Unidentified acids of strong prognostic significance in severe malaria.
OBJECTIVE
To calculate, using the Stewart approach to acid-base disorders, the strong anion gap as an estimate for the contribution of unmeasured plasma anions other than lactate to the metabolic acidosis that characterizes severe falciparum malaria and to assess its relative prognostic significance.


METHODS
Cohort study.


METHODS
The intensive care unit of an infectious diseases hospital in southern Vietnam.


METHODS
Consecutive adult patients (n = 268) with severe falciparum malaria.


METHODS
The intervention was clinical management in a dedicated unit. We measured baseline venous lactate, electrolytes, biochemical variables, admission arterial blood pH, and gas tensions for calculation of the strong anion gap.


RESULTS
The mean (95% confidence interval) admission strong anion gap was 11.1 (10.4-11.9) mEq/L, compared with lactate (geometric mean, 95% confidence interval) at 2.9 (2.7-3.2) mmol/L. Strong anion gap had a high predictive value for mortality (area under the receiver operating characteristic curve 0.73 (95% confidence interval, 0.65-0.82), which was independent of plasma lactate and creatinine concentrations. Renal failure and hepatic dysfunction were both associated with, but were not the sole determinants of, high levels of strong anion gap.


CONCLUSIONS
In severe malaria, unidentified anions other than lactate are the most important contributors to metabolic acidosis, a major cause of death. The strong anion gap is a powerful prognostic indicator in patients with severe malaria.
Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
Arjen M
AM
Dondorp
Tran Thi Hong
TT
Chau
Nguyen Hoan
NH
Phu
Nguyen Thi Hoang
NT
Mai
Pham Phu
PP
Loc
Ly Van
LV
Chuong
Dinh Xuan
DX
Sinh
Ann
A
Taylor
Tran Tinh
TT
Hien
Nicholas J
NJ
White
Nicholas P J
NP
Day
D000136:Acid-Base Equilibrium; D000138:Acidosis / Q000097:blood* / Q000209:etiology* / Q000503:physiopathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D003422:Critical Care / Q000379:methods; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D016778:Malaria, Falciparum / Q000097:blood* / Q000150:complications* / Q000175:diagnosis / Q000401:mortality; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010710:Phosphates / Q000097:blood; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D016019:Survival Analysis; D014744:Vietnam / Q000453:epidemiology
D010710:Phosphates; D019344:Lactic Acid; D003404:Creatinine