Advertisement

Reference values for strong ion difference—A novel tool for fetal metabolic assessment

      Abstract

      Objectives

      The aim of this pilot study was to establish reference values for strong ion difference (SID) in umbilical cord blood and investigate the feasibility of evaluating fetal metabolism according to the comprehensive approach to acid–base abnormalities, based on Stewart's physiochemical theory.

      Study design

      A prospective observational study. Women who underwent an elective cesarean section at term (n = 40) were compared to women who completed a normal spontaneous delivery at term (n = 40). The primary outcome was the establishment of normal values for SID in the umbilical cord vein. We also compared acid–base variables in the umbilical vein between the groups.

      Results

      The apparent SID in the umbilical vein was 34.61 ± 3.92 mequiv./L after normal delivery and 35.98 ± 2.56 mequiv./L after elective cesarean section (the effective SID is 37.43 ± 1.93 and 38.29 ± 2.38 mequiv./L, respectively). The pH values were similar in both groups, but the pCO2 was significantly higher and the plasma principal weak acids (albumin and phosphate) were significantly lower after cesarean sections.

      Conclusions

      SID enables a comprehensive approach to acid–base abnormalities in the neonate, making it a potential additional tool for evaluating fetal acid–base status.

      Keywords

      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'

      References

        • Helwig J.T.
        • Parer J.T.
        • Kilpatrick S.J.
        • Laros Jr., R.K.
        Umbilical cord blood acid–base state: what is normal?.
        Am J Obstet Gynecol. 1996; 174: 1807-1812
        • ACOG Committee Opinion No. 348, November 2006
        Umbilical cord blood gas and acid–base analysis.
        Obstet Gynecol. 2006; 108: 1319-1322
        • Stewart P.A.
        Modern quantitative acid–base chemistry.
        Can J Physiol Pharmacol. 1983; 61: 1444-1461
        • Kellum J.A.
        Determinants of blood pH in health and disease.
        Crit Care. 2000; 4: 6-14
        • Corey H.E.
        Stewart and beyond: new models of acid–base balance.
        Kidney Int. 2003; 64: 777-787
        • Fencl V.
        • Jabor A.
        • Kazda A.
        • Figge J.
        Diagnosis of metabolic acid–base disturbances in critically ill patients.
        Am J Respir Crit Care Med. 2000; 162: 2246-2251
        • Sirker A.A.
        • Rhodes A.
        • Grounds R.M.
        • Bennett E.D.
        Acid–base physiology: the ‘traditional’ and the ‘modern’ approaches.
        Anaesthesia. 2002; 57: 348-356
        • Kaplan L.J.
        • Kellum J.A.
        Initial pH, base deficit, lactate, anion gap, strong ion difference, and strong ion gap predict outcome from major vascular injury.
        Crit Care Med. 2004; 32: 1120-1124
        • Martin M.
        • Murray J.
        • Berne T.
        • Demetriades D.
        • Belzberg H.
        Diagnosis of acid–base derangements and mortality prediction in the trauma intensive care unit: the physiochemical approach.
        J Trauma. 2005; 58: 238-243
        • Zehtabchi S.
        • Soghoian S.
        • Sinert R.
        Utility of Stewart's strong ion difference as a predictor of major injury after trauma in the ED.
        Am J Emerg Med. 2007; 25: 938-941
        • Balasubramanyan N.
        • Havens P.L.
        • Hoffman G.M.
        Unmeasured anions identified by the Fencl–Stewart method predict mortality better than base excess, anion gap, and lactate in patients in the pediatric intensive care unit.
        Crit Care Med. 1999; 27: 1577-1581
        • Kellum J.A.
        Clinical review: reunification of acid–base physiology.
        Crit Care. 2005; 9: 500-507
        • Wallach J.
        Interpretation of diagnostic tests.
        8th ed. Lippincott Williams & Wilkins, Philadelphia, PA2007
        • Ronco C.
        Critical care nephrology.
        1st ed. Kluwer Academic Publishers, Dordrecht1998
        • Reynolds F.
        • Seed P.T.
        Anaesthesia for caesarean section and neonatal acid–base status: a meta-analysis.
        Anaesthesia. 2005; 60: 636-653
        • Dudenhausen J.W.
        • Luhr C.
        • Dimer J.S.
        Umbilical artery blood gases in healthy term newborn infants.
        Int J Gynecol Obstet. 1997; 57: 251-258