Affiliation:
1. Fetal Physiology and Neuroscience Group, Department of Physiology The University of Auckland Auckland New Zealand
2. Nuffield Department of Women's and Reproductive Health, The John Radcliffe Hospital University of Oxford Oxford UK
3. Department of Obstetrics and Gynaecology The University of Auckland Auckland New Zealand
4. Starship Children's Hospital Auckland New Zealand
Abstract
AbstractObjectiveDeceleration area (DA) and capacity (DC) of the fetal heart rate can help predict risk of intrapartum fetal compromise. However, their predictive value in higher risk pregnancies is unclear. We investigated whether they can predict the onset of hypotension during brief hypoxaemia repeated at a rate consistent with early labour in fetal sheep with pre‐existing hypoxaemia.DesignProspective, controlled study.SettingLaboratory.SampleChronically instrumented, unanaesthetised near‐term fetal sheep.MethodsOne‐minute complete umbilical cord occlusions (UCOs) were performed every 5 minutes in fetal sheep with baseline paO2 <17 mmHg (hypoxaemic, n = 8) and >17 mmHg (normoxic, n = 11) for 4 hours or until arterial pressure fell <20 mmHg.Main outcome measuresDA, DC and arterial pressure.ResultsNormoxic fetuses showed effective cardiovascular adaptation without hypotension and mild acidaemia (lowest arterial pressure 40.7 ± 2.8 mmHg, pH 7.35 ± 0.03). Hypoxaemic fetuses developed hypotension (lowest arterial pressure 20.8 ± 1.9 mmHg, P < 0.001) and acidaemia (final pH 7.07 ± 0.05). In hypoxaemic fetuses, decelerations showed faster falls in FHR over the first 40 seconds of UCOs but the final deceleration depth was not different to normoxic fetuses. DC was modestly higher in hypoxaemic fetuses during the penultimate (P = 0.04) and final (P = 0.012) 20 minutes of UCOs. DA was not different between groups.ConclusionChronically hypoxaemic fetuses had early onset of cardiovascular compromise during labour‐like brief repeated UCOs. DA was unable to identify developing hypotension in this setting, while DC only showed modest differences between groups. These findings highlight that DA and DC thresholds need to be adjusted for antenatal risk factors, potentially limiting their clinical utility.
Funder
Auckland Medical Research Foundation
Health Research Council of New Zealand
Health Services and Delivery Research Programme
Subject
Obstetrics and Gynecology
Cited by
4 articles.
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