The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts


Roy Ramirez1, Troy Taylor1, Fahmi Abubaker1, John Cleary1, James Cappon1

Methods: A new generation of MaxblendR Gas Blenders (Maxtec Inc., Salt Lake City, UT) with built in O2 analyzers were being introduced to our institution, and bench testing was performed. Twenty blenders were tested by exposing the sensor to 0.21 FIO2 by attaching the blender air hose only to a calibrated air source and then adjusted. The blender oxygen gas hose was then attached to a 100% oxygen source and readings were observed.

Results: When the blender was set at 21% and then connected to an oxygen source, the measured oxygen reading (MOC) commonly exceeded the true oxygen concentration of 21%. In four blenders, the MOC increased by <0.5%.
However, 16 blenders (80%) had a mean MOC increase of 1.45%, with one device increasing 2.9%. Subsequently, Maxtec was notified of the situation, and the inaccurate blenders were returned for inspection. The manufacturer was able to more precisely adjust these blenders to a mean MOC increase of 0.36% and a maximum increase of 1.0% when set at 21%. These findings prompted us to perform the same bench testing to all blenders at our institution from various manufacturers. Twenty blenders were tested with a mean FIO2 change of 0.53% and a MOC of 2.6%. Two blenders (10%) failed testing, and had an increased FIO2 reading of 2.5% and 2.6% respectively. These two blenders were removed from service.

Conclusion: This oxygen blender calibration study illustrates the importance of due diligence when introducing new devices to an institution. The clinical implications of inaccurate low concentration oxygen delivery are particularly large in the vulnerable extremely premature and congenital heart disease patient populations. As in our experience, pre-clinical biomedical device testing can and should lead to a robust manufacturer response.

1. Lily. C Chow MD, Kenneth W. Wright MD, Augusto Sola, MD and the CSMC Oxygen Administration Sturdy Group. Can Changes in Clinical Practice Decrease the Incidence of Severe Retinopathy of Prematurity in Very Low Birth Weight Infants? PEDIATRICS Vol. 111 No. 2 February 2003, pp. 339-345

2. Silka MJ. Double-outlet ventricles. In: Garson A, Bricker JT, Fisher DJ, Neish SR, eds. The Science and Practice of Pediatric Cardiology. 2nd ed. Baltimore: Williams & Wilkins; 1997:1505-23