Bacterial contamination and frequency of changing ventilator circuitry

A questionnaire sent to 40 intensive care units showed that ventilator circuits were changed every 24 h in 62% and every 48 h in 20% of the units. A similar survey in 40 special-care baby units showed that only 9.7% changed circuits daily and the majority were changed weekly (38.7%) or between patients (38.7%). A prospective study of bacterial contamination of circuits in adult patients showed that when water humidification was used, 28/72 samples from inspiratory and 31/72 from expiratory tubing were contaminated with Gram-negative bacilli. None of 48 sets of tubing was contaminated when a heat-moisture exchanger was used and only one expiratory tube was contaminated in tubing from 45 neonates using a water humidifier. Gram-negative bacilli were isolated from the mouths of 21/36 adults and 6/12 neonates, and also from 6/17 hands of staff after changing circuits. It is suggested that circuits with water humidification may be changed every 48 h in adult patients, and between patients or weekly in neonatal units or between patients if a heat-moisture exchanger is used. Handwashing after removal of a circuit is of major importance in the prevention of spread of infection.