The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

THE TRUTH ABOUT THE ROLE OF RESPIRATORY CARE EQUIPMENT IN THE ETIOLOGY OF NOSOCOMIAL INFECTION

Dean Hess, PhD, RRT Assistant Professor of Anaesthesia Harvard Medical School Assistant Director of Respiratory Care Massachusetts General Hospital Boston, MA

Pneumonia is a recognized complication of mechanical ventilation. For many years, there was concern that the ventilator circuit may play an important role in the development of this complication. Although the ventilator circuit is almost always contaminated, it is now well established that microorganisms in the circuit originate from the patient -- thus it is more likely that the patient contaminates the circuit than vice versa. It should not be surprising that ventilator circuit change interval does not adversely affect the rate of ventilator-associated pneumonia. In fact, there is evidence that the pneumonia rate may increase with frequent ventilator circuit changes. Ventilator circuits can be safely changed at infrequent intervals with little risk to the patient and considerable cost savings. Issues that should be considered relative to the ventilator circuit and ventilator-associated pneumonia include the type of humidification, the use of in-line nebulizers, contamination of the bag-valve resuscitator at the bedside, and use of open versus closed suction. The available evidence suggests that the type of humidification used during mechanical ventilation has no impact on the rate of ventilator-associated pneumonia -- i.e., cascade versus wick humidifier, open versus closed humidifier fill, heated versus unheated circuits, active versus passive humidification. Medication nebulizers can be a source of circuit contamination and metered-dose inhalers may provide less risk. Bedside bag-valve resuscitators have also been shown to be frequently contaminated and care must be exercised to avoid contamination of the patient's airway with these devices. In-line suction catheters allow secretion clearance without disconnection of the patient from the ventilator. Although this may prevent aerosolization of organisms from the patient into the critical care environment, there is little evidence that the use of these catheters affects ventilator-associated pneumonia rates. However, it has been shown that these catheters do not need to be changed daily -- they can be changed infrequently without increased risk of ventilator-associated pneumonia and with considerable cost savings. Ventilator-associated pneumonia usually results from pharyngeal secretions aspirated around the cuff of the artificial airway. A recently-introduced endotracheal tube that provides continuous aspiration of subglottic secretions has been shown to decrease the rate of ventilator-associated pneumonia.

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.

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