Usefulness of end-tidal carbon dioxide as an indicator of dehydration in pediatric emergency departments: A retrospective observational study.

Physician assessment of hydration status is one of the most important factors in the management of dehydration in the pediatric emergency department (ED). Overestimating dehydration may lead to overtreatment with intravenous fluids or unnecessary hospitalization, whereas underestimation may lead to delayed therapy and aggravation of symptoms. Various methods to estimate hydration status have been proposed, including use of physical findings, body weight, and laboratory results. These methods are subjective, invasive, or inappropriate for application in the ED. A few studies have investigated the use of end-tidal carbon dioxide (ETCO2) as an acidosis parameter in cases of gastroenteritis and diabetic ketoacidosis. We aimed to evaluate the usefulness of ETCO2 as an objective and noninvasive dehydration parameter for children.A retrospective observational study was conducted in the regional emergency center of a tertiary university hospital for a period of 1 year. We included patients from the ED whose primary diagnosis was acute gastroenteritis. Among these, we enrolled patients with recorded ETCO2 and bicarbonate concentration (HCO3) levels. We collected information of clinical characteristics, vital signs, clinical dehydration scale (CDS) scores, laboratory test results, and final disposition. Correlations between ETCO2 and HCO3 as well as CDS scores were analyzed.A total of 105 children were finally enrolled in the study. All participants underwent laboratory testing and were mildly to severely dehydrated, with mean serum HCO3 20.7 ± 3.5 mmol/L. A total 95 (90.5%) patients had a CDS score <5, which is considered mild dehydration, and 10 (9.5%) patients had CDS ≥5, considered moderate-to-severe dehydration. The mean ETCO2 level was 32.1 ± 6.1 mmHg. Pearson correlation indicated a weak link between ETCO2 and HCO3 (correlation coefficient = 0.32), despite being statistically significant (P = .001). In addition, ETCO2 and CDS score showed a weak negative correlation (r = -0.20, P < .05).ETCO2 can be considered a simple, noninvasive parameter for identifying dehydration among patients in the pediatric ED. Though weak, ETCO2 showed a correlation with HCO3 level as well as CDS. In the future, a prospective study with a large number of pediatric patients is warranted.