Spectral and Time-Domain Analyses of Heart-Rate Variability in Children with Severe Upper Airway Obstruction

Objective: Heart rate variability (HRV) is a noninvasive index of neural activity of the heart. This study assessed the heart-rate variability response in children with severe upper airway obstruction. Material and Methods: A prospective trial was carried out in 15 children with severe adenoid and/or tonsil hypertrophy, compared to 15 age matched healthy children in order to attempt to relate such changes. Frequency domain measurements of the high and low frequency bands and the ratio low frequency/high frequency were derived from Holter electrocardiography recordings and computed by Fast Fourier analysis for five minute intervals. Time domain measurements were derived from 24 hour Holter recordings. Results: All spectral analysis of heart rate variability was altered in both preoperative and postoperative (three months after the operation) recordings compared to the control group. In both groups, time domain indices were significantly lower compared to the control group. Mean R-R values were sig- nificantly reduced in pre and postoperative groups compared with control group, with the night time mean R-R values being signifi cantly lower (p 0.05). These results indicate the increased frequency domain parameters in two groups. Conclusion: In this study, patients demonstrated altered volume loads and autonomic response. Further studies are needed to assess when such cardiac findings normalize upon relief of the upper airway obstruction.