Abstract
BACKGROUND: Despite the critical role of central airway dimensions in clinical practice, comprehensive normative data remain scarce globally, particularly for diverse ethnic populations. This study aims to establish the first high-resolution computed tomography (HRCT) based reference values for tracheobronchial anatomy in Indian adults, addressing a significant gap in precision medicine. METHODS: This retrospective cross-sectional study was conducted at Kasturba Hospital, Manipal, India. HRCT chest scans performed between January 1, 2021, and March 31, 2024, were screened, and 503 adults (277 males, 226 females; aged 20-80 years) with normal findings were included. Primary outcomes were normative tracheal and bronchial dimensions (lengths, diameters, cross-sectional areas). Secondary outcomes included age and gender-based variations, correlations with demographics, and predictive models for airway device selection. Inclusion criteria were HRCT scans with normal thoracic findings and adequate inspiratory effort. Exclusion criteria included thoracic, pulmonary or cardiac abnormalities, prior airway surgery, presence of airway devices, or severe imaging artifacts. Data were analysed using t-test, one-way ANOVA, Pearson correlations, and multiple linear regression. Statistical significance was set at p < 0.05. RESULTS: Indian males exhibited significantly larger airways than females (tracheal length: 109.5 ± 8.9 mm vs. 100.5 ± 7.4 mm, p < 0.001; distal tracheal area: 311.3 ± 111.1 mm² vs. 227.6 ± 92.9 mm², p < 0.001). Notably, 54.5% of subjects had a more vertical left bronchus, contradicting classical anatomical dogma. High rates of short right main bronchi (< 23 mm) were observed in 49.5% of subjects, increasing the risk of double-lumen endobronchial tube misplacement. The distal tracheal diameter was strongly correlated with bronchial dimensions (r = 0.621, p < 0.001), providing evidence-based device selection. CONCLUSION: This study provides the first population-specific normative data for central airway dimensions in Indian adults, revealing profound ethnic variations with immediate clinical implications for airway management, thoracic surgery, and personalised medical device design. The findings underscore the necessity of region-specific reference standards to optimise patient safety and highlight the influence of ethnicity on airway anatomy.