Biomaterial Database

Fetal heart rate variability with hypoxemia in an instrumented sheep model. 2019

A Bhide, and J Johnson, and J Rasanen, and G Acharya

Women's Health and Perinatology Research Group, Department of Clinical Medicine, UiT - Arctic University of Tromsø, Tromsø, Norway.

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. CONCLUSIONS 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.

UI	MeSH Term	Description	Entries
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D010313	Partial Pressure	The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Partial Pressures,Pressure, Partial,Pressures, Partial
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011446	Prospective Studies	Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.	Prospective Study,Studies, Prospective,Study, Prospective
D001784	Blood Gas Analysis	Measurement of oxygen and carbon dioxide in the blood.	Analysis, Blood Gas,Analyses, Blood Gas,Blood Gas Analyses,Gas Analyses, Blood,Gas Analysis, Blood
D003654	Deceleration	A decrease in the rate of speed.	Decelerations
D005260	Female		Females
D005333	Fetus	The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.	Fetal Structures,Fetal Tissue,Fetuses,Mummified Fetus,Retained Fetus,Fetal Structure,Fetal Tissues,Fetus, Mummified,Fetus, Retained,Structure, Fetal,Structures, Fetal,Tissue, Fetal,Tissues, Fetal
D005865	Gestational Age	The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated from the onset of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization. It is also estimated to begin from fertilization, estrus, coitus, or artificial insemination.	Embryologic Age,Fetal Maturity, Chronologic,Chronologic Fetal Maturity,Fetal Age,Maturity, Chronologic Fetal,Age, Embryologic,Age, Fetal,Age, Gestational,Ages, Embryologic,Ages, Fetal,Ages, Gestational,Embryologic Ages,Fetal Ages,Gestational Ages
D006340	Heart Rate, Fetal	The heart rate of the FETUS. The normal range at term is between 120 and 160 beats per minute.	Fetal Heart Rate,Fetal Heart Rates,Heart Rates, Fetal,Rate, Fetal Heart,Rates, Fetal Heart