title: Correlation of arterial fetal base deficit and lactate changes with severity of variable heart rate decelerations in the near-term ovine fetus.
abstract: OBJECTIVE
  Recent guidelines classify variable decelerations without detail as to degree of depth. We hypothesized that variable deceleration severity is highly correlated with fetal base deficit accumulation.
  
  
  METHODS
  Seven near-term fetal sheep underwent a series of graded umbilical cord occlusions resulting in mild (30 bpm decrease), moderate (60 bpm decrease), or severe (decrease of 90 bpm to baseline <70 bpm) variable decelerations at 2.5 minute intervals.
  
  
  RESULTS
  Mild, moderate, and severe variable decelerations increased fetal base deficit (0.21 ± 0.03, 0.27 ± 0.03, and 0.54 ± 0.09 mEq/L per minute) in direct proportion to severity. During recovery, fetal base deficit cleared at 0.12 mEq/L per minute.
  
  
  CONCLUSIONS
  In this model, ovine fetuses can tolerate repetitive mild and moderate variable decelerations with minimal change in base deficit and lactate. In contrast, repetitive severe variable decelerations may result in significant base deficit increases, dependent on frequency. Modified guideline differentiation of mild/moderate vs severe variable decelerations may aid in the interpretation of fetal heart rate tracings and optimization of clinical management paradigms.
authors.affiliation: Department of Obstetrics and Gynecology, LA BioMed at Harbor-UCLA Medical Center, Torrance, CA, USA. mikeross@ucla.edu
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ross
authors.forename: Marquis
authors.initials: M
authors.lastname: Jessie
authors.forename: Kevin
authors.initials: K
authors.lastname: Amaya
authors.forename: Brad
authors.initials: B
authors.lastname: Matushewski
authors.forename: L Daniel
authors.initials: LD
authors.lastname: Durosier
authors.forename: Martin G
authors.initials: MG
authors.lastname: Frasch
authors.forename: Bryan S
authors.initials: BS
authors.lastname: Richardson
mesh_terms: D000138:Acidosis / Q000503:physiopathology*; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005311:Fetal Hypoxia / Q000503:physiopathology*; D005323:Fetal Monitoring; D005333:Fetus / Q000503:physiopathology*; D006340:Heart Rate, Fetal / Q000502:physiology*; D019344:Lactic Acid / Q000097:blood*; D011247:Pregnancy; D012756:Sheep; D014470:Umbilical Cord / Q000098:blood supply
chemical_list: D019344:Lactic Acid