Periodically changing ventilator circuits is not necessary to prevent ventilator-associated pneumonia when a heat and moisture exchanger is used

OBJECTIVE: To analyze the efficacy of periodically changing ventilator circuits for decreasing the rate of ventilator-associated pneumonia when a heat and moisture exchanger (HME) is used for humidification. The Centers for Disease Control and Prevention recommended not changing the circuits periodically. DESIGN: Randomized, controlled trial conducted between April 2001 and August 2002. SETTING: A 24-bed, medical-surgical intensive care unit in a 650-bed, tertiary-care hospital. PATIENTS: All patients requiring mechanical ventilation during more than 72 hours from April 2001 to August 2002. INTERVENTIONS: Patients were randomized into two groups: (1) ventilation with change of ventilator circuits every 48 hours and (2) ventilation with no change of circuits. Throat swabs were taken on admission and twice weekly until discharge to classify pneumonia as endogenous or exogenous. RESULTS: Three hundred four patients (143 from group 1 and 161 from group 2) with similar characteristics (age, gender, Acute Physiology and Chronic Health Evaluation 11 score, diagnostic group, and mortality) were analyzed. There was no significant difference in the rate of pneumonia between the groups (23.1% vs 23.0% and 15.5 vs 14.8 per 1,000 ventilator-days). There was no significant difference in the incidence of exogenous pneumonia per 1,000 days of mechanical ventilation (1.71 vs 1.25). There was no difference in the distribution of microorganisms causing pneumonia. CONCLUSIONS: Circuit change using an HME for humidification does not decrease pneumonia and represents an unnecessary cost.