Elevations in End-Tidal CO₂ With CO₂ Use During Pediatric Endoscopy With Airway Protection: Is This Physiologically Significant?

Background: Inflation of the gastrointestinal lumen is vital for proper visualization during endoscopy. Air, insufflated via the endoscope, is gradually being replaced with carbon dioxide (CO₂) in many centers, with the intention of minimizing post-procedural discomfort due to retained gas. Recent studies suggest that the use of CO₂ during pediatric esophagogastroduodenoscopy (EGD) with an unprotected airway is associated with transient elevations in exhaled CO₂ (end-tidal CO₂, EtCO₂), raising safety concerns. One possible explanation for these events is eructation of insufflation gas from the stomach. Objectives: To distinguish eructated versus absorbed CO₂ by sampling EtCO₂ from a protected airway with either laryngeal mask airway (LMA) or endotracheal tube (ETT), and to observe for changes in minute ventilation (MV) to exclude hypoventilation events. Methods: Double-blinded, randomized clinical trial of CO₂ versus air insufflation for EGD with airway protection by either LMA or ETT. Tidal volume, respiratory rate, MV, and EtCO₂ were automatically recorded every minute. Cohort demographics were described with descriptive characteristics. Variables including the percent of children with peak, transient EtCO₂ ≥ 60 mmHg were compared between groups. Results: One hundred ninety-five patients were enrolled for 200 procedures. Transient elevations in EtCO₂ of ≥60 mmHg were more common in the CO₂ group, compared to the air group (16% vs 5%, P = 0.02), but were mostly observed with LMA and less with ETT. Post-procedure pain was not different between groups, but flatulence was reported more with air insufflation (P = 0.004). Conclusion: Transient elevations in EtCO₂ occur more often with CO₂ than with air insufflation during pediatric EGD despite protecting the airway with an LMA or, to a lesser degree, with ETT. These elevations were not associated with changes in MV. Although no adverse clinical effects from CO₂ absorption were observed, these findings suggest that caution should be exercised when considering the use of CO₂ insufflation, especially since the observed benefits of using this gas were minimal.