6Stam Am.Ventilator associated pneumonia and equency of circuit changes[J].Am J Infect Control,1998,26(1):71-73.
7Pingletan D C,Boten M A,Limper A H,et al.Cross-colonization with pesudomenasa aerugrmans of patient in an intensive care unit[J].Am Respir Crit,1998,102:5 535.
8Crap M J,Munro C I.Ventilator associated pneumonia:clinical significance and implications for nursing[J].Heart Lung,1997,26(4):419-429.