Objectives: The aims of this study were to measure diameters of the cricoid ring and left main bronchus in Asian adult patients and to assess the accuracy of double lumen tube size selected according to cricoid and left main bronchus diameter, respectively.
Design: Retrospective observational study.
Setting: Academic, tertiary care hospital.
Participants: Preoperative CT scans from 87 men and 94 women who had undergone general anesthesia for lung operations.
Interventions: No intervention.
Measurements and main results: The diameters of the cricoid ring and left main bronchus were measured from thoracic computed tomography images after correction of slant. The "best-fit" size of double lumen tube was determined by comparing diameter of the left main bronchus and cricoid ring with the diameter of the double lumen tube. Diameters of the cricoid ring and left main bronchus were both significantly greater in men compared with women (p < 0.0001). Shapes of cricoid rings were different between genders (p < 0.0001), while shapes of the left main bronchus were not significant different (p = 0.343). With reference to the "best fit" size, the rate of agreement of cricoid ring size, left main bronchus size, and height size for men were 100%, 100%, and 94.3%. For women, the rate of agreement of cricoid ring size, left main bronchus size, and height size were 94.7%, 63.8%, and 51.1%.
Conclusions: The "best fit" size of a double lumen tube should be decided by a combination of diameters of the cricoid ring and the left main bronchus.
Keywords: cricoid ring; double-lumen tube; left main bronchus, computed tomography.
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