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2. Sampling frequency of fetal heart rate impacts the ability to predict pH and BE at birth: a retrospective multi-cohort study

Author

Li, Xuan, primary, Xu, Yawen, additional, Herry, Christophe, additional, Durosier, L Daniel, additional, Casati, Daniela, additional, Stampalija, Tamara, additional, Maisonneuve, Emeline, additional, Seely, Andrew J E, additional, Audibert, Francois, additional, Alfirevic, Zarko, additional, Ferrazzi, Enrico, additional, Wang, Xiaogang, additional, and Frasch, Martin G, additional

Published
2015
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5. The timing and degree of fetal systemic and cerebral inflammatory responses correlate with a subset of heart rate variability measures: Evidence of cholinergic anti-inflammatory pathway activation in sepsis

Author

Durosier, L. Daniel, primary, Siontas, Dora, additional, Cao, Mingju, additional, Herry, Christophe, additional, Green, Geoff, additional, Batkin, Izmail, additional, Burns, Patrick, additional, Fecteau, Gilles, additional, Desrochers, André, additional, Seely, Andrew, additional, and Frasch, Martin G., additional

Published
2013
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7. Sampling frequency of fetal heart rate impacts the ability to predict pH and BE at Birth : a retrospective multi-cohort study

Author

Enrico Ferrazzi, Yawen Xu, Tamara Stampalija, François Audibert, Andrew J.E. Seely, Martin G. Frasch, L. Daniel Durosier, Daniela Casati, Christophe L. Herry, Xuan Li, Emeline Maisonneuve, Xiaogang Wang, Zarko Alfirevic, Li, Xuan, Xu, Yawen, Herry, Christophe, Durosier, L. Daniel, Casati, Daniela, Stampalija, Tamara, Maisonneuve, Emeline, Seely, Andrew J. E., Audibert, Francoi, Alfirevic, Zarko, Ferrazzi, Enrico, Wang, Xiaogang, and Frasch, Martin G.

Subjects
Male, Pediatrics, Physiology, labour, Cohort Studies, Models, Pregnancy, Retrospective Studie, Heart Rate, Fetal Monitoring, Labor, Obstetric, Obstetrics, Gestational age, fetal heart rate, Heart Rate, Fetal, Hydrogen-Ion Concentration, Statistical, fetus, Acidosi, embryonic structures, Cohort, Female, Acidosis, Cohort study, Human, medicine.medical_specialty, Biophysics, Biomedical Engineering, fetu, Reproducibility of Result, monitoring, prediction, sampling rate, Humans, Labor, Obstetric, Reproducibility of Results, Retrospective Studies, Computational Biology, Fetal, Physiology (medical), Heart rate, medicine, Fetus, Models, Statistical, business.industry, Retrospective cohort study, medicine.disease, Fetal heart rate, Biophysic, Cohort Studie, business, Model
Abstract

Fetal heart rate (FHR) sampling rate used on the bedside is equal or less than 4 Hz. Current FHR analysis methods fail to detect incipient fetal acidemia. In a fetal sheep model of human labour we showed that FHR sampling rates near 1000 Hz are needed to detect fetal acidemia. Trans-abdominal fetal ECG (t-a fECG) sampling FHR at 900 Hz combined with a complex signals bioinformatics approach showed promise in a human cohort. Here we validate this finding in a retrospective human cohort study by comparing the performance of the same bioinformatics approach to predict pH and BE at birth in the cohorts with FHR sampled either at 4 Hz or at 900 Hz.The 4 Hz FHR recording data sets consisted of the open access intrapartum CTG data base with n = 552 subjects used to develop the predictive model and another cohort of prospectively recruited n = 11 labouring women to then validate it. 900 Hz FHR data set comprised two prospectively recruited t-a fECG cohorts of n = 60 and n = 23 subjects. Recruitment criteria were similar across the cohorts. We have determined the goodness of fit (R(2)) and root mean square error (RMSE) as the performance indicators of the model on each cohort.The clinical characteristics of all cohorts were similar (gestational age 280 ± 8 d; gender 50% male; birth body weight 3.5 ± 0.5 kg; pH and BE at birth 7.25 ± 0.1 and -5.7 ± 3.4 mmol L( - 1), respectively; 1' and 5' Apgar scores at birth 8.5 ± 1.4 and 9.4 ± 0.6, respectively). The 4 Hz FHR cohort rendered-for pH and BE-R(2) = 0.26 and 0.2 and RMSE = 0.087 and 3.44, respectively. This could not be confirmed in the validation cohort for neither pH nor BE prediction. The 900 Hz FHR cohort rendered-for pH and BE-R(2) = 0.9 and 0.77 and RMSE = 0.03 and 1.70, respectively, and the pH prediction was validated.In our model, lower FHR sampling rate increased the predicted error range ~3-4 fold. We show that increasing FHR sampling rate to 900 Hz improves prediction of fetal pH and BE at birth. This should improve early identification of babies at risk of brain injury.

Published
2015

8. Sampling rate of heart rate variability impacts the ability to detect acidemia in ovine fetuses near-term.

Author

Durosier LD, Green G, Batkin I, Seely AJ, Ross MG, Richardson BS, and Frasch MG

Abstract

Background: To evaluate the impact of sampling rate on the predictive capability of continuous fetal heart rate (FHR) variability (fHRV) monitoring for detecting fetal acidemia during labor, we tested the performance of the root mean square of successive differences (RMSSD) in R-R intervals from the ECG when acquired with the sampling rate of 4 Hz currently available in FHR monitors, in comparison to the gold standard of 1000 Hz., Methods: Near-term ovine fetuses (N = 9) were chronically prepared with precordial electrodes for recording ECG, vascular catheters for blood sampling, and an umbilical cord occluder. For 1 min every 2.5 min, animals underwent mild partial umbilical cord occlusions (UCO) × 1 h, moderate partial UCO × 1 h, then complete UCO × 2 h, or until arterial pH reached <7.00. Arterial blood samples were drawn at baseline and every 20 min during the UCO series. RMSSD was calculated continuously in 5 min windows using an automated, standardized system (CIMVA.com). RESULTS are presented as mean ± SEM with significance assumed for p < 0.05., Results: Repetitive UCO resulted in pH decreasing from 7.35 ± 0.01 to 7.00 ± 0.03. In all nine animals, RMSSD increased from 16.7 ± 1.0 ms at baseline to 44.4 ± 2.3 ms, 70 ± 15 min prior to reaching the pH nadir when sampled at 1000 Hz. When sampled at 4 Hz, RMSSD at baseline measured 36.1 ± 6.0 ms and showed no significant increase during the UCO series until the pH nadir was reached. Consequently, early detection of severe hypoxic-acidemia would have been missed in all fetuses., Conclusion: RMSSD as a measure of fHRV when calculated from FHR sampled at 1000 Hz allowed for the early detection of worsening hypoxic-acidemia in each fetus. However, when calculated at the low sampling rate of 4 Hz used clinically, RMSSD remained unchanged until terminally when the nadir pH was reached. For early detection of fetal acidemia during labor, more sensitive means of acquiring FHR are therefore recommended than currently deployed, e.g., trans-abdominal fetal ECG.

Published
2014
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