Neonatal CPAP Breathing Apparatus Design

1. Neonatal CPAP Breathing Apparatus Design Andrea Holland Mindy Leelawong Sponsor: Bill Walsh, MD Monday, March 22, 2004

2. Project Overview • Continuous Positive Airway Pressure (CPAP) breathing apparatus • Assists respiration by forcing air at a pressure ranging from 4-8 cmH2O • Primarily used for infant respiratory distress 1

3. Problems • Nosepiece pressure causes injuries to the delicate skin of the nasal area

4. Problems • Mask • Septal erosion • Nasal bridge contusion • Prongs • Nasal flaring • Septal erosion • Snubbing2 http://www.eme-med.co.uk/products/product-29-45420.pdf

5. CPAP Administration • Complication rate: 20% • St. George’s Hospital, London2 • Duration of use before complication: 2 weeks • Vanderbilt NICU • Polin and Shani (2002)1

6. Objectives • Analyze the applied force of the device on the nasal area • Determine the cause of specific injury • Suggest revisions to current device http://www.eme-med.co.uk/products-neo-infant_flow.asp

7. Possible Alternatives • Intubation • Hyperventilation • Higher incidence of chronic lung disease • Tracheal irritaion/infection • Highly invasive • Decreased weight gain • Nasopharyngeal Tube CPAP • Pressure necrosis • High airway resistance • Invasive1

8. Possible Alternatives - continued • “Iron Lung” – Negative Pressure • Obstruction of upper airway • Neck sores • Restriction of access to infants3 • Bloxsom Air Lock • Restriction of access to infants • No evidence of efficacy in trials4 • Head Box • Compression of vessels at neck • Neck contusions • Restriction of access to infants • Leaks easily1 Iron Lung3 Bloxsom Air Lock4

9. Friction Sizing Incorrect nosepiece or bonnet size Limited nosepiece size range Pressure Position of device in relation to infant’s nose Weight of device Tightness of seal Hypothesis http://www.eme-med.co.uk/products-neo-infant_flow.asp

10. After Before Testing • Modeling Clay • Initial pressure points • Molding Gel • Deformation over time

11. Current Work • Gathering statistical information on low-birth weight infants on CPAP • Long-term analysis using alginate gel • Determining better prong design • Biomaterial research • Meetings with our adviser and professors • Finishing IWB and QFD

12. Work Completed • Researched similar designs • Researched problem and possible causes • Developed soft gel model representing infant skin • Literature search • Young’s modulus of skin (inconsistent, ~3.5) • Possible causes • Frequency (widely disputed)

13. Work Completed - continued • Tested models to determine location and nature of damage • Consulted with professors on skin-like materials • Consulted with doctors and nurses in the NICU on specific problems and possible remedies • Analyzed clay deformation

14. Project Limitations • Mathematical representations • Measurements • Young’s modulus of model • Pressure exerted by device • Limited literature on infant skin

15. Future Work • April 2004 • Formalized list of recommendations and conclusions • optimal use • future design considerations • New prong/mask design and material • Device weight reduction • Suggested Prototype? • Poster presentation • Finalized Paper

16. Acknowledgements Dr. Bill Walsh, MD Dr. Paul King Shirley Carpenter http://www.vanderbiltchildrens.com/interior.php?mid=208 http://frontweb.vuse.vanderbilt.edu/vuse_web/directory/facultybio.asp?FacultyID=49

17. Questions?

18. References • Polin, R.A, R. Sahni.  Newer experience with CPAP.  Semin Neonatol. 2002 Oct;7(5):379-89. • Robertson NJ, McCarthy LS, Hamilton PA, Moss AL. Nasal deformities resulting from flow driver continuous positive airway pressure.Arch Dis Child Fetal Neonatal Ed. 1996 Nov;75(3):F209-12. • Corrado A, Gorini M, Villella G, De Paola E. Negative pressure ventilation in the treatment of acute respiratory failure: an old noninvasive technique reconsidered.Eur Respir J. 1996 Jul;9(7):1531-44. • Kendig JW, Maples PG, Maisels MJ. The Bloxsom air lock: a historical perspective. Pediatrics. 2001 Dec;108(6):E116.