The utility of phase rectified signal averaging in diagnosing fetal distress

Abstract

Objectives Fetal heart rate variability is known as a marker of fetal wellbeing. The variables of phase rectified signal averaging – acceleration capacity and deceleration capacity (AC/DC) – were found to have a significant prognostic value in fetal growth restriction (FGR). Methods A total of 168 pregnant women at 26–28 weeks were examined. The patients with AGA fetases (N = 36) were enrolled in group 1. eFGR without fetal distress (N = 64) were group 2. eFGR with fetal distress (N = 68) = group 3. We used Cardiolab Babycard equipment (the "KhAI Medica" Scientific Research Centre, Ukraine) to non-invasive fetal electrocardiography. Fetal distress was diagnosed via Doppler ultrasound in case of the RD UA, absent A-wave in the DV, and umbilical vein pulsations.The results thus obtained were analysed with an ANOVA test. The significance was set at p-value <0.05. The correlations coefficients were estimated with Spearman's test. Results The maximally decreased AC/DC values were in Group 3 (p < 0.05). The variables of phase rectified signal averaging were lower in Group 2 than in Group 1 (p < 0.05) but higher than in Group 3 (p < 0.05). Thus, the delayed neurological maturation and the autonomic malfunction could be the reasons for fetal distress in FGR. The considerable correlation was detected in the appropriate to gestational age fetuses (R = 0.64, p < 0.05). In Groups 2 and 3, the force of correlation was almost similar (respectively, R = 0.62, p < 0.05; R = 0.68, p < 0.05). Therefore, AC/DC is a prospective marker for the detection of fetal compromise. This result was supported by a significant correlation in the pair “AC/DC vs umbilical blood pH” in all groups. The coefficients of correlation were: R = 0.70, p < 0.05; R = 0.68, p < 0.05; R = 0.72, p < 0.05 in Group 1, 2 and 3, respectively. Conclusions Fetal AC/DC variable is a sensitive tool for the detection of fetal distress in FGR.