Is Serum Bicarbonate Level Associated With Negative Outcomes in Pediatric Patients?: A Retrospective Cohort Study

Abstract

Objectives: Early identification of children at risk for adverse outcomes is important. Serum bicarbonate is easily collected and widely available. We described the relationship between bicarbonate and adverse outcomes in children presenting to the emergency department (ED).

Methods: We conducted a retrospective cohort study of children aged 0 to 17 years from January 1, 2007, to December 31, 2011, who had a serum bicarbonate measured in the ED. Primary outcome was the predictive ability of bicarbonate for the individual components of the composite outcome that included at least one of the following: intensive care unit admission, assisted ventilation, inotropic support, cardiopulmonary resuscitation, or death. Secondary outcome was the relationship between bicarbonate level of greater and less than 13 mEq/L and the composite outcome.

Results: We reviewed 16,989 charts, of which 432 had an adverse outcome. Receiver operating characteristic curve analysis showed that a bicarbonate level of less than 18.5 mEq/L predicted inotropic support with an area under the curve of 0.69 (95% confidence interval [CI], 0.60-0.77; P < 0.001) and death with an area under the curve of 0.75 (CI, 0.66-0.85; P < 0.001). Significantly more patients with bicarbonate level of less than 13 mEq/L had at least 1 adverse outcome compared with those with bicarbonate level of greater than 13 mEq/L (4.4% vs 2.5%, P = 0.001), odds ratio 1.96 (95% CI, 1.3-2.97).

Conclusions: Among children presenting to the ED, bicarbonate level of 18.5 mEq/L had fair specificity in predicting inotropic support and death. Negative outcomes are significantly associated with bicarbonate level of less than 13 mEq/L. Bicarbonate should routinely be measured in children at risk of clinical deterioration.