Sample size calculation
cough
According to our previous pilot studies, the incidence of cough induced by extubation was 95% in Group C, 45% in Group L, 60% in Group T, and 15% in Group F. We set α = 0.05 and β = 0.25, with a sample drop-out rate of 15%. Using PASS 15, we calculated a minimum sample size of 59 cases in each group (a total of 236 cases).