Experience of Wound Bed Preparation with Different Methods

Abstract

The ultimate goal of wound care is to obtain wound closure either by natural process or by use of surgical technique and so all the steps need to be taken with a plan to reach the goal at the earliest. While performing skin grafting, closure of the existing wound is the aim, but the procedure also creates another wound (though superficial), causes pain, and may have healing issues. Optimal bed preparation is mandatory to obtain successful uptake of skin graft and to avoid loss of precious skin autograft. Every wound has its own unique needs and demands. Different agents and methods are often needed to meet these demands. It is essential to accrue experience and develop insight into the efficacy, utility, and advantages of different approaches for wound bed preparation. The availability, cost of the method, socioeconomic status of the patient, type of health care system, ease of access to facility, expertise—all these and many other factors play a role in deciding the choice of method for wound bed preparation. It is possible that different methods may be developed, evaluated, and found to be useful in different countries or different parts of the same country too. The author has evaluated methods spread over a wide spectrum including indigenously prepared topical agent, barrier foam dressing prepared using advanced technology, porcine xenografts which are not available in India, and skin allografts from the very first skin bank in India set up by the author and colleagues. The experience shared here looks at the ability of the method to control infection, inflammation, pain besides the time taken to achieve effective wound bed preparation and frequency of dressing change needed, along with ease of training.

1. Introduction

The aim of treating a patient with a wound is to correct the systemic factors and to achieve wound closure, either by natural processes or by using surgical techniques. To achieve this end concept of wound bed preparation was proposed by Dr. Falanga and Dr. Sibbald in the year 2000 [1] and updated thereafter. Besides controlling systemic aberrations such as cardiac failure, diabetes mellitus, liver or renal dysfunction, vascular insufficiency, etc., successful management of the wound environment needs thorough understanding and assessment of multiple factors related to the wound. The components that need attention include the following [1].

1. Tissue management

2. Infection and inflammation management

3. Moisture balance

4. Epithelial advancement

The author has had a long association with wounds—burn and nonburn. Besides developing a simple, cheap, and easily available dressing for wounds [2], the author had the opportunity to conduct clinical trials to evaluate new topical agents, wound dressings and xenografts and skin allografts and their role in wound bed preparation. Some of these studies have been published and some are being shared here for the first time. It is hoped that this may provide a stimulus for research in the field of wound bed preparation.

A full-thickness wound that is not likely to achieve closure by natural process or secondary suturing, or is likely to cause esthetic/functional issues if left to heal on its own by secondary intention, needs skin grafting to achieve wound closure. Hence while assessing the efficacy of a new tool in achieving optimal wound bed preparation, it is essential to evaluate the following factors -

1. Time taken to achieve wound status ready to receive skin graft -This includes separation of necrotic tissue, infection control, relief from inflammation and edema, satisfactory vascularization, and healthy granulation.

2. Success of skin grafting procedure.

3. Availability and cost of the agent/method under evaluation.

Observations such as relief of pain, ease, and conformability of dressing, frequency of dressing change, absence of toxicity, allergy; ease of training family members about the performance of wound care procedures are other important considerations.

Though it would be ideal to have a controlled trial, the presence of multiple variables affecting wound response, makes it very difficult to have absolutely comparable study and control groups. The study related to the topical agent being shared here, in brief, is unpublished data.

2. Topical agent: Panchvalkal

2.1 The product

It is hot ethanolic extract of barks of five trees added to liquefied petroleum jelly. The names of the trees are Ficus Bengalensis, Ficus Religiosa, Ficus Infectoria, Ficus Glomerata, and Azadirachta Indica.

It was shown to have broad-spectrum antimicrobial activity which included Staphylococcus aureus, Pseudomonas Aeruginosa, Escherichia coli, Proteus V, Streptococcous Pyo., anaerobes.

Studies related to mutagenicity, skin toxicity, oral toxicity, mucus membrane irritation revealed the product to be safe.

2.2 The study

To evaluate the efficacy and safety of Panchvalkal as topical agent for wound dressing.

After obtaining approval from the institutional ethics committee, an open-labeled clinical trial was conducted in 2003 enrolling 100 patients with wounds after obtaining informed consent.

Initial surgical debridement was performed when needed. The wound was cleaned with normal saline. The topical agent under evaluation was applied over the wound and covered with paraffin impregnated tulle gras. This was covered with secondary dressing of gamjee and fixed with appropriate method (bandage or tape). The dressing was changed every alternate day and the wound was evaluated for slough, exudate, pain, inflammation along with wound photograph at regular intervals. The time taken to reach endpoint was noted. The endpoint was readiness for skin grafting, secondary suturing, wound closure by contraction, and/or epithelization.

The results have been provided here in brief (unpublished data). There were 73 males and 27 females included in the study. The mean age of the patients was 39.71 years with range of 13 to 75 years. The most frequent cause of the wound was complex skin and soft tissue infection (CSSTI) (Table 1) including abscess, necrotizing fascitis. Surgical site infection or guillotine amputation stump, fresh burns were the causes of wounds in 23 patients.

Etiology	No. of patients
CSSTI	47
SSI	23
Injury—Nonburn	17
Burn injury	13
Total	100

Table 1.

Wound Etiology (topical agent).

In 43 out of 100 enrolled patients, the wounds were sterile at the time of entry in the trial and this included patients with fresh burns, postoperative wound gapes, and some bed sores. These wounds continued to remain sterile at the end of the study. In 57 patients wounds grew various pathogens at the time of entry in the study. S. aureus and P. aeruginosa were the most common isolates, followed by Klebsiella, Proteus, E. coli, and then Acinetobacter in a few. In 24 of 57 patients (42.1%) the wound became sterile before the endpoint was reached. The remaining wounds swab cultures grew P. aeruginosa and Klebsiella. None of the wounds grew Streptococci at any time in the study. Reduction of edema, wound discharge, slough, pain are all indicators of control of infection and related inflammation.

Tables 2 and 3 provide the observations about the time taken to reach endpoint and methods used to achieve wound closure. Total 70 wounds out of 100 required split-thickness skin grafting (STSG) to achieve wound closure and 45 of these had reached the endpoint in less than 7 days and the remaining 31 were ready for STSG by 14 days. The graft take was complete in 66 of 70 (94.3%) wounds and in 4 cases partial graft loss was noted. This indicates good graft bed preparation.

Time in days	Depth of wound	No. of patients
Within 7 days	Full-thickness	45
Between 7 and 14 days	Full + mixed depth thickness	31
More than 14 days	Full + Partial thickness	24
Total		100

Table 2.

Time taken to reach endpoint (topical agent).

Wound depth	STSG	Epithelization	Contraction	Secondary suturing	Total
Full-thickness	67	Nil	14	11	92
Mixed depth	3	3	Nil	Nil	6
Superficial	0	2	Nil	Nil	2
Total	70	5	14	11	100

Table 3.

Method of wound closure (topical agent).

2.3 Conclusions

1. Significant reduction in wound slough, exudate from the wound, abatement in the signs of inflammation such as edema (Figure 1a–c), pain was noted from as early as the second day of starting the application of topical agent under trial. The difference between these parameters at enrollment and at the endpoint was statistically significant with p < 0.05.

2. The agent was found to be suitable for diabetic foot wounds too (Figure 2a and b).

3. The successful take of skin graft (94.3%) indicates that the wound bed preparation achieved was optimal in terms of wound vascularization as well as infection control.

4. No side effects, local reactions were noted and the topical agent was well tolerated by the patients.

Figure 1.

a. Necrotising fasciitis after surgical debridement. b. Wound at endpoint on day 14. c: After skin grafting.

Figure 2.

a. Diabetic foot ulcer. b. Ulcer at endpoint.

This study led to commercial preparation (Treval) of this topical agent and the use could be continued. But due to the inadequate availability of appropriate quality barks of necessary trees, the preparation of the product had to be stopped in a year or two. We lost an indigenously prepared natural product with good efficacy for wound bed preparation.

3. Porcine xenograft

Porcine xenograft has been used for wound bed preparation with the hope of improving the take of skin autograft over burn and nonburn wounds [3, 4]. A recently published article [5] compared the use of porcine xenografts with no specific method for wound bed preparation and concluded that there was no difference in these two methods in terms of wound closure. But the author’s experience differs from this study.

Though porcine xenografts are in use for wound management in many countries, these are not available in India for regular use. There is no published report from India about the use of porcine xenografts over different types of wounds. Hence, it is important to share this Indian experience about use of porcine xenografts.

A randomized controlled trial was conducted at LTM Medical college and general hospital by the author and colleagues in 2009–2010 after approval from the institutional ethics committee. The unpublished data of this clinical trial is being shared here. After randomization of the patients, the type of wound care the patient was to receive was explained to the patient in detail and informed consent was obtained. None of the patients enrolled in the study group refused to accept the porcine xenograft.

3.1 Clinical trial—Comparison between Porcine Xenograft and usual wound dressing for wound bed preparation—A randomized controlled trial

3.1.1 Study design and protocol

Patients with wounds on any part of the body were randomized to study (Porcine xenograft (PX)) or to control (usual dressing (UD)) group. The presence of diabetes mellitus was not an exclusion criterion.

Porcine xenograft is not commercially available in India. So, full-thickness porcine skin was procured from the abattoir after the pig was stunned and then skinned as is the usual procedure there. This skin was brought to the laboratory in the department and split-thickness skin grafts were taken with all aseptic precautions using Humby’s handle and blade. The grafts were treated with antibiotics (Crystalline penicillin + Gentamycin) and then preserved in 85% Glycerol following the same method as used for skin allograft preservation. These porcine xenografts were used as required by washing them with normal saline till soft. Grafts were covered with paraffin impregnated gauze after application on the wound. Secondary dressing and fixation were with Gamgee and bandage or tape.

The control group received wound dressing with the application of topical agents such as povidone Iodine ointment or Framycetin cream covered by primary nonadherent (impregnated tulle gras) and secondary dressing and bandage or tape fixation.

3.2 Results

The wound parameters evaluated were same as described in the previous experience with Panchvalkal topical agent. The epidemiological data has been provided in Table 4. It reveals that the study and control groups were comparable in all aspects such as age and gender of patients, location of body parts involved, etiology of wounds, presence of exudate. The commonest comorbidity observed in both groups was diabetes mellitus. Other comorbid conditions observed in both groups were hypertension, ischemic heart disease, tuberculosis, addiction to smoking and these were comparable between the two groups. The difference in the duration of symptoms was not statistically significant.

Characters	Study group (PX); 30 patients	Control group (UD); 30 patients
Age range and mean	20 to 60 yrs. (41.7 yrs)	20 to 63 yrs. (40.7 yrs)
Men	22	25
Women	8	5
Extremity involvement	25	22
Other body parts	5	8
Burn & non-burn trauma	12	11
Infective & other wounds	18	19
Seropurulant exudate	22	23
No exudate	8	7
Diabetes mellitus	14	16
Duration of symptoms (Mean)	17.7 Days	8.3 Days

Table 4.

Epidemiological data of study and control group (PX and UD).

The observations at the endpoint (which was the readiness of the wound to receive STSG) have been presented in Table 5. The difference observed in the reduction in wound size at the endpoint was not statistically significant. The wounds in the study group treated with porcine xenografts achieved better microbial clearance as compared to the control group. At the endpoint, 15 out of 30 wounds in PX group and 6 out of 30 wounds in the UD group did not grow any organisms on culture (Table 6). This difference was statistically significant. At enrollment, the isolates grown from the wounds in PX group were E. coli, MRSA, Pseudomonas, and Klebsiella. At the endpoint, no wounds in PX group had a polymicrobial infection and the organism grown from 15 wounds were Proteus in 10 and Acinetobacter in 5. In UD group at enrollment 18 wounds and at endpoint 21 wounds showed growth of single isolates. These included Klebsiella, Pseudomonas, MSSA, E. coli at enrollment and Proteus, MRSA, Acinetobacter, and E. coli at the end point. No wound showed the presence of streptococci at endpoint. The initial pain score was comparable in both study (6.83) and control (6.66) group. But the reduction in pain score indicating relief of pain was statistically significant in the study (PX) group as compared to the control group. The mean number of days required to reach the endpoint were 8.66 in study group and 12.7 days in the control group (Figure 3a and b). This difference was statistically significant.

Results	Study group (PX) 30 pts; Number of patients (%)	Control group (UD) 30 pts; Number of patients (%)
Reduction in wound size	22 (73.3%)	20 (66.6%)
No microbial growth	15 (50%)	6 (20%)*
Clearance of slough	28 (93.4%)	25 (83.3%)
Reduction in pain score VAS	3.83 (Mean)	1.26 (Mean)*
Days to reach endpoint	8.66 days (Mean)	12.7 days (Mean)*

Table 5.

Presentation of observations at the endpoint (PX and UD).

VAS – Visual analog scale * P value <0.05 Significant.

Microbial Culture	Study group; 30 pts (PX) Enrollment	Study group; 30 pts(PX); Endpoint	Control group 30 pts (UD) Enrollment	Control group; 30 pts (UD); Endpoint
No isolate	8 (26.6%)	15 (50%)	7 (23.3%)	6 (20%)*
Polymicrobial	2	0	5	3
Monomicrobial	20 (66.6%)	15 (50%)	18 (60%)	21 (70%)
Total	30	30	30	30

Table 6.

Outcome of microbial culture at entry and endpoint (PX and UD).

* P value <0.05 Significant.

Figure 3.

a. Wound after excision of carbuncle. b. Application of porcine xenografts. c. Wound bed preparation on day 5.

3.3 Conclusion

This study suggested that in comparison to the usual wound dressing the wound bed preparation was achieved earlier, with a significant reduction in pain and control of microbial load when porcine xenograft was applied over the wounds. An associated benefit was the reduction in the frequency of dressing change in the study group. The patients had to be admitted in the hospital or had to attend an outpatient clinic for a dressing change. Porcine xenografts were accepted by all patients randomized to study group.

In 86% of the patients in study group xenograft adherence to the wound bed was noted. But the xenograft uptake (vascularization) was not noted in any wound. Chiu and Burd [4] observed that adherence of porcine xenograft to the wound is related to its antimicrobial action. Adherence thus indicates the possibility of subsequent improvement in skin autograft take.

Raimer and colleagues [6] found porcine xenografts to be useful in the management of wounds following Mohs micrographic surgical procedures.

Almost 40 years ago Ersek et al. [7] commented that porcine xenograft helps to maintain appropriate wound moisture and prevents cellular desiccation.

Though porcine xenograft was observed to be a useful temporary biological wound cover, it is not readily available in India. So, its use continues to require special efforts, and hence though feasible, it is not very common. This field is certainly open for a future venture in India.

4. Cadaveric skin allograft

Though the positive impact of cadaveric skin allografts has been well recognized for several decades, in India the first cadaver skin bank with the ability to procure, process, and store the allografts was established by the author and her supportive colleagues in April 2000 at LTM Medical College and General Hospital, Mumbai [8].

Burd [9] and others [10] associated mainly with burn management have noted that Allografts are more effective than Xenografts in achieving burn wound epithelization as well as wound bed preparation for subsequent wound closure with skin autograft. But the availability of cadaver skin allograft remains limited and hence alternative methods are essential.

The experience of the author in the utilization of skin allograft has been published [11] and is being shared here in brief with data updated to August 2010. Over about 10 years and 6 months cadaver skin allografts were used in 215 patients. The majority of these were burned patients except for seven patients (four with nonburn trauma and three with necrotizing fasciitis) in whom the allografts were used for wound bed preparation. The different clinical situations that led to the utilization of skin allografts have been shown in Table 7. The allografts provided remarkable pain relief besides promotion of epithelization reducing the need for autograft. Excellent wound bed preparation was achieved by control of infection (Figure 4a–c), maintenance of moisture balance, improved wound vascularization, and control of protein loss from wound leading to improved general condition. The autograft take was observed to be 100%. These effects have been observed by many [9, 12, 13]. Nonburn wounds too showed control of slough formation and improved vascularity with the use of skin allografts (Figure 5a and b). In case of failure of autograft take, use of skin allograft salvaged the situation and re grafting could be avoided (Figure 6a and b). Allograft was used for wound closure as intermingled grafting (Figure 7a and b).

Indication	Number of patients (%)
Primary excision and temporary wound closure	56 (26.1%)
Promotion of epithelization	54 (25.1%)
Poor general condition	33 (15.3%)
Wound bed preparation	72 (33.5%)
Total	215 (100%)

Table 7.

Utilization of skin allografts.

Figure 4.

a. Burn wound unsuitable for skin autograft due to infection, poor granulation. b. Wound bed preparation after application of skin allografts. c. Wound closure with autograft in two sittings.

Figure 5.

a. Necrotising fasciitis wound post debridement. b. Wound improvement with skin allografts.

Figure 6.

a. Loss of skin autograft. b. Salvage using skin allografts.

Figure 7.

a. Intermingled skin allograft and autograft. b. Outcome of intermingled skin grafting.

Skin allografts are also effective as method of temporary wound closure for chronic nonhealing wounds such as venous ulcers and diabetic ulcers as allografts stimulate the release of growth factors and cause modification of the wound microenvironment [14, 15].

4.1 Conclusion

Skin allograft was found to be extremely effective in controlling infection, improving wound vascularity, reducing pain, promoting epithelization, improving general condition—all this with fewer dressing change procedures. Once again it was apparent that skin alone is the best replacement for lost skin. But the possibility of disease transmission, the immunogenicity of allograft, and the limited availability of allografts are the main hurdles in the use of skin allografts. Probably, tissue-engineered skin would provide an effective but certainly expensive answer to achieve wound closure for many [13].

5. Barrier foam dressing

Several types of wound dressings are available and the choice depends on the condition of the wound. The condition of a wound may vary from time to time depending on multiple factors such as infection, slough, discharge, and hence the choice of appropriate dressing should also change accordingly. Moist wound healing is a well-accepted concept, but excessive wound exudate is harmful for optimal wound bed preparation as it damages the extracellular matrix. Foam is an absorptive material that can be useful as a dressing for exuding wounds [1]. Foams impregnated with antimicrobials (most often Silver) have been in use for more than a decade and these are drug-eluting type of dressings. The antimicrobial action of these agents needs penetration through the cell wall of the organism. This mechanism itself is likely to lead to the development of resistant organisms [16]. Besides, sustained release of antimicrobial is likely to lead to cytotoxicity.

To overcome this issue barrier foam dressing has been prepared using NIMBUS technology [17]. This has polyurethane foam coated with poly diallyl-dimethyl ammonium chloride which is a quaternary ammonium compound—a surface-active agent. The technology is such that it does not permit leaching of the active agent from the foam and the antimicrobial action is due to contact with the microbial cell wall and not by entry inside the organism. This mechanism prevents the development of resistant organisms [17]. The study conducted by Tran et al. revealed that this barrier foam dressing effectively inhibits bacterial attachment and the formation of biofilm [18]. The dressing can be used as primary dressing without the application additional topical agent on the wound.

An open-labeled study was conducted by the author to evaluate the safety and efficacy of barrier foam dressing. The study details and the outcome has been published [19].

5.1 Conclusion

On completion of the study, the conclusion was that the foam dressing was effective in absorbing and reducing the wound exudate which reflects control of wound infection (Figure 8a and b). It aided the separation of necrotic tissue from the wound bed and hence good wound bed preparation was achieved (Figure 9a and b). Dressing change was not painful. It was easy to train the relatives to do the wound dressing.

Figure 8.

a. Diabetic foot ulcer. b. Wound bed preparation at endpoint.

Figure 9.

a. Amputation stump. b. Wound bed preparation at endpoint.

This barrier foam dressing is now available commercially.

6. Discussion

From the moment a wound occurs its journey towards closure begins. Besides the management of systemic factors, the role played by different components of wound care methods is extremely crucial in augmenting the process of wound closure. The components include wound cleaning agents, methods of wound debridement, topical agents, various dressing materials, skin and skin substitutes, and specific methods such as Negative Pressure Wound Therapy (NPWT), multilayered compression bandages. Some of these methods have been discussed in other chapters in this book.

Relatively simple modification like silver ion impregnation in porcine xenografts provides effective antimicrobial wound dressing for colonized chronic wounds according to Ersek [20]. This characteristic could be useful in wound bed preparation of significantly infected wounds with resistant organisms. A successful skin grafting procedure is life-saving for patients with large burns. Ersek has also reported significant improvement in the take of widely meshed skin autograft when covered with silver-impregnated porcine xenograft [21]. This modification would certainly increase the cost of the treatment but then our patient population does extend over a wide socioeconomic spectrum. The author has no personal experience of use of this product. New developments are always welcome but certainly, need appropriate evaluation and identification of indications for the use of new product or method.

New technologies, new agents aiding debridement, new concepts related to temporary or permanent wound closure methods to aid wound bed preparation and wound closure will certainly continue to develop. Out of multiple methods available for wound bed preparation, the choice would continue to depend on the properties and quality of the method and the need of the wound at that point in time. The same method may not be appropriate for all wounds and hence thorough understanding of different methods is essential while working in the field of wound care. The choice of the method also depends on its availability, cost, affordability of the patient, access to the health care facility, the familiarity of the healthcare worker with the method, possible undesirable effects, and acceptance by the patient. Difficult access, financial constraints may make it necessary to train the family members of the patient to perform the wound care procedure. This situation would certainly have an impact on the choice of wound bed preparation method. Development of new methods will continue and consideration of all the above-mentioned issues is essential while conducting proper evaluation of these methods.

7. Conclusions

Here, the author has shared her experience of evaluating different methods from topical agent, barrier foam dressing to xenografts and allografts. Each of these has its place in wound bed preparation. The topical agent, indigenously prepared was found to be effective in controlling infection, inflammation and led to good wound bed preparation. But it is no longer available. The barrier foam dressing uses a different technology and was found suitable for infected, exuding wounds with necrotic material along with ease of dressing change and easy training of family members. Though the study was not a controlled trial, the author would prefer barrier foam dressing over the conventional wet to dry dressing method which is painful and training of family member is difficult. Porcine xenografts were found to be effective in control of infection, pain and aided epithelization and wound bed preparation leading to successful graft take. But consistent and focused effort is needed to make it available in India as an indigenous product. Skin allografts played an excellent role not only in preparing the wound bed, reducing the need for skin autograft but also lead to remarkable improvement in the general condition of the patient, particularly with large burn wounds. But deceased donor skin donation is still a relatively new concept in India, the availability of skin allograft is limited.

It is hoped that this sharing of experiences would provide food for thought, the stimulus for development of newer products using indigenously available resources, blooming of new concepts adaptable for the patient population in given region or country. The appropriate evaluation of these innovations would identify the indications, make them cost-effective and affordable to the vast population of patients with wounds spread all over the world.