Noninvasive capnometry in a pediatric population with respiratory emergencies

This study was designed to investigate the reliability, safety, and efficacy of measuring end tidal CO2 (ETCO2) in nonintubated pediatric patients presenting to an emergency department (ED) with respiratory emergencies.

Eighty-five children were enrolled in a clinical, prospective, observational study at a university-affiliated children's hospital. Children age four weeks to 15.3 years with upper and lower respiratory diseases were enrolled by convenience sampling over a five-month period.

ETCO2 measurements were obtained on each patient by oral/nasal side-stream capnometry. When a consistent waveform was obtained, the value was compared with a capillary arterial partial pressure of CO2 (CapCO2), oxygen saturation (O2Sat), and clinical observations.

Study patients had a mean ETCO2 reading of 33 mmHg with a standard deviation (SD) of 4.6 mmHg and CapCO2 reading of 36 mmHg with a SD of 4.5 mmHg. Pulmonary findings, final diagnosis, and age did not significantly alter the relationship between CapCO2 and ETCO2. The relationship between CapCO2 and ETCO2 was significant (t = 14.9, P < 0.0001, r = 0.87), with a 95% confidence interval for prediction of +/-5 mmHg.

Dependable ETCO2 values can be obtained using an oral/nasal capnometry circuit, and they consistently correlate with CapCO2 in a pediatric population with upper and lower respiratory diseases. Noninvasive ETCO2 analysis is safe and reliable within the limitations of this study group. Further exploration is necessary to determine the value of this technology in assisting with clinical decisions in the patient with impending respiratory failure.