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 0.62Sorbact 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 KCICompression (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>.