The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

LARGE VOLUME NEBULIZER OXYGEN CONCENTRATION DELIVERY IS LESS ACCURATE AT HIGH FIO2 SETTINGS IN A LABORATORY MODEL

Blake R, Baker L, Gooderum K, Johnson S, Kettler B, McDonald K, Petersen E, Renner H, Shafer M, Ward J, RRT, Plevak D, MD, Findlay J, MD. University of Minnesota/Mayo Clinic College of Medicine, Rochester, MN

Background:

Large volume nebulizers (LVN) are commonly used in clinical practice to deliver inspired oxygen. Respiratory care professionals often rely on the marked settings on the LVN to be an accurate reflection of delivered FI02.

Objective:

We performed this investigation to see if two commonly used LVNs in our practice delivered accurate FI02 at both high and low settings. We also wanted to establish if one device in our practice was more accurate than the other. Additionally, we compared the two devices at high and low settings to determine if their delivered FI02's differed.

Methods:

The FI02 delivered by ten RCI (Hudson RCI, Temecula, CA) and ten AirLife (Cardinal Health Corporation, McGaw Park, IL) LVNs were measured. Prior to testing each LVN, the oxygen analyzer was calibrated at room air (0.21), the oxygen flow meter was calibrated and set at 10 Lpm, and the H cylinder regulator pressure was confirmed at 50-55 psi. FI02 delivered by the RCI LVN was measured across its low (0.35) and high (.98) FI02 marked settings. FI02 was measured for AirLife LVN at its low (0.35) and high (1.0) marked settings. Each LVN used in the investigation received three measurements at both the low and high settings. Measured FI02 levels delivered by each LVN were compared to the FI02 of marked settings. Students T-test was used to compare FI02 delivered by the two devices at both the low and high settings. Results are expressed as means and standard deviation.  All data was collected in a laboratory setting.

Results:

FI02 delivered at the low marked FI02 setting:

·        RCI LVN: 0.35 ± 0.004

·        AirLife: 0.35 ± 0.005

·        P = 0.38.

FI02 delivered at the high marked FI02 setting:

·        RCI LVN: 0.90 ± 0.03

·        AirLife LVN: 0.90 ± 0.04

·        P = 0.83.

Conclusion:

Commonly used LVNs deliver highly accurate FI02 levels at low FI02 settings (0.35).  At high FI02 settings (0.98-1.0), LVNs are not as accurate. The FI02s measured at high settings were 0.08-0.1 below the marked settings, which may be of clinical significance in some cases. There was no statistical difference in the performance of the two LVNs. However, the AirLife LVN did have broader standard deviation indicating greater intra-device variability.

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