Prospective, randomized study of ventilator-associated pneumonia in patients with one versus three ventilator circuit...

To assess the effect on the rate of ventilator-associated pneumonia (VAP) of decreasing the frequency of ventilator circuit changes from three times to once per week.

Prospective, randomized trial.

Medical intensive care unit (MICU), a 12-bed, critical-care internal medicine unit, and neurosciences intensive care unit (NICU), a 21-bed, predominantly adult neurosurgical unit, of an urban university hospital.

All 447 patients requiring mechanical ventilation during October 1992 through June 1993.

Patients were allocated randomly on the basis of permanent medical record numbers: those with odd numbers had circuits changed three times per week, those with even numbers once per week. Intensive-care-unit surveillance was conducted in accordance with definitions and methods of the National Nosocomial Infections Surveillance System.

In the MICU, the one-change-per-week group had a VAP rate of 7.3 per 1,000 ventilator days, versus 5.9 for the three-per-week group (P = .6). In the NICU, the one-change-per-week group had a rate of 12.2 per 1,000 ventilator days, versus 12.6 for the three-per-week group (P = .9). Considering patients in both units ventilated for no more than 7 days, the one-change-per-week group had a VAP rate of 5.9 per 1,000 ventilator days, versus 9.0 per 1,000 for the three-changes-per-week group (odds ratio [OR], 0.65; 95% confidence interval [CI95], 0.25 to 1.69). Including patients in the two units maintained on mechanical ventilation for more than 7 days, the one-change-per-week group had a VAP rate of 13.2 per 1,000 ventilator days, versus 9.6 per 1,000 for the three-changes-per-week group (OR, 1.37; CI95, 0.71 to 2.65).

Decreasing the frequency of ventilator circuit changes from three times to once per week had no adverse effect on the overall rate of VAP. Less frequent ventilator circuit changes may decrease the incidence of VAP among patients ventilated for no more than 1 week. However, the incidence of VAP may be higher among patients with once weekly circuit changes ventilated for more than 1 week.