title: Adaptive shut-down of EEG activity predicts critical acidemia in the near-term ovine fetus.
abstract: In fetal sheep, the electrocorticogram (ECOG) recorded directly from the cortex during repetitive heart rate (FHR) decelerations induced by umbilical cord occlusions (UCO) predictably correlates with worsening hypoxic-acidemia. In human fetal monitoring during labor, the equivalent electroencephalogram (EEG) can be recorded noninvasively from the scalp. We tested the hypothesis that combined fetal EEG - FHR monitoring allows for early detection of worsening hypoxic-acidemia similar to that shown for ECOG-FHR monitoring. Near-term fetal sheep (n = 9) were chronically instrumented with arterial and venous catheters, ECG, ECOG, and EEG electrodes and umbilical cord occluder, followed by 4 days of recovery. Repetitive UCOs of 1 min duration and increasing strength (with regard to the degree of reduction in umbilical blood flow) were induced each 2.5 min until pH dropped to <7.00. Repetitive UCOs led to marked acidosis (arterial pH 7.35 ± 0.01 to 7.00 ± 0.03). At pH of 7.22 ± 0.03 (range 7.32-7.07), and 45 ± 9 min (range 1 h 33 min-20 min) prior to attaining pH < 7.00, both ECOG and EEG amplitudes began to decrease ~fourfold during each FHR deceleration in a synchronized manner. Confirming our hypothesis, these findings support fetal EEG as a useful adjunct to FHR monitoring during human labor for early detection of incipient fetal acidemia.
authors.affiliation: Department of Obstetrics and Gynaecology, Department of Neurosciences, CHU Ste-Justine Research Center Université de Montréal, Montreal, Quebec, Canada mg.frasch@umontreal.ca.
authors.forename: Martin G
authors.identifier: http://orcid.org/0000-0003-3159-6321
authors.initials: MG
authors.lastname: Frasch
authors.affiliation: Department of Obstetrics and Gynaecology, Department of Neurosciences, CHU Ste-Justine Research Center Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Lucien Daniel
authors.initials: LD
authors.lastname: Durosier
authors.affiliation: Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada.
authors.forename: Nathan
authors.initials: N
authors.lastname: Gold
authors.affiliation: Department of Obstetrics and Gynaecology, Department of Neurosciences, CHU Ste-Justine Research Center Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Mingju
authors.initials: M
authors.lastname: Cao
authors.affiliation: Department of Obstetrics and Gynecology, University Western Ontario, London, Ontario, Canada.
authors.forename: Brad
authors.initials: B
authors.lastname: Matushewski
authors.affiliation: Imaging Program Lawson Health Research Institute, London, Ontario, Canada.
authors.forename: Lynn
authors.initials: L
authors.lastname: Keenliside
authors.affiliation: Department of Mathematics, Bar-Ilan University, Ramat-Gan, Israel.
authors.forename: Yoram
authors.initials: Y
authors.lastname: Louzoun
authors.affiliation: Department of Obstetrics & Gynecology, LA BioMed at Harbor-UCLA Medical Center, Torrance, California.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ross
authors.affiliation: Department of Obstetrics and Gynecology, University Western Ontario, London, Ontario, Canada.
authors.forename: Bryan S
authors.initials: BS
authors.lastname: Richardson
keywords: Acidosis; ECOG; EEG; FHR; Fetus; asphyxia; hypoxia; monitoring