ASSESSMENT OF SPONTANEOUS BAROREFLEX SENSITIVITY IN NEONATES

Aims-To determine whether it is possible to assess baroreflex sensitiv ity in neonates by studying only spontaneous variations in systolic bl ood pressure and heart rate. Methods-ECG and non-invasive blood pressu re signals were continuously studied in 14 preterm neonates (term 29-3 2 weeks) and five term neonates (term 40-41 weeks). Non-invasive blood pressure measures were obtained using a Finapres placed around the ch ild's wrist. Both signals (EGG and blood pressure), sampled at 400 Hz, were digitised by an A/D converter and stored in a binary mode on mag netic disk. An inhouse software QRS detection algorithm was used to de fine R peaks of the QRS complexes with an accuracy greater than 2 ms. Four 4 minute periods were recorded in each infant. The slope of the l inear regression of RR intervals versus systolic blood pressure was ca lculated in each period and the mean value of the four slopes was then considered as the index of baroreflex sensitivity (in ms/mm Hg) in ea ch neonate. Results-Spontaneous baroreflex sensitivity was lower in pr eterm neonates than in term neonates (mean(SD): 4.07 (2.19) ms/mm Hg v s 10.23 (2.92) ms/mm Hg). Conclusion-Baroreflex sensitivity can be ass essed in term and preterm neonates by studying spontaneous variations in systolic blood pressure alone. This method could be useful for stud ying the ontogeny of baroreflex sensitivity and might therefore provid e information about the maturation of the autonomic nervous system.