Objective: To measure changes in end-tidal carbon dioxide levels (ETco2) with different sedation/analgesia (midazolam, ketamine, ketamine plus midazolam, midazolam plus fentanyl, and propofol) during pediatric minor surgical procedures and to determine whether there were significant increases in ETco2 with different drugs.
Methods: We conducted a prospective, randomized, clinical trial of 126 children who needed sedation/analgesia in pediatric intensive care unit in a university hospital. Patients were randomly assigned to 1 of 5 treatment groups. Group K received only intravenous (IV) ketamine 1 mg/kg; group M, IV midazolam 0.15 mg/kg; group KM, IV ketamine 1 mg/kg plus IV midazolam 0.1 mg/kg; group MF, IV midazolam 0.1 mg/kg plus IV fentanyl 2 μg/kg; and group P, IV propofol 2 mg/kg. Side stream, nasal cannula ETco2 tracings were recorded on a capnograph (Capnostat, Marquette). Recordings began prior to the administration of medications and continued throughout the procedure until the patient was fully awake. The primary outcome variable was the difference between peak ETco2 before and during sedation/analgesia. This value was determined by scanning the records for the peak ETco2 averaged over 5 breaths before and after the administration of medications.
Results: There was neither any statistical difference between presedation/analgesia and postsedation/analgesia ETco2 levels in the 5 groups (P > 0.05) nor any difference in the first 3 groups between presedation/analgesia, sedation/analgesia, and postsedation/analgesia (K, M, and KM) (P > 0.05). In the midazolam plus fentanyl and propofol groups, mean ETco2 during sedation/analgesia was higher than the mean ETco2 during presedation/analgesia and postsedation/analgesia (P < 0.05). Twenty-one patients (16, 6%) had respiratory depression [hypercarbia (ETco2 > 50 mm Hg) or hypoxia (oxygen saturation > 90% for over 1 minute)], 21 patients (16, 6%) had hypercarbia, and 4 patients (3.2%) had both hypoxia and hypercarbia. One of 4 patients was in the MF group, and 3 were in the P group. Two subjects (8%) in the KM group, 7 (28%) in the MF group, and 13 (52%) in the P group had hypercarbia.
Conclusions: This study demonstrated that propofol and midazolam-fentanyl produced a higher incidence of respiratory depression and higher mean ETco2 during sedation/analgesia than presedation and postsedation/analgesia. Capnography can serve as a useful monitoring tool in the evaluation of ventilation during sedation or sedation/analgesia in clinically stable children.