RESUMEN
Pneumonia is one of the infections of highest relevancy in Intensive Care Units, and according to the incidence of pneumonia associated to mechanical ventilation, the frequence of the ventilator external circuits change is still a topic of discussion. We decided to modify the protocol of change in our unit, from doing it every 48 hours to every 7 days. We performed a prospective study in 108 patients attended in a Polyvalent ICU who underwent mechanical ventilation during more than 24 hours. We formed two groups, in Group 1 we changed circuits every 48 hours and in Group 2 the circuits were changed every 7 days, without using bacterian filters in any of the groups. The results obtained in Group 1 were of an accumulated incidence of pneumonia associated to mechanical ventilation of 18% and density of incidence of 21.1 pneumonias per 1000 days of mechanical ventilation. In Group 2 we obtained an accumulated incidence of pneumonia associated to mechanical ventilation of 19% and a density of incidence of 20.5 pneumonias per 1000 days of mechanical ventilation. In the analysis of data there were no significant statistic differences between both groups. The cost of respirator external circuits was diminished in 27% in Group 2. We conclude that the circuits change every 7 days does not produce an increase in the frequence of pneumonia associated to mechanical ventilation, with the expense of the respirator external circuits being remarkably reduced.