Development of a Manual on the Technique of Applying the Unna Boot in Patients With Venous Leg Ulcers

A venous leg ulcer (VLU), also known as a varicose ulcer, stasis ulcer, or phlebostatic ulcer, is the most common ulcer of the leg, accounting for about 70% of all ulcerations.¹ It usually occurs in the medial aspect of the leg as a result of chronic venous insufficiency and venous hypertension in the standing position.^2–5 The clinical features of VLUs include increased skin temperature of the lower extremities, edema, varicose veins, and skin changes, such as stasis eczema, skin sclerosis, and hyperpigmentation, especially in the malleolar region and distal third of the leg.² Venous ulcers usually present with slow progression, infiltration at the edge of the ulcer, slough in the wound bed, and, in most cases, secondary infection.³ In general, the ulcer arises after trauma and may be preceded by erysipelas, cellulitis, and/or stasis eczema.^3–5

Venous leg ulcers may occur in people of productive age.⁴ In many cases, individuals with VLUs withdraw from work, which can exacerbate socioeconomic conditions,⁴ potentially making those with VLUs unable to afford care. This condition also can cause several changes in lifestyle due to walking difficulty, pain, and the presence of wound exudate and odor, which may lead to changes in mood, family relationships, and social life.^6–8

In 1882, German dermatologist Paul Gerson Unna developed a zinc oxide paste (Unna paste) to treat dermatitis associated with VLUs and later combined the paste with bandages (Unna boot), which became the principle of active compression therapy for VLUs. In the United States, the Unna boot is a widely used compression therapy for VLUs.^9,10 Over the past 30 years, the Unna boot has been commercialized as a product composed of an inelastic (no-stretch or short-stretch) bandage impregnated with a paste containing zinc oxide, glycerin, acacia, castor oil, and white petrolatum to prevent hardening, making the product flexible.⁵ The bandage creates a high counter-pressure during walking and maintains a low resting pressure.¹¹ The bandage composition varies among different manufacturers and may contain cotton-viscose, nylon, polyester, or other materials in different proportions, thereby affecting the quality of the bandage in resisting static pressure, preventing edema, and decreasing venous hypertension.^12,13 

Compression therapy is considered the gold standard for the treatment of venous disease in many countries.¹⁴ It significantly increases the healing rate of VLUs and reduces the risk of recurrence.¹⁴ Despite its benefits, health professionals often use advanced technologies in the treatment of VLUs, with underutilization of compression therapy.^14,15

The development of an effective educational tool for health professionals may improve the quality of care for patients and enhance wound healing by helping health professionals better understand the health care needs of a target population as well as propose actions for health promotion and effective interventions to address local problems.¹⁶ All educational activities should be guided by a broad societal perspective, allowing ample possibilities for reflection.¹⁷

The aim of this study was to develop and validate a manual on the technique of applying the Unna boot in patients with VLUs for the use of health professionals. 

This descriptive study was approved by the university’s research ethics committee and was performed in accordance with the ethical standards of the Declaration of Helsinki and its subsequent amendments. Written informed consent for the use of clinical data and photographic records for scientific purposes and publication was obtained from all participants prior to their inclusion in the study, and anonymity was assured. 

The study was conducted in 3 stages. The first stage consisted of a search for similar educational materials to guarantee the originality of the present study and a literature review. The first stage was conducted in November 2017 on search engines Google, Google Scholar, and Yahoo as well as the following websites: the Brazilian Society of Vascular Surgery, the Brazilian Society of Phlebology, the Brazilian Society of Dermatology, and the Brazilian Association of Enterostomal Therapy. The keywords “venous ulcers,” “varicose ulcers,” “leg ulcers,” “lymphatic ulcers,” “compression therapy,” “bandage,” “lower limb ulcer treatment,” and “manual” were searched.

The second stage involved the development of the manual, including the selection of content, writing, the creation of illustrations, and layout design. The content selection was based on a literature review covering the period from January 2000 to December 2018 and was limited to articles in the Portuguese, Spanish, and English languages that were available in full text. A literature search was performed using the Cochrane Library, MEDLINE/PubMed, and Scientific Electronic Library Online (SciELO) databases, and the search engine, Google Scholar, using the keywords “manuals,” “venous ulcers,” “varicose ulcers,” “leg ulcers,” “diagnosis,” “therapeutics,” “healing,” “compression bandages,” and “health education technologies” as well as their combinations in Portuguese, Spanish, and English.

The third stage included the assessment of content validity by an expert panel, assessment of content adequacy, proofreading, and request of an International Standard Book Number. A video demonstration of the technique of applying the Unna boot in patients with VLUs also was created as an additional didactic material. 

Content validity determines the degree to which elements of a measuring instrument are relevant to and representative of the targeted construct for a particular phenomenon of interest.¹⁸ The manual was validated for content by an expert panel through a questionnaire, according to the Delphi technique,^19,20 in the search for a consensus among the evaluators. The number of experts in a panel is dependent on the phenomenon to be studied.^19,20

A total of 12 health professionals with postgraduate qualifications in VLU management and compression therapy or who had at least 3 years of experience in wound care were selected for the study.²¹ The experts received an invitation letter via email, a copy of the manual, the video demonstration, and a 15-item questionnaire for the evaluation of the manual. The questionnaire assessed the topics: Structure and Presentation (11 items), evaluating the overall presentation, general organization, structure, strategy of presentation, coherence, formatting, grammar and usage, and quality of illustrations; and Relevance (4 items), regarding the level of importance of the manual as an educational tool. It was rated on a 5-point Likert-type scale, ranging from inadequate to very adequate and had instructions for the experts to optionally express their opinions in the provided space.²² 

The content validity index (CVI), which is widely used in health research,²³ was calculated to determine the proportion or percent of experts who were in agreement on certain aspects of the manual. The CVI was obtained considering the number of responses adequate or very adequate for each item divided by the total number of responses (CVI Formula). 

When a panel is composed of 6 or more experts, the CVI for each item should be ≥ 0.78 for content validation of an instrument.²⁴

The overall CVI was calculated as the sum of the CVI values of all items divided by the number of items (Overall CVI Formula). The minimum overall agreement of 90% was required among experts for validation of the manual.

The developed manual consists of an informative, relevant text in Brazilian Portuguese and sequences of photographs illustrating the technique of applying the Unna boot in patients with VLUs. The text was written in a clear, simple, concise, and engaging style.²¹ Photographs of wounds and drawings were used to illustrate the technique, making the content more didactic and attractive. The draft version of the manual was sent to a professional graphic designer for the drawing of illustrations and layout design. The layout of the manual followed the Brazilian Standard NBR-6029.²⁵

To the authors’ knowledge, no manual on the technique of applying the Unna boot in patients with VLUs for the use of health professionals was found in the search for similar educational tools, guaranteeing the originality of the study.

All 12 experts invited to participate in the study accepted the invitation. Of the 12, 8 were nurses and 4 were physicians (2 vascular surgeons, 1 plastic surgeon, and 1 intensivist); all had postgraduation qualifications and experience in wound care management and teaching, and all of them worked in public institutions.

The 12 experts considered the 11 items from the topic Structure and Presentation as very adequate (n = 114), adequate (n = 16), and partially adequate (n = 2), for a total of 132 responses. All items in this topic were validated in the first round of consultation (CVI > 0.78), as shown in Table 1. Some experts made important suggestions for the improvement of the manual. One suggested the inclusion of a glossary containing all definitions found in the manual. Others detected the presence of typing errors and caption numbering errors, which were corrected. 

The 12 experts considered the 4 items from the topic Relevance as very adequate (n = 45), adequate (n = 2), and partially adequate (n = 1), for a total of 48 responses. All items in this topic were validated in the first round of consultation (CVI > 0.78), as seen in Table 2. Item 1 (“The content portrays key elements that need to be addressed”) was evaluated as partially adequate by an expert, who highlighted the need to include a subsection on contraindications to the Unna boot because many health professionals are unaware or lack information about this issue. 

In the first round of consultation, the manual achieved an overall CVI of 0.98, which is greater than the minimum overall CVI of 0.90 required for validation purposes. All suggestions provided by the experts were evaluated, and the manual was revised accordingly.

The second round of consultation then was carried out with the same experts 10 days after the completion of the first round, confirming the overall CVI of 0.98, indicating that 98% consensus was reached among the experts.

The final version of the manual contains 29 pages with text, photos, and illustrations, as well as a demonstration video showing the step-by-step technique of applying the Unna boot in patients with VLUs (Figure).

In addition to topical therapy, compression therapy is of fundamental importance in the treatment of VLUs. It is considered the gold standard and should be applied by trained personnel.^8,26 Thus, a manual describing in detail the technique of applying the Unna boot in patients with VLUs and a demonstration video were created for the use of health professionals.

Compression therapy is widely used to prevent or treat venous diseases and is characterized by the pressure exerted on the leg by materials that may have different elastic properties. The working pressure of a rigid compression system, composed of inelastic (no-stretch or short-stretch) bandages, rises from the resistance the bandage exerts to counteract muscle movement, thereby increasing venous return. Resting pressure is the result of compression systems on the leg at rest. Rigid compression systems have little or no extensibility and low resting pressure, requiring ambulation to increase the pumping action.²⁷ Elastic compression systems use long-stretch bandages and provide sustained working and resting pressures.^12,28,29

Learning how to apply the Unna boot can be time-consuming and requires a trained professional. The quality of the compression system is positively related to the expertise of the health professional who applies it.^12,30,31 The Unna boot is a zinc oxide-impregnated paste bandage, which moisturizes the skin and has anti-inflammatory, astringent, cytolytic, and antiseptic properties, providing comfort to the patient, in contrast to elastic compression (dry) therapies.³² It may be combined with a primary silver dressing or systemic antibiotic therapy in patients with infected VLUs.³³ 

The manual shows a bandage measuring 10 cm in width and 9.14 m in length being applied to the foot, forming a figure-eight with overlapping 5 to 6 layers in the ankle region and using about 50% of the whole bandage. It then was wrapped to just below the knee. Even after the reduction in the volume of the affected leg, the compression pressure is maintained when the correct tension is applied during the procedure. The bandage characteristics, such as textile structure, quality of the material, width, and length, have an important impact on the reduction of edema and aggravating factors.³⁴

In general, manuals are constructed based on the literature and experience acquired by health professionals in their daily practice, containing relevant information to answer the users’ most common questions. The information provided may support clinical decision-making by describing standardized procedures, thus resulting in systematization and improvement in the quality of patient care.⁹ The purpose of developing this manual was to provide appropriate guidelines on the technique of applying the Unna boot in patients with VLUs. It was created to improve the education and training of health professionals in the control of chronic VLUs. An educational manual on health care has to be based on scientific evidence and written using the adequate language to achieve the objective of guiding activities that recover, develop, or strengthen physical or mental capacities of patients, in turn promoting health and social reintegration.^17,21

The selection of content for the manual was based on a literature review on related topics and the text was written to be relevant to the local context.^35,36 Photographs and drawings were selected to make the instrument didactic and attractive for health professionals, as illustrations play an important role in the communication process.^21,37

The content of the manual was validated by health professionals specialized in wound care or involved in research activities, using both the Delphi technique^38–41 and CVI.^22,36,42 The experts made important suggestions for the improvement of the manual. Language quality and writing style may have a marked impact on the interest of health professionals in the instrument.⁹ Health communication should inform and influence both individual and collective decisions associated with health improvement.⁹ The manual achieved an overall CVI of 0.98 in both rounds of consultation, which exceeds the minimum overall CVI of 0.90 required for validation purposes, and therefore it was considered validated.

The small number of experts participating in the panel may be seen as a limitation of the study. Further studies with a larger number of experts from different Brazilian states, representing different regional cultures, is necessary to extend the results.

The present study described the development of an educational manual to guide health professionals to the use of correct techniques in the management of VLUs, which may accelerate wound healing and thus enhance the quality of life in individuals with VLUs. The manual may contribute to filling the gap in information on the technique of applying the Unna boot in patients with VLUs. 

Further studies on the development of new didactic resources, such as websites, e-books, and protocols are necessary to guide health professionals in the management of patients with VLUs. 

Authors: Edmundo Martins, Jr, RN, MS¹; Leila Blanes, RN, PhD¹; Christiane Steponavicius Sobral, MD, PhD²; and Lydia Masako Ferreira, MD, PhD³

Affiliations: ¹Graduate Program in Science, Technology and Management Applied to Tissue Regeneration, Federal University of São Paulo (UNIFESP), São Paulo, Brazil; ²Hospital of Face Defects, Brazilian Red Cross, São Paulo, Brazil; and ³Division of Plastic Surgery, Department of Surgery, UNIFESP

Correspondence: Edmundo Martins, Jr, RN, MS, Division of Plastic Surgery, UNIFESP Rua Botucatu, 740, 2o. andar, CEP: 04023-062 São Paulo, SP, Brazil; edmartinsjunior13@gmail.com 

Disclosure: The authors disclose no financial or other conflicts of interest.