EXCHANGE OF BREATHING CIRCUITS IN INTENSI VE-CARE - ONCE-A-DAY OR ONCE A WEEK

In an investigation of infection control methods for respirator system s in 89 randomly selected German intensive care units as a part of the NIDEP study (Nosocomial Infections in Germany - Surveillance and Prev ention), it was found that respirator systems were exchanged daily in about 50% of the intensive care units. However, Craven el: al. found t hat changing circuits (including tubing and exhalation valve and the a ttached humidifier) every 24 h rather than every 48 h was independentl y associated with the occurrence of nosocomial pneumonia. On the basis of these result and recent studies, the current situation in the lite rature was analyzed in order to make recommendations for exchanging ve ntilator circuits. Methods: Based on the extensive analysis of the lit erature by the Hospital infection Control Practices Advisory Committee (HICPAC), we could limit our investigation to the years after 1994. A MEDLINE search was done, and abstracts from congresses of the past fe w years were considered. The main focus of the analysis was the develo pment of pneumonia and not the contamination of the breathing circuit. The following methodological factors were analyzed far the most impor tant published studies: design, applied definitions of pneumonia, sam pie size, comparability of study groups, inclusion and exclusion crite ria. The results of the different studies were compared considering th e potential bias factors. Results and discussion:There were nine prosp ective controlled studies on this topic, In all studies, the authors t ried to investigate whether a longer interval between ventilator circu it exchange (more than 48 h) is safe or whether it is possible to leav e the circuits unchanged (without using breathing filters). The design and results of the available studies were analyzed. The three most im portant studies were compared very carefully (Table 1 and 2),and a rec ommendation for infection control measures for ventilator circuits was made as a modification of the HICPAC guidelines. In addition,the devi ce-associated pneumonia rates of ventilated intensive care patients in the NIDEP study were analyzed separately according to a daily or a 48 -h or longer interval of ventilator circuit exchange. For patients wit h daily exchange,we found a device-associated rate of 17.4 per 1000 ve ntilator days and for those with longer intervals a rate of 7.9 per 10 00 ventilator days. Only considering those patients without heat and m oisture filters, the figures were 14.8 versus 6.1. These differences w ere not significant because of the small number of patients investigat ed. Conclusion:The available studies show clear advantages of not rout inely exchanging the ventilator circuit, including tubing, exhalation valve and the attached humidifier, more often then every 7 days for an individual patient. Based on these findings, the current practice in most German intensive care units should be reevaluated.