Fetal Heart Rate Fragmentation.

Matilde Costa,Mariana Xavier,Teresa S Henriques,Inês Nunes

doi:10.3389/fped.2021.662101

Abstract

Intrapartum fetal monitoring's primary goal is to avoid adverse perinatal outcomes related to hypoxia/acidosis without increasing unnecessary interventions. Recently, a set of indices were proposed as new biomarkers to analyze heart rate (HR), termed HR fragmentation (HRF). In this work, the HRF indices were applied to intrapartum fetal heart rate (FHR) traces to evaluate fetal acidemia. The fragmentation method produces four indices: PIP-Percentage of inflection points; IALS-Inverse of the average length of acceleration/deceleration segments; PSS-Percentage of short segments; PAS-Percentage of alternating segments. On the other hand, the symbolic approach studied the existence of different patterns of length four. We applied the measures to 246 selected FHR recordings sampled at 4 and 2 Hz, where 39 presented umbilical artery's pH ≤ 7.15. When applied to the 4 Hz FHR, the PIP, IASL, and PSS showed significantly higher values in the traces from acidemic fetuses. In comparison, the percentage of “words” and showed lower values for those traces. Furthermore, when using the 2 Hz, only IASL, W0, and achieved significant differences between traces from both acidemic and normal fetuses. Notwithstanding, the ideal sampling frequency is yet to be established. The fragmentation indices correlated with Sisporto variability measures, especially short-term variability. Accordingly, the fragmentation indices seem to be able to detect pathological patterns in FHR tracings. These indices have the advantage of being suitable and straightforward to apply in real-time analysis. Future studies should combine these indexes with others used successfully to detect fetal hypoxia, improving the power of discrimination in a larger dataset.

Highlights

In the twentieth century, technical advances led to the development of continuous electronic monitoring of fetal heart rate (FHR) and uterine contraction (UC) signals, a technology known as cardiotocography (CTG) [1]
When applied to FHR, we found that the indices seem to detect pathological patterns in FHR tracings, such as those from acidemic fetuses
As the parasympathetic nervous system is more responsible for variations in short-term heart rate variability (STV), it might be reduced in central nervous system hypoxia/ acidosis [23]

Summary

Introduction

Technical advances led to the development of continuous electronic monitoring of fetal heart rate (FHR) and uterine contraction (UC) signals, a technology known as cardiotocography (CTG) [1]. This technology constitutes the primary screening method to allow early recognition of fetal distress related to intrapartum fetal hypoxia/ acidosis. On average, the arterial pH of a healthy fetus is around 7.35, whereas, at birth, the average pH of the umbilical artery blood is around 7.25 In this sense, it is considered that moderate neonatal acidosis/acidemia will occur when the pH is, at least, below 7.15 [1]

Methods

Results

Discussion

Conclusion