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Moist wound healing with occlusive dressings.

The "clean and dry" battle call has long echoed through the corridors of many a nursing home: clean, dry floors, clean, dry sheets, clean, dry residents. In the field of wound care management, however, the "if it's dry, it must be clean" adage has led to practices that not only delay wound healing but may actually cause reinjury with every dressing change.

Despite the frustrations associated with wound care management in the nursing home population, the healing process is far from mysterious. In the normal healthy individual, it's actually very difficult to prevent a wound from healing. The key is to provide the best possible healing environment and to simply let the body proceed with the healing process without subjecting the wound to interventions that interfere with repair.

Moisture--an essential for keeping every cell in the body alive and functioning--is central to that ideal healing environment. In the early 1960s, the misconception that wounds will heal if "nice and dry" was refuted with evidence of moisture's positive impact on wound healing. Three decades later, however, translating that awareness into widely accepted clinical practice is still an ongoing process.

Thirty years of experimental and clinical evidence has confirmed that the moisture or exudate produced by the wound contains everything required for the healing process: growth factors for new cell and vessel formation, enzymes to rid the wound of necrotic tissue, and white blood cells to protect against infection. Dry gauze dressings soak up that vital fluid and rob the wound of the growth factors and enzymes required for healing. Further, removing the gauze during dressing changes causes continual reinjury that slows the process significantly.

Conversely, moist, occlusive dressings provide the best possible means to protect that fluid, maintain direct contact with the wound, and in the process provide the best possible chance for healing.

The first of the occlusive dressings was a moisture vapor permeable polyurethane film introduced in the US in the early 1970s for use as a preoperative drape. Nurses--primarily ETs, who are accustomed to improvising to keep wounds clean and collect fluids-- then began experimenting with the dressings as wound coverings that not only prevented exudate leakage on their "clean, dry sheets" but also seemed to accelerate healing and reduce pain.

In the early 1980s, the first hydrocolloid dressings (Duoderm) were introduced after numerous clinical studies had shown that the gel-type, polymer dressings not only healed experimental superficial wounds faster than gauze, but also facilitated healing of most (previously) recalcitrant pressure and leg ulcers.|1-4~

Mounting Evidence for Hydrocolloids

The benefits of wound healing products that retain moisture continue to be underscored in numerous studies that show reductions in time to healing, infection rates, pain and costs over the long-term. The market place has responded with over 100 occlusive dressings, including the polyurethane and hydrocolloid dressings, as well as water-based hydrogel dressings, polymer foams, pastes and gels used to fill in wound cavities, and combinations of the above.

In early animal studies, re-epithelialization of superficial wounds permitted to heal in a moist environment (covered with plastic wrap) was significantly mote rapid than that of wounds covered with conventional gauze dressings.|5~ This was later confirmed in several clinical trials.

Fluid from deeper wounds also contains growth factors (platelet-derived, fibroblastic, and epidermal) needed for healing. In vivo, that exudate stimulates the proliferation of keratinocytes (epidermal cells), fibroblasts, endothelial cells, and even smooth muscle cells.|6~ Wound exudate also contains proteolytic enzymes that clean the wound by breaking down and eliminating necrotic and fibrinous tissues -- the necessary first step in the healing process.|7~

In addition to keeping moisture in, some of the occlusive dressings serve as highly effective protective barriers against external contamination. In vivo studies of the Duoderm family of hydrocolloid dressings demonstrate that the dressings serve as a barrier against Pseudomonas, Staph aureus, HIV, and Hepatitis-B.|8-9~

A recent study of the same hydrocolloid dressings suggests that they also reduce the risk of cross-contamination via airborne bacteria. Investigators reported that removing a gauze dressing from a small (180 |cm.sup.2~) acute wound releases approximately 720 bacteria per 80 liters of ambient air. More than 50% of the bacteria released were still present after 20 minutes. When removing the hydrocolloid dressing, the number of bacteria after one minute was approximately one-fifth the amount observed for gauze, declining to 112 bacteria/80 liters of air after 20 minutes.|10~

Multiple studies have shown that the overall infection rate underneath occlusive dressings is much lower (2.6%) than that underneath conventional gauze-type dressings (7.1%)|11~ This is true even when a topical antibacterial agent is used with the gauze dressing. This is because the gauze dressing, by soaking up the wound fluid, makes the wound more vulnerable to bacterial invasion. The occlusive dressing, on the other hand, enables the body to essentially fight its own battle.

Use of occlusive dressings also helps to dissolve excess fibrin in the wound, as well as so-called fibrin clots commonly observed in the small blood vessels surrounding venous ulcers. If the wound is kept moist, the proteolytic enzymes not only destroy fibrin, but one hydrocolloid dressing has been shown to be able to dissolve these clots. While compression alone dissolves some of these clots, compression applied over a hydrocolloid dressing has been shown to eliminate 86% of the clots after one week.|12~

Use of occlusive dressings also stimulates angiogenesis (new blood vessel growth.)|13~ Deeper wounds need to fill in with granulation tissue, replacing dermis and blood vessels before re-epithelialization can occur.

Also, contrary to the view that contact with ambient oxygen is required for healing, research has shown that a very low oxygen gradient helps stimulate the formation of granulation tissue and new blood vessels, especially with deep wounds. Vessel formation actually slows down significantly when experimentally exposed to a large oxygen supply.|14~

From the symptomatic standpoint, the greatest benefit derived from moist healing with occlusive dressings is a significant reduction in pain. The best controlled clinical studies of occlusive dressings and pain have been conducted in alert responsive patients able to verbalize their level of discomfort with respect to treatment of venous ulcers, skin graft donor sites, and burns. A statistically significant difference in pain levels, for example, was documented in bum patients treated with hydrocolloid dressings versus traditional silversulfadiazine gauze dressings.|15~

Studies of the effect of treatments on pressure ulcer pain are limited. However, studies of leg ulcers, abrasions, biopsy sites, burns, and donor sites have consistently shown that wounds are significantly less painful when treated with an occlusive dressing than when covered with a conventional gauze-type dressing. Savings Achieved

While the per piece cost of occlusive dressings is, of course, greater than that of gauze, the long-term savings with the use of the moist dressings can be profound. The largest savings is in nursing care, as has been documented recently.|16~ While gauze dressings are changed several times each day, occlusive dressings may remain on a pressure ulcer for up to seven days.

Another potential source of monetary savings not often taken into consideration is the reduced need for ancillary supplies used during traditional gauze dressing changes: gloves, tape, secondary dressings and soiled pads. The cost of these items add up quickly when used two to three times daily per patient. While formal studies have not yet been conducted, the greatest potential savings may ultimately be in the form of a reduction in surgical intervention, hospitalizations, and long-term recovery for wounds that previously failed to heal with conventional treatment. For example, 50% to 80% of venous ulcers treated with hydrocolloid dressings and compression will heal without any surgical intervention or hospital admission.|17~ These patients also remain ambulatory rather than requiring bed rest.

Wound Assessment

A number of variables contribute to the rate of wound healing: nutritional status, such as low albumin levels in the elderly that are further depleted by pressure ulcers, poorly controlled diabetes or other conditions that compromise the immune system, and the availability of pressure-relieving measures and devices. Crucial to monitoring the effectiveness of treatment is a thorough and accurate quantitative assessment of all chronic wounds at diagnosis and throughout treatment and follow-up.

First, a correct diagnosis has to be made. For example, compression, the treatment of choice for venous ulcers, is contraindicated for arterial ulcers. Also, a non-healing wound in a bed-ridden patient does not have to be a pressure ulcer. It can be a fistula, a tumor, or skin breakdown secondary to an infection and moisture (i.e. candida).

Second, particularly in chronic wounds, it is important to objectively evaluate whether or not the wound is improving. It is very easy to forget what the wound looked like a week ago. It is also important to use a standard assessment method; all caregivers will therefore "speak the same language."

Clean the wound (using a non-irritating substance, such as saline) before starting your assessment. The wound can be measured with a measuring tape (width and length), or you can trace the margins on an acetate sheet or sturdy plastic bag. If you use a plastic bag, cut off the "dirty" part of it and discard it. The tracing can either be kept in the patient's chart (not forgetting to date it!) or you can calculate wound area by putting it over 1 cm or 0.5 cm grid paper. If your facility has a camera, take a photograph before initiating treatment.

Depth can be measured by gently inserting a sterile swab into the deepest portion of the wound. Hold the swab at skin level and, after removal, put it next to the measuring guide. If there is any tunneling, i.e. areas that extend beyond and underneath the wound margins, note where it is and try to obtain a depth measurement.

Finally, look at the wound and describe what you see. If there is a little bit of black tissue, estimate how much (i.e. 20% of total wound size); if half the wound is covered with yellow fibrin, write down "50% fibrinous tissue." Also, evaluate the surrounding skin. Is it red, white (macerated), warm, tender? After thoroughly evaluating the patient and the wound, you may then start treatment. Treatment Tips: Acute Wounds

Candidates for treatment with occlusive dressings are patients with superficial or deep chronic wounds (pressure and leg ulcers). These dressings also have a role with acute wounds, which include skin graft donor sites, second degree burns, biopsy sites, any wound from minor surgical procedures, and skin tears. It is important to remember that skin tears should not be covered with adhesive occlusive dressings. Some dressings, such as hydrogels, are not adhesive. While this makes them difficult to use for pressure ulcers, they are ideally suited for covering the fragile skin of residents who have developed skin tears. All other acute wounds will benefit from the use of adhesive occlusive dressings. For example, in a controlled study of 124 shave biopsies, 31% of wounds treated with the hydrocolloid dressing Duoderm were healed after seven days, compared with only 12% of those treated with a topical antibiotic ointment and conventional dressing.|24~

Stage I Pressure Ulcers

Among chronic wounds, Stage I and superficial Stage II wounds are extremely common in the nursing home population. A Stage I pressure ulcer appears as a red, non-blanching area. Though the skin is still intact, blood vessel damage has already occurred and the area should be managed accordingly, using immediate preventive pressure redistribution with replacement mattresses or overlays, and frequent repositioning.

Sometimes, reducing pressure is sufficient to reverse the non-blanchable erythema. At times, for the incontinent resident, a thin hydrocolloid or polyurethane film occlusive dressing helps to reduce friction or protect the area. It is important to remember that polyurethane dressings adhere to the skin because they are coated with an acrylic adhesive, whereas most hydrocolloid dressings do not adhere immediately to the skin; rather, their so-called wet-tack feature makes them adhere more strongly over time as moisture is absorbed into the dressing.

When applied over Stage I areas, the dressing and surrounding skin should be inspected every day. If it looks as though no exudate has been absorbed into the dressing (i.e., the skin is still intact), the dressings should be left in place for up to seven days before changing. Sometimes the skin will proceed to break down, revealing the damage that was not visible before: a Stage III or IV pressure ulcer.

Stage II Pressure Ulcers

Stage II pressure ulcers--involving a small amount of the dermis--are the most common in the nursing home population. These are often exacerbated by friction, shear and/or contact with urine and feces in incontinent patients. In most patients, measures to redistribute the pressure and use of an adhesive occlusive dressing will result in healing within a relatively short period of time. The wound should be rinsed with saline solution to facilitate assessment. During daily inspection, increased exudate will be visible as fibrin breaks down, and dressings changes every 24 to 48 hours may be required early in the healing process. Once the wound becomes cleaner, dressing changes are less frequent. If healing isn't evident in about two weeks, pressure reduction and topical treatment measures should be re-evaluated.

Fortunately, infection is relatively rare in superficial pressure ulcers. But if warmth, redness, swelling, tenderness, or elevated temperature is documented, a wound culture should be obtained. Cleanse and debride the wound before taking a swab culture, or obtain a biopsy. Based on the culture results, a course of systemic antibiotics should be prescribed. Not all dressings can be used on infected wounds, and it is important to read a product's package insert to determine whether or not you can continue use of the dressing. Venous Ulcers

Seventy percent of leg ulcers are venous ulcers and most are superficial. Once the diagnosis is confirmed to rule out arterial involvement, initial assessment should include inspection for a clean wound bed and signs of infection (cellulitis).

Hydrocolloids are the dressing of choice for leg ulcers because they reduce pain, dissolve fibrin and are hypoallergenic. Most of these patients have a history of leg ulcers, and their use of a large number of topical agents over time may have produced hypersensitivity to many topicals.

The dressing should be covered with an unna boot (zinc oxide paste) and a compression bandage, both of which are usually left in place for up to seven days.

With this treatment, most venous ulcers will heal after two months. It is important, however, to measure and evaluate these wounds once a week. Recent studies have shown, in fact, that the percent reduction in ulcer area after two to four weeks predicts treatment outcome.|17-18~ If a 30% reduction is not evident by this time, the diagnosis, patient compliance and treatment modality used should be re-evaluated.

Once the ulcer is healed, it is important to continue use of compression bandages or stockings to prevent recurrence

Deep Pressure Ulcers

Deep pressure ulcers (Stage III and IV) are full-thickness wounds. State IV pressure ulcers can extend down to, and into, bone, muscle or tendon. Reported time to healing of these wounds varies from six or seven weeks to three to six months. Results of a study involving 51 nursing homes showed that, using their standard pressure ulcer treatments, 28% of Stage III and 20% of Stage IV ulcers were healed after three months.|19~

Again, appropriate measures to redistribute pressure (including turning or mobilizing the patient) must be instituted, and the patient's nutritional status should be optimized. Studies have shown that these wounds can benefit from the use of occlusive dressings, as well, and most wounds so treated can be expected to heal after six or seven weeks.|20~ Not all dressings are approved for use on these deep wounds, however, so be sure to read the product's package insert before application.

Polyurethane film dressings are not commonly used in this indication because they tend to not remain in place when too much exudate is present. Hydrocolloid dressings, particularly those designed to absorb more exudate, are used more often. It is important to remember, though, that -- particularly if the wound contains some necrotic or fibrous material -- the amount of exudate will increase during the first week or so, and the dressing cannot be expected to remain in place for more than two or three days. Therefore, try to experiment with different application techniques, and always try to have an adequate margin (one-and-a-half inches) between the edge of the wound and the border of the dressing.

Most importantly, inspect the dressing (and surrounding skin) every day, for two reasons: First, if the dressing has absorbed so much exudate that the discoloration (which occurs as a result of fluid absorption) is close to the border of the dressing, change it. Do not wait for the dressing to start leaking. This will save you the trouble of cleaning the bed, and it will save the skin surrounding the ulcer by not exposing it to moisture. Second, if the surrounding skin has become warm, tender or red, the wound may be infected. The treatment of an infected deep ulcer is the same as that of an infected Stage II ulcer, although if bone is exposed, further studies may be indicated to rule out the presence of osteomyelitis.

Special Wounds/Special Circumstances

Even though the use of occlusive dressings will facilitate debridement, sometimes it is better to debride the wound surgically. Indications for surgical debridement include: the presence of necrotic tissue that is hard and fused to the wound margin, or the presence of necrotic tissue in an immunosuppressed patient.

Wounds that are particularly deep and/or that have undermined edges or tunneling, such as State IV pressure ulcers, often require the application of a wound filler. Several gels, granules and pastes are available for this. Most can be applied underneath an occlusive dressing.

Some wound care products, such as calcium alginate dressings,|21~ are especially designed to absorb large amounts of exudate. They can be quite useful in these situations, but research has shown that when the amount of wound exudate diminishes, their use should be discontinued to facilitate the healing process.|21~

Conclusion

Wounds are a fact of life. Particularly in the elderly or severely debilitated nursing home resident, the occurrence of chronic wounds cannot always be prevented. It is important to remember, however, that the treatment modality selected can have a profound impact on the healing process, as well as on the patient's quality of life and the cost of care. Fortunately, we have learned a great deal about wound healing during the past 30 years. We can insist on using treatment modalities that have been shown to be safe and effective in controlled clinical studies, and can apply that knowledge to help achieve optimal patient care.

References

1. Alvarez OH, Mertz PM, Eaglstein WH. The effect of occlusive dressing on collagen synthesis and epithelialization in superficial wounds. J Surg Res 1983;35:142-148.

2. Cherry GW, Ryan T, McGibbon D. Trial of a new dressing in venous leg ulcers. Practitioner 1984;228:1175-1178.

3. Tudhope M. Management of pressure ulcers with a hydrocolloid occlusive dressing: Results in twenty-three patients. J Ent Ther 1984;11:102-105.

4. Yarkony GM, Lukanc C, Carle TV. Pressure sore management: Efficacy of a moisture-reactive occlusive dressing. Arch Phys Med Rehabil 1984;65:597-600.

5. Winter GD. Formation of scab and the rate of epithelialization on superficial wounds in the skin of the domestic pig. Nature 1962;193:293-294.

6. Bolton LL, Johnson CL, van Rijswijk L. Occlusive Dressings: Therapeutic Agents and Effects on Drug Delivery. In: Shear N (Ed.). Clinics in Dermatology 1992;9:573-583.

7. Chen WYJ, Rogers AA, Lydon MJ. Characterization of biologic properties of wound fluid collected during early stages of wound healing. J Invest Derm 1992;99:559-564.

8. Mertz PM, Marshall DA, Eaglstein WH. Occlusive wound dressing to prevent bacterial invasion and wound infection. J Am Ac Derm 1985;12:662-668.

9. Bowler PG, Delargy H, Prince D, Fondberg L. The viral harrier properties of some occlusive dressings and their role in infection control. Wounds 1993;5:1-8. 10. Lawrence JC, Lilly HA, Kidson A. Wound dressings and airborne dispersal of bacteria. The Lancet 1992;339:807.

11. Hutchinson JJ, McGuckin M. Occlusive dressings: a microbiologic and clinical review. Am J Inf Contr 1990;18:257-268.

12. Mulder G, Jones R, Cederholm-Williams S, Cherry G, Ryan T. Fibrin cuff lysis in chronic venous ulcers treated with a hydrocolloid dresssing. In J Derm 1993;32:304-306.

13. Lydon MJ, Hutchinson JJ, Rippon et al. Dissolution of wound coagulum and promotion of granulation tissue under DuoDERM. Wounds 1989;1:95-106.

14. Knighton D, Hunt TK, Scheunstuhl H, et al. Oxygen tension regulates the expression of angiogenesis factor by macrophages. Science 1983;221:1283-1285.

15. Madden M, Nolan E, Finkelstein J, Yurt RW et al. Comparison of an occlusive and a semi-occlusive dressing and the effect of the wound exudate upon keratinocyte proliferation. J Trauma 1989;29:924-931.

16. Xakellis GC, Chrischilles EA. Hydrocolloid versus saline-gauze dressings in treating pressure ulcers: A cost-effectiveness analysis. Arch Phys Med Rehab 1992;73:463-469.

17. Margolis DJ, Gross EA, Wood CR, Lazarus GS. Planimetric rate of healing in venous ulcers of the leg treated with pressure bandage and hydrocolloid dressing. J Am Acad Derm 1993;28:418-421.

18. van Rijswijk L and the Multi-Center Leg Ulcer Study Group. Full-thickness leg ulcers: patient demographics and predictors of healing. J Fam Pract 1993;36:625-632.

19. Brandeis GH, Morris JN, Nash DJ, Lipsitz LA. History of pressure ulcers in elderly nursing home residents. JAMA 1990;264:2905-2909.

20. van Rijswijk L. Full-thickness pressure ulcers: Patient and wound-healing characteristics. Decubitus 1993;6:16-21.

21. Barnett SE, Varley SJ. The effects of calcium alginate on wound healing. Ann Roy Coll Surg 1987;69:153-155.

22. Hermans MHE. Hydrocolloid versus Tulle gauze in the treatment of abrasions in cyclists. Int J Sports Med 1991;12:581-584.

23. Cordts PR, Hanrahan LM, Rodriguez AA et al. A prospective randomized trial of Unna's boot versus DuoDERM CGF Hydroactive dressing plus compression in the management of venous leg ulcers. J Vasc Surg 1992;15:480-486.

24. Nemeth AJ, Eaglstein WH, Taylor JR et al. Faster healing and less pain in skin biopsy sites treated with an occlusive dressing. Arch Dermatol 1991;127:1679-1683.

25. Gorse GJ, Messner RL. Improved pressure sore healing with hydrocolloid dressings. Arch Derm 1987;123:766-771.

Lia Van Rijswijk is a Newtown, Pennsylvania-based nurse consultant for health care corporations, acute and long-term care facilities, and home care agencies. She has published over 25 articles on wound care in publications such as Journal of Family Practice, Decubitis, Dermatology Nursing, Cutis, Wounds, Journal of Enterostomal Therapy, and Clinics in Dermatology. She is a contributing editor for Ostomy & Wound Management, and Geriatric Dermatology, and is currently writing two chapters in a wound care text for physical therapists. She has conducted numerous clinical studies, both as a clinician and as the manager of the department of clinical affairs of a health care company. She is a frequent lecturer on wound care and wound healing at local and national meetings and is a member of the Wound, Ostomy and Continence Nurses Society, and the Dermatology Nurses Association.
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Author:Rijswijk, Lia Van
Publication:Nursing Homes
Date:Jan 1, 1994
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