Spectral analysis of time series of events: effect of respiration on heart rate in neonates

Certain types of biomedical processes such as the heart rate generator can be considered as signals that are sampled by the occurring events, i.e. QRS complexes. This sampling property generates problems for the evaluation of spectral parameters of such signals. First, the irregular occurrence of he...

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Bibliographic Details
Published in:Physiological measurement 2009-01, Vol.30 (1), p.43-61
Main Authors: van Drongelen, Wim, Williams, Amber L, Lasky, Robert E
Format: Article
Language:English
Subjects:
Algorithms
Computer Simulation
Heart Rate
Humans
Infant, Newborn - physiology
Models, Cardiovascular
Respiration
Signal Processing, Computer-Assisted
Time Factors
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Summary:Certain types of biomedical processes such as the heart rate generator can be considered as signals that are sampled by the occurring events, i.e. QRS complexes. This sampling property generates problems for the evaluation of spectral parameters of such signals. First, the irregular occurrence of heart beats creates an unevenly sampled data set which must either be pre-processed (e.g. by using trace binning or interpolation) prior to spectral analysis, or analyzed with specialized methods (e.g. Lomb's algorithm). Second, the average occurrence of events determines the Nyquist limit for the sampled time series. Here we evaluate different types of spectral analysis of recordings of neonatal heart rate. Coupling between respiration and heart rate and the detection of heart rate itself are emphasized. We examine both standard and data adaptive frequency bands of heart rate signals generated by models of coupled oscillators and recorded data sets from neonates. We find that an important spectral artifact occurs due to a mirror effect around the Nyquist limit of half the average heart rate. Further we conclude that the presence of respiratory coupling can only be detected under low noise conditions and if a data-adaptive respiratory band is used.
ISSN:0967-3334
1361-6579
DOI:10.1088/0967-3334/30/1/004