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 (ETCO(2)) as an acidosis parameter in cases of gastroenteritis and diabetic ketoacidosis. We aimed to evaluate the usefulness of ETCO(2) 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 ETCO(2) and bicarbonate concentration (HCO(3)(−)) levels. We collected information of clinical characteristics, vital signs, clinical dehydration scale (CDS) scores, laboratory test results, and final disposition. Correlations between ETCO(2) and HCO(3)(−) 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 HCO(3)(−) 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 ETCO(2) level was 32.1 ± 6.1 mmHg. Pearson correlation indicated a weak link between ETCO(2) and HCO(3)(−) (correlation coefficient = 0.32), despite being statistically significant (P = .001). In addition, ETCO(2) and CDS score showed a weak negative correlation (r = −0.20, P < .05). ETCO(2) can be considered a simple, noninvasive parameter for identifying dehydration among patients in the pediatric ED. Though weak, ETCO(2) showed a correlation with HCO(3)(−) level as well as CDS. In the future, a prospective study with a large number of pediatric patients is warranted.