[Bacterial contamination of the inspiratory circuit of artificial ventilation apparatus: influence of the frequency of circuit renewal and the duration of ventilation].

In a study concerning contamination of artificial ventilators (Drager model UV1), the influence of 2 parameters was assessed: the frequency of changing the circuit (2 and 4 days) and the interval between admission of the patient into the intensive care unit and obtaining the sample. As a function of these variables, 4 groups of 15 patients each were constituted. The levels of contamination noted at 4 sites in the inspiratory phase tubing (cascade humidifier, condensate collector, tubing nearest to the patient and tubing nearest to the humidifier) and in the gas flow showed no significant difference between the groups, regardless of whether the circuit was changed after 2 or 4 days, or whether the patient had been recently admitted to the department or had been there for at least 6 days. Quantitative and qualitative study of bacteria showed that the one(s) contaminating the inspiratory phase tubing were the same as the one(s) colonizing the tracheal secretions of the patient, and that the most contaminated areas were those nearest to the patient (proximal tubing, collector), which confirms the retrograde contamination of the circuit.