Heart Rate Variability in the Perinatal Period: A Critical and Conceptual Review

Abstract

Neonatal intensive care units (NICUs) greatly expand the use of technology. There is a need to accurately diagnose discomfort, pain, and complications, such as sepsis, mainly before they occur. While specific treatments are possible, they are often timeconsuming, invasive, or painful, with detrimental effects for the development of the infant. In the last 40 years, heart rate variability (HRV) has emerged as a noninvasive measurement to monitor newborns and infants, but it still is underused. Hence, the present paper aims to review the utility of HRV in neonatology and the instruments available to assess it, showing how HRV could be an innovative tool in the years to come. When continuously monitored, HRV could help assess the baby's overall wellbeing and neurological development to detect stress-/painrelated behaviors or pathological conditions, such as respiratory distress syndrome and hyperbilirubinemia, to address when to perform procedures to reduce the baby's stress/pain and interventions, such as therapeutic hypothermia, and to avoid severe complications, such as sepsis and necrotizing enterocolitis, thus reducing mortality. Based on literature and previous experiences, the first step to efficiently introduce HRV in the NICUs could consist in a monitoring system that uses photoplethysmography, which is low-cost and non-invasive, and displays one or a few metrics with good clinical utility. However, to fully harness HRV clinical potential and to greatly improve neonatal care, the monitoring systems will have to rely on modern bioinformatics (machine learning and artificial intelligence algorithms), which could easily integrate infant's HRV metrics, vital signs, and especially past history, thus elaborating models capable to efficiently monitor and predict the infant's clinical conditions. For this reason, hospitals and institutions will have to establish tight collaborations between the obstetric, neonatal, and pediatric departments: this way, healthcare would truly improve in every stage of the perinatal period (from conception to the first years of life), since information about patients' health would flow freely among different professionals, and high-quality research could be performed integrating the data recorded in those departments.

The neonatal assessment manual score (NAME) for improving the clinical management of infants: a perspective validity study

“…However, future studies might shed light on additional elements to take into account. Following the expert panel’s judgment, the NAME model might also be enhanced by integrating physiological parameters like heart rate, respiratory rate, blood pressure, SpO 2 , temperature (vital signs already monitored in NICUs) [ 47 , 48 ], or heart rate variability – a measurement that is emerging as reliable and valid to predict and monitor the infants’ clinical progression [ 49 ].…”

A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows

“…Changes in fHR and fHRV during labor can reveal alterations in fetal reserve to survive the trial of labor and in ANS development, specifically, also in vagus nerve modulation (Chiera et al, 2020 ). However, it is important to highlight that so far fHR monitoring has not been enough to prevent fetal injury during labor and, consequently, long-term complications.…”

“…On the other hand, the ANS activity, as measured through heart rate variability (HRV)—a non-invasive biomarker evaluating the variability of the time intervals between successive heartbeats—is affected by the developmental and health conditions of both fetus and infant. Heart rate variability analysis can give paramount hints about the fetus' or newborn's well-being and allow clinicians to predict the occurrence of even deadly complications ( Table 1 ) (Stone et al, 2013 ; Al-Shargabi et al, 2017 ; Massaro et al, 2017 ; Chiera et al, 2020 ; Frasch, 2020 ). Indeed, the first findings relating HRV alterations to fetal death, thus hinting to a potential predictive role of HRV, date back to the early sixties of the twentieth century (Hon and Lee, 1963 ).…”

A Comprehensive Review of Techniques for Processing and Analyzing Fetal Heart Rate Signals

“…In spite of this wide availability of techniques and approaches for FHRV assessment, only weak predictive indications about fetal hypoxia and neonatal injuries can be achieved through the algorithms and methodologies developed so far [17]. In addition, while there are multiple, and also recent, examples of literature studies that review and discuss the available methodologies and metrics used both in research and in clinical practice to analyze the heart rate variability (HRV) of adult subjects [31][32][33][34], the field of fetal heart monitoring, despite a few examples of works focused on the neonatal and perinatal medicine [35,36], still lacks a comprehensive overview of the techniques employed in the analysis of FHRV.…”