title: Correlation of cord blood pH, base excess, and lactate concentration measured with a portable device for identifying fetal acidosis.
abstract: OBJECTIVE
  To determine the effectiveness of portable lactate analyzers in identifying fetal acidosis by correlating arterial and venous lactate values from umbilical cord blood with lactate, pH, and base excess measurements from central laboratory analyzers.
  
  
  METHODS
  We performed a prospective study using arterial and venous cord blood from 52 women with a singleton fetus delivered at term. We evaluated the correlation between the cord blood lactate concentration measured using two of the same portable devices (Lactate Plus, Nova Biomedical) with the result from a central laboratory analyzer. Analyses of the correlation between arterial lactate concentration measured on the portable device with arterial pH and base excess were then performed.
  
  
  RESULTS
  We observed a median arterial pH of 7.24 (range 7.05 to 7.35) and a median arterial lactate concentration of 3.7 mmol/L (range 1.7 to 8.8 mmol/L). An excellent correlation was observed between lactate concentrations measured by the two portable devices (arterial R² = 0.98 and venous R² = 0.98), and between the portable device and the central laboratory analyzer (arterial R² = 0.94 and venous R² = 0.95). In our population, the optimal cut-offs to predict a pH < 7.20 or a base excess > -8.0 mmol/L were a lactate concentration of 4.9 mmol/L and 5.3 mmol/L, respectively, according to receiver operator characteristic analysis. With a lactate concentration > 4.9 mmol/L, the portable device had a sensitivity of 82% and a specificity of 90% to identify samples with an arterial pH < 7.20.
  
  
  CONCLUSIONS
  Cord blood lactate concentration measured with a portable device is a good predictor of cord blood base excess and pH. Future studies should be designed to correlate scalp blood lactate measurements with clinical outcomes.
authors.affiliation: Department of Biochemistry, Centre hospitalier de l'Université de Montréal, Montreal QC.
authors.forename: Lyne
authors.initials: L
authors.lastname: Labrecque
authors.affiliation: Department of Biochemistry, Centre hospitalier de l'Université de Montréal, Montreal QC.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Provençal
authors.affiliation: Department of Biochemistry, Centre hospitalier de l'Université de Montréal, Montreal QC.
authors.forename: Aurore
authors.initials: A
authors.lastname: Caqueret
authors.affiliation: Department of Obstetrics and Gynecology, Centre hospitalier de l'Université de Montréal, Montreal QC.
authors.forename: Bi Lan
authors.initials: BL
authors.lastname: Wo
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, Université Laval, Quebec QC.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Bujold
authors.affiliation: Department of Biochemistry, Centre hospitalier de l'Université de Montréal, Montreal QC.
authors.forename: François
authors.initials: F
authors.lastname: Larivière
authors.affiliation: Department of Obstetrics and Gynecology, Centre hospitalier de l'Université de Montréal, Montreal QC.
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Bédard
mesh_terms: D000138:Acidosis / Q000175:diagnosis*; D005312:Fetal Blood / Q000378:metabolism*; D005315:Fetal Diseases / Q000175:diagnosis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood*; D011296:Prenatal Diagnosis / Q000295:instrumentation* / Q000379:methods*; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D019344:Lactic Acid
keywords: fetal scalp; lactate; point-of-care testing; portable device