Background and Goal of Study: The length of right main bronchus is essential for proper placement of right sided double lumen tubes or right endobronchial blockers. Regarding the physical difference among populations, we hypothesized that Thai people might have shorter right main bronchus compared to Westerners. This studywas conducted to measure the average length of the right main bronchus in Thai patients in supine and lateral positions after the left-sided double lumen intubation.Materials and methods: The research design was cross sectional. After approval from the institute ethical committee, the study was carried out in 50consecutive surgical patients undergoing thoracic procedures. A left sided double lumen tube was inserted and its position was confirmed by a flexible fiberopticbronchoscope. A length of right main bronchus was measured in supine and lateral decubitus positions. Data regarding the length of right main bronchus was expressed as mean ±sd. with a 95% confidence interval. Appropriate statistical tests including unpaired or paired t-tests were used when appropriate at a statistically significant level of 0.05.Results and discussion: Out of 50 patients, 27 were female. All were adults with the age of 57 ±14 years old, weight 54.79 ±10.34 kg, height 159.5 ±7.34 cm, and BMI 21.83 ±3.91 kg/m2. The average length of the right main bronchus in the supine position was 1.72 ±0.75 cm with the 95% CI of 1.5, 1.94. The mean lengths were 1.62±0.84 cm. and 1.83±0.64 cm in female and male respectively (p=0.34). Compared to the supine position, there was a statistically significant increase in length of the right main bronchus in the lateral decubitus position to 1.87 ±0.83 cm (p=0.043, 95% CI of 1.64, 2.1 cm).Conclusion: The result of this study provides information regarding the length of right main bronchus in both supine and lateral decubitus position in patients undergoing thoracic procedures. The information could help anesthesiologist to properly place right sided endobronchial blockers or tubes, thereby, protecting the right upper lung against atelectasis or aspiration during the thoracic procedures.

The length of right main bronchus in supine and lateral positions after left-sided double lumen intubation