Fetal to Neonatal Heart Rate Transition during Normal Vaginal Deliveries: A Prospective Observational Study.

Documentation of fetal to neonatal heart rate (HR) transition is limited. The aim of the current study was to describe HR changes from one hour before to one hour after normal vaginal deliveries. We conducted a prospective observational cohort study in Tanzania from 1 October 2020 to 30 August 2021, including normal vaginal deliveries with normal neonatal outcomes. HR was continuously recorded from one hour before to one hour after delivery, using the Moyo fetal HR meter, NeoBeat newborn HR meter, and the Liveborn Application for data storage. The median, 25th, and 75th HR percentiles were constructed. Overall, 305 deliveries were included. Median (interquartile range; IQR) gestational age was 39 (38-40) weeks and birthweight was 3200 (3000-3500) grams. HR decreased slightly during the last 60 min before delivery from 136 (123,145) to 132 (112,143) beats/minute. After delivery, HR increased within one minute to 168 (143,183) beats/min, before decreasing to around 136 (127,149) beats/min at 60 min after delivery. The drop in HR in the last hour of delivery reflects strong contractions and pushing. The rapid increase in initial neonatal HR reflects an effort to establish spontaneous breathing.

Distribution of heart rate and responses to resuscitation among 1237 apnoeic newborns at birth.

AIM OF THE STUDY: Describe the distribution of the first recorded heart rate (HR) in apnoeic term/near-term newborns, HR responses to basic resuscitation (no intubation, chest compressions and/or medication), and relationship to 24-h outcomes. We also document patient characteristics and care provider behaviour stratified by first HR. METHODS: Descriptive study from July 2013 through June 2018 at Haydom Hospital in Tanzania. All deliveries were observed by assistants recording data. Bag-mask ventilation and ECG data were recorded by resuscitation monitors. Newborns with ≥5 ventilations and ECG signal-data were included. RESULTS: 1237 term/near-term newborns with median (25th, 75th percentiles) gestation 38 (37, 40) weeks and birth weight 3140 (2750, 3500) grams fulfilled inclusion criteria. The first HR, measured median 102 (73, 144) s after birth following drying/stimulation, was distributed into two peaks with centres around 60 and 165 bpm, 51% were ≥100 bpm. After ventilation, the HR distribution shifted to a single-peak, with median 161 bpm. At least one low-high HR transition crossing 100 bpm was noted in 44% of newborns. The HR increase occurred over median 9.2 (6.2, 13) s, was 60 (43, 77) bpm, and 86% followed a ventilation sequence of 23 (16, 34) s duration. 72% of the newborns with first HR < 60 bpm survived following ventilations only. Both first and final HR were significantly related to 24-h outcomes. CONCLUSIONS: The first recorded HR was distributed into two peaks on each side of 100 bpm. Ventilation increased HR in most newborns. Lower first and final HR were related to gradually more adverse 24-h outcomes.

Fresh stillborn and severely asphyxiated neonates share a common hypoxic-ischemic pathway.

OBJECTIVE: To characterize, among non-breathing flaccid neonates at delivery, immediate heartrate and responses to ventilation in relation to the clinical diagnosis of fresh stillbirth (FSB) or early neonatal death (END) within 24 hours. METHODS: The present cross-sectional study included all deliveries at Haydom Hospital in rural Tanzania between July 1, 2013, and July 31, 2016. Ventilation parameters and heartrate were recorded by monitors with ventilation and dry-electrocardiography sensors. Perinatal characteristics were recorded on data forms by trained research assistants. RESULTS: Among 12 789 neonates delivered, 915 were ventilated; among ventilated neonates, there were 53 (6%) FSBs and 64 (7%) ENDs. Electrocardiography was used in 46 FSBs and 55 ENDs, and these neonates were included in a subanalysis. Initial heartrate was detected in 27 (59%) of 46 FSBs and 52 (95%) of 55 ENDs, and was lower in FSBs (52 ± 19 vs 76 ± 37 bpm; P=0.003). More ENDs responded to ventilation (53% vs 9%; P<0.001), with heartrate increasing above 100 bpm. Heartrate at ventilation discontinuation was higher among ENDs (115 ± 49 vs 52 ± 33 bpm; P<0.001). CONCLUSION: Progression to FSB or END after intrapartum hypoxia/anoxia is probably part of the same circulatory end-process. Distinguishing FSB from severely asphyxiated newborns is clinically difficult and probably influences estimated global perinatal mortality rates.

Feasibility of a prototype newborn resuscitation monitor to study transition at birth, measuring heart rate and ventilator parameters, an animal experimental study.

BACKGROUND: Every year, an estimated 10 million babies are born, non-breathing and in need of resuscitation. Advances in management have been made over the past decades, however, approximately 700.000 yearly deaths result from this global problem. A prototype newborn resuscitation monitor (NRM) (Laerdal Global Health, Stavanger, Norway) has been developed with the purpose of studying newborn resuscitation. The monitor has the ability to continuously display HR using dry electrode ECG technology, to measure tidal volume, pressure and end tidal CO2, and to store the results for later analysis. Such monitor could enhance the care providers performance, and hence survival of neonates, by displaying the quality and response of the given care. The aim of this preclinical study was to describe the abilities of the NRM to measure ventilation and heart rate parameters against pathophysiological responses to different induced conditions in a piglet i.e. increased deadspace, pressure and washout of surfactant. METHODS: Piglets were chosen for the study, as they have tidal volumes of approximately 6 ml/kg, resembling the human neonate. Five piglets were anesthetized and intubated before starting positive pressure ventilation (PPV). The dry electrode ECG sensor of the NRM was placed over the abdomen, and experiments performed: (1) inducing different ventilation scenarios and (2) lavage of surfactant. RESULTS: The NRM was capable of continuously displaying HR and detecting inflicted changes in ventilation and compliance of piglets. It could measure inflated and exhaled volume, the pressure of the ventilations and also the end tidal CO2. CONCLUSIONS: The NRM provides objective feedback in anesthetized animals, and may be used in clinical studies and hopefully generate new knowledge on neonatal transition and resuscitation. The monitor may be further developed for use in both low and high-resource settings.

Automatic Detection and Parameterization of Manual Bag-Mask Ventilation on Newborns.

OBJECTIVES: Birth asphyxia is a condition where a fetus suffers from lack of oxygen during birth. Intervention by manual ventilation should start within one minute after birth. Bag-mask resuscitators are commonly used in situations where ventilation is provided by a single health care worker. Due to a high complexity of interactions between physiological conditions of the newborns and the clinical treatment, the recommendations for bag-mask ventilation of infants remains controversial. The purpose of this paper is to illustrate the processing and parameterization of ventilation signals recorded from the Laerdal newborn resuscitation monitor into meaningful data. METHODS: Basic signal processing approaches are applied on various signal channels (airway pressure, flow, CO 2, and ECG) to detect events related to ventilation activities. RESULTS: Different types of events are detected and parameterized to describe the characteristics of ventilation procedure. CONCLUSIONS: Efficient detection algorithms as well as parameterization of ventilation events could be useful for retrospective analysis of resuscitation data, for example, by finding the association between different ventilation parameters and positive responses of newborns. SIGNIFICANCE: Information about ventilation events and ventilation parameters could potentially be useful during a resuscitation situation by giving immediate feedback to the health care provider.