2007 OPEN FORUM Abstracts
A BENCH STUDY TO DETERMINE AND COMPARE THE MAXIMUM TOTAL DOSE VOLUME VS. MAXIMUM “USEFUL” DOSE VOLUME OF 33 OXYGEN CONSERVING DEVICES
R. Diesem1, R. McCoy1
Background: Oxygen conserving devices have different capabilities and limitations, many of which are not known or understood by the clinicians prescribing oxygen therapy and the patients using this equipment. Dose volumes vary widely across different devices. At the same setting, one device may deliver twice as much oxygen per dose as another device. However, how this dose volume is delivered is also noteworthy, as a higher dose does not necessarily equate to higher patient oxygenation. Oxygen delivered late in the inhalation cycle does not reach the alveoli and is not useful to the patient. The purpose of this bench study is to note the maximum total dose volume of several conserving devices, as well as their maximum “useful” dose volumes. For the purpose of this bench study, “useful” oxygen is considered to be that which is delivered within the first 60% of the inhalation cycle.
Methods: Using a Hans Rudolph Series 1101 breathing simulator to act as a patient, 33 different oxygen conserving devices in four categoriesâPneumatic Regulator, Electronic Regulator, Liquid Oxygen Portables, and Portable Concentratorsâwere tested on the bench to find each unit’s maximum total dose volume at the device’s highest delivery setting. Dose volume data was obtained on each unit at four different breathing patterns with breath rates of 15, 20, 25 and 30 bpm. Maximum “useful” dose volumes were determined by calculating the oxygen volume delivered within the first 60% of inhalation.
Results: No two devices had the same maximum total and maximum “useful” dose volumes at any tested breath rate. Maximum total dose volumes across all devices at 15/20/25/30 bpm ranged from 26/26/25/26 mL to 118/103/98/98 mL; maximum “useful” volumes ranged from 26/26/25/26 mL to 97/96/86/72 mL. The widest differences between total dose and “useful” dose volumes tended to occur on pneumatic conservers; only 2 of 12 tested pneumatic conservers had equivalent total and “useful” doses at all tested breath rates. At 15 and 20bpm, total and “useful” doses were equivalent on all portable concentrators tested, and 3 of 5 portable concentrators had equivalent total and “useful” dose volumes at all tested breath rates.
Conclusion: Oxygen conserving devices widely differ in their maximum dose capabilities, as well as their maximum “useful” dose capabilities. Patients and clinicians should be knowledgeable about the oxygen conserving devices the patients are using.