Evaluation of end tidal capnography and upper airway ultrasonography for confirmation of endotracheal tube placement in adult patients undergoing elective surgery: Capnography versus ultrasonography for endotracheal tube placement

Abstract

Introduction: Capnography has been considered the gold standard method for confirmation of endotracheal tube placement. The current cross-sectional observational study was undertaken to compare upper airway ultrasonography and capnography for confirmation of endotracheal tube placement in patients undergoing elective surgery. Methods: 75 adult patients (18-60 years of age) belonging to ASA physical status I or II, scheduled for elective surgery under general anaesthesia requiring oral endotracheal intubation were enrolled for the study. After intubation, proper placement of endotracheal tube was confirmed by chest auscultation, end tidal capnography and upper airway ultrasonography simultaneously. Sensitivity, specificity, positive and negative predictive values of both capnography and ultrasonography were computed. Results: Using capnography, the position of endotracheal tube was found to be in the trachea in 72 patients (96%) and not in the trachea in 3 patients (4%). Ultrasonography was able to detect all 3 esophageal intubations but failed to confirm 2 endotracheal intubations. Capnography had sensitivity, specificity, positive and negative predictive values all at 100%. Ultrasonography had sensitivity of 97.22%, specificity of 100%, positive predictive value of 100% and negative predictive value of 60%. The kappa value was 0.737 which indicates a good correlation between capnography and upper airway ultrasound. Conclusion: Ultrasonography provides a real time dynamic visualization of the endotracheal tube. This study was able to demonstrate that ultrasonography is an acceptable, faster and safer method for confirming endotracheal tube placement. However, further studies are recommended to determine the best approach for emergency situations, patients with a difficult airway, and in critical care settings.