[Investigation of a patient with difficult endotracheal intubation].

Unusually difficult endotracheal intubation was encountered during anesthetic induction of a 41-year-old male, necessitating use of a bronchofiberscope. The usual pre-operative analysis had shown no problems, such as tracheal tumor or stricture. Due to difficult intubation, post-operative evaluations were made and no abnormalities were found. However, investigation of the lateral roentgenogram showed a much greater than average backward bend in the patient's trachea under the vocal cord. It is likely that the sharp bend of the trachea was responsible for difficult intubation.