Introduction
The purpose of this study was to investigate some of some of the profound adverse effects of SDB (sleep disordered breathing) in a sample made of a large population base and clinical children sample. The major area of focus was the Cardiac Autonomic Modulation and the effect that Sleep Disordered Breathing has on this functionality in children.
Purpose
It is common knowledge that an apnea episode is usually accompanied by a characteristic pattern of fluctuations in heart rate. Studies on adults conducted by several researchers seem to indicate that there is a clear relationship between SDB and lower HRV. This ultimately indicates that individuals with apnea have an impaired or a weakened cardiac autonomic modulation. Low HRV has also been associated with incident cardiovascular diseases. However according to Laio et etal (2010) “the effect that SDB has on the cardiac autonomic control in children is relatively unknown”.
This study was therefore designed to find out if there is an association between SDB and impaired HRV indices and therefore indicating cardiac autonomic modulation impairment in a normal population based sample and another clinical based children sample (Liao et etal 2010).
Method
The population utilized in this study came from PSCC (Penn State Child Cohort which is actually a study based on population that investigates the correlates and prevalence of SDB in small children. The study was evaluated and reviewed by that Penn State University College of Medicine Institutional Review Board and also the GCRC review board. In addition and every participant and their guardians or parents acknowledged full consent before the study was initiated (Liao et etal 2010). The sample was composed of a population based sample comprising 700 individuals and a clinical sample of 34 children who had previously been diagnosed with SDB. The SDB was defined along the parameters of Apnea Hypnea Index (AHI) hour over a night of polysomnograhy. Heart Rate Variability (HRV) of was used to measure the cardiac autonomic modulation by analyzing the RR beat to beat interval data that had been collected in the polysomnograhy. A second order polynormial model was used to remove the usually slow and non-stationary movements of the HRV signal. This helped to produce HRV data for a total of 616 patients. From this analysis, several, it became possible to calculate some frequency domain indices including: Low Frequency power, High Frequency Power, RR Interval standard deviation and the Mean Heart rate. Other variables involved in the investigation included sex, race, snore status, sleep efficiency and BMI 9 (Liao et etal 2010).
Results
The results were recorded and tabulated. It was found that the mean sleep disorder (SD) age was actually 21 months with 25% non white and 49% male. There was the presence of AHI in 73% of the population and no SDB, 25% had mild SDB while 1.2% had moderate SDB. It was also found that among those individuals with moderate SDB, “the means of HRV- HF power were considerably lower than those of children without SDB while the trend was vice versa for the LF power to the HF power ratio (LF/HF)” (Liao et etal 2010).
Discussion
In the young children sample, there is a low prevalence of moderate SDB in children (AHI ≥5) and the actual figure is 1.2%. On the other hand, the mild SDB prevalence is relatively high at 25.5% (Liao et etal 2010). The most critical finding of this study is the considerable HRV indices decrease in children not having SDB. THE finding is supportive of the initial study thesis that there is a significant association between moderate SDB and impaired HRV profile particularly in the weaker parasympathetic modulation and sympathetic overflow direction.
Conclusion
The main conclusion that can be drawn from the results of this study is that SDB in young and healthy children as well as in clinical patients is to a huge part associated with impaired or weakened cardiac autonomic modulation. This means that there is weak parasympathetic modulation and sympathetic overflow, which can contribute to increased risks of heightened cardiac associated events in individuals with SDB even before they attain the “high risk age”
Reference
Liao, D., Li, X., Rodriguez-Colon, S. M., Liu, J., Vgontzas, A. N., Calhoun, S., & Bixler, E. O. (2010). Sleep-disordered breathing and cardiac autonomic modulation in children. Sleep Medicine, 11(5), 484-488.
