A Clinical Study on Predicting the Depth of Double-Lumen Tube Insertion Based on Height and Sitting Height

Plain-language summary

This study employed a combined observational derivation and randomized validation approach to establish and evaluate predictive models for the depth of DLT insertion (Figure 1). Initially, a total of 98 patients scheduled for thoracic surgery involving one-lung ventilation were screened for participation. Sixteen patients were subsequently excluded because DLT was not performed, resulting in 82 participants included in the final analysis. This phase led to the development of three predictive formulas for DLT insertion depth: based on standing height (Depth = 1.083 + 0.166 × standing height), sitting height (Depth = 0.32 × SH), and an integrated model combining body height and sternum-carina distance (Ds-c: Depth = 1.543 + 0.155 × standing height + 0.202 × Ds-c). The subsequent phase involved a triple-arm randomized controlled trial (RCT) with 336 patients to compare these predictive models. Sample size was calculated to detect a 0.3 cm error reduction with 90% power (α=0.05), requiring 102/group; 112/group were enrolled accounting for 10% attrition. The random allocation ratio was 1:1:1, ensuring equal distribution among three groups: standing height (height-based formula), sitting height (sitting height-based formula), and CT (CT-guided formula). Prespecified primary endpoints were: (1) Absolute error (continuous; mean difference in cm), (2) Clinical accuracy (binary; proportion with optimal positioning). Secondary outcomes included tube mispositioning rates.

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