A novel approach to calculate the required volume of air for bronchial blockers in young children

Introduction Bronchial blocker balloons inflated with small volumes of air increase balloon pressure, involving a risk of airway injury especially in young children. However, there are no established guidelines regarding the appropriate volumes of air required to provide safe bronchial occlusion. Methods This study aimed to introduce a novel method for calculating the amount of air required for safe bronchial blocker balloon occlusion for one lung anesthesia in young children. We included 79 pediatric patients who underwent video‐assisted thoracoscopic surgery at our hospital. Preoperatively, the balloon pressure and corresponding diameter of 5F bronchial blockers inflated with different volumes of air were measured. Intraoperatively, bronchial diameters measured by computerized tomographic scans were matched to the ex vivo measured balloon diameters. The quality of lung isolation, incidence of balloon repositioning, and airway injury were documented. Postoperatively, airway injury was evaluated through fiberoptic bronchoscopy. Results Balloon pressure and balloon diameter showed linear and nonlinear correlations with volume, respectively. The median lengths of the right and left mainstem bronchi were median (interquartile range) range: 5.3 mm (4.5–6.3) 2.7–8.15 and 21.8 (19.6–23.4) 14–29, respectively. Occluding the left mainstem bronchus required <1 mL of air, with a balloon pressure of 27 cm H 2 O. The isolation quality was high with no case of mucosal injury or displacement. Occluding the right mainstem bronchus required a median air volume of 1.3 mL, with a median balloon pressure of 44 cm H 2 O. One patient had poor lung isolation due to a tracheal bronchus and another developed mild and transient airway injury. Conclusion The bronchial blocker cuff should be regarded as a high‐pressure balloon. We introduced a new concept for safe bronchial blocker balloon occlusion for one‐lung ventilation in small children.