Identifying the ideal tracheostomy site based on patient characteristics during percutaneous dilatational tracheostomy without bronchoscopy

We previously reported that percutaneous dilatational tracheostomy (PDT) can be safely performed 2 cm below the cricothyroid membrane without the aid of a bronchoscope. Although our simplified method is convenient and does not require sophisticated equipment, the precise location for tracheostomy cannot be confirmed. Because it is recommended that tracheostomy be performed at the second tracheal ring, we assessed whether patient characteristics could predict the distance between the cricothyroid membrane and the second tracheal ring. Data from 490 patients who underwent three-dimensional neck computed tomography from January 2012 to December 2015 were analyzed, and the linear distance from the upper part of the cricoid cartilage (CC) to the lower part of the second tracheal ring (2TR) was measured in the sagittal plane. The mean CC-to-2TR distance was 25.26 mm (95% CI 25.02-25.48 mm). Linear regression analysis showed that the predicted CC-to-2TR distance could be calculated as -5.73 + 0.2 × height (cm) + 1.22 × sex (male: 1, female: 0) + 0.01 × age (yr) -0.03 × weight (kg) (adj. R2 = 0.55). These results suggest that height and sex should be considered when performing PDT without bronchoscope guidance.