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Aerosolized Drug Delivery Using Continuous Positive Airway Pressure Device Joe Decker Patrick Kurkiewicz Problem Statement A method is needed for automated delivery of respiratory anti-inflammatory drugs, like albuterol, to patients as they use continuous positive airway pressure (CPAP) device. Annie Loevinger Steve Welch Client: Dr. Mihai Teodorescu, MD 1 Advisor: John Webster, PhD2 1 Department of Geriatrics, Gerontology and Sleep Medicine – School of Medicine and Public Health and Center for Sleep Medicine and Sleep Research - University of Wisconsin Madison 2Department of Biomedical Engineering – University of Wisconsin Madison Background Sleep Apnea Final Design • Occurs when the trachea of the subject closes during sleep, repeatedly waking the subject and causing chronic sleep deprivation • Affects over 12 million Americans Function •Detects breathing cycle from microphone attached to CPAP machine and amplifies/filters signal. •Uses LabJack U3 to process breathing cycle and determines when to turn switch on. •Switch activates ultrasonic nebulizer, which delivers drug to patient. Continuous Positive Airway Pressure (CPAP) devices • Includes a pressure source, a circuit, and tubing to a mask worn by a patient • Provides positive pressure to assist in patient breathing. • Used for sleep apnea or in ambulatory situations for patients with asthma. Nebulizer Column Inhale • Aerosolizes liquid medication into a mist of many small liquid droplets (1 – 10 m) • Often used with albuterol sulfate, a bronchodilator. Jet Nebulizer • Uses pressurized air • Efficiency ~ 39+/-3%** Ultrasonic Nebulizer • Uses ultrasonic waves • Efficiency ~ 86+/-5%** Microphone Circuit Output (V) Nebulizer devices Exhale 2 Image from Webster, J.G. 2009. Medical Instrumentation. Hoboken, NJ: John Wiley & Sons, Inc. Piezoelectric Plate 1.5 Ultrasonic Nebulizer (above right) •Uses high-frequency piezoelectric crystal to Threshold aerosolize drug for patient delivery 1 Program 0.5 patient 0 Image from www.mece.ualberta.ca/arla/tutorial.htm Image from www.sonozap.com/nebulizer.htm Design Specifications The drug delivery device should: • Deliver nebulized medication within the CPAP circuit. • Be compatible with any CPAP device currently on the market. • Be capable of daily use, for at least 8 hours at a time. • Deliver up to three 3 mL doses of medication during usage. • Allow the user to sleep comfortably and safely during use. • Include a user-programmable feature to specify dosage and delivery timing. CPAP Nebulized Albuterol Sulfate 0 5 10 15 20 Time (s) 25 30 Item Vendor Purpose Cost Ultrasonic Humidifier Wal-Mart For ultrasonic piezoelectric component $30.56 Ultrasonic Humidifier Home Depot To replace broken piezoelectric component from first ultrasonic humidifier $31.64 PVC pipe fittings/ piping ACE Hardware For connection of piezoelectric component to the CPAP circuit $6.50 DAQ Board LabJack For processing of signals to and from microphone and piezoelectric component. $111.99 Microphone Radio Shack Detection of CPAP flow and subject’s breathing for more efficient use of Albuterol. $4.00 DC Voltage Adapter Prime Electronic Components To provide the required power to the DAQ board / microphone $11.83 PC tubing 1.25” I.D. US Plastic To serve as a clear reservoir to hold liquid to be nebulized $9.87 Pipe Fittings McMaster-Carr To replace PVC pipe fittings purchased earlier with something less bulky. $14.14 120 V Switch DigiKey Will switch power to piezoelectric component on and off to control nebulization amount $4.15 CPAP unit UW-Hospital Used to test feasibility of prototype ideas Donated Albuterol Nebulizer Doses UW-Hospital Used to test feasibility of prototype ideas Donated Total Breathing Cycle Waveform 2.5 Budget 35 40 •Detects breathing rate waveform (left) from microphone amplifier/filter circuit •Averages past 3 breathing cycles to estimate next cycle •Can program when to turn on/off ultrasonic nebulizer based on estimated breathing rate Testing •Left: Spectrophotographic curve for albuterol at 269 nm. •Right: Observed albuterol concentration of the bulk solution during nebulization and theoretical albuterol concentration if no albuterol were nebulized. •Data indicates that observed albuterol concentration was lower than theoretical concentration if no albuterol were nebulized $224.68 Future Work • R&D work will continue in January, 2010. • Change design of Albuterol reservoir so that the following problems are solved: – Heating of Albuterol Solution – Inadequate mixing of nebulized drug with CPAP flow • Acquire data pertaining to % nebulized drug that makes it to the CPAP mask • Automate nebulization and create user interface with adjustable dosage settings based on this information. • Conduct “Stage I” trials in Dr. Teodorescu’s sleep research lab. References American Sleep Apnea Association (ASAA). www.sleepapnea.org Dhand, R. 2004. Basic Techniques for Aerosol Delivery During Mechanical Ventilation. Respiratory Care. Vol. 49, No. 6: June 2004. Estes, M. C., Fiore, J., Mechlenburg, D. M., Ressler, H., and Kepler, J. 2005. Method and Apparatus for Providing Positive Airway Pressure to a Patient. US Patent, 6,932,084. Assigned to RIC Investments, Inc. Franca, E.E.T., Dornelas de Andrade, A. F., Cabral, G., Filho, P. A., Silva, K.C., Filho, V. C. G., Marinho, P. E. M., Lemos, A., and Parreria, V.F. 2006. Nebulization associated with bi-level noninvasive ventilation: Analysis of pulmonary radioaerosol deposition. Respiratory Medicine. Is. (2006) 100, 721-728. **Gessler T; Schmehl T; Hoeper M M; Rose F; Ghofrani H A; Olschewski H; Grimminger F; Seeger W. 2001. Ultrasonic versus jet nebulization of iloprost in severe pulmonary hypertension. The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology 2001;17(1):14-9. Hess, D. R. 2007. The Mask for Noninvasive Ventilation: Principles of Design and Effects on Aerosol Delivery. J. Aerosol Med. Vol. 20, Supplement 1. LabJack U3. 2009. U3 Specs. [Onine] www.labjack.com/u3/specs Sanders, M. H. and Zdrojkowski, R. J. 1992. Method and Apparatus for Maintaining Airway Patency to Treat Sleep Apnea and Other Disorders. US Patent, 5,148,802. Webster, J.G. 2009. Medical Instrumentation. Hoboken, NJ: John Wiley & Sons, Inc. Acknowledgements Dr. Mihai Teodorescu—Department of Geriatrics, Gerontology and Sleep Medicine Dr. John Webster—Department of Biomedical Engineering Jim Maynard – Department of Chemistry