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How to determine and use base excess (BE) in perinatal medicine.
Z Geburtshilfe Neonatol. 2007 Dec; 211(6):224-9.ZG

Abstract

BACKGROUND

Foetal hypoxia may lead to multi-organ failure and cerebral injury. Usually this process is accompanied by severe metabolic acidosis. The base excess (BE) determined in umbilical artery (UA) blood is the most appropriate parameter to evaluate metabolic acidosis. The correct determination of BE therefore is of paramount importance both for the jeopardised foetus and the obstetrician in litigation. In blood, BE is dependent on the oxygen saturation [sO2 (%)] of haemoglobin (cHb). Due to the normally low foetal pO2 values in UA blood (median: ca. 18 mmHg) sO2 is low as well; therefore computational correction of BE to - by definition - 100 % oxygen saturation seems to be mandatory. This paper presents an analysis of this complex problem in obstetrics.

METHODS

pH, pCO2, pO2 and cHb were measured in UA blood of 6 302 term infants delivered spontaneously using equipments from Radiometer (Copenhagen). BE was computed according to the equation of Siggaard-Andersen actually used in many blood-gas analysers. sO2 (%) was computed for HbF using the algorithm of Ruiz et al. . The numerical correction of BE was achieved with an equation given again by Siggaard-Andersen . APGAR indices after 1 minute were used.

RESULTS

Median BE in UA was - 4.6 and the mean was - 4.9 +/- 3.0 mmol / L, respectively. Correction of BE (BEoxy.) to the actual (calculated) oxygen saturation (%) leads (always) to lower values: a median BE (oxy.) in UA of - 7.4 and a mean of - 7.6 +/- 3.2 mmol / L, respectively. There is no correlation between BE and sO2 in UA blood: r = 0.0078, p = 0.532, n = 6 302 (mean oxygen saturation: 27.7 +/- 18.3 %). The median cHb amounted to 15.2 and the mean to 15.0 +/- 2.6 g %, respectively. The median delta-BE,UA(BE - BEoxy.) amounts to 2.74 mmol / L; the maximum delta-BE reached 5.2 mmol / L in this sample. Correction of BE to 100 % oxygen saturation based on the (calculated) real oxygen saturation (%) leads to significantly (p = 0.0099) higher correlations with the APGAR index (1 min) and pCO2 in UA (p << 10 (-4)) as well.

CONCLUSION

Correction of BE in UA, i. e., correction of BE to 100 % oxygen saturation using the (calculated) actual oxygen saturation (%) of the blood sample is mandatory in perinatal medicine. Correction uniformly leads to lower BE values (median: 2.7 mmol / L) and significantly higher correlation coefficients with important clinical variables (e. g., the APGAR index).

Links

Publisher Full Text (DOI)

Authors+Show Affiliations

Roemer VM
International Institute of Foeto-Maternal Medicine Detmold e. V., Detmold, Germany. vmr.dr@t-online.de

MeSH

Acidosis, RespiratoryAlgorithmsBlood Gas AnalysisCarbon DioxideCarboxyhemoglobinFemaleFetal BloodFetal HemoglobinFetal HypoxiaHumansHydrogen-Ion ConcentrationInfant, NewbornOxygenPregnancyReference ValuesRetrospective Studies

Pub Type(s)

Journal Article

Language

eng

PubMed ID

18176902

Citation

Roemer, V M.. "How to Determine and Use Base Excess (BE) in Perinatal Medicine." Zeitschrift Fur Geburtshilfe Und Neonatologie, vol. 211, no. 6, 2007, pp. 224-9.
Roemer VM. How to determine and use base excess (BE) in perinatal medicine. Z Geburtshilfe Neonatol. 2007;211(6):224-9.
Roemer, V. M. (2007). How to determine and use base excess (BE) in perinatal medicine. Zeitschrift Fur Geburtshilfe Und Neonatologie, 211(6), 224-9. https://doi.org/10.1055/s-2007-981337
Roemer VM. How to Determine and Use Base Excess (BE) in Perinatal Medicine. Z Geburtshilfe Neonatol. 2007;211(6):224-9. PubMed PMID: 18176902.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - How to determine and use base excess (BE) in perinatal medicine. A1 - Roemer,V M, PY - 2008/1/8/pubmed PY - 2008/4/10/medline PY - 2008/1/8/entrez SP - 224 EP - 9 JF - Zeitschrift fur Geburtshilfe und Neonatologie JO - Z Geburtshilfe Neonatol VL - 211 IS - 6 N2 - BACKGROUND: Foetal hypoxia may lead to multi-organ failure and cerebral injury. Usually this process is accompanied by severe metabolic acidosis. The base excess (BE) determined in umbilical artery (UA) blood is the most appropriate parameter to evaluate metabolic acidosis. The correct determination of BE therefore is of paramount importance both for the jeopardised foetus and the obstetrician in litigation. In blood, BE is dependent on the oxygen saturation [sO2 (%)] of haemoglobin (cHb). Due to the normally low foetal pO2 values in UA blood (median: ca. 18 mmHg) sO2 is low as well; therefore computational correction of BE to - by definition - 100 % oxygen saturation seems to be mandatory. This paper presents an analysis of this complex problem in obstetrics. METHODS: pH, pCO2, pO2 and cHb were measured in UA blood of 6 302 term infants delivered spontaneously using equipments from Radiometer (Copenhagen). BE was computed according to the equation of Siggaard-Andersen actually used in many blood-gas analysers. sO2 (%) was computed for HbF using the algorithm of Ruiz et al. . The numerical correction of BE was achieved with an equation given again by Siggaard-Andersen . APGAR indices after 1 minute were used. RESULTS: Median BE in UA was - 4.6 and the mean was - 4.9 +/- 3.0 mmol / L, respectively. Correction of BE (BEoxy.) to the actual (calculated) oxygen saturation (%) leads (always) to lower values: a median BE (oxy.) in UA of - 7.4 and a mean of - 7.6 +/- 3.2 mmol / L, respectively. There is no correlation between BE and sO2 in UA blood: r = 0.0078, p = 0.532, n = 6 302 (mean oxygen saturation: 27.7 +/- 18.3 %). The median cHb amounted to 15.2 and the mean to 15.0 +/- 2.6 g %, respectively. The median delta-BE,UA(BE - BEoxy.) amounts to 2.74 mmol / L; the maximum delta-BE reached 5.2 mmol / L in this sample. Correction of BE to 100 % oxygen saturation based on the (calculated) real oxygen saturation (%) leads to significantly (p = 0.0099) higher correlations with the APGAR index (1 min) and pCO2 in UA (p << 10 (-4)) as well. CONCLUSION: Correction of BE in UA, i. e., correction of BE to 100 % oxygen saturation using the (calculated) actual oxygen saturation (%) of the blood sample is mandatory in perinatal medicine. Correction uniformly leads to lower BE values (median: 2.7 mmol / L) and significantly higher correlation coefficients with important clinical variables (e. g., the APGAR index). SN - 0948-2393 UR - https://www.unboundmedicine.com/medline/citation/18176902/How_to_determine_and_use_base_excess__BE__in_perinatal_medicine_ DB - PRIME DP - Unbound Medicine ER -