20 medical workers were assigned to perform TI within 120s with either Direct laryngoscopy TI or light-guided TI technique, which was selected randomly and then converted to the alternative one until they complete 5 cases with each of the two techniques. The time of EG started from mouth opening of the patient to the exposure of the glottis. The time of TI also started from mouth opening of the patient to the completion of inserting the tracheal guide to the tracheal and sealing it with cuff inflation. The EG time, Cormack-Lehane (C&L) grades, TI time, one-time success rate, and the overall success rate in using the two TI techniques were recorded.