Utility of end-tidal carbon dioxide monitoring in intramuscular ketamine sedation in the pediatric emergency department

ABSTRACT

PURPOSE: Recently, the use of end-tidal carbon dioxide (ETCO₂) monitoring has been suggested for early detection of hypoventilation over oxygen saturation (S(P)O₂) monitoring. We aimed to determine the usefulness of capnography in monitoring patients sedated using intramuscular (IM) ketamine in the pediatric emergency department (ED). METHODS: This study retrospectively reviewed medical records of patients younger than 16 years who were sedated using IM ketamine and whose ETCO₂ values were documented in the ED. Age, sex, American Society of Anesthesiologists physical status classification (ASA classification), and purpose of sedation were investigated. Vital signs were recorded at pre-sedation, 5 and 10 minutes after sedation, and after recovery. Hypoventilation was defined as S(P)O₂< 95%, ETCO₂≥ 50 mmHg or ≤ 30 mmHg, or increase in ETCO₂≥ 10 mmHg from the baseline without tachypnea. RESULTS: A total of 49 patients were investigated; 42 of them belonged to ASA classification I, and 7 to II. There was no patient with S(P)O₂< 95%, or ETCO₂≥ 50 mmHg, or increase in ETCO₂≥ 10 mmHg from the pre-sedation value. However, 5 patients had an ETCO₂≤ 30 mmHg, and 4 of them (8.2%) had normal respiratory rate and were suitable for hypopneic hypoventilation. Ten patients showed abnormal range of ETCO₂ (normal range, 35-45 mmHg), but did not meet the definition of hypoventilation. No one had clinically serious respiratory events. CONCLUSIONS: During sedation using IM ketamine, 8.2% of the patients had hypopneic hypoventilation without hypoxemia, and they were all younger than 36 months. Capnography for patients sedated using IM ketamine in the ED is useful in detecting hypopneic hypoventilation, and has the potential for preventing clinically serious respiratory events in patients, especially toddlers.