2003 OPEN FORUM Abstracts
VIASYS Hi-Ox80 mask does not provide higher oxygen concentrations when compared to the Hudson non-rebreather mask at 12L/min flow during ex-vivo ventilation.
Hinsch LA, McMenamin AM, Zempel MK, Belhumer AP, Evans KD, Heng SK, Ward JJ, RRT, Plevak DJ, MD. Rochester Community & Technical College-Mayo Clinic, Rochester, MN
Background: Certain clinical situations require non-invasive administration of high oxygen concentration (F1O2) in spontaneously breathing patients. Hudson non-rebreather (HNR) masks are commonly used to deliver a F1O2> 0.6. VIASYS (VHO) is advertised to deliver a F1O2 of 0.8 with an oxygen flow of 8 L/min. The cost per mask of HNR is $2.50 and $15.00 for the VHO. We compared the F1O2 delivered by the HNR mask and the VHO mask in an ex-vivo breathing model.
Method: We tested three HNR masks (Hudson RCI Temecula, CA) and three VHO masks (VIASYS Healthcare Respiratory Technologies Yorba Linda, CA). A Laerdal intubation mannequin (Laerdal Medical Corp. Wappingers Falls, NY), served as a facial-interface for the six masks. Inspiratory demand was triggered by a connection of the mannequin's trachea to one side of a two-compartment mechanical test lung (Michigan Instruments, Inc. Grand Rapids, MI). The test-lung was linked to the opposite test lung which was driven by a Puritan Bennett 7200 Series ventilator (Tyco Healthcare/Mallinckrodt, St. Louis, MO) in the continuous ventilation mode (CMV) with a peak flow setting of 60 LPM. CO2 was bled-in at a rate of 300 ml/min into the test lung to simulate physiological conditions. Frequency and tidal volumes were set to produce minute ventilation (VE) of 5L, 7.5L, 9L, 10L, 11.25L, 13.5L, 15L, and 18L. The masks were connected to an Ohmeda flowmeter (Ohmeda Medical, Laurel, MD) set at 12 LPM. The flowmeter was connected to a 50 psig wall outlet. F1O2 was measured by the Puritan Bennett 7820 Oxygen Monitor placed in-line with the mannequin trachea. F1O2 for each mask was measured at each VE. Regression analysis was used to determine Pearson Correlation Coefficients (F1O2 vs. VE) and to compare the slopes of lines of identity. Student T test was used to determine differences in the F1O2 between the 2 mask brands. One-way ANOVA was used to determine the differences in mean F1O2 amongst the six individual masks.
Results:The mean F1O2 via HNR was higher (63.88+/-4.94) than that achieved by VHO (59.92+/-5.54) p=0.008. This difference was primarily due to increased F1O2 achieved by the HNR at VE of 10L/min or less (66.67+/-4.3 vs. 61.02+/-6.5, p=0.009). At a VE greater than 10 L/min, the two devices behaved similarly. F1O2 achieved by HNR dropped as VE increased (r= -0.68,slope -0.547, p=0.00). There was no correlation between VE and F1O2 achieved by VHO (r= -0.20, slope -0.15 p=0.31). The slopes differed by a statistically significant degree (p=0.000). There was a statistically significant difference (p=0.008) between mean F1O2 achieved by the 6 masks. All 3 HNR provided a higher mean F1O2 than the 3 VHO masks. There was no data point in which the VHO was able to achieve a F1O2 of 0.8.
Conclusion: VHO did not outperform HNR. In fact, the HNR appeared to provide higher oxygen concentrations for VE of 10L/min or less. VHO does not seem to provide added value for the additional expense.