MAP or DBP in all neonates (100%). Cosinor analyses showed that the circaseptan component in blood pressure and heart rate was more prominent than the circadian variation. Conclusion. The circaseptan rhythm in blood pressure and heart rate is likely endogenous, determined in part by nature rather than only by culture. Similar results were obtained at other geographic locations.