Please use this identifier to cite or link to this item: http://ahro.austin.org.au/austinjspui/handle/1/9376
Title: Comparison of three methods to estimate plasma bicarbonate in critically ill patients: Henderson-Hasselbalch, enzymatic, and strong-ion-gap.
Authors: Story, David A;Poustie, Stephanie J;Bellomo, Rinaldo
Affiliation: Department of Anaesthesia, Austin and Repatriation Medical Centre, University of Melbourne, Victoria.
Issue Date: 1-Dec-2001
Citation: Anaesthesia and Intensive Care; 29(6): 585-90
Abstract: We have previously found poor agreement between Henderson-Hasselbalch and enzymatic methods for estimating plasma bicarbonate concentration in critically ill patients. In this study we compared these two established methods with a new method for estimating bicarbonate using the strong-ion-gap equation. The strong-ion-gap is derived from the Stewart approach to acid-base physiology. One hundred data sets were collected from records of routine daily blood samples in critically ill patients. Bland-Altman analyses were used to compare the three methods. We proposed that bias greater than +/- 1 mmol/l and limits of agreement wider than bias +/- 2 mmol/l were clinically important, Comparing the Henderson-Hasselbalch method to the enzymatic method, the bias was 2.1 mmol/l and the limits of agreement were -1.8 mmol/l to 5.9 mmol/l. Comparing the Henderson-Hasselbalch method to the strong-ion-gap method, the bias was -9.1 mmol/l and the limits of agreement were -17.1 mmol/l to -1.1 mmol/l. Comparing the enzymatic to the strong-ion-gap method, the bias was -11.2 mmol/l and the limits of agreement were -18.2 mmol/l to -4.2 mmol/l. This study found poor agreement between the two established bicarbonate assays and worse agreement between the established assays and the strong-ion-gap method. The strong-ion-gap method is currently too inaccurate for clinical application, but may have future use.
Internal ID Number: 11771599
URI: http://ahro.austin.org.au/austinjspui/handle/1/9376
URL: http://www.ncbi.nlm.nih.gov/pubmed/11771599
Type: Journal Article
Subjects: Acid-Base Imbalance.blood
Bicarbonates.blood
Blood Gas Analysis.methods
Carbon Dioxide.blood
Critical Illness
Humans
Hydrogen-Ion Concentration
Intensive Care Units
Prospective Studies
Spectrophotometry
Appears in Collections:Journal articles

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