tFoetal heart rate (FHR) variability is known to be a very important feature in the diagnosis of foetal well-being. Despite its clinical importance and the widespread use of foetal monitoring, a standard definitionof FHR variability (FHRV) and an agreement concerning the methodologies to be employed in its evalu-ation are still lacking. Often, FHRV is computed in tracts of FHR signals in which both accelerations anddecelerations are absent, thus making it very difficult to assess it for signals with several and closelyspaced events of this kind.In this work, we propose an automated method for estimating the FHRV signal, defining it as thedifference between the FHR signal and the floatingline, where the latter is the imaginary line that followsaccelerations and decelerations, taking into account the frequency characteristics of these events.We tested the software developed for this purpose on both simulated and real FHR signals (sets of 50signals). In the case of simulated signals, the average value of the mean square error vector between thesimulated floatingline and that estimated was only 0.04 bpm2. In the case of real signals, however, inabsence of a reference gold standard, the estimated floatinglines were visually assessed by a team of fiveexpert obstetricians who judged them matching to the definition in 96% of cases.As regards the evaluation of FHRV, using the simulated FHR signals, we compared the estimated valueswith the reference values of short term variability (STV) and sympathovagal balance (SVB), two verysignificant parameters employed in computerised foetal monitoring, and obtained an error lower than1.5% for the STV index, and an underestimation of the SVB index with an error of about 4.5%.Finally, we compared the proposed method for the estimation of the floatingline with more traditionalfilters (moving average and FIR with Hamming window) which showed, on average, a worse performance(quantified by mean square errors up to five times higher).
Evaluation of floatingline and foetal heart rate variability
Romano M;
2018-01-01
Abstract
tFoetal heart rate (FHR) variability is known to be a very important feature in the diagnosis of foetal well-being. Despite its clinical importance and the widespread use of foetal monitoring, a standard definitionof FHR variability (FHRV) and an agreement concerning the methodologies to be employed in its evalu-ation are still lacking. Often, FHRV is computed in tracts of FHR signals in which both accelerations anddecelerations are absent, thus making it very difficult to assess it for signals with several and closelyspaced events of this kind.In this work, we propose an automated method for estimating the FHRV signal, defining it as thedifference between the FHR signal and the floatingline, where the latter is the imaginary line that followsaccelerations and decelerations, taking into account the frequency characteristics of these events.We tested the software developed for this purpose on both simulated and real FHR signals (sets of 50signals). In the case of simulated signals, the average value of the mean square error vector between thesimulated floatingline and that estimated was only 0.04 bpm2. In the case of real signals, however, inabsence of a reference gold standard, the estimated floatinglines were visually assessed by a team of fiveexpert obstetricians who judged them matching to the definition in 96% of cases.As regards the evaluation of FHRV, using the simulated FHR signals, we compared the estimated valueswith the reference values of short term variability (STV) and sympathovagal balance (SVB), two verysignificant parameters employed in computerised foetal monitoring, and obtained an error lower than1.5% for the STV index, and an underestimation of the SVB index with an error of about 4.5%.Finally, we compared the proposed method for the estimation of the floatingline with more traditionalfilters (moving average and FIR with Hamming window) which showed, on average, a worse performance(quantified by mean square errors up to five times higher).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
