University of Oulu

Bhide, A., Johnson, J., Rasanen, J. and Acharya, G. (2019), Fetal heart rate variability with hypoxemia in an instrumented sheep model. Ultrasound Obstet Gynecol, 54: 786-790. doi:10.1002/uog.20259

Fetal heart rate variability with hypoxemia in an instrumented sheep model

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Author: Bhide, A.1,2; Johnson, J.3,4; Räsänen, J.5,6,7;
Organizations: 1Women's Health and Perinatology Research Group, Department of Clinical Medicine, UiT ‐ Arctic University of Tromsø, Tromsø, Norway
2Fetal Medicine Unit, St George's Hospital, London, UK
3Department of Clinical Science, Intervention & Technology (CLINTEC), Division of Obstetrics and Gynecology, Karolinska Institute, Stockholm, Sweden
4Centre for Fetal Medicine, Karolinska University Hospital, Stockholm, Sweden
5Department of Obstetrics and Gynecology, Helsinki University Hospital, Helsinki, Finland
6Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland
7Oregon Health and Science University, Portland, OR, USA
Format: article
Version: accepted version
Access: embargoed
Persistent link: http://urn.fi/urn:nbn:fi-fe202002206045
Language: English
Published: John Wiley & Sons, 2019
Publish Date: 2020-12-04
Description:

Abstract

Objective: To examine the effect of hypoxemia on fetal heart rate (FHR) variability, using an instrumented pregnant sheep model.

Methods: In this prospective study, 19 pregnant sheep were instrumented under general anesthesia, at a mean gestational age of 127 days. After a 5‐day recovery period, hypoxemia was induced by attaching the mother to a rebreathing circuit. Hypoxemia was sustained for 120 min, following which it was reversed until maternal and fetal partial pressure of oxygen (pO₂) returned to baseline. FHR recordings at baseline, after 30 and 120 min of hypoxemia and at recovery were analyzed to calculate short‐term variation (STV) in 16 epochs of 3.75 s, every minute. Phase‐rectified signal averaging (window length (L) = 10, time (T) = 2 and scale (S) = 2) was used to calculate FHR acceleration (AC) and deceleration (DC) capacities.

Results: At baseline, mean ± SD fetal pO₂ was 2.90 ± 0.38 kPa. Acute hypoxemia was associated with a significant reduction in mean pO₂ at 30 (1.62 ± 0.37 kPa) and 120 (1.51 ± 0.16 kPa) min. Mean ± SD fetal pO₂ at recovery was 2.86 ± 0.32 kPa. At baseline, median STV, AC and DC were 1.307 (interquartile range (IQR), 0.515–2.508) ms, 1.295 (IQR, 0.990–2.685) beats per minute (bpm) and 1.197 (IQR, 0.850–1.836) bpm, respectively. At 30 min of hypoxemia, the values were 1.323 (IQR, 0.753–2.744) ms, 1.696 (IQR, 1.310–3.013) bpm and 1.584 (IQR, 1.217–4.132) bpm, respectively. At 120 min of hypoxemia, they were 1.760 (IQR, 0.928–4.656) ms, 3.098 (IQR, 1.530–5.163) bpm and 3.054 (IQR, 1.508–4.522) bpm, respectively. At recovery, they changed to 0.962 (IQR, 0.703–1.154) ms, 1.228 (IQR, 1.071–2.234) bpm and 1.086 (IQR, 0.873–1.568) bpm, respectively. Hypoxemia for 30 and 120 min was associated with a significant increase in DC compared to baseline (P = 0.014 and 0.017, respectively). The changes in STV and AC were not significant.

Conclusion: Acute hypoxemia is associated with a significant increase in the DC of FHR in a fetal sheep model.

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Series: Ultrasound in obstetrics & gynecology
ISSN: 0960-7692
ISSN-E: 1469-0705
ISSN-L: 0960-7692
Volume: 54
Issue: 6
Pages: 786 - 790
DOI: 10.1002/uog.20259
OADOI: https://oadoi.org/10.1002/uog.20259
Type of Publication: A1 Journal article – refereed
Field of Science: 3111 Biomedicine
Subjects:
Funding: This study was funded by the Regional Health Authority of northern Norway.
Copyright information: © 2019 ISUOG. Published by John Wiley & Sons Ltd. This is the peer reviewed version of the following article: Bhide, A., Johnson, J., Rasanen, J. and Acharya, G. (2019), Fetal heart rate variability with hypoxemia in an instrumented sheep model. Ultrasound Obstet Gynecol, 54: 786-790, which has been published in final form at https://doi.org/10.1002/uog.20259. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.