Download - MR Airway Pressure Device
MR Airway Pressure DeviceGroup MembersLaura SheehanKevin Johnson
Jon CappelNoelle Simatic
Client Dr. Victor Haughton
Advisor Prof. Mitch Tyler
AbstractAn airway pressure device was designed for use in an MR imager. This device will assist our client in studying CSF flow during Valsalva maneuvers performed by children with Chiari I malformation. Current research suggests that CSF flow decreases during Valsalva maneuvers in these patients. The final product consists of a rigid mouthpiece, pressure transducer, and compressed air operated valve system.
Motivation
• Dr. Haughton is radiologist at UW-Hospital with a specialty in
neuroradiology• Research interest in CSF disorders• Device needed to measure airway
pressure during MR imaging• Current devices are not MR
compatible
Problem Statement
• Our client needs a device to monitor exhalation pressure exerted during a Valsalva maneuver– Specifically for studying CSF flow – Images of the spine will be taken using MR imaging
• Research will be focused on children with Chiari I malformation– Current studies show that CSF flow decreases during
Valsalva maneuvers in these patients– This causes patient symptoms to worsen
• Pressure measurement would be beneficial for data analysis and accuracy
Client Specifications
Needs to be MR compatiblePressure must be measured from beginning
of Valsalva through mid expirationSmall to minimize dead air spaceUsable by both alert and anesthetized
patients
Device to measure airway pressure during Valsalva maneuver in pediatric patients with Chiari I malformations
Chiari I Malformations
http://www.chiariclinic.org
Valsalva Maneuver• Expiratory effort against a closed glottis• Increases pressure within the thoracic
cavity
http://www.valsalva.org
MR Requirements• Utilizes strong
magnetic fields (1-3 T)• Non-magnetic
materials• No metal touching the
patient• Must not affect image
quality• Comply with
geometric constraints of GE Signa scanners and single channel head coil
Final DesignComponents• Rigid mouthpiece• Silicon diaphragm pressure transducer• End cap with tubing barb
Features• Device can be autoclaved – Transducer can be sterilized
• Functions using compressed air and vacuum• Device is small to minimize dead air space• Can be used during normal breathing as well as
during a Valsalva maneuver
Testing• Device was calibrated using a manometer• 3 members of our design team served as
subjects for volunteer testing• Maximum pressure during Valsalva was
recorded• Data was acquired using Labview and
graphed in Matlab• Additional testing was performed in the
MR suite at the Waisman Center
Results• Subject was able to breathe normally and
perform Valsalva using the device• Device can withstand a pressure of at
least 90 mm Hg– Typical child maximum airway pressure is 60
mm Hg• Device was found to be MR compatible
and is easy to operate
Future Work• Obtain a 3-way valve for compressed air
and vacuum supply• Construct alternative prototype with
balloon valve for comparison• Research human subjects testing
requirements
Acknowledgements We would like to thank the following
individuals for their assistance this semester:– Dr. Haughton, Department of Radiology– Professor Tyler, Department of Biomedical
Engineering–Matt O’Brien, Pulmonary Function Lab– Rick and Larry, ECB Machine Shop