DRESSINGS

Gauze, Impregnated Gauzes, and Contact Layers

Renee Cordrey* Program in Physical Therapy, The George Washington University, Washington, District of Columbia.

Abbreviations Background: Gauze has long been used as a primary and secondary dressing. and Acronyms It is frequently impregnated with substances for bactericidal, moisture- BIPP ¼ bismuth, iodoform, and balance, hemostatic, or debridement purposes. Contact layers (CLs) provide a paraffin paste nonadherent protective layer over the wound when needed. CL ¼ contact layer The Problem: Though commonly used, gauze is potentially recognized to harm wound tissue through desiccation and adhesion. Contemporary research on CMS Centers for Medicare ¼ gauze is largely limited to being the control group of a product trial. Impre- and Medicaid Services gnated gauzes vary widely in the materials used. Iodoform, commonly im- MRSA ¼ methicillin-resistant pregnated on gauze, is weakly antimicrobial and can be toxic when absorbed. staphylococcus aureus Basic/Clinical Science Advances: Wet-to-dry dressings (WTDDs) are not sup- MWH ¼ moist wound healing ported in modern wound care, as they slow healing and destroy viable tissue. NPWT ¼ negative pressure Gauze dressing orders should be written ‘‘moist-to-damp.’’ The composition of a wound therapy CL can affect cell viability and interface pressure through negative pressure PHMB ¼ polyhexamethylene therapy. Gauze dressing changes release more bacteria into the air than other biguanide types of dressings. Gauze has long been impregnated with various substances.

WTDD ¼ wet-to-dry dressing The most recently used materials have antimicrobial and hemostatic properties. Clinical Care Relevance: WTDDs are more expensive over the course of care *Correspondence: Program in Physical Therapy, despite its inexpensive supply cost. Iodoform and bismuth dressings may result The George Washington University, 900 23rd St. in allergic reactions, toxicity with cognitive changes, and multisystem prob- NW, 6th Floor, Washington, DC, 20037 (e-mail: lems. CLs can reduce tissue trauma with dressing changes, with different types [email protected]). preferred for different wounds. Gauze may be impregnated with a large number of substances to achieve different goals, both during manufacturing or at the point of care. Conclusion: Despite evidence against the use of WTDDs, they are still used. There is limited evidence on impregnated gauzes (other than iodoform) and CLs, but they are commonly used. More research should be done on gauzes, im- pregnated gauzes, and CLs.

BACKGROUND wound filler or cover, made wet or GAUZE HAS BEEN used to support kept dry, and used as a secondary wound healing throughout recorded dressing to secure a primary product. history. Healers have impregnated Sterile cotton gauze was first mass- gauze or other materials such as produced1 in 1891. Since then, gauze papyrus, lint, sponges, or wool with has evolved into a wider variety of honey, wine, vinegar, poultices, products and sizes, including rolls for salves, and other compounds thought wrapping extremities or ribbons for to aid healing.1,2 packing into tracts=tunnels, and a Gauze is a versatile product. It is choice of woven cotton or nonwoven commonly used to absorb blood and synthetic gauze. exudate. It is applied with pressure Heavily used since the early 20th to achieve hemostasis, placed as a century are contact layers (CLs).

120 ADVANCES IN WOUND CARE, VOLUME 1 Printed in U.S.A. j Copyright ª 2010 by Mary Ann Liebert, Inc. DOI: 10.1089=awc.2009.0155 GAUZE, IMPREGNATED GAUZES, AND CONTACT LAYERS 121

Early CLs included tulle gras,3 a wide-mesh net BASIC SCIENCE CONTEXT material coated with a blend of paraffin, oil, and In 1962, Winter published his seminal paper sup- Balsam of Peru. Later, CLs included a synthetic porting moist wound healing (MWH) as superior to net or mesh, uncoated or coated. CLs serve several dry wounds.4 Wounds that are kept moist heal functions. They may be used directly on the wound faster, with less scarring, a better cosmetic out- to reduce trauma from dressing changes while al- come, and fewer infections. lowing exudate and topical agents to pass through Critical colonization and infection are well un- it to and from the wound. CLs also prevent adhe- derstood to impair wound healing through the sion to dressings, especially with negative pressure production of inflammatory cytokines and bacterial wound therapy (NPWT) or over skin grafts. toxins, which lead to a prolonged inflammatory Gauze products are frequently impregnated phase of wound healing. with a number of substances (Table 1). In the The choice of dressing can influence the wound quest to provide wound care for minimal cost, the bed’s moisture and bacterial loads, thus influenc- pennies-per-use cost of gauze has been appealing, ing wound viability and progression. Depending as well as its wide availability and general ease of on its use, gauze may dry or hydrate the wound and use. However, there are several areas of concern is typically very permeable to bacteria. with some gauze applications, and the previously popular gauze ‘‘wet-to-dry dressings’’ (WTDDs) has fallen out of favor because of the tissue trauma EXPERIMENTAL MODEL OR MATERIAL— and wound desiccation associated with its use. ADVANTAGES AND LIMITATIONS Because it has long been the ‘‘standard of care,’’ Table 1. Common uses of impregnated gauzes there has been little research on gauze, especially Impregnated recently. Most research has been on the treatment Ingredient for the control group, with the test product usually proving superior to gauze for wound healing. These retentive Moisture- Absorbent Absorbent trials are often sponsored by the manufacturer of desiccation desiccation Hemostasis Hemostasis point of use impregnated Debridement Debridement Non-adherent Manufactured Contact Layer Contact Anti-microbial Wound drying/ Impregnated at Primary Dressing Dressing Primary Moisture-additive Moisture-additive the product. As gauze and impregnated gauzes are Sodium Chloride (saline) inexpensive, there is little financial incentive to Hypertonic invest in studies. Published papers on these ma- Sodium Chloride (dry) terials may be based on clinical experience or pro- Iodoform fessional opinion. Studies rarely compare CLs. Petrolatum Those that do include few types and these studies Paraffin often are not replicated or expanded. Bismuth and Petrolatum Iodoform has proven to be more bacteriostatic BIPP than bactericidal in vitro.5 However, it is thought Oil Emulsion Hydrogel that it may react with body fluids and become Honey more bactericidal in vivo. However, the research PHMB on this question is limited, and it has not been Cellulose examined for decades in the context of current Chitosan knowledge. Other antimicrobial substances, such Kaolin as cadexomer iodine and Dakins solution, have Zeolite been studied as stand-alone products, not neces- Polymer sarily impregnated on gauze. (See Section 3, Legend: Primary effects Secondary effects Antibacterial Dressings for more information on This table represents the most commonly used impregnation substances. Clinicians antimicrobial substances.) often manually impregnate gauze with other desired substances. This technique The contemporary research cited in this chapter may be especially valuable in resource-poor nations where preimpregnated was produced in western nations with access to dressings may be unavailable or prohibitively expensive. The properties of saline advanced wound care. Resource-poor nations may gauze vary depending on use—whether placed wet, moist or dry, and whether removed wet, damp, or dry. Hemostatic dressings vary in use across manufacturers. not have access to these more expensive prod- Some are designed to be left in place as a primary dressing, whereas others are ucts, and so more of traditional materials may be designed to be temporary until clotting occurs, at which point they are removed encompassed in the primary approach. Therefore, and a different primary dressing is applied. Dark gray shades: primary effects; light older research may prove valuable when these gray shades: secondary effects. BIPP ¼ bismuth, iodoform, and paraffin paste; PHMB ¼ polyhexamethylene products are the only available ones. Research on biguanide. outcomes in these settings is important. 122 DRESSINGS

There is a commercially available hypertonic salt- DISCUSSION OF FINDINGS impregnated dry gauze designed to debride slough. AND RELEVANT LITERATURE Iodoform gauze has been used to prevent or treat Gauze has been used since ancient times, because infection since 1837.14 In the 1880s there was a of its availability, ease of use, inexpensive cost, fami- debate over the toxicity of iodoform because of liarity, and longevity in practice, as well as clinicians’ the complications from its use, including several lack of knowledge about the variety of alternatives deaths.14 Iodoform and bismuth are common sensi- available.6 tizers,15–17 with an allergic reaction rate for bismuth, Plain gauze is commonly used in several man- iodoform, and paraffin paste (BIPP) dressings up to ners. Dry gauze is often used on closed surgical 11% after a second exposure.18 Despite these risks, sites to absorb any exudate and provide a mild and a weak antimicrobial effect,14,15,19–22 it is still barrier from the environment. With moistened in use. gauze or a wet-to-moist dressing, gauze is wet with normal saline, or other liquid TAKE-HOME MESSAGE solution, and changed several times daily to prevent the wound from drying. For Basic science advances WTDDs, saline-moistened gauze is ap- There is little research on gauze, impregnated gauze, and CLs. Most modern plied to the wound and allowed to dry research is on a control group’s standard of care while another product is being before removal to facilitate debridement. studied. The studies focused on these products are older.

Fifty years post-Winter, WTDDs con- 6–8 Iodoform is incompatible with silver nitrite, metallic salts, strong oxidi- tinue to be prevalent. zers, and strong bases.23 Though gauze dressings appear inex- pensive, it has been demonstrated that WTDDs are not supported in modern wound care. 5 these dressings are actually much more Iodoform is more bacteriostatic than bacteriocidal. expensive than advanced dressings be- Iodoform and other substances may respond differently in in vivo and cause of the labor involved multiple times in vitro environments. perday,longertimetohealing,greater CL composition affects cell viability. need for pain medications, and a higher Clinical science advances infection risk.6–12 As the moisture evapo- Gauze and impregnated substances have been used since ancient times. rates the wound bed cools, slowing healing through vasoconstriction, reducing oxy- There is a wide variety of CLs and impregnated gauzes (which may serve gen release by hemoglobin, and reducing as CLs or primary dressings). They serve several purposes, including the the mobility and activity of leukocytes.6 following: The gauze also becomes hypertonic, Protection of the wound bed through nonadherence, leading to re- drawing fluid from the wound bed, caus- duced pain, bleeding, and trauma, ing dessication.6,7 In addition to inhibiting Bacteriostatic or bacteriocidal environment, MWH, WTDDs tightly adhere to slough Hemostasis, and granulation tissue. As a result, dress- Management of moisture balance. ing changes cause significant trauma to the newly growing tissue through nonse- Gauze and impregnated gauzes may promote or hinder MWH, depending on the product and its use. lective debridement6,8 and a prolonged inflammatory state. Of particular concern Gauze is not an adequate bacterial barrier, especially when wet. for patients lacking coagulation, WTDDs Greasy, oily, or gel-based substances on the gauze may provide better also increase the risk of bleeding upon occlusion. dressing removal.3 For these reasons, Iodoform and bismuth are strong allergic sensitizers. Centers for Medicare and Medicaid Ser- With a WTDD, evaporative cooling delays wound healing through va- vices (CMS) regulations for long-term care soconstriction, reduced leukocyte activity, and increased oxygen binding. indicate that this approach should be As the moisture evaporates from a WTDD, it becomes more hypertonic, used only for mechanical debridement desiccating the wound as it pulls fluid osmotically. when the wound has no significant viable 13 Polyhexamethylene biguanide-impregnated gauze may be helpful in re- tissue. Clinicians often re-wet the gauze ducing the risk of Methicillin-resistant Staphylococcus aureus (MRSA) before removal to reduce the adherence and other infections. and associated pain, thus preventing me- The removal of gauze dressings releases significant amounts of bacteria chanical debridement while maintaining into the air. the disadvantages of a dry wound bed.8 GAUZE, IMPREGNATED GAUZES, AND CONTACT LAYERS 123

and cross-contamination is also higher Relevance to clinical care with gauze. Compared with a hydrocolloid, Despite inexpensive supply costs, gauze dressings have a higher total gauze dressing changes resulted in five cost of care. times the amount of bacteria released into The clinician can impregnate gauze with nearly any solution, gel, or paste the air.33,34 at the point of care. Woven cotton gauze adheres to tissue Wound-care professionals must be aware of the risks and benefits of more strongly than nonwoven synthetic each product being used. gauze and may shed fibers, especially if Sudden changes in behavior, mental status, neurological status, renal cut. These tiny foreign bodies prolong function, or overall medical condition should trigger assessment of iodine inflammation and may form granulomas or bismuth levels if dressings containing them have been used. If toxicity in the tissue. is suspected or confirmed, the type of dressing must be changed and There has been little research on CLs; supportive measures implemented. Hemodialysis or chelation may be nec- however, their value is clinically recog- essary in severe cases. nized. They are most commonly a syn- With systemic absorption, iodoform can transmit to a fetus through the thetic mesh, either raw or coated with a placenta or to an infant via breastmilk, causing hypothyroidism.37 nonadherent material such as petrola- CLs are used to reduce tissue trauma and pain at dressing changes with tum, oil, or silicone. CLs may dry and NPWT,35 over skin grafts, and with fragile tissue. stick if left in place too long or the exudate is sanguinous.3 The composition and per- Each type of CL has advantages and disadvantages, and the clinician meability of a CL used under NPWT will should consider which option best serves a particular patient. affect the force at the surface, and so this should be considered in planning care.35 Iodoform may be absorbed systemically, espe- Petrolatum-impregnated gauze resulted in lower cially if the wound is large or if it is used for a local pressure than the foam alone or with silicone prolonged time. The Material Safety Data Sheet or mylar-polyester CLs. (See Section 11, Topical for iodoform23 labels it a severe health risk with Negative Pressure Therapy for Acute and Chronic multiple problems, such as inhalation, ingestion, Wounds.) or transdermal absorption, including dermatitis, The composition of the CL affects cell viability. irritation, and effects on the cardiovascular sys- In vitro tulle gras with chlorhexadine produced a tem, nervous system, liver, and kidneys. Other re- significant reduction in fibroblasts and keratino- ported symptoms of iodoform toxicity include cytes, whereas a silicone-coated viscose CL showed acid=base disturbance, thyroid disorders, abnor- an increase in the number of fibroblasts after 3 days mal liver function, and neutropenia.24 of treatment, but not 7.36 There are many reported cases of iodoform toxi- city causing reversible cognitive impairment,5,15,25–29 with both iodopor gauze and BIPP-impregnated CAUTION, CRITICAL REMARKS, gauze. Bismuth can result in systemic toxicity.24 AND RECOMMENDATIONS Iodoform may affect peripheral nerves. Gauze im- At this time there is little independent research on pregnated with an iodophor paint placed adjacent to impregnated gauzes and CLs. Most product trials a nerve blocked conduction.30 Thesameeffectwas compare their efficacy to plain gauze, which usu- not found with iodoform gauze, but facial paralysis ally is not conducive to wound healing, making the has been noted with BIPP use.31 alternatives appear superior. Comparative trials of Gauze may be impregnated with antimicrobial products within or across categories are rare. Many agents. Antiseptics such as Dakin’s solution have published articles are commentary or informa- broad cytotoxicity, but may be used in limited sit- tional pieces based on opinion or experience. uations. (See Section 3, Antibacterial Dressings.) There are some reports that silicone-coated CLs One study32 found a 24% reduction in surgical site may be more difficult to apply and are more time infections and a 48% reduction in MRSA surgical consuming than other CLs.38 They also have been site infections with an antimicrobial gauze im- reported to adhere less to the wound base, however, pregnated with polyhexamethylene biguanide. and may be a better choice in some cases, despite a Gauze is often used as a secondary dressing to higher cost.39 secure primary dressings and provide a bacterial Despite the wide array of advanced wound prod- barrier. However, 64 layers of dry gauze are re- ucts available, and the knowledge base that has quired to block bacteria.33 Moist gauze is even more accumulated about the harm WTDDs and iodoform- permeable to bacteria.6 The risk of aerosolization impregnated gauze may cause to wounds, they are 124 DRESSINGS

still in common use by nonwound specialists. Efforts properties of CLs and impregnated substances, must be taken by the wound-healing community to comparative research should be conducted so that bring the practice of wound care by all health pro- wound-care professionals will be able to select the fessionals up to current standards. optimum product for a given wound. Despite being highly toxic, iodoform is still used New impregnations are sure to be developed, in open wounds. The Material Safety Data Sheet with multiple aims. Recently, several gauze im- advises wearing protective garments to prevent pregnations previously reserved for emergency skin contact when working with iodoform. It is not, settings have become available for achieving he- however, a carcinogen.23 mostasis. Another new product impregnated with a polymer designed to maintain moisture balance by FUTURE DEVELOPMENT moving fluid between the dressing and the wound There is a need for further work in this area, with as needed has been developed. Real-world out- new products being developed, and the efficacy of comes for these products should be studied. new and existing products being explored. The older dressings, such as gauze, petrolatum ACKNOWLEDGMENT gauze, BIPP, and iodoform gauze, have some evi- None. dence available about their use, both favorable and unfavorable, albeit mostly decades old. The newer products have limited independent research. As AUTHOR DISCLOSURE STATEMENT there is much variability in the composition and No competing financial interests exist.

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