Biomedical Engineering Reference
In-Depth Information
Yarn
flat or texturized
Table 3.2.4-6 Sample test methods for large-diameter textile grafts
Test
Required
regulatory
testing
Routine
quality
testing
Fabric
woven or knit
Visual inspection for defects
X
X
Initial cleaning
Water permeability
X
X
Longitudinal tensile strength
X
Compaction, if rqd.
Burst strength
X
X
Crimping
Usable length
X
X
Relaxed internal diameter
X
X
Pressurized internal diameter
X
Heat setting
Wall thickness
X
Suture retention strength
X
External support
Kink diameter/radius
X
Final cleaning
Dynamic compliance
X
Animal trials
X
Inspection
packaging and sterilization
Shelf life
X
Sterility
X
X
Fig. 3.2.4-12 Typical graft finishing operation.
Biomaterials/toxicity and
pyrogen testing
X
X
polymer, textile, and final product will be safe and ef-
ficacious.
Table 3.2.4-6
is a list of the suggested test
methods used in the development of a textile-based
vascular
(disposable) products, and wovens for reusable items.
Most of these barrier-type fabrics are made from cellu-
lose (cotton, viscose rayon, and wood pulp), P, and
PP fibers. Many fabrics contain finishes that render them
water repellent depending on the clinical need. Addi-
tionally, such fabrics must generally be fire retardant
because of the risk of explosions due to exposure to
flammable gases used for anesthesia. In applications such
as facemasks, the fabric must minimize the passage of
bacteria through the mask. This can be ensured by en-
gineering the appropriate pore size distribution in the
filtration fabric (
Schreuder-Gibson, 2002
). Antibacterial
coatings are also placed on surgical drapes to minimize
the risk of wound contamination. Drapes and protective
apparel typically require some assembly that can be done
either through conventional sewing or by ultrasonic
seaming methods. The latter method is preferred for
those products used in sterile fields since the holes cre-
ated by conventional sewing needles can render the fabric
permeable to liquids and liquid-borne pathogens. Drapes
are usually constructed of a nonwoven fabric laminated
to a plastic film to ensure that they are impervious to
blood and other fluids. Another common use of textiles is
in the fabrication of adhesive tapes. These tapes generally
graft
for
large
vessel
replacement
(
ANSI/
AAMI/ISO, 2001
).
Applications
The application of fibers and biotextiles as components
for implant devices is widespread and covers all aspects
of medicine and health care. Textiles are used as basic
care items such as drapes, protective apparel, wound
dressings, and diapers and in complex devices such as
heart valve sewing rings, vascular grafts, hernia repair
meshes, and percutaneous access devices.
Drapes and protective apparel
The most common nonimplantable medical use of tex-
tiles is for protective surgical gowns, operating room
drapes, masks, and shoe covers. Nonwovens and wovens
are most frequently used for these applications, with
nonwovens being the material of choice for single-use
