In cleansing wounds, don't overlook the 'how'

Key issues to consider before you apply

By Liza G. Ovington, PhD, CWS

President

Ovington & Associates

Ft. Lauderdale, FL

Wound cleansing is a topic that will invariably generate a lively discussion about what type of solution should be used - normal saline, a solution containing a surfactant, a solution containing antimicrobial ingredients, a solution you would put in your eye, and so on. As interesting as such discussions may be, they are only half the story when it comes to wound cleansing. No matter what you use as the cleansing solution, even more important is how you deliver that solution to the wound.

Cleansing is defined as a physical (as opposed to chemical) process of loosening and removing microorganisms, cellular debris, and other foreign materials from the wound's surface. Notice that this definition does not involve "killing" anything. Wound disinfection is a chemical process during which you are attempting to kill bacteria in the wound without killing endogenous cells such as fibroblasts and white blood cells.

Therefore, by definition, wound cleansing ought to utilize a non-toxic solution that is delivered to the wound in such a way as to gently agitate and then wash away surface contaminants. If contaminants are deeper in the wound tissue, then some type of wound debridement may be called for.

The wound cleansing solution is often used in conjunction with gentle scrubbing with sterile gauze or with a sponge. Such gentle scrubbing can enhance the removal of surface contaminants if performed with care not to impart mechanical trauma to the tissues. Cleansing solutions also may be delivered to the wound surface as a stream or spray, which must be of sufficient strength to loosen bacteria and foreign materials. This type of delivery is called irrigation and will be discussed here in more detail.

Wound irrigation may be performed by several methods, but there are some basic concerns regarding any method of wound irrigation. These include:

· The impact pressure of the irrigant solution at the wound surface.

The 1994 Pressure Ulcer Treatment Guidelines prepared by the Agency for Health Care Policy and Research (AHCPR) in Rockville, MD, recommend optimal irrigation pressures of four to 15 pounds of pressure per square inch (psi) of tissue for safe and effective wound cleansing. This recommendation is based on research findings that systematically compared the effectiveness of irrigant solutions delivered at different pressures in removing bacteria and debris from wounds. Quantitative studies by Rodeheaver and others have demonstrated that increasing the pressure of irrigant solutions enhances the efficacy of cleansing. In one study, pressures of 20 psi and 25 psi did not significantly enhance cleansing as compared to pressures of 15 psi.

There is also concern that pressures higher than 15 psi may actually drive contaminants into, rather than off of, tissues. In one of Rodeheaver's studies, an irrigant solution composed of saline with a blue dye was delivered to experimental wounds at 15 psi and at 20 psi. Subsequent excision and analysis of the irrigated wounds revealed that the 15 psi irrigation showed only superficial penetration of the dye solution into tissues, while the 20 psi irrigation penetrated the entire thickness of the tissues.

· Distance of the irrigant source from the wound surface.

The distance of the irrigant source from the wound surface directly affects the impact pressure of the irrigant solution. In general, the further from the wound surface, the lower the impact pressure. If you are using a system that claims to deliver a specific pressure of irrigant, be sure to note the recommended distance from the wound surface. If a distance of six inches is recommended and you hold it within two inches of the surface, you may achieve a much higher impact pressure than you intend. Conversely, holding it further away than six inches will generate a lower and perhaps less effective or even ineffective impact pressure.

· Splashing of the irrigant solution.

Using a pressurized stream of irrigant to cleanse the wound surface may result in some splashing of the solution. Splashing is a concern because it may then become a vector for contamination of other wounds on the patient, of the patient environment, or of the caregiver. Adequate personal protection (goggles, gloves, clothing) and sterile fields should be utilized during irrigation procedures. Some of the commercially available irrigation systems incorporate disposable splashguards or shields as part of the equipment. (For a list of commercial products, see box, above.)

· Angle of contact.

The angle of contact between the irrigant solution and the wound surface is a contributing factor to splashing. One study of a pressurized product by Weller suggested that a 45-degree angle minimizes splashing of the irrigant solution.

· Irrigation methods.

How does one achieve the recommended irrigation pressure range of four psi to 15 psi? You can construct an appropriate combination of syringe and angiocatheter (needles may introduce a needlestick hazard), or you may use one of several commercially available irrigation systems. Such systems often consist of a specially equipped IV bag, a pre-combined syringe and tip, or a pressurized canister. Some manufacturers also claim that their packaging of commercial wound cleansers incorporates a spray or squeeze nozzle that delivers the cleanser at a pressure between four psi and 15 psi (remember to check the label for the appropriate distance for the nozzle to be held from the wound surface).

If you choose a commercially available irrigant system or pre-packaged cleanser, be sure to read all the instructions for its use. If, on the other hand, you choose to combine syringes and angiocaths, there are some general rules to follow. The AHCPR Pressure Ulcer Treatment Guidelines quote the work of Rodeheaver in a table listing the irrigation pressure of a 35ml syringe equipped with a 19 gauge angiocatheter as 8 psi, which is near the middle of the recommended range. The general rules for other combinations are as follows:

- The larger the syringe, the lower the impact pressure of the irrigating solution.

- The larger the angiocatheter bore, the greater the impact pressure.

The following combinations of syringes and needles are quoted from Rodeheaver's work to illustrate these concepts:

6 ml syringe + 19 gauge needle = 30 psi

12 ml syringe + 19 gauge needle = 20 psi

35 ml syringe + 19 gauge needle = 8 psi

35 ml syringe + 25 gauge needle = 4 psi

35 ml syringe + 21 gauge needle = 6 psi

35 ml syringe + 19 gauge needle = 8 psi

The decision of when to cleanse and with what to cleanse may vary depending on institutional policy, wound type, or wound status. Once these decisions are made, appropriate irrigation pressures will contribute to the efficacy of the cleansing process.

Recommended reading

Bergstrom N, Bennett MA, Carlson CE, et al. Treatment of Pressure Ulcers. Clinical Practice Guideline No. 15. AHCPR Publication No. 95-0652. Rockville, MD: Department of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research; December 1994.

Rodeheaver GT. "Wound Cleansing, Wound Irrigation, Wound Disinfection." In: Krasner D, Kane D. Chronic Wound Care. 2nd ed. Wayne, PA: Health Management Publications; 1997, pp. 97-108.

Rodeheaver GT, Pettry D, Thacker JG, et al. Wound cleansing by high-pressure irrigation. Surg Gynecol Obstet 1975; 141:357-362.

Weller K. In search of efficacy and efficiency. An alternative to conventional wound cleansing modalities. Ostomy/Wound Management 1991; 37:23-28.