Deciding how to decide the correct double-lumen tube: a narrative review of methods and evidence.

The selection of the appropriate size of a double-lumen tube (DLT) is a critical yet often underestimated aspect of thoracic anaesthesia. The present narrative review evaluates traditional and emerging methods for determining DLT size, including anthropometric formulas, chest X-rays, CT scans, and ultrasonography. Despite the prevalence of height- and gender-based predictions, mounting evidence underscores their restricted correlation with airway anatomy. Chest X-rays and CT scans have been shown to offer more accurate estimations of tracheobronchial dimensions, while ultrasound has been identified as a promising bedside tool. Recent meta-analytic evidence and technological advancements, including 3D reconstruction and AI-based modelling, may support a more personalised and safer approach. It is recommended that a pragmatic, image-guided strategy be employed to minimise airway trauma, improve lung isolation, and optimise patient outcomes.