The patients were randomized to receive oral decontamination with 2% chlorhexidine solution or normal saline solution 4 times per day until their endotracheal tubes were removed. The outcome measures were the development of VAP and oropharyngeal colonization with gram-negative bacilli.
A sample size of 108 patients per group was estimated to
be necessary in order to determine whether oral decontamination
with 2% chlorhexidine solution could reduce the rate
of VAP from 14 to 7 episodes per 1,000 ventilator-days with
5% type I error (1-sided) and 80% power. The data were
analyzed by descriptive statistics, the unpaired Student t test,
x2 square statistics, and the Mann-Whitney U test, as appropriate.
A P value of .05 or less was considered statistically
significant.