A Comparison of a Silicone Wire-Reinforced Tube with the Parker and Polyvinyl Chloride Tubes for Tracheal Intubation Through an Intubating Laryngeal Mask Airway in Patients with Normal Airways Undergoing General Anesthesia

BACKGROUND: The intubating laryngeal mask airway (ILMA) is used in the management of difficult intubation. Usually, a silicone wire-reinforced tube is inserted for tracheal intubation. Because the silicone wire-reinforced tube is expensive, alternatives, such as polyvinyl chloride (PVC) and posterior beveled Parker tubes, are worth considering. We compared the blind intubation success rates among the silicone wire-reinforced tube, the Parker tube, and the PVC tube, and identified laryngeal structures preventing tracheal intubations through the ILMA. METHODS: Sixty-three adult patients were randomized into three groups: Group I (n = 20) silicone wire-reinforced tube, Group II (n = 21) Parker tube, and Group III (n = 22) PVC tube. Demographic and clinical continuous data were compared with the analysis of variance with the Scheffe test for post hoc analysis. Frequencies and percentages were compared with the x2 test. RESULTS: Tracheal intubation was successful from the first attempt in 18 of 20 patients in Group I (silicone wire-reinforced tube), which was significantly higher than the success rate in either Group II (12 of 22 patients) (Parker tube) or Group III (10 of 21 patients) (PVC tube). With clockwise or anticlockwise rotation of the tracheal tube, the number of successful intubations did not change in Group I, but it increased to 19 of 22 patients in Group II and to 12 of 21 patients in Group III. The rate of successful intubation between patients in Group I (90%) and Group II (86%) was not significantly different after manipulation of the tracheal tube (P = 0.72). However, the rate of successful tracheal intubations in patients of Group III (57%) was significantly lower in comparison to patients in both Group I (P = 0.02) and Group II (P = 0.03). In 3 of the 22 patients of Group II and in 9 of the 21 patients of Group III in whom blind intubation was not possible, the obstruction was due to the epiglottis tubercule. CONCLUSIONS: Manipulation improved the success rate of intubation with the Parker tube through the ILMA rendering it a possible alternative to the silicone wire-reinforced tube.