Download Delivery of Inhaled Drugs through CPAP

Team Members:
Sara Karle
Ashley Matsick
Michele Lorenz
Emily Maslonkowski
Client: Dr. Mihai Teodorescu
Advisor: Prof. Mitch Tyler
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Problem Statement
Background
Motivation
Design Constraints
Mechanical Design
Circuit Design
Future Work
• Create a device:
– for in-home use
– to provide pulsed delivery of inhaled
steroids
– in line with commercial CPAP machines
– using the ventilation circuit and flow
generated by the CPAP
• Obstructive Sleep Apnea:
Cessation of breathing during sleep despite effort to breathe
- Most common in obese adults
- Muscles relax, causing airway to collapse
- Side effect range: drowsiness to heart attack
- Treated with Continuous Positive Airway
Pressure (ASAA 2007)
unobstructed
obstructed
http://www.cpap.com
• Continuous Positive Airway Pressure (CPAP)
– Delivers steady pressure of room air
• Patients generally require a pressure b/t 6-14 cm H2O
– Humidifier often integrated
– Mask types can vary
Nasal
Full face
http://www.directhomemedical.com
Hybrid
CPAP machine by Respironics
http://remstarpro2.respironics.com/
• Metered-dose Inhalers (MDIs):
- Used to treat respiratory illnesses
- Combine active ingredients with
propellant
- Require priming + moderate
shaking before actuation
- Upright actuation required
- Most effective drug delivery
occurs during inhalation (Dhand 2004)
http://www.solvay-fluor.com
• Patients with obstructive sleep apnea also
commonly have asthma
• Asthma symptoms worsen in early morning
• Chronic asthma symptoms treated with inhaled
steroids
• Delivery with CPAP forces drug deeper into
lungs
• Need for fast-acting inhaler during the day may
be minimized by treatment at night (Teodorescu 2007)
• Agitate MDI to mix drug and propellant
• Depress inhaler to deliver drug
• Detect breathing pattern to coordinate
drug delivery with inhalation
• Interface with existing CPAP ventilation
circuit
• Size, weight, and noise levels appropriate
for in-home use
• Design alternatives (cams):
– Multi-ridge cam
(vibration + actuation in single rotation)
Pros: Single motor, 1 rotation
http://en.wikipedia.org/wiki/Cam
Cons: Large cam, inflexible
– Double spring + single cam
(holding + actuation bumps)
Pros: Single motor, 1 rotation
Cons: Spring dampening,
need for complete testing
– Double cam design (Fall 2003/Spring 2004)
• Adapted from previous BME 400 design group
• 2 rotating cams & 2 motors
– 1 each for shaking, actuation
Testing performed (Fall ’03/Spring ‘04):
- Effect of shaking amplitude/frequency on MDI
dose delivery
Demonstrated that automatic shaking approximated
manual shaking
http://homepages.cae.wisc.edu/
• Pros:
~bme200/mdi/secure/
- Shaking, actuation can be finely controlled
- Easy/inexpensive control system
• Cons:
- Weight, size of 2 motors (limits location of integration)
LabVIEW timer

Setpoint: 4:00 am
Action: power on 
Vibration cam

Setpoint: “X” rotations
Action: power off , power on 
http://sine.ni.com
Thermocouple
Detecting
inhalation
inexpensive
lower precision than
Thermistor
RTD

fast response
Setpoint:
T° threshold
less sensitive than
Action: power off 
power on 
Thermistor
Actuation cam

Setpoint: 1 rotation
Action: power off 
• Machine cams and construct mechanical
shaker/actuator
• Test drug delivery with UV spectroscopy
• Interface device with existing CPAP
ventilation circuit
• Write LabVIEW program: detect inhalation,
power to motors
• Human subjects testing
Dhand, R. “Basic Techniques for Aerosol Delivery During Mechanical Ventilation.”
Respiratory Care, 49.6 (2004): 611-622.
Quinn K, Lam Y, Vanderpool R. “Automated MDI Vibrational Device,” Madison, WI:
University of Wisconsin-Madison (2004): 44.
“Sleep Apnea Information,” American Sleep Apnea Association. 3 Oct 2007
<http://www.sleepapnea.org/info/index.html>
Teodorescu, Mihaela. Personal Interview. 13 Sept 2007
Teodorescu, Mihai. Personal Interview. 13 Sept 2007