The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

A CLINICAL COMPARISON OF PORTABLE OXYGEN SYSTEMS: CONTINUOUS FLOW COMPRESSED GAS VS. OXYGEN CONCENTRATOR GAS DELIVERED WITH AN OXYGEN CONSERVING DEVICE

J. Lewarski BS RRT1, G. Mikus RRT1, G. Andrews BS RRT1, R. Chatburn BS RRT FAARC2 1Hytech Homecare, Mentor OH; 2University Hospitals of Cleveland, Cleveland OH


Background:
Declining home oxygen reimbursement along with growing demand for small ambulatory oxygen (O2) systems has encouraged the development of new ambulatory O2 technologies. Recently, O2 concentrators capable of filling small compressed gas cylinders have entered the market. Although it is well established in literature that O2 produced from concentrators at >88% delivered in continuous flow is clinically equivalent to 99.6% USP gas (traditional compressed oxygen), there are no data evaluating concentrator gas delivered via an oxygen-conserving device (OCD). To test the hypotheses of equivalent benefit, we compared patient responses and tolerance of continuous flow (CF) USP O2 versus compressed concentrator gas delivered via OCD in current home oxygen users.

Methods: We selected the HomefillÒ II oxygen concentrator and transfill system (Invacare, Elyria, Ohio), which includes a proprietary ML6 cylinder configured with a pneumatic OCD (EasyPulseÒ, Precision Medical, Northhampton PA). We used 9 patients in a prospective, randomized, crossover design. Patients were selected from a pool of existing home O2 users from one home medical equipment provider. All patients were previously diagnosed with uncomplicated COPD and regularly using an ambulatory O2 system. Additional selection criteria included: stable condition, O2 prescription of 3 LPM or less and ability to carry portable. Physician orders were obtained for each patient. Patients were randomly assigned one of the following delivery systems: CF 99.6% O2, or 93% O2 concentrator gas via the ML6 with the OCD. Liter flow and settings for O2 were consistent with their current prescription. On different days, each patient underwent 1 of the 2 test walks with the selected delivery system. A standard 6-min walk protocol was used while SPO2 and heart rate were continuously monitored and recorded. Objective measures of SPO2, HR, and distance walked along with subjective determination of breathlessness using a Borg Scale were used to evaluate the patient condition before and after each walk. Physiologic data were compared via 2-way ANOVA. The Borg Scale data was analyzed via Wilcoxon Rank Sum Test. A power analysis was performed for an effect size of 10% change in SPO2 and 15 beats/min for HR.

RESULTS: All patients tolerated the test. The table shows mean (standard deviation):

  Device SpO2 Heart Rate Borg Score
Before After Before After Before After
99.6% O2 constant flow 97% (1) 90% (7) 81 (13) 112 (15) 85 (1) 111 (2)
93% O2 with conserver 96% (1) 88% (11) 83 (11) 115 (10) 85 (1) 111 (1)


There was no effect of device on either SpO2 or heart rate (p=0.792). Statistical power was > 0.90. There was no difference in Borg score (p = 0.63).

Conclusions
: These results suggest that the lower percentage O2 output by the concentrator system does not adversely affect clinical outcomes when using an O2-conserving device. O2 derived from a concentrator at 93% O2 and delivered in conjunction with a pneumatic O2-conserving device provides the same clinical benefit as the standard 99.6% O2 continuous flow device. Practical benefits of a transfilling oxygen concentrator system include patient freedom to refill their compressed gas cylinders at their own schedule, leading to improved portability. Providers should experience a substantial decrease in the high and recurring operational costs associated with the provision of ambulatory O2 systems.

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