High frequency band limits in spectral analysis of heart rate variability in preterm infants.

OBJECTIVES: The current study aims to assess different high-frequency (HF) band power calculations based on different frequency bandwidth values, and compare them with the time domain the root mean square of successive RR differences (RMSSD) value in preterm infants. METHODS: At week 32, electrocardiogram (ECG) and breathing rate (BR) were recorded for 24 h on 30 preterm infants born between 28 and 32 weeks. The recording held in the neonatal intensive care unit without any interruption of routine. RESULTS: The median 24 h BR was 40-78 breaths per minute. The RMSSD was highly and positively correlated with frequency bands that were based on each preterms BR range, or on a constant frequency with band limits of 0.4-2 Hz. CONCLUSIONS: At week 32, HF band Hz limits should be calculated based on each child's breathing rate, generally between 0.4 and 2 Hz.

Heart rate and heart rate variability parameters at rest, during activity and passive standing among children with cerebral palsy GMFCS IV-V.

AIMS: To describe and compare heart rate (HR) and heart rate variability (HRV) at rest, during active movements and passive standing among children with cerebral palsy (CP), with Gross Motor Function Classification System (GMFCS) levels IV and V, and to describe the association between daily physical activity and HRV. METHODS: Thirty children with CP were included aged 6-12 years. HR and HRV parameters were recorded during rest, during Gross Motor Functional Measure (GMFM) assessment, during two minutes of repeated performance of the highest activity achieved in the GMFM, and during passive standing. Parents were asked to inform about any habitual physical activities their child participates outside school in the previous 4 months. RESULTS: Children with GMFCS IV increased their HR and reduced HRV values during the GMFM assessment, the repeated task and during passive standing, while no such effect was noted among children with GMFCS V. Children participated in a limited range of activities with a median frequency of three times a week (range 1-6 times), with insignificant differences between GMFCS levels. No significant differences were noted in HR or HRV parameters based on activity level. CONCLUSIONS: Only children with GMFCS IV responded to passive and active manipulation of the cardiac autonomic system. This may imply that the HR autonomic regulation system has an opportunity to be influenced by training in this group of children.