INTRODUCTION

Diabetic foot ulcer (DFU) is a common complication of uncontrolled diabetes with annual incidence between 9.1 and 26.1 million worldwide.[1] By definition, DFU is a full-thickness wound which is present at a level distal to the ankle in patients with diabetes.[23] DFU can lead to foot amputation which can be prevented by better understanding of diabetes and DFU. The first step in DFU management is proper assessment and clinical examination of wound. Treatment of DFU starts with control of diabetes followed by debridement and wound care with appropriate dressing and culture-based antibiotic coverage. There are several conventional guidelines of wound care and dressing techniques in DFU.[4] One of them is vacuum-assisted closure (VAC) therapy which promotes healing by applying the specialized dressing over the ulcer bed using the subatmospheric negative pressure. This therapy was alternatively termed as negative pressure wound therapy (NPWT) in a series of patients which was first published 13 years ago.[5] Combining NPWT with irrigation of normal saline cleanses the wound and lessens the bacterial bioburden. Thus it helps in wound bed optimization and is a more effective therapy than VAC alone.[6] Wound assessment is another aspect of DFU management for deciding whether the wound is prepared or not for coverage. The present study uses DEPA score as a wound assessment tool in DFU and attempts to address the benefits of NPWT with irrigation of normal saline in wound bed preparation.

MATERIALS AND METHODS

RESULTS

All 11 patients studied were males with diagnosis of infected DFU. Maximum number of patients in this series was above 60 years of age [Table 1]. Most patients have duration of diabetes for more than 10 years. Majority of the patients were found to have Staphylococcus aureus growth in DFU. The mean time for NPWT application was 15 days. Healthy infection-free granulation tissue was obtained in all patients. The mean time of wound preparation, which was calculated from wound debridement to final surgical procedure, was 18.7 days.

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Figure 1

DFU at left heel. (A) Before NPWT instillation therapy. (B) NPWT instillation therapy. (C) After NPWT instillation therapy. (D) Medial plantar harvesting. (E) Medial plantar flap coverage

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Figure 2

DFU medial and lateral midfoot. (A) Before NPWT application. (B) After NPWT application. (C) Reverse sural flap coverage

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Figure 3

(A) DFU with necrotizing fasciitis with right tendo-achilles region. (B) After NPWT instillation. (C) Skin grafting over tendo-achilles region

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Final surgical procedures were executed in all patients, and split skin grafting was performed in seven patients. Four patients had wound coverage: reverse sural flap (2), medial plantar flap (1), and local flap (1).

We achieved success with coverage of diabetic foot wound after wound preparation by NPWT with normal saline irrigation. No complications related to NPWT were observed. Three patients had a mild local itching complaint, which was successfully treated with oral medication.

DISCUSSION

Diabetes mellitus is a metabolic disease with increasing prevalence in India, which poses significant healthcare and financial burden for patients due to increasing mortality and morbidity because of its complications. At present, India is having the second highest number of people with DM next to China and accounts for almost 1/6th of the diabetic patients in the world, and the prevalence rate of diabetes in India is 2.4% in rural and 12–17% in urban population.[7]

The persistent hyperglycemia in diabetic patients with poor glycemic control leads to micro- and macrovascular complications. DFUs are the most common complications of uncontrolled diabetes mellitus. Most of the patients in this study belonged to the age group of more than 60. Similarly, Saseedharan et al.[8] also suggested male predominance (n=11, 59.7%) in a study on 261 patients, revealing that DFU is more common in old age and male gender.

Most patients (n=6, 54.5%) have duration of diabetes less than 10 years, with mean duration of 9.09 in the present series. Similarly, Jyothylekshmy et al.[9] in a study suggested 56% of patients with duration of diabetes <10 years and mean duration of 8.5 ± 4 years. All 11 patients in our study had controlled diabetic status. Duration of diabetes and diabetic status during treatment have an impact on outcome of DFU management. Antibiotics, offloading, dressings, NPWT therapy, and other modalities of wound management are ineffective if patients have uncontrolled diabetes, so daily monitoring of blood glucose level and judicious use of anti-diabetic therapy are necessary for glycemic control.

Diabetic foot infection is usually present as cellulitis, ulcer, and necrotizing fasciitis. This infection is another common cause of morbidity in patients with DFU, leading to complications such as gangrene and eventually amputation.

Management of DFU includes appropriate culture and sensitivity-based antibiotic coverage with frequent microbiological examination of bacterial flora over the bed of DFU. We performed swab culture and sensitivity of antimicrobial agents test to assess the microbial flora and found that the majority of patients in first wound culture has S. aureus (n=5, 45.4%) growth in DFU. Other bacterial floras that was isolated in the present series were Pseudomonas aeruginosa, Escherichia coli, and Proteus mirabilis. Ramakant et al.[10] studied the bacterial etiology and antibiotic sensitivity pattern of DFU in India in 1632 cultures. The most common pathogens in the first culture were P. aeruginosa (20.1%), S. aureus (17.2%), and E. coli (16.3%).

Debridement forms mainstay treatment for DFU for reducing the bacterial load and desloughing the devitalized tissue and usually performed prior to NPWT application. There are various methods of debridement.[11] Sharp surgical debridement is the most effective and fastest method of debridement. DFU with heavy exudate needs a dressing that absorbs moisture, whereas dry wounds need topical treatments that add moisture. Topical antimicrobial agents as well as antimicrobial impregnated wound dressings might be useful for preventing or treating mild infections. The drawback of conventional dressing is that it is always associated with extended wound preparation time adding discomfort to the patients.

NPWT is an alternative of these conventional dressings which reduces the bioburden of wound. NPWT reduces the wound surface area and promotes granulation tissue formation with added advantage of low complication rate, greater comfort to the medical team and patient, reduced time of hospitalization, reduced use of antibiotics, and number of dressing change.[12131415] Other studies also suggest that NPWT is more effective than these wound dressing and topical antimicrobial.[616]

NPWT with irrigation is a modification of the conventional NPWT therapy, combining the benefits of NPWT with controlled delivery of topical solutions [such as cleansers (normal saline), antiseptics, and antibiotics to the wound bed]. This modification involves the instillation of substances into the sealed wound via an additional tubing system while the vacuum pump is paused. The foam is thus impregnated with the instilled fluid. This process helps; the topical solution comes into contact with the entire area between the foam and the wound surface.[17]

In the present study, the mean time for NPWT (with NS irrigation) application was 15 days, ranging from 10 to 25 days. Apelqvist et al.[18] showed similar results of normal saline with the mean duration of 12 days for NPWT with irrigation, four cycles per day. Additionally, there are clinical observations that NPWT with irrigation by saline is more effective in wound healing than NPWT alone.

NPWT is a very useful therapy, although the cost related to NPWT is a drawback of this excellent therapy and especially the added feature like irrigation with normal saline further increases the cost, so the authors recommended this therapy especially to those patients who can afford this therapy.

The DEPA score was used to analyze the wound status before and after NPWT instillation therapy. This scoring was initially proposed by a Jordan University Hospital (2004) that creates a score according to depth (D), extent of bacterial colonization (E), phase of healing (P), and associated etiology (A). Each component can be scored, according to its severity, from 1 to 3, and a total score ranging from 3 to 12. The outcome measure of healing was significantly associated with higher scores[19] [Table 2].

In a study of 84 patients with DFU, Younes and Albsoul[20] suggested that 32 patients had a DEPA score of ≤6, 34 patients had a DEPA score of 7–9, and 18 patients had a DEPA score of ≥10. All patients with DEPA scores ≤6 had excellent healing, whereas only 15% of those with a score of ≥10 had complete healing in <20 weeks. In conclusion, an increasing DEPA score is associated with increased risk of amputation and poor healing. Furthermore, inclusion of the phase of ulcer healing into the DEPA system increases the accuracy of predicting the outcome of DFUs. In the present series, we also found the same results with most of the patients of DFU presented with DEPA scores more than 7 and after application of NPWT instillation therapy, patients showed significant improvement with decrease in DEPA score below 6 [Table 3].

In the present series, the mean time of wound preparation which was calculated from the time of wound debridement to final surgical procedure was 18.7 days, ranging from 13 to 32 days. A study of Kim et al.[21] on 142 patients compared NPWT instillation and NPWT no-instillation groups and concluded that time to final surgical procedure was significantly shorter for the 6- and 20-min dwell time groups (7.8 ± 5.2 and 7.5 ± 3.1 days, respectively) compared with the no-instillation group (9.23 ± 5.2 days) (P ≤ 0.05).

After wound preparation with granulation over the DFU is done, final surgical procedures were executed. In the present series, split skin grafting is performed in seven patient. Four patients had wound coverage: reverse sural flap (two), medial plantar flap (one) and local flap (one). We achieved success in all the 11 patients with satisfactory coverage of DFU having success in achieving the granulated wound bed for coverage by NPWT with normal saline irrigation. In a study by Zelen et al.,[22] a total of 14 out of 19 (74%) patients healed completely, with a median healing time of 34 days (range 9–114). This success rate is comparable to our result, which further proves the efficacy of NPWT with irrigation.

The drawback of this study is the small sample size with lack of control group, which did not allow direct comparison of NPWT with irrigation feature with conventional NPWT. Further, a large series is needed to prove the efficacy of instillation therapy of NPWT dressing over the NPWT.

CONCLUSION

NPWT normal saline instillation therapy has both economic and clinical advantages in wound bed preparation. Use of this therapy has advantage in faster healing rates, reduced dressing changes, as well as reduced time of wound preparation. Usually, the diabetic foot wound is assessed on the basis of clinical examination; we in our series found that along with clinical examination, DEPA score is an important tool for the assessment of wound preparation which gives exact information for timing of wound coverage once diabetic foot wound is prepared.