ACCURACY OF A NOVEL REUSABLE 3D-PRINTED DUAL ETCO₂–O₂ ADAPTER COMPARED WITH THE SENTRI NASAL CANNULA FOR END-TIDAL CARBON DIOXIDE MONITORING IN SPONTANEOUSLY BREATHING PATIENTS UNDERGOING REGIONAL ANAESTHESIA

Abstract

Background: End-tidal carbon dioxide (EtCO₂) monitoring in spontaneously breathing patients undergoing regional anesthesia is essential for the early detection of hypoventilation. Conventional devices, such as the Sentri nasal cannula, are widely used; however, limitations in sampling efficiency and oxygen delivery persist. A novel reusable 3D-printed dual EtCO₂–O₂ adapter was developed to address these issues. Methods: In this prospective comparative study, spontaneously breathing adult patients scheduled for regional anesthesia were monitored using both the 3D-printed dual adapter and Sentri nasal cannula. The primary outcome measures included the accuracy of EtCO₂ values compared with arterial blood gas (PaCO₂) correlation. The secondary outcomes assessed ease of use, patient comfort, and oxygen delivery efficiency. Results: The 3D-printed adapter demonstrated EtCO₂ values with a strong correlation with PaCO₂, comparable to those of the Sentri nasal cannula. Bland–Altman analysis revealed narrower limits of agreement with the novel adapter, indicating its improved accuracy. Patient comfort scores were similar between the devices, whereas oxygen delivery was more consistent with the dual adapter. No adverse events were observed. Conclusion: The reusable 3D-printed dual EtCO₂–O₂ adapter provides accurate end-tidal carbon dioxide monitoring with reliable oxygen supplementation, offering a cost-effective and sustainable alternative to the Sentri nasal cannula in spontaneously breathing patients undergoing regional anaesthesia.