Strong ion gap is associated with mortality in pediatric burn injuries

Severe burn injury produces significant tissue damage, resulting in metabolic acidosis. Current methods of acid-base evaluation are based on dependent variables that may not be accurate after burn injury. The strong ion method of acid-base evaluation is based on independent variables and may accurately predict outcomes in severely burn-injured patients. The authors hypothesize that an increased strong ion gap present on admission will be associated with mortality in severely burn-injured pediatric patients. A retrospective chart review was performed of burn-injured pediatric patients with a TBSA 20% or greater. Data collected included age, TBSA burn injury, mechanism of injury, survival, ventilator days, hospital length of stay, intensive care unit length of stay, and admission laboratory values. Apparent and effective strong ion difference (SIDa, SIDe) were calculated. The strong ion gap (SIG) was determined as the difference between SIDa and SIDe. A total of 48 patients were included in the study. Mean age (years) and TBSA were 7.9 ± 0.8 years and 56.8 ± 2.6%. Eleven patients (23%) died. Mean TBSA for survivors (54.2 ± 2.9%) did not significantly differ from that of nonsurvivors (65.7 ± 5.34%). Ten patients suffered inhalation injury, which was associated with an odds ratio of 10.1* for mortality. Mean SIDa was 44.2 ± 3.2 for the entire study population. Survivors had a significantly lower SIDa (36.6 ± 0.5) than nonsurvivors (59.7 ± 13*). Mean SIDe for all patients was (25 ± 0.7) and did not differ significantly between survivors (24.7 ± 0.7) and nonsurvivors (25.8 ± 2). SIG for nonsurvivors (33.91 ± 14*) was significantly higher than for survivors (14.9 ± 0.3). Controlling for both TBSA and inhalation injury, death was associated with both an increased SIDa (B = 19.3*) and SIG (B = 17.3*). SIG is increased in severely burn-injured pediatric patients, indicating the presence of metabolic acidosis. Furthermore, an increased SIG is significantly associated with mortality. (*P <.05.).