2005 OPEN FORUM Abstracts
RESISTANCE OF THE RTUBE EXHALED BREATH CONDENSATE COLLECTOR
Brian K. Walsh, RRT-NPS, RPFT; John Hunt, MD. University of Virginia Pediatric Respiratory Medicine; Charlottesville, Virginia
Background: Measurement of biomarkers in exhaled breath condensate (EBC) provides a new non-invasive research tool to study airway chemistry and inflammation in lung disease. These assays have potential clinical utility in patient management. The RTubeT is a single patient use disposable EBC collection device through which a patient orally breathes, utilizing 2 one way valves that allow room air to be inhaled while directing all exhaled airflow through a 9 inch polypropylene collection chamber cooled by an aluminum sleeve. This process condenses the aqueous components of exhaled breath, as well as enlarging and trapping particles that are evolved by turbulent flow from the airway lining fluid.
Methods: We chose three RTubes with and without filter at random and monitored mouth piece pressures using a Timeter Instrument Calibration Analyzer RT-200 Series. Flows of 0.5 to 15 L per minute were used to determine expiratory resistance. These flows simulate tidal breathing in most patient population in which the device will be used.
Results: Graph 1 illustrates the resistance across the valve of the RTubes with and without filters. The average resistance for all tubes was 0.20 cmH20/liter.
Conclusion: Used in the standard fashion, the RTube system provides minimal expiratory flow resistance at physiologic flow levels, although has the capacity to add to anatomical PEEP with higher peak tidal flows.