Page 16 - Manual of Equine Field Surgery

12 PRESURGICAL PREPARATION AND ASSESSMENT

chlorhexidine. Although uncommon, 011e disad- normal saline or lactated Ringer's solution, meet

vantage of povidone-iodine is a skin reaction, these criteria and are the most commonly used

which seems to be more frequent after clipping, solutions. Tap water is often used initially to

scrubbing, rinsing with 70°/o alcohol, spraying reduce gross contamination i11 heavily contami-

with povidone-iodine solution, and bandaging. nated wounds. In these cases, subsequent lavage

Detergent forms of chlorhexidine should not be with sterile isotonic fluid may help restore tissue

used around the eye, because exposure may lead normotonicity and reduce edema.

to corneal edema and bulbous keratopathy."? Wound lavage should also be considered for

The mechanical effect of scrubbing the wound closed wounds. The advantages of flushing a

with these antiseptic soaps is helpful i11 removing closed wound include the dilution and mobiliza-

debris and reducing bacterial concentration at the tion of exudates and the delivery of medication.

wound surface. A marked delay in wound healing The disadvantages are that bacteria can be readily

occurs if the soap is not thoroughly rinsed from introduced into the wound and dead space may

the wound. Additionally, even though these anti- be created or expanded.

septics are effective, much of the bacterial popt1-

lation i11 the skin resides in protected hair follicles,

sebaceous glands, and crevices in the lipid coat of WOUND DEBRIDEMENT

the superficial epithelium.

The goal of debridement is to obtain fresh, clean

wound margins and skin edges for primary closure

WOUND LAVAGE and to remove contaminated tissues and foreign

material so that wound healing can progress effi-

Bacteria adhere to the wound surface by an elec- ciently during second-intention healing.

trostatic charge. Lavage cleans the wound of Debridement involves the removal of dead or

debris and reduces the bacterial numbers, inflam- damaged tissue, foreign bodies, and bacteria that

matory mediators, and substances that potentiate compromise local defense mechanisms. Liberal

infection. In addition, lavage stimulates periph- removal of contaminated fascia, fat, and muscle

eral microcirculation through its gentle massag- and careful retention of bone, tendons, nerves,

ing action, which may favor the formation of and major vessels are important. Fascia, fat, and

granulation tissue. Lavage is easy to perform, muscle all have excellent blood supply and

requires no special equipment, is cost effective, provide excellent media for the growth of conta-

and is well tolerated by most patients. minating organisms. Although skeletal muscle is

Lavage solutions are most effective when deliv- not replaced, tl1ere are usually sufficient remain-

ered by a fluid jet of at least 8 psi." Pressures of ing muscle fibers or alternative muscle groups

10 to 15 psi are approximately 80°/o effective in available to make up for the loss. Small pieces of

removing substances that potentiate infection and bone that have lost their blood supply should be

adherent bacteria from a wound.5 Although this removed.

pressure cannot be achieved by gravity flow or

lavage with a bulb syringe, adequate pulsatile Surgical Debridement

pressure can be attained by forcefully expressing

lavage solutions from a 35- or 60-mL syringe Surgical debridement may be accomplished in a

through an 18-gauge needle or by using a spray variety of ways (en bloc, layered, or staged). E11

bottle or a Waterl'ik. The WaterPik delivers 40 to bloc resection is probably the most effective

50mL/min at 10 to 15 psi at the low-intermediate method of surgical debridement but may result in

setting and is effective for heavily contaminated the loss of some viable tissue. With this technique,

wounds. Care must be taken not to drive conta- the entire wound is excised at its margins such

minants deeper into the wound or inadvertently that all wounded and contaminated tissue is

separate loose fascial planes. removed. This method is primarily reserved for

The ideal lavage solution should be sterile, iso- draining tracts and areas where significant tissue

tonic, norrnothermic, nontoxic, and compatible loss can occur without consequence. With layered

with antibiotic or disinfectant medications that debridement, tissue removal is started at the most

may be added. Isotonic crystalloids, such as superficial tissue layer and is continued into the

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