Extending Ventilator Circuit Change Interval Beyond 2 Days Reduces the Likelihood of Ventilator-Associated Pneumonia

¹ From the Department of Veterans Affairs, Edward Hines, Jr. Hospital, Hines, Ill; Loyola University Chicago Stritch School of Medicine, Maywood, Ill
² From the Loyola University Chicago Stritch School of Medicine, Maywood, Ill
³ From the Centers for Disease Control and Prevention, Atlanta
⁴ From the Department of Veterans Affairs, Edward Hines, Jr. Hospital, Hines, Ill

Objective: To determine the risk of acquiring ventilator-associated pneumonia (VAP) and the impact on costs when extending ventilator circuit change intervals beyond 2 days to 7 and 30 days.

Design: Prospective 4-year review of mechanically ventilated patients.

Setting: The respiratory and medical ICUs of an 800-bed tertiary teaching Veterans Affairs hospital.

Patients: All adult patients receiving mechanical ventilation from January 1991 through December 1994.

Interventions: Ventilator circuits with active heated water humidifiers were changed at 2-day intervals during a 2-year control period, followed by 7-day and 30-day intervals (for 1 year each). Heated wire circuits were adopted with the 30-day interval. The rate of VAP per 1,000 ventilator days was calculated for each circuit change interval group. Survival analysis was used to model VAP with ventilator circuit change to determine risk.

Results: During the study period, 637 patients received mechanical ventilation. During the 2 years with 2-day change intervals, the VAP per 1,000 ventilator days was 11.88 (n=343), compared with 3.34 (n=137) and 6.28 (n=157) for 7-day and 30-day change intervals, respectively. The risk of acquiring a VAJP for those with a circuit change every 2 days was significantly greater (relative risk, 3.1; p=0.0004; 95% confidence interval, 1.662, 5.812) than those with the 7- and 30-day circuit changes. Extending circuit change intervals reduced supply and labor costs averaging $4,231/yr for each ventilator in use.

Conclusions: Circuit change intervals of 7 and 30 days have lower risks for VAP than the 2-day intervals, yielding substantial reductions in morbidity as well labor and supply costs.

Key Words: infection • mechanical ventilation • pneumonia

Submitted on August 15, 1996
Accepted on September 9, 1997

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