HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS REGISTER		Author Keyword(s) Vol Page [Advanced]

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this link to a friend Similar articles in this journal Similar articles in PubMed Add article to my folders Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Adams, B D Articles by Hunter, C J Search for Related Content PubMed PubMed Citation Articles by Adams, B D Articles by Hunter, C J

The anion gap does not accurately screen for lactic acidosis in emergency department patients

US Army, Department of Emergency Medicine, San Antonio Uniformed Services Health Education Consortium, Brooke Army Medical Center, San Antonio, TX, USA

Correspondence to:
Correspondence to:
Dr B D Adams
US Army, Department of Emergency Medicine, San Antonio Uniformed Services Health Education Consortium, Brooke Army Medical Center, San Antonio, TX 78234, USA

Introduction: Lactic acidosis portends a poor prognosis in trauma, sepsis, and other shock states and is useful for triaging and resuscitating emergency department (ED) patients. The authors sought to determine whether the AG is a reliable screen for lactic acidosis when applied specifically in the ED setting.

Methods: The authors performed a retrospective cohort study over a seven month period. Subjects were all ED patients that had a serum lactate obtained. Sensitivity analyses of the AG for detecting presence of lactic acidosis were calculated for the traditional AG normal value (AG <12) and for the lower AG normal value when using newer ion selective electrode assays (AG <6).

Results: Serum lactate levels were ordered in the ED on 440 occasions. 137 samples were excluded by protocol. Using an AG cutoff of 12, the sensitivity for detecting lactic acidosis was 58.2%, specificity was 81.0%, and the negative predictive value was 89.7%. Using the AG cutoff of 6, the sensitivity was 93.2%, the specificity was 17.3%, and the negative predictive value was 91.8%.

Conclusions: The traditional definition of AG >12 was insensitive for the presence of lactic acidosis. Using the revised AG of >6 is more sensitive but non-specific for lactic acidosis. The authors conclude that employing the AG as a screen for LA may be inappropriate in ED patients. Instead, they recommend ordering a serum lactate immediately upon suspicion of a shock state. A prospective study to confirm these findings is needed.

Abbreviations: AG, anion gap; LA, lactic acidosis; NPV, negative predictive value; PPV, positive predictive value; ROC, received operated curve

Keywords: lactic acidosis; serum anion gap; sensitivity and specificity; emergency service; hospital; resuscitation

This article has been cited by other articles:

				C H Dinh, R Ng, A Grandinetti, A Joffe, and D C Chow Correcting the anion gap for hypoalbuminaemia does not improve detection of hyperlactataemia. Emerg. Med. J., August 1, 2006; 23(8): 627 - 629. [Abstract] [Full Text] [PDF]

				The Anion Gap Is Not a Good Screen for Lactic Acidosis Journal Watch Emergency Medicine, June 13, 2006; 2006(613): 4 - 4. [Full Text]