Abstract
Background: Patients that wear non-invasive ventilation devices at home for chronic respiratory failure are admitted the hospital and continue non-invasive therapy as an inpatient in the acute care setting. These patients sometimes require oxygen. Per the user manual, oxygen may be added at either the mask or device. This study aimed to find optimal placement of the oxygen "bleed-in" adaptor. We wanted to find out which place gave the highest delivered amount of oxygen in the most consistent manner.
Methods: We used a DreamStation BiPAP machine (Respironics Inc., Murrysville, PA) with the standard 15mm circuit connected to a Michigan Instruments (Kentwood, MI) test lung via mannequin head with a small full face mask. A V500 ventilator (Dräger Medical, Lübeck, Germany) was used to simulate breathing. FIO2 was measured via an oxygen analyzer placed into the top port of the test lung. Continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BiPAP) modes were tested. CPAP pressures were set at common end positive airway pressures (EPAP) of 5, 8, 10, 12, 15, and 20 cm H2O. The same EPAP levels were used with BiPAP with the inspiratory positive airway pressure (IPAP) was set at 5 cm H2O above EPAP. The oxygen adaptor was placed in-line at the mask and the device for all pressure settings. Oxygen flow was set in 2 L/min increments from 2 – 12 L/min for two minutes or until equilibration occurred. Flow was turned off and the next test was not started until the oxygen analyzer returned to room air.
Results: All data was analyzed through IBM SPSS software v25 (IBM, Armonk, New York). The mean change of FIO2 (%) for every 2 L/min increase while on CPAP averaged 2.84 ± 0.55 at the mask and 3.73 ± 0.41 at the device. The mean change of FIO2 (%) for every 2 L/min increase while on BiPAP averaged 5.78 ± 2.95 at the mask and 5.73 ± 0.96 at the device. Changes in FIO2 were significant when on CPAP and when the oxygen adaptor was at the device, P = .01. There were no significant changes (P = .97) in FIO2 between oxygen adaptor placement when the mode was BiPAP.
Conclusions: Placement of the oxygen adaptor at the device appears to give a higher FIO2 with CPAP. FIO2 on BiPAP is higher when the oxygen adaptor is at the mask, however it is not significant. Oxygen placement at the device does offer less variation on both modes. The results of this study were based on one device; further studies could be done to confirm findings.
Data Analysis Table
Footnotes
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