Curvature of the left main bronchus caused by postural change from supine to left lateral position

This study was designed to examine deviation of the bronchus by postural change from supine to lateral position during spontaneous respiration. Fifteen healthy volunteers [13 men and 2 women, mean age: 34 years (range 26-42)] participated. Chest radiograms (anterior-posterior) were acquired in the order of supine, left lateral, and right lateral position. The bilateral bronchus angles and secondary carina angles were measured in the acquired images, and the angles were compared between the supine and lateral positions to evaluate deviation of the bronchus in the lateral position. The left secondary carina angle in the supine position was 61.3° ± 4.0° and it significantly increased to 65.5° ± 6.0° in the left lateral position (P = 0.001), but no significant difference was noted in the left bronchus angle between the supine and left lateral positions (P = 0.158). The curvature of left main bronchus, which we defined more than 5° increase in secondary carina angle, was observed in a half of the male participants during left lateral position. We should be aware of these anatomical changes due to the surgical posture as a possible cause for ventilation failure during one-lung ventilation.