title: Measures of acidosis with repetitive umbilical cord occlusions leading to fetal asphyxia in the near-term ovine fetus.
abstract: OBJECTIVE
  Increasing frequency of severe variable decelerations is associated with acidemia. However, there is little understanding of its development or normalization rate.
  
  
  METHODS
  To quantify the time course of acidemia, 10 near-term fetal sheep underwent a series of mild (1 minute every 5 minutes), moderate (1 minute every 3 minutes), and severe (1 minute every 2 minutes) umbilical cord occlusions (UCO), lasting 1 hour each or until fetal arterial pH decreased to less than 7.00.
  
  
  RESULTS
  Each minute of UCO resulted in base deficit (BD) and lactate increases at rates of 0.56 and 0.35 mmol/L per minute, respectively. During a 2 h recovery, BD and lactate normalized at rates of 0.09 and 0.04 mmol/L per minute. BD correlated highly with lactate (r = 0.95; P < .001).
  
  
  CONCLUSIONS
  Our findings in the near-term ovine fetus suggest that the knowledge of fetal BD deterioration and recovery rates can aid assessing fetal acidemia during labor.
authors.affiliation: Department of Obstetrics and Gynecology, Lawson Health Research Institute, University of Western Ontario, London, ON, Canada.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Frasch
authors.forename: Martin G
authors.initials: MG
authors.lastname: Grasch
authors.forename: Martin G
authors.initials: MG
authors.lastname: Frasch
authors.forename: Roy Z
authors.initials: RZ
authors.lastname: Mansano
authors.forename: Laron
authors.initials: L
authors.lastname: McPhaul
authors.forename: Robert
authors.initials: R
authors.lastname: Gagnon
authors.forename: Bryan S
authors.initials: BS
authors.lastname: Richardson
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ross
mesh_terms: D000138:Acidosis / Q000175:diagnosis*; D000818:Animals; D005260:Female; D005311:Fetal Hypoxia / Q000209:etiology / Q000503:physiopathology*; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012756:Sheep; D047929:Term Birth; D014470:Umbilical Cord / Q000098:blood supply*