The primary hypothesis relates to the main outcome criteria of this study, which is post-extubation morbidity as measured by the presence or absence of stridor after tracheal extubation. The null-hypothesis Ho is defined as no difference in the incidence rates of post-extubation morbidity between cuffed and uncuffed groups. The null-hypothesis (Ho: u-Diff = 0) will be compared with the alternative hypothesis (H1: u-Diff <> 0). The study is designed to detect a clinically unacceptable deterioration of 1.5% above the baseline airway-injury rate of 2.5% when using uncuffed tubes with a power of 90% and a type I error probability of less than 5%.