An overlooked aspect on metabolic acidosis at birth: blood gas analyzers calculate base deficit differently
Open accessAbstract
OBJECTIVE: Metabolic acidosis (MA) at birth is commonly defined as umbilical cord arterial pH < 7.0 plus base deficit (BD) ≥ 12.0 mmol/L. Base deficit is not a measured entity but is calculated from pH and Pco(2) values, with the hemoglobin (Hb) concentration [Hb] included in the calculation algorithm as a fixed or measured value. Various blood gas analyzers use different algorithms, indicating variations in the MA diagnosis. The objective was therefore to calculate the prevalence of MA in blood and extracellular fluid with algorithms from three blood gas analyzer brands relative to the Clinical and Laboratory Standards Institute (CLSI) algorithm. DESIGN: Comparative study. SETTING: University hospital. SAMPLE: Arterial cord blood from 15 354 newborns. MAIN OUTCOME MEASURE: Prevalence of MA. METHODS: Blood was analyzed in a Radiometer ABL 735 analyzer. Base deficit was calculated post hoc with algorithms from CLSI and Corning and Roche blood gas analyzers, and with measured and fixed (9.3 mmol/L) values of [Hb]. RESULTS: The prevalence of BD ≥12.0 mmol/L in blood was with the CLSI algorithm 1.97%, Radiometer 5.18%, Corning 3.84% and Roche 3.29% (CLSI vs. other; McNemar test, p < 0.000001). Likewise, MA prevalences were 0.58, 0.66, 0.64 and 0.64%, respectively (p≤ 0.02). Base deficit ≥ 12.0 mmol/L and MA rates were lower in extracellular fluid than in blood (p≤ 0.002). Algorithms with measured or fixed Hb concentration made no differences to MA rates (p≥ 0.1). CONCLUSIONS: The neonatal metabolic acidosis rate varied significantly with blood gas analyzer brand and fetal fluid compartment for calculation of BD.
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When calculating with different equations and in different BD compartments, we found an interanalyzer difference in diagnosing BD >12.0 mmol/L of up to 426%.
“When calculating with different equations and in different BD compartments (provided below), we found an interanalyzer difference in diagnosing BD >12.0 mmol/L of up to 426%.”
From Umbilical cord pH, blood gases, and lactate at birth: normal values, interpretation, and clinical utility. (2023) · cites this paper as [24]
The Results and Discussion distinguish interanalyzer from intra-analyzer comparisons. The maximum interanalyzer difference was 163% for BD in blood and 210% for BD in extracellular fluid; 426% was the maximum intra-analyzer difference between compartments. (LLM, conf=0.94)
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- Authors
- MOKARAMI, P., WIBERG, N., & OLOFSSON, P.
- Affiliations
- Lund University (SE)
- Venue
- Acta Obstetricia Et Gynecologica Scandinavica
- Publisher
- Wiley
- Published
- 2012-03-12
- Volume
- 91
- Issue
- 5
- Pages
- 574-579
- ISSN
- 0001-6349 (ISSN-L)
- 1600-0412
- OpenAlex
- W2158982304
- Cited by
- 28
- References
- 22
- Citations by year
- 2026: 1 · 2025: 1 · 2024: 4 · 2023: 2 · 2021: 3 · 2020: 2 · 2019: 5 · 2016: 3 · 2015: 3 · 2014: 2 · 2013: 2
- FWCI
- 1.77
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Acta Obstetricia Et Gynecologica Scandinavica (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Lunds Universitet
- Region Skåne
- Topics
- Health Sciences › Medicine › Nephrology › Renal function and acid-base balance
- Health Sciences › Medicine › Physiology › Clinical Laboratory Practices and Quality Control
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Clinical Biochemistry › Metabolism and Genetic Disorders
- Keywords
- neonatal metabolic acidosis, base deficit, umbilical cord blood, blood gas analyzer, calculation algorithm, hemoglobin levels, extracellular fluid, cordocentesis, neonates
- MeSH terms
- Acidosis, Algorithms, Blood Gas Analysis, Fetal Blood, Humans, Infant, Newborn, Prevalence, Extracellular Fluid
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