non-invasive electrophysiological assessment in evaluating for intra uterine growth restriction

Background and Aim : The NIFECG is an emerging technology which obtains fetal heart rate (FHR)information from the maternal abdomen and provides real time visualization of the fetalelectrophysiological process. The signal is obtained using surface electrodes, similar to those utilized inadult electrocardiography. Previously, technological limitations had been the main limiting factor to itsuptake. The predominant issues encountered were in relation to the low signal-to-noise ratio (SNR) of thefetal electrocardiogram (FECG) signal [due to its low electrical amplitude (1/50th that of the maternal ECGsignal)] which is buried within the large maternal ECG (MECG) signal and background noise and theattenuation posed to signal conduction by the vernix caseosa. Nevertheless, recent signal processingtechniques and data processors have sparked a renaissance into its utility which has helped develop moreconsistent non-invasive acquisition methods.Methods : For the following review, a systematic search of peer reviewed literature was performed,searching PUBMED, Ovid MEDLINE and EMBASE from 2012 to present. The outcomes of interestincluded NIEA (Non-invasive electrophysiological assessment) parameters [P wave duration, PR interval,QRS duration, QT interval, T/QRS ratio, short term variability (STV) and long term variability (LTV)].Results : studies were identified as suitable for inclusion. The utility of NIEA in particular, QRS and QTduration, T/QRS ratio, STV and PRSA analysis displayed utility and merit further consideration inevaluating for IUGR. Issues identified in the review were in relation to variances in definition of IUGR.Conclusion : The findings of this review however, suggest that there may be a role for these techniques inimproving the detection of IUGR. This is hypothesized to be in relation to the cardiovascular and autonomicadaptations which occur with IUGR fetuses. In particular, the QRS and QT duration, T/QRS ratio, STVand PRSA analysis (LTV) show promise in augmenting the detection algorithms.

Keywords:

Fetal electrocardiogram , Intra uterine growth restriction