Changing ventilator tubing circuits every seven days versus every 72 hours: proposed practice based on literature review

Is disinfection of mechanical ventilation tubing needed at home?

INTRODUCTION

Home mechanical ventilation is used to treat chronic alveolar hypoventilation. Maintenance protocols for home ventilation circuits (HVC) remain empirical and unproven. We have investigated (1) the cleanliness and sterility of the HVC used by home ventilated patients and (2) the efficiency of tubing cleaning and decontamination protocols recommended to them and used for 12 months or more.

METHOD

HVC cleanliness was assessed in 39 severe restrictive ventilated patients (16 (T) tracheostomy vs. 23 (N) noninvasive) and in 7 new valves as control. In the first experiment (Exp1), a visual and bacteriologic inspection of the expiratory valve (Eva) was conducted during a consultation in our centre. Eva visual cleanliness was assessed on a 10-point scale and Eva bacteriologic contamination analysis was performed on a dry smear. In the second experiment (Exp2), these analyses were repeated after a cleaning sequence chosen at random, either chemical (ammonium-chlorhexidine complex) (A) or mechanical by dishwasher (B).

RESULTS

In Exp1, 69% of Eva were dirty. Dirtiness was worse in (T) than in (N) (5.3 vs. 2; p<0.001). There was a significant positive correlation between visual cleanliness and bacteriologic contamination (r=0.56; p<0.001). Eva in group (T) were more contaminated than in group (N) (p<0.001). Eva contamination rates reached 22% in group (N) but without the presence of any potentially pathogenic organisms (PPO) and 81% in group (T) where 19% were PPO. In Exp2, EVA visual cleanliness was better after dishwasher cleaning (B) compared to chemical (A) (0.16 vs. 1.05; p<0.001) with similar bacteriological decontamination.

CONCLUSION

HVC from noninvasive ventilated patients are dirty but not contaminated by PPO. We recommend washing them in a dishwasher or with detergent and hot water without specific disinfection. PPO contaminated 1/5 of invasive HVC, for which we recommend dishwasher cleaning. Decontamination is only indicated when tubing is visually very dirty or/and when tracheostomized patients are particularly sensitive to respiratory tract infections. The expiratory valve must be carefully washed specifically, with care that its balloon is not placed under water.

Physiological changes occurring with positive pressure ventilation: Part one

Critically ill patients requiring mechanical ventilation are subject to a variety of complications and adverse effects associated with positive pressure ventilation. An awareness of the major physiological effects is important, as recognition, prevention and appropriate treatment of complications is critical to optimizing patient outcome. Pierson (1990) suggests that complications due to ventilation occur with greater frequency than is generally appreciated, and can be a response to suboptimal ventilatory management as a result of poor communication and lack of understanding. This may also adversely affect patient comfort, morbidity and outcome. This can be avoided by improved knowledge of both the function of ventilators and the adverse effects associated with mechanical ventilation. Intensive care nurses face the challenge of caring not only for critically ill patients but also for complex machinery. To improve the delivery of care to the patients, an understanding of the machines and their adverse effects is essential. This increases the nurses' confidence and allows them to focus on the patients and associated problems while maintaining safe and informed care. With the introduction of mechanical ventilation, major physiological changes occur, for example airway resistance and intrathoracic pressures are increased and lung mechanics are altered. The following article provides explanation as to how and why mechanical ventilation produces these changes, and highlights areas where they occur.