2001 OPEN FORUM Abstracts
Use of Total Face Mask (TFM) Resultsin Increased Responsiveness when Compared with Six Other Masks During Ex-vivoNoninvasive Ventilation
Flaby GW, BakerJE, 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 clinicianhas several options when choosing masks for non-invasive ventilation. It wasour hypothesis that mask style would not effect patient-ventilator responsiveness.
Methods: We tested seven masksused 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 (LaerdalMedical Corp. Wappingers Falls, NY), served as a facial-interface for the sevenmasks. A Respironics Vision® ventilator responded to inspiratorydemands triggered by a connection of the mannequin?s trachea to one side ofa two-compartment mechanical test lung (Michigan Instruments, Inc.). The Vision®was set in the BiPAP S/T mode with10 cmH20 IPAP and 5 cmH20EPAP. Its test-lung was linked to the opposite test lung which was driven bya Mallinckrodt Puritan Bennett 7200 ventilator in the continuous ventilationpressure 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=0.075L/cm H20; resistance =5 cmH2O/L/sec. Data from the mannequin?sventilation was obtained using a pneumotachometer and pressure transducer placednear the airway and connected to a system for signal amplification and datarecording (Astro-Med Inc., West Warwick, RI). The inspiratory delay interval(DI) was defined as the time between the negative inspiratory pressure deflectionto the point pressure reached baseline (EPAP) level. Ten measurements were madefor each mask. Data were summarized as mean ± standard deviation (SD). Datawere analyzed using ANOVA followed by student t-tests. Each mask?s internaldead-space was also measured when applied to the mannequin?s face.
|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 theTFM interface resulted in a shorter inspiratory delay interval when comparedto the other 6 masks evaluated. This was in spite of an internal mask dead spaceof 1365 ml, which was greater than the other 6. We feel the improved responsivenessmay be due to the mask?s facial seal design.