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Determining Properties of Wound Dressings for Negative
Pressure Wound Therapy
Lora Aboulmouna, Lisa Lewicki, Ryan Frye
What is NPWT?
The application of sub-atmospheric pressure to a sealed wound for the purpose of removing fluid and stimulating a cellular response through the mechanical stretching of wound tissue.
Process: Material inserted into wound bed Sealant drape Fluid drain tube Vacuum Applied
-50 to -120 mmHg
Pioneer Technology
Aims to discover and create solutions in the healthcare community beginning with advancements in wound care while bridging the gap between healthcare technology and nature Green healthcare Discover the benefits of Sorbact and likelihood of
commercial success
Mentor: Josh Smith, Vice President of Pioneer Technology
Advisor: Dr. Jack Fisher, Associate Clinical Professor of Plastic Surgery at Vanderbilt University
Wound Dressings
Sorbact
Gauze
KCI Foam
Project Goals
To determine
Material resistance Flow rate Pressure gradient Saturation points
of the three materials in a negative pressure environment.
Build a model that provides a controlled environment
Equating the Materials
Procedure: Obtained three materials with equal masses Measured water displacement in a graduated
cylinder of each sample Mass and volume were used to determine the
density of each material
Material Density (g/ml)
Gauze 1.48
KCI Foam 0.62
Sorbact 1.36
Preliminary Experiment: Material Behavior in NP Environment Used skin analog in
mold to simulate wound bed
Inserted appropriate material amount
Covered with sealant drape
Applied pressure of 180 mmHg Observed material
compression
Results of Preliminary Experiment
All materials compressed under negative pressure
Sorbact Gauze KCI
Compression (mm)
16 19 13
Design Setup
Clinical Pressure Ranges:
-50 to -120 mm Hg
Bernoulli’s Principle: Height of
water Fluid velocity Vacuum
Pressure Density Head losses
Pipe
h
Q
P = -180 mm Hg
Design Obstacles
Resistance of tubing
Flow meter range accuracy (o.4 to 40 mL/min)
Small flow rates may cause readings to not be significantly different
All flow travels through materials
Varying Pressure
Future Directions
Obtain accurate flow measurements Awaiting shipment of proper flow meter
Test flow while varying pressure
Test saturation Weigh materials before and after saturation
References
Borgquist O, Ingemansson R, Malmsjö M. Wound edge microvascular blood flow during negative pressure wound therapy: examining the effects of pressures from -10 to -175 mmHg. Plast Reconstr Surg In press.
Ljungh, A, N Yanagisawa, and T Wadström. "Using the principle of hydrophobic interaction to bind and remove wound bacteria." Journal of Wound Care 15.4 (2006): n. pag. Web. 6 Nov 2010.
Smith, Jan, and Peter Robertsson. Method for Dressing a Wound. , 2010. Web. 27 Oct 2010. <http://www.google.com/patents/about?id=ApHVAAAAEBAJ&dq=sorbact>
"Science Behind the Therapy — KCI." Science Behind The Therapy. Web. <http://www.kci1.com/KCI1/sciencebehindthetherapy>.