Initial pH, base deficit, lactate, anion gap, strong ion difference, and strong ion gap predict outcome from major vascular injury.
OBJECTIVE
This study determines whether acid-base data obtained in the emergency department correlate with outcome from major vascular injury.


METHODS
Observational, retrospective record review of trauma patients requiring vascular repair (torso or extremity, January 1988 to December 1997). Data included age, Injury Severity Score, injury mechanism, survival, laboratory profiling, calculated anion gap, strong ion difference, and strong ion gap. Patients were divided into survivors and nonsurvivors with comparison by Student's t-test; significance was assumed for p < or = .05. Multivariate logistic regression was used for further analysis of univariate predictors of mortality, and receiver operator characteristic curves were generated for mortality from each variable.


METHODS
Urban level I trauma facility.


METHODS
Trauma patients requiring vascular repair of torso or extremity injury.


METHODS
None.


RESULTS
Both nonsurvivors (n = 64) and survivors (n = 218) were similar with respect to age (31 +/- 9 vs. 31.5 +/- 10.5, p = 0.15) and injury mechanics (81% penetrating in survivors vs. 83% penetrating in nonsurvivors, p = .71). Non-survivor Injury Severity Score exceeded that of survivors (27.5 +/- 7.8 vs. 12.4 +/- 9.4, p < .001). Nonsurvivor pH (7.06 +/- 0.15 vs. 7.34 +/- 0.08, p < .001) and apparent strong ion difference (31.38 +/- 4.39 vs. 37.53 +/- 3.86, p < .001) were significantly lower, whereas nonsurvivor standard base excess (-17.9 +/- 5.1 vs. -2.9 +/- 4.4 mEq/L, p < .001), lactate (11.1 +/- 3.6 vs. 3.6 +/- 1.5 mmol/L, p < .001), anion gap (28.2 +/- 4.1 vs. 15.6 +/- 3.1, p < .001), and strong ion gap (10.8 +/- 3.2 vs. 2.4 +/- 1.8, p < .001) were higher. All but one nonsurvivor had initial emergency department pH < or = 7.26, standard base excess < or = -7.3 mEq/L, lactate > or = 5 mmol/L, and strong ion gap > or = 5 mEq/L. All of the acid-base descriptors were strongly associated with outcome, but the strong ion gap discriminated most strongly with an area under the receiver operator characteristic of 0.991 (95% confidence interval, 0.972-0.998).


CONCLUSIONS
The initial emergency department acid-base variables of pH, base deficit, lactate, anion gap, apparent strong ion difference, and strong ion gap discriminate survivors from non-survivors of major vascular injury. The strong ion gap is most strongly predictive of mortality following major vascular trauma.
Kaplan
Lewis J
LJ
Yale University School of Medicine, Department of Surgery, Section of Trauma, Critical Care, and Emergency General Surgery, USA.
Kellum
John A
JA
D000136:Acid-Base Equilibrium; D000137:Acid-Base Imbalance / Q000097:blood / Q000209:etiology / Q000401:mortality; D000328:Adult; D017677:Age Distribution; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D001784:Blood Gas Analysis; D001808:Blood Vessels / Q000293:injuries*; D016002:Discriminant Analysis; D004636:Emergency Service, Hospital; D017052:Hospital Mortality; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015601:Injury Severity Score; D019344:Lactic Acid / Q000097:blood*; D016015:Logistic Models; D009104:Multiple Trauma / Q000150:complications* / Q000401:mortality / Q000601:surgery; D017063:Outcome Assessment, Health Care; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D014193:Trauma Centers
D019344:Lactic Acid