Preparation of the Surgical Site
Many methods are used to prepare skin for aseptic surgical procedures. The Agricultural Animal Care and Use Program at the University of Illinois Urbana-Champaign recommends the following method, based on published research results for agricultural animals and input from board-certified veterinary surgeons working with agricultural animals.
Step 1: Hair Removal
- Using a clipper with a #40 surgical blade, generously clip the hair or wool from the area surrounding the proposed surgical site.
- Isopropyl alcohol applied to the site will facilitate clipping.
- Coarser shearing clippers may be required initially in heavily-wooled sheep.
- Remove clipped hair/wool and associated debris using a brush and/or vacuum and discard.
- If applicable, brush the coat adjacent to the clipped area to remove loose hair and debris that could contaminate the surgical site if the animal or surgical drape were to move.
- In poultry, pluck feathers from the area surrounding the surgical site and discard them.
- A razor can be used to create a closer shave, if desired, but is not needed in most cases.
Step 2: Preliminary Skin Preparation
Note: If the area is grossly contaminated with organic debris, use soap and tap water to remove prior to performing the preliminary skin preparation.
Goal = remove gross debris and transient skin flora
- Apply a generous amount of surgical scrub solution (see below) to the clipped area and scrub the skin with gauze sponges or a surgical brush. Rinse with water or saline. Repeat as needed until the site is free of visible debris. The site is tentatively considered clean when:
- Water beads as it flushes across the skin.
- A 4 x 4 gauze sponge passed over the site appears clean.
- Soak 4 x 4 gauze sponges in 70% isopropyl alcohol. Wipe the scrubbed skin, beginning at the anticipated incision site and working outward. Check for any remaining debris. Repeat if necessary until gauze remains completely free of visible debris.
Step 3: Local Anesthesia (If Applicable)
- A local anesthetic agent should be administered after the preliminary skin preparation but before the final preparation.
- Needles used to administer local anesthetic should never be reinserted into the bottle.
Step 4: Final Skin Preparation
Goal = (1) substantially reduce resident skin flora to prevent infection and (2) achieve the residual antiseptic activity. It is not possible to completely sterilize the skin.
Note: The final skin preparation should be performed in the surgical suite
- Sterile surgical gloves should be worn for the final skin preparation. Supplies, including solutions, must be sterile.
- Saturate numerous gauze sponges with antiseptic scrub (see below). Starting with one to three sponges, scrub the skin in small circular motions, working from the anticipated incision site to the periphery of the clipped area. Discard sponges as you reach the periphery.
- Pick up the gauze sponges by carefully folding and grasping the corners without contacting any other portion of the sponge.
- Alternatively, use a pair of sterile forceps to grasp the sponges.
- Repeat the above scrubbing pattern with fresh antiseptic-soaked gauze sponges, always working from the center to the periphery of the clipped area. Continue until the skin has had five minutes of contact time with the antiseptic.
- After five minutes of preparation, carefully rinse the site with sterile 0.9% saline or 70% isopropyl alcohol until "beading" occurs on the skin. This indicates that the area is free of fat and/or soap residue.
- AACUP does not recommend pouring saline or alcohol near the contaminated skin edges in a manner that would cause "backwash" over the clean skin. If necessary, apply the solution to sterile gauze and rinse.
- Allow the alcohol to air dry.
- Complete the final skin preparation by applying a light coat of antiseptic surgical solution (not scrub; see below) with a spray bottle.
Antiseptic Soaps and Solutions
The most common antiseptic soaps and solutions used for surgical preparation of agricultural animals are povidone-iodine (Betadyne), chlorhexidine gluconate (Nolvasan), and 70% isopropyl alcohol. The advantages and disadvantages of each are summarized in the table below. (From Am J Infect Control, Volume 27, Number 2, 1999.)
AACUP recommends the use of Nolvasan scrub in combination with alcohol for skin preparation. Nolvasan has a substantial residual effect, is more effective in the face of organic debris (preliminary skin preparation), and was shown to reduce bacterial numbers on bovine skin significantly better than povidone-iodine. It is also less likely to cause skin irritation. Alcohol has no residual effect but effectively removes fat and soap from the skin.
Phisohex (hexachlorophene) must be avoided because of neurotoxicity potential.
Note: antiseptic soaps and solutions must be kept in covered containers to avoid contamination. Certain bacteria and fungi can survive in these products.
Mechanism and Spectrum of Activity of Antiseptic Agents Commonly Used for Preoperative Skin Preparation and Surgical Scrubs
|Agent||Mechanism of Action||Gram-Positive Bacteria||Gram-Negative Bacteria||Mtb||Fungi||Virus||Rapidity of Action||Residual Activity||Toxicity||Uses|
|Alcohol||Denature proteins||E||E||G||G||G||Most rapid||None||Drying, volatile||SP, SS|
|Chlorhexidine||Disrupt cell membrane||E||G||P||F||G||Intermediate||E||Ototoxicity||SP, SS|
|Iodine/Iodophors||Oxidation/substitution by free iodine||E||G||G||G||G||Intermediate||Minimal||Absorption from the skin with possible toxicity, skin irritation||SP, SS|
|PCMX||Disrupt cell wall||G||F||F||F||F||Intermediate||G||More data needed||SS|
|Tricloan||Disrupt cell wall||G||G||G||P||U||Intermediate||E||More data needed||SS|
Abbreviations: E, excellent; F, fair; G, good; Mtb, Mytobacterium tuberculosis; P, poor; PCMX, para-chloro-meta-xylenol; SP, skin preparation; SS, surgical scrubs; U, unknown.