Accuracy of a Novel Oxygen Mask Designed for Mainstream Capnometer in Non-intubated Pediatric Patients

Abstract

Background: Capnography is useful for identifying postoperative apnea in non-intubated children. A Cap-ONE mask is a multi-functional face mask which can allow oxygen supply and simultaneous end-tidal CO2 (ETCO2) measurement in infant and pediatric as well as an adult patient. However, the accuracy of the ETCO2 measured via Cap-ONE has not been well evaluated especially in infant and pediatric patient. The aim of this study was to examine the correlation and level of agreement between ETCO2 obtained via Cap- ONE mask and arterial blood gas partial pressure of CO2 (PaCO2) in postoperative non-intubated pediatric patients in the intensive care unit (ICU). Methods: Postsurgical pediatric patients scheduled to admit to the ICU with invasive arterial pressure monitoring from April 2015 to March 2017 were enrolled. Patients with cardiac disease or facial abnormalities were excluded from the study. After arrival at the ICU, either small-sized (for 7-20 kg) or medium-sized (for 20-40 kg) Cap-ONE mask was installed on a patient face with oxygen supply at 5 L/min; then ETCO2 measurement was started. Once stabilized, the sample of arterial blood gas was analyzed to measure PaCO2. The relationship between ETCO2 and PaCO2 was examined by simple regression analysis. A Bland Altman plot was used to evaluate agreement between these two measurements. Results: A total of 77 ETCO2-PaCO2 paired values were obtained from 29 patients. In 23 (79.3%) patients, dexmedetomidine was administrated for sedation. The mean ± SD for ETCO2 and PaCO2 was 39.0 ± 8.5 mmHg and 41.5 ± 6.5 mmHg respectively (small group; 35.2 ± 8.7 mmHg and 37.8 ± 5.3 mmHg, medium group; 41.8 ± 7.3 mmHg and 44.2 ± 5.8 mmHg). Correlation coefficient (R2) was 0.554 (P<0.01) between ETCO2 and PaCO2 (small group; R2=0.431, medium group; R2=0.515). The mean bias ± SD between ETCO2 and PaCO2 was -2.38 ± 5.69 mmHg. The 95% level of agreement ranged from -13.54 to+8.78 mmHg (small group; -2.60 ± 6.55 mmHg, medium group; -2.40 ± 5.10 mmHg). Conclusion: ETCO2 obtained from Cap-ONE mask is correlated well with PaCO2 in postoperative non-intubated pediatric patients (aged 7 months to 14 years). The present study demonstrated that the Cap-ONE mask can provide a continuous, non-invasive, relatively reliable respiratory measurement in non-intubated, lightly sedated pediatric patients.