Utility of Stewart's strong ion difference as a predictor of major injury after trauma in the ED.
BACKGROUND
Base deficit (BD) is a validated surrogate for lactate in injured patients and correlates with trauma severity. Stewart proposed a more comprehensive measure of acidosis based on the strong ion difference (SID) (SID = Na + K + Mg + Ca - CL - lactate [mEq/L]). We compared operating characteristics of BD, anion gap (AG), and SID in identifying major injury in emergency department (ED) trauma patients.


METHODS
This was a retrospective review. Major injury was defined as Injury Severity Score > or =15, blood transfusions, or significant drop in hematocrit. Receiver operating characteristic curves compared BD, AG, and SID in differentiating major from minor injuries.


RESULTS
The study included 1181 patients. Both BD and SID were significantly (P = .0001) different after major vs minor injury (mean difference, 3.40; 95% confidence interval, 2.70-4.00 and mean difference, 2.50; 95% confidence interval, 1.90-3.10, respectively). Receiver operating characteristic curves were minimally different from one another (P = .0035).


CONCLUSIONS
Stewart's SID can identify major injury in the ED.
Zehtabchi
Shahriar
S
Department of Emergency Medicine, SUNY Downstate and Kings County Hospital, Brooklyn, NY 11203, USA.
Soghoian
Samara
S
Sinert
Richard
R
D000137:Acid-Base Imbalance / Q000097:blood / Q000175:diagnosis*; D000138:Acidosis / Q000175:diagnosis; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001639:Bicarbonates / Q000097:blood; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015601:Injury Severity Score; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D014947:Wounds and Injuries / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology
D001639:Bicarbonates; D019344:Lactic Acid