RESUMO
Objective To evaluate the accuracy of different anatomic landmark methods in determining the size of nasopharyngeal airway.Methods Fifty-two patients of both sexes,aged 16-60 yr,of American Society of Anesthesiologists physical status Ⅰ to Ⅲ,with body mass index of 18-30 kg/m2,scheduled for elective awake craniotomy for supratentorial tumors under sedation-awake-sedation anesthesia,were included.For each patient,the distance from the apex of nose to the right tragus (NT),distance from apex of nose to the right mandibular angle (NM),and thyro-mental distance (TM) were measured and marked on a transnasal tube correspondingly.The patients were placed in supine position without pillow,topical anesthesia (nasal mucosal surface) was performed with 2％ lidocaine,and patients were sedated with midazo1am,propofol and dexmedetomidine.When Observer's Assessment of Alertness/Sedation Scale score was 2 or 3 points,the tube was transnasally inserted to each marked depth.When the three marked depths mentioned above were reached,the positions of the tube's tip were checked using a fiberoptic bronchoscope and recorded as:above epiglottis (the tip of the tube was placed between the epiglottis and the free edge of soft palate) or below epiglottis (the tip of the tube placed at or beyond the epiglottis).Results When the depth reached the NT mark,the tube's tip was above epiglottis in 14 cases (27％),and the tube's tip was below epiglottis in 38 cases (73％).When the depth reached the NM mark,the tube's tip was above epiglottis in 31 cases (60％),and the tube's tip was below epiglottis in 21 cases (40％).When the depth reached the TM mark,the tube's tip was above epiglottis in 52 cases (100％).Compared with the NM and NT methods,the TM method had a higher probability with the tube's tip above epiglottis when used to determine the depth of insertion (P＜0.01).Conclusion TM anatomic landmark method provides higher accuracy in determining the size of nasopharyngeal airway.