Optimal length and angle of a new lightwand device (Trachlight)

To investigate the effects of angle and length of the Trachlight lightwand and the effect of obesity on transillumination of the neck and difficulty of intubation.

Prospective, randomized study.

Operating room of a university hospital.

270 patients, aged 30 to 70 years, requiring anesthesia.

Three different studies were performed. 1) One hundred twenty adults for general anesthesia to test the effect of the angle, 2) 120 patients for the length of the extrusion, and 3) 30 patients with body weight > or = 120% of the standard (Broca's formula) versus 30 with body weight < 120% of the standard to test the effect of the obesity. 1) The lightwand was bent at 20 degrees, 40 degrees, 60 degrees, or 80 degrees with 0 cm extruded from the endotracheal tube; 2) the lightwand was exposed from the endotracheal tube with -0.5, 0, 1, 2, 3, or 4 cm with 40 degrees angle; and 3) the effect of obesity was tested with 40 degrees angle and 0-cm extrusion. Endotracheal intubation was performed using the lightwand. Transillumination of the light at neck and the difficulty of intubation were assessed.

1) A 20 degrees angle decreased the transillumination and an 80 degrees angle increased the number of difficult intubation. 2) Transillumination decreased with -0.5 cm and 0 cm extrusion. Difficult intubation increased with the extrusion > or = 3 cm. 3) Transillumination decreased and difficult intubation increased in the patients with body weight > or = 120% of the standard.

To increase the success rate of tracheal intubation using the lightwand, the lightwand should be bent in 40 degrees to 60 degrees, with the extrusion of 1 to 2 cm from the tracheal tube. For obese patients with body weight > or = 120% of the standard, the lightwand was not useful.