Chest
Original Research: SLEEP MEDICINEBench Model To Simulate Upper Airway Obstruction for Analyzing Automatic Continuous Positive Airway Pressure Devices
Section snippets
Patient Simulator
We modified the patient simulator model previously described33 by including an obstructive valve servocontrolled by a motor (HS-325BB; Hitec RCD; Powey, CA). This new model was able to reproduce not only real flow and snoring signals obtained from patients' recordings, but also the corresponding resistance of the upper airway (Fig 1). A driving signal generated by the computer was fed into the analog servocontrol of the motor, which regulated the aperture of the valve. The obstructive valve was
RESULTS
Tables 1and 2summarize the results of the different tests. The responses of the devices when subjected to a continuous repetition of apneas with obstruction (test 1, panel B in Fig 2) are shown in Figure 4. All the devices increased the pressure in response to this event but with different strategies. Devices F1, O1, and O3 increased the pressure linearly up to the maximum pressure allowed but with different speeds. Devices F2, F3, F4, F5, and O2 increased the pressure stepwise with differences
DISCUSSION
In this study, we developed a bench model to mimic not only the flow and snoring patterns obtained from patients, but also the corresponding upper airway obstruction. With this model, the new generation of APAP devices can be tested in the bench by reproducing the phenomena that occur in obstructive events. We analyzed several APAP devices capable of detecting the upper airway patency with respect to other devices based only on the analysis of the flow shape and snoring. The responses of the
ACKNOWLEDGMENT
The authors thank Mr. M. A. Rodriguez for technical assistance.
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Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestjournal.org/misc/reprints.shtml)
Dr. Rigau was an employee of Measure, Check & Control GmbH & Co. KG at the time that this study was carried out and at present is employed by Sibel S.A. Josep M. Montserrat has no declared conflict of interest. Dr. Wöhrle received 38.500 Euros from Weinmann GmbH and 27.000 Euros from ResMed/MAP for lectures between 2002 and 2004. Dr. Wöhrle also received 25.000 Euros from Measure, Check & Control GmbH & Co. KG as a research grant. Ms. Plattner is an employee of Measure, Check & Control GmbH & Co. KG. Mr. Schwaibold is an employee of Measure, Check & Control GmbH & Co. KG. Dr. Navajas has no declared conflict of interest. Dr. Farré has no declared conflict of interest.
This study was carried out in the Unitat de Biofísica i Bioenginyeria (Universat de Barcelona, Spain) within the framework of a research contract with Measure, Check & Control GmbH & Co. KG.
This work was supported in part by Measure, Check & Control GmbH & Co. KG, by Fondo de Investigación Sanitaria (V-2003-RED C11 F-O), and by Ministerio de Ciencia y Tecnología (SAF2002–03616 and SAF2004–00684).