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Use of Total Face Mask (TFM) Results
in Increased Responsiveness when Compared with Six Other Masks During Ex-vivo
Noninvasive Ventilation
Flaby GW, Baker
JE, Dubbs RL, Harty EE, Wolff SJ, Ikar AM, Tellinghuisen LR, Ward JJ, RRT,
Plevak DJ, MD, Stroetz RW, RRT.
Rochester Community & Technical College-Mayo Foundation, Rochester, MN
Background: Today?s clinician
has several options when choosing masks for non-invasive ventilation. It was
our hypothesis that mask style would not effect patient-ventilator responsiveness.
Methods: We tested seven masks
used in our practice: Spectrum® Disposable facemask-small (SR), -medium
(MR), -large (LR), Total Face Mask (TFM), nasal mask (N) [Respironics Inc. Pittsburg,
PA]; Mirage® medium (RM) [ResMed Corp, San Diego CA]; and Nasal Pillows
(P) [Mallinckrodt Inc. St. Louis, MO]. A Laerdal intubation mannequin (Laerdal
Medical Corp. Wappingers Falls, NY), served as a facial-interface for the seven
masks. A Respironics Vision® ventilator responded to inspiratory
demands triggered by a connection of the mannequin?s trachea to one side of
a two-compartment mechanical test lung (Michigan Instruments, Inc.). The Vision® was set in the BiPAP S/T mode with10 cmH20 IPAP and 5 cmH20
EPAP. Its test-lung was linked to the opposite test lung which was driven by
a Mallinckrodt Puritan Bennett 7200 ventilator in the continuous ventilation
pressure control mode (CMV-PC) with f=18 breaths and PIP= 30 cmH20.
The system was characterized to simulate a high drive state (P 0.1= -8.0 cmH2O).
The mechanical characteristics of both sides of the Michigan lung were: compliance=0.075
L/cm H20; resistance =5 cmH2O/L/sec. Data from the mannequin?s
ventilation was obtained using a pneumotachometer and pressure transducer placed
near the airway and connected to a system for signal amplification and data
recording (Astro-Med Inc., West Warwick, RI). The inspiratory delay interval
(DI) was defined as the time between the negative inspiratory pressure deflection
to the point pressure reached baseline (EPAP) level. Ten measurements were made
for each mask. Data were summarized as mean ± standard deviation (SD). Data
were analyzed using ANOVA followed by student t-tests. Each mask?s internal
dead-space was also measured when applied to the mannequin?s face.
Results:
| Mask |
SR à |
MR à |
LR à |
RM Y |
TFM |
NM Y |
P à |
| Delay interval (ms) ±
SD |
211± 10 |
209± 14 |
212± 13 |
192± 10 |
168± 13 |
183± 16 |
216± 34 |
vs. Y, P<0.05
Y vs. à, P<0.05
Conclusions: Use of the
TFM interface resulted in a shorter inspiratory delay interval when compared
to the other 6 masks evaluated. This was in spite of an internal mask dead space
of 1365 ml, which was greater than the other 6. We feel the improved responsiveness
may be due to the mask?s facial seal design.
OF-01-103
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