Background: Mechanical ventilator circuits are commonly changed at 48-h intervals. This frequency may be unnecessary because ventilator-associated pneumonia often results from aspiration of pharyngeal secretions and not from the ventilator circuit. We compared the ventilator-associated pneumonia rates and costs associated with 48-h and 7-day circuit changes.
Methods: Ventilator circuits were changed at 48-h intervals during the control period (November 1992 to April 1993) and at 7-day intervals during the study period (June 1993 to November 1993). Nosocomial pneumonias were prospectively identified using the criteria of the Centers for Disease Control and Prevention. The annual cost difference of changing circuits at 48-h and 7-day intervals was calculated using the distribution of ventilator days for the control and study periods.
Results: There were 1,708 patients, 9,858 ventilator days, and a pneumonia rate of 9.64 per 1,000 ventilator days in the control group (48-h circuit changes). There were 1,715 patients, 9,160 ventilator days, and 8.62 pneumonias per 1,000 ventilator days when circuits were changed at 1-week intervals (study group). Using a logistic regression model, there were significantly greater odds of developing a ventilator-associated pneumonia in surgical patients (odds ratio 1.77, P = 0.02) and patients in critical care units (odds ratio 1.54, P = 0.05), but no significant risk of ventilator-associated pneumonia in patients in whom circuits were changed at 1-week intervals (odds ratio 0.82, P = 0.22). Changing circuits at 7-day intervals resulted in a 76.6% ($111,530) reduction in the annual cost for materials and salaries.
Conclusions: We found no difference in pneumonia rates with ventilator circuit changes at 48-h and 7-day intervals. Ventilator circuits can be safely changed at weekly intervals, resulting in large cost savings.