Accuracy of ultrasonography in determining laryngeal mask airway position: evaluation using 3D-CTR / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the accuracy of ultrasonography in determining the laryngeal mask airway position using three-dimensional CT reconstruction (3D-CTR) images as the standard.Methods:One hundred and thirty-four patients, aged 18-64 yr, weighing 30-100 kg, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective cerebral vascular interventional stent surgery in our hospital, were selected.Cervical ultrasonography was performed before and after laryngeal mask airway placement, and digital subtraction angiography was performed during operation to obtain 3D-CTR images.Neck ultrasound and 3D-CTR images were analyzed and graded.Results:A total of 125 patients completed the study.At the vertical position of the laryngeal mask airway, ultrasonic grading was positively correlated to 3D-CTR grading ( r=0.742, P<0.05). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ultrasound in determining the rotation of the laryngeal mask airway was 73.0% (95% CI 62.0%-84.4%), 92.8% (95% CI 86.9%-98.7%), 89.1% (95% CI 80.5%-97.7%), 81.0% (95% CI 72.6%-89.4%), and 74.2% (95% CI 65.2%-81.1%), respectively.In terms of laryngeal mask airway depth grading, the correlation between ultrasonic grading was positively correlated to 3D-CT grading ( r=0.332, P<0.05). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ultrasound in determining the depth of the laryngeal mask airway was 58.5% (95% CI 46.9%-70.1%), 93.3% (95% CI 87.2%-99.4%), and 90.5% (95% CI 82.0%-99.0%), 67.5% (95% CI 57.7%-77.3%), and 33.2% (95% CI 16.8%-47.8%), respectively.The positive predictive value of ultrasound in determining the optimal placement of the laryngeal mask airway was 61.1% (95% CI 48.6%-73.6%). Conclusion:Although ultrasound cannot measure the depth of the tip of the laryngeal mask airway into the esophagus, it has higher accuracy in determining the rotation and can be used as a reliable tool for clinical detection of the position of the laryngeal mask airway, especially the rotation.