title: [Diagnosis of neonatal metabolic acidosis by eucapnic pH determination].
abstract: The identification of a metabolic acidosis is a key criterion for establishing a causal relationship between fetal perpartum asphyxia and neonatal encephalopathy and/or cerebral palsy. The diagnostic criteria currently used (pH and base deficit or lactatemia) are imprecise and non-specific.
  
  
  OBJECTIVE
  The study aimed to determine among a low-risk cohort of infants born at term (n = 867), the best diagnostic tool of metabolic acidosis in the cordonal from the following parameters: pH, blood gases and lactate values at birth.
  
  
  METHODS
  The data were obtained from arterial blood of the umbilical cord by a blood gas analyser. The parameter best predicting metabolic analysis was estimated from the partial correlations established between the most relevant parameters.
  
  
  RESULTS
  The results showed a slight change in all parameters compared to adult values: acidemia (pH: 7.28 ± 0.01), hypercapnia (56.5 ± 1.59 mmHg) and hyperlactatemia (3.4 ± 0.05 mmol/L). From partial correlation analysis, pCO(2) emerged to be the main contributor of acidemia, while lactatemia was shown to be non-specific for metabolic acidosis. Seven cases (0.81 %) showed a pH less than 7.00 with marked hypercapnia. The correction of this respiratory component by EISENBERG's method led to the eucapnic pH, classifying six out of seven cases as exclusive respiratory acidosis.
  
  
  CONCLUSIONS
  It has been demonstrated that the criteria from ACOG-AAP for defining a metabolic acidosis are incomplete, imprecise and generating errors in excess. The same is true for lactatemia, whose physiological significance has been completely revised, challenging the misconception of lactic acidosis as a specific marker of hypoxia. It appeared that eucapnic pH was the best way for obtaining a reliable diagnosis of metabolic acidosis. We proposed to adopt a simple decision scheme for determining whether a metabolic acidosis has occurred in case of acidemia less than 7.00.
authors.affiliation: Université J-Fourier, Grenoble, France. claude.racinet@orange.fr
authors.forename: C
authors.initials: C
authors.lastname: Racinet
authors.forename: G
authors.initials: G
authors.lastname: Richalet
authors.forename: C
authors.initials: C
authors.lastname: Corne
authors.forename: P
authors.initials: P
authors.lastname: Faure
authors.forename: J-F
authors.initials: JF
authors.lastname: Peresse
authors.forename: X
authors.initials: X
authors.lastname: Leverve
mesh_terms: D000138:Acidosis / Q000175:diagnosis*; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000097:blood; D007231:Infant, Newborn; D019344:Lactic Acid / Q000097:blood; D011247:Pregnancy; D012680:Sensitivity and Specificity; D014469:Umbilical Arteries
chemical_list: D002245:Carbon Dioxide; D019344:Lactic Acid
keywords: Acidemia; Acidose métabolique; Acidose respiratoire; Acidémie; Asphyxie fœtale perpartum; Base deficit; Cerebral palsy; Déficit de base; Eucapnic pH; Fetal perpartum asphyxia; Lactatemy; Lactatémie; Metabolic acidosis; Newborn; Nouveau-né; PH eucapnique; Paralysie cérébrale; Reference values; Respiratory acidosis; Valeurs de référence