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- Title
Fetal heart rate variability with hypoxemia in an instrumented sheep model.
- Authors
Bhide, A.; Johnson, J.; Rasanen, J.; Acharya, G.
- Abstract
<bold>Objective: </bold>To examine the effect of hypoxemia on fetal heart rate (FHR) variability, using an instrumented pregnant sheep model.<bold>Methods: </bold>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.<bold>Results: </bold>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.<bold>Conclusion: </bold>Acute hypoxemia is associated with a significant increase in the DC of FHR in a fetal sheep model. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.
- Subjects
HEART beat; FETAL heart rate; SHEEP; PARTIAL pressure; HYPOXEMIA
- Publication
Ultrasound in Obstetrics & Gynecology, 2019, Vol 54, Issue 6, p786
- ISSN
0960-7692
- Publication type
journal article
- DOI
10.1002/uog.20259