Background: Few studies have investigated the difference of bacterial contamination between conventional reused ventilator systems and disposable closed ventilator-suction systems. The aim of this study was to investigate the bacterial contamination rates of the reused and disposable ventilation systems, and the association between system disconnection and bacterial contamination of ventilator systems.

Methods: The enrolled patients used a conventional reused ventilator system and a disposable closed ventilator-suction system, respectively, for a week; specimens were then collected from the ventilators' internal system to evaluate human and environmental bacterial contamination. The sputum specimens from patients were also analyzed in this study.

Results: The detection rate of bacteria in the conventional reused ventilator system was substantially higher than that in the disposable system. The inspiratory and expiratory limbs of disposable closed ventilator-suction system had higher bacterial concentrations than the conventional reused ventilator system. The bacterial concentration in the heated humidifier (HH) of the reused system was significantly higher than that in the disposable system. Positive associations existed among the bacterial concentrations at different locations in the reused and disposable ventilator systems, respectively. The predominant bacteria identified in the reused and disposable ventilator systems included Acinetobacter spp., Bacillus cereus, Elizabethkingia spp., Pseudomonas spp., and Stenotrophomonas (Xan) maltophilia.

Conclusion: Both the reused and disposable ventilation systems had high bacterial contamination rates after one week of use. Disconnection of the ventilator systems should be avoided during system operation for decreasing the risks of environmental pollution and human exposure, especially for the disposable system.

The intubated and mechanically ventilated patients were enrolled from the Intensive Care Unit of Chang Gung Memorial Hospital, Taiwan. The experimental study group was assigned to a disposable ventilator system combined with an auto-filled heated humidifier (HH), a closed suction catheter, and a closed aerosol therapy procedure with a valved T-adaptor. According to clinical commonly used system, the control study group was assigned to use with conventional reused ventilator system, combined with a manually filled HH, an open suction catheter, and a conventional aerosol therapy procedure. Every patient was use above both ventilator systems.

Inclusion Criteria:

• the mechanically ventilated patients in the ICU

Exclusion Criteria:

• the sputum culture results of the patients indicated the presence of drug-resistant bacteria, influenza virus, and early extubation.

A total of 16 patients (10 men and 6 women, aged between 20 and 91 years) were included for the final analysis. Patients had been on a mechanical ventilator for 17-46 days, and had a primary diagnosis of sepsis, septic shock, cardiac arrest, pneumonia (CAP or HAP), chronic obstructive pulmonary disease, respiratory failure, acute respiratory distress syndrome, or lung contusion.