The clinical implication of the vocal cords-carina distance in anaesthetized Chinese adults during orotracheal intubation.

BACKGROUND Previous studies have identified no strong correlation between patients' height and tracheal length in anaesthetized patients. We have attempted to compare vocal cords-carina distance (VCD) in Chinese patients with the dimensions of five commonly used tracheal tubes. In addition, we attempted to find a surface anatomy measurement that would identify patients with 'short tracheas'. METHODS We measured VCD in 130 anaesthetized Chinese patients with a fibreoptic bronchoscope. Also measurements were obtained of the distal ends of five commonly used tracheal tubes. We undertook various surface anatomy measurements on the patients' chest and neck region to predict those patients with short tracheas. RESULTS VCD averaged 12.6 (SD 1.4) cm. In seven patients (5%) this distance was particularly short (between 8.8 and 10.4 cm). Many of the commonly used tracheal tubes would be placed close to or beyond the carina when the black intubation guide mark(s) is (are) at the level of the vocal cords. The VCD of <or=11 cm (short trachea) could be predicted by patient height of <or=167.5 cm and a thyrosternal distance of <or=28.5 cm with limited reliability. CONCLUSIONS A significant number of patients with short VCD in our study group could be at risk of endobronchial intubation with many of the tracheal tubes. Patient height and thyrosternal distance can be useful in predicting short tracheas.