ASSESSMENT OF A NOVEL REUSABLE 3D-PRINTED DUAL ETCO₂–O₂ UNIVERSAL ADAPTER FOR END-TIDAL CARBON DIOXIDE MONITORING DURING REGIONAL ANAESTHESIA:A PROSPECTIVE COMPARATIVE CROSSOVER STUDY

Abstract

Objective: Capnography is an important method for continuous monitoring of ventilation during anaesthesia and procedural sedation. However, reliable end-tidal carbon dioxide (EtCO₂) monitoring in spontaneously breathing patients receiving oxygen through a conventional face mask can be difficult. This study evaluated the clinical performance of a novel reusable three-dimensional (3D)-printed dual EtCO₂–O₂ universal adapter designed for use with a standard Hudson mask. Materials & Methods: This prospective comparative crossover study was conducted among 60 adult patients undergoing elective surgery under regional anaesthesia with spontaneous ventilation. EtCO₂ measurements were recorded using the novel reusable 3D-printed adapter and the commercially available Sumi Hi-Capno Facemask under identical clinical conditions. Arterial partial pressure of carbon dioxide (PaCO₂) was used as the reference standard. The primary outcome was EtCO₂ measurement accuracy. Secondary outcomes included PaCO₂–EtCO₂ gradient, Bland–Altman agreement, waveform quality, clinical feasibility, and cost profile. Results: The mean arterial PaCO₂ was 39.78 ± 2.91 mmHg. The mean EtCO₂ was 37.89 ± 2.98 mmHg with the novel adapter and 37.68 ± 3.34 mmHg with the Sumi Hi-Capno Facemask. The mean PaCO₂–EtCO₂ gradient was 1.89 ± 1.46 mmHg for the novel adapter and 2.10 ± 1.77 mmHg for the Sumi Hi-Capno Facemask, with no significant difference between devices. Bland–Altman analysis showed acceptable agreement with PaCO₂. Successful waveform acquisition was achieved in all patients. Discussion and conclusion: The novel reusable 3D-printed dual EtCO₂–O₂ adapter demonstrated EtCO₂ measurement accuracy, agreement with PaCO₂, waveform quality, and clinical feasibility comparable to the Sumi Hi-Capno Facemask. Its reusable design may provide a cost-effective alternative for routine capnographic monitoring during regional anaesthesia, especially in resource-limited settings.