The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts


Ryan Stecks3, Shirley J. Holt4, Tom Leisenring3, Randy Willis3, Gary R. Lowe1, Mark J. Heulitt2,4; 1Respiratory Care/Nursing Research, Arkansas Children’s Hospital, Little Rock, AR; 2Department of Pediatrics, Critical Care Medicine Section, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR; 3Respiratory Care, Arkansas Children’s Hospital, Little Rock, AR; 4Arkansas Children’s Hospital Research Institute, Little Rock, AR

Background: Respiratory Therapists (RTs) use oxygen cylinder systems (OCS) with built in regulators on a daily basis. RTs rarely question the accuracy of flows being delivered. We decided to validate the actual flow rates being delivered by the OCS, and hypothesized that actual flow rates would be within +/- 10% of the set flow rate on the regulator. Methods: A bench study was undertaken to validate the flow rates of the OCS used in our institution. The study design compared actual flow rates to pre-set flow rates at 1, 5, 10, and 15 LPM on five different D-size cylinders. This design was tested at tank pressures of 2000, 1000, and 600 psig on aluminum oxygen cylinders. Measurements of respiratory flow were acquired and averaged over a 30 second period using the MP-100 computerized data acquisition system. Flow was measured utilizing a 0-35 LPM calibrated PNT. Flow of 100% oxygen was calibrated using a TLO-15 calibrated flowmeter. The flow accuracy was verified with a calibrated syringe. All output signals were routed via an analog channel box into the MP-100 data acquisition unit converting them into digital signals that were processed with a computer. Signals were obtained at a rate of 1000 samples per second. Room temperature and barometric pressure remained constant over the testing period (23.3? C, 753 mmHg). Results: The averaged flow rates of the five cylinders at various cylinder pressures were within a range of +/-10%. As cylinder pressures decreased, the observed flow rates also decreased, but did not exceed set flows beyond the hypothesized +/- 10% range. The manufacturer validates regulators on an annual basis. The process includes placing the flow rate on 10 LPM, and accepting if flow > 7 LPM (30% variance), then placing the flow rate on 15 LPM and accepting 11 LPM (26% variance), and then back to 10 LPM to ensure repeatability. Conclusion: In this bench study, the D-sized OCS delivered flow rates within a +/- 10% range. This was a limited study, and further research needs to be done on other sized tanks and composition to ensure the accuracy of the flow rates. Sponsored Research - None

Equipment Used in Experimental Design