A comparison of two silicone-reinforced tracheal tubes with different bevels for use with the intubating laryngeal mask

Seventy consecutive patients were randomly allocated for intubation through the intubating laryngeal mask airway using a straight reinforced silicone tracheal tube with either a conventional or a modified bevel. The conventional bevel was firm, wedge-shaped and with a leading edge at the side. The modified bevel was soft, hemispherical and with a leading edge in the midline. The intubating laryngeal mask position was adjusted until optimal ventilation was obtained and intubation was attempted using the randomised device. If tactile resistance was felt, a predetermined sequence of adjusting manoeuvres were utilised before a subsequent attempt. The first-attempt successful intubation rate with the conventional bevel was 23/37 (62%) and with the modified bevel was 28/33 (85%). The second-attempt successful intubation rate for the conventional bevel was 12/37 (32%) and for the modified bevel was 4/33 (12%). Intubation failed after three attempts for one patient in each group. Fewer overall intubation attempts were required with the modified bevel (p = 0.033). We conclude that intubation success rates through the intubating laryngeal mask with a straight silicone-reinforced tube are higher with a soft, hemispherical bevel with a leading edge in the midline compared with the firm, wedge-shaped bevel with a leading edge at the side.