Table 3.

Results of ultrasound vs video-assisted laryngoscope

	Video-assisted laryngoscope
Ultrasound	Positive	Negative
Correct	102	0
Incorrect	0	3

Video-assisted laryngoscope: identifying the relationship of vocal cords and depth markers. Positive: vocal cords lied between two depth markers; otherwise it is negative. Ultrasound: identifying the distance between upper edge of cuff and the glottis. Correct: the distance between upper edge of cuff and glottis was in the range of 1.9–4.1 cm; otherwise it is incorrect.