Resumen

HERNANDEZ, Carmen E. Correlación del perfil biofísico y del equilibrio ácido-base en pacientes de alto riesgo obstétrico. Rev Obstet Ginecol Venez [online]. 2007, vol.67, n.1, pp.5-13. ISSN 0048-7732.

Objective: To determine the relation between the fetal biophysical variables and the acid base status of the arterial and venous blood sample of the umbilical cord. Methods: Clinical prospective study in 50 patients with criteria of obstetrical high risk, admitted with indication of cesarean section. A fetal biophysical profile according to Manning and col., and assessment of amniotic fluid volume by the Phelan method were performed. After clamping the umbilical cord, arterial and venous blood samples were obtained for analysis of acid base status. Setting: Delivery room at the Maternidad “Concepción Palacios”, Caracas. Results: Patient were allocated into two groups according to the total score of the biophysical profile, with a cut point value of 6 and it was correlated with the biochemical parameters. Metabolic acidosis was observed both in arterial and venous blood in the group with score smaller than 6 points, significant in pH, pressure of oxygen, CO₂  pressure and bicarbonate. Fetal pH in relation to absence of each one of the variables, showed decrease that was marked when the affected variable was the fetal corporal movements. High sensitivity and specificity was observed, being able to detect a 84 % of fetuses with fetal distress, also, when a healthy fetus was identified by biophysical profile it is certain in 74 %. Conclusions: A strong relationship between fetal biophysical profile and acid base status was found. The first altered variable was the fetal cardiac reactivity, with low variations in pH values. The absence of fetal corporal movements, with low values of fetal pH, was associated to severe hypoxia and several degrees of hypercapnia and hypoxemia. Arterial pH was used separately like gold standard for each variable.

Palabras clave : Acid base status; Fetal biophysical profile.