wound-healing-reading-chapters

SRPS Volume 10, Number 7, Part 1
including alginates, adhesive-coated films, hydrocolloids,
hydrogels, foams, and absorptive powders
and pastes.
Katz et al 251 compared the effects of 6 commercially
available semiocclusive dressings on the healing
of contaminated surface wounds. All the materials
tested were equally effective in increasing
the rate of reepithelialization; all, however, produced
microenvironments that were conducive
to the growth of bacteria. Although occlusive dressings
may provide a physical barrier to exogenous
microorganisms, by themselves they are unable to
prevent infection once pathogens are introduced,
and may actually promote infection by encouraging
bacterial proliferation, particularly with prolonged
occlusion.
Alginates are particularly well suited for use in
wounds with heavy exudates. Upon contact with
the wound exudate, the alginate is converted to
a sodium salt, which results in a hydrophilic gel
and an occlusive environment that promotes
wound healing. The dressing must be changed
when the gel-like substance begins to weep exudate.
252
Creams are opaque, soft solids or thick liquids
intended for external application. Medications are
dissolved or suspended in the emulsion base, a
water–oil substance. Creams are usually applied to
moist, weeping lesions and have a slight drying
effect. Creams can be formulated to aid in drug
penetration into or through the skin. Ointments
are semisolid preparations that melt at body temperature
and are used for their emollient properties.
Their primary role in wound healing is to aid
in rehydrating the skin and for topical application of
drugs.
Foam dressings consist of hydrophobic polyurethane
sheets with a nonabsorbent, adhesive
occlusive cover. Foam dressings are very absorbent
and nonadherent to the wound. Because
they absorb environmental water, reepithelialization
does not occur as readily as under moisture-promoting
dressings.
Film dressings are transparent polyurethane membranes
with water-resistant adhesives. They are
highly elastic and conform easily to body contours.
Film dressings are semipermeable to moisture and
oxygen and impermeable to bacteria. The trapped
moisture promotes autolytic debridement, but can
also macerate the wound in the event of heavy
exudate. Because the membrane is transparent,
film dressings are best for visual monitoring of
wounds. They do not hold up well in friction areas,
and the adhesive can tear the skin in elderly
patients. 253
Gauze dressings are highly permeable to air and
allow rapid moisture evaporation. They can stick to
newly formed granulation tissue and damage it
when dressing is removed, and dressing changes
can be painful. In addition, both woven and nonwoven
gauze will leave behind some lint and fibers
which can harbor bacteria.
Hydrocolloid dressings are completely impermeable
and therefore should not be used for dressing
wounds with anaerobic infections. These dressings
adhere well, are comfortable for the patient, and
are effective in absorbing minimal to moderate
amounts of exudate. Hydrocolloid dressings are
well suited for wounds over high-friction areas.
Hydrogel dressings are simply starch and water
polymers that are manufactured as gels, sheets, or
impregnated gauze. They rehydrate a wound, and
because of their high water content, they do not
absorb large amounts of wound exudate.
Vacuum-assisted Closure (V.A.C.) Dressing
V.A.C. dressings provide a negative-pressure
environment around the wound that helps remove
interstitial fluid and edema and improve tissue oxygenation.
They also remove inflammatory mediators
that suppress the normal progression of wound
healing. 130,131 Granulation tissue forms more rapidly
and bacterial counts decrease to