Key result
Phonocardiography and abdominal electrocardiography showed high correlation for mean intervals (r=0.98), but temporal and spectral FHRV indices differed significantly (P<0.05) above 0.28Hz.
Why the study?
Does phonocardiography provide foetal heart rate variability indices equivalent to abdominal electrocardiography in pregnant women?
Observational (n=15)
Does phonocardiography provide foetal heart rate variability indices equivalent to abdominal electrocardiography in pregnant women?
Effect estimate: r=0.98
p-value: p=< 0.05
Temporal and spectral foetal heart rate variability indices derived from phonocardiography differ significantly from those derived from abdominal electrocardiography, particularly at higher frequencies.
Phonocardiography FHRV indices differ from abdominal ECG above 0.28 Hz; leaves open equivalence for fetal monitoring and requires prospective validation.
The agreement of the phonocardiographic method to provide foetal heart rate variability (FHRV) indices equivalent to those derived from abdominal electrocardiography was tested. 15 pregnant women were recruited in order to obtain antepartum foetal phonocardiograms and abdominal electrocardiograms three minutes long. From the respective sound (SS) and electric (RR) time series, typical temporal and spectral indices of FHRV were computed and compared. Means of the SS and RR intervals were not significant (P> 0.05) and these showed a correlation r=0.98. However, the temporal indices, P(TOT), HF and LF/HF presented differences (P< 0.05), since SS values were higher. Spectral coherence decreased below 0.5 for frequencies above 0.28+ 0.07 Hz, where bands resembling maternal and foetal breathing movements were noted. Particularly above 0.28Hz, temporal and spectral FHRV indices derived from phonocardiography and electrocardiography show differences. Quality of the signal, processing techniques, and maternal and foetal respiratory factors could account to explain these.
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Ortiz et al. (2002) conducted an observational in Pregnancy (n=15). Phonocardiography vs. Abdominal electrocardiography was evaluated on Foetal heart rate variability (FHRV) indices (r=0.98, p=< 0.05). Phonocardiography and abdominal electrocardiography showed high correlation for mean intervals (r=0.98), but temporal and spectral FHRV indices differed significantly (P<0.05) above 0.28Hz.
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