Determination of the anatomical angulation of the right upper-lobe bronchi and left main bronchi relative to the coronal plane: a retrospective CT analysis to guide the placement of double-lumen tubes

Background Double-Lumen Tubes (DLTs) remain the common method for One-Lung Ventilation (OLV) in clinical practice. Nevertheless, optimal size selection and accurate placement are still challenging. A precise understanding of the anatomical relationships among the trachea, bronchi, and surrounding structures is essential. This study aim to determine the true anatomical angulation of the right upper-lobe bronchi and the left main bronchi relative to the coronal plane. Methods In this retrospective study, 400 consecutive patients were enrolled: 200 aged 18–60 years and 200 aged > 60 years. High-resolution thoracic CT images of these patients was retrieved, and the following parameters were measured: cross-sectional area and perimeter at the origin of main bronchus, the angle between the right upper-lobe bronchial orifice and the coronal plane, and the angle between the left main bronchial orifice and the coronal plane. Results The right upper-lobe bronchi had a mean angulation of−5.35 ± 13.04° and the most often angled between − 10°~0° (36.2%), followed by -20°~ -10° (22.8%) and < -20°(9.8%), the left main bronchi was more acutely angled (−9.57 ± 12.60°) and the frequently formed angle of -10°~0° (38.2%), followed by -20°~-10° (25.3%) and < -20° (16%). Compared with the younger group (18–60 years, n = 200), patients older than 60 years group (n = 200) weighed slightly less (67.03 ± 12.13kg vs 64.63 ± 11.11kg, p  = 0.04), whereas sex distribution, height and left main bronchial perimeter were similar ( p  = 0.08). The older group exhibited significantly steeper posterior angulation of both the right upper-lobe bronchi (−7.70 ± 13.84° vs−3.00 ± 11.75°, p  < 0.01) and the left main bronchi (-11.34 ± 12.20° vs -7.80 ± 12.77°, p  < 0.01), a larger left main bronchial orifice area (1.44 ± 0.41cm ² vs 1.36 ± 0.32 cm², p  = 0.02), and a longer right main bronchial orifice perimeter (4.93 ± 0.81cm vs 4.75 ± 0.63 cm, p  = 0.01), while the difference in right upper-lobe area (1.70 ± 0.51cm ² vs 1.62 ± 0.43 cm²) did not reach significance ( p  = 0.07). Conclusions Individualized rotation of right-sided double-lumen tube and left-sided double-lumen tube based on the angle of the right upper-lobe bronchi and the left main bronchi relative to the coronal plane on preoperative CT may improve the first attempt success rate of the intubation of double-lumen tubes.