Objective To investigate correlation between patients' respiratory tract infection after tracheotomy and environmental factor. Methods A total of 60 patients undergoing surgical operation were randomly divided into research group(patients after tracheotomy) and control group(critical patients without tracheotomy), with 30 cases in each group. Observation and comparison were made on germ-carrying status of materials, air, pharyngeal secretion and nursing staff before and after p H changes, incidence of respi...