¹JR, ²Assistant Professor, ³Associate Professor, Department of Surgery, MIMER Medical College, Pune, Maharashtra, INDIA.

Email: drkshirsagars@gmail.com

Table 1: Age and gender distribution

Most common type of chronic ulcer observed in present study was diabetic ulcer (69.6%) followed by venous ulcers (19.6%) and pressure ulcers (10.7%). No difference was seen in the study groups on the basis of type of ulcer (p-0.59).

Table 2: Type of ulcer

At the end of 1 and 2 weeks, 53.6% and 96.4% cases of NPWT group had granulation tissue as compared to only 21.4% and 64.3% cases in conventional group. The difference was statistically significant (p<0.01). By the end of 3 weeks, 96.4% of the cases in NPWT group had granulation tissue as compared to 89.3% cases in conventional group (p-0.61).

Table 3: Granulation tissue appearance

The wound contraction rate was significantly faster with NPWT therapy. The difference in the rate of wound contraction was apparent since 1^st week. By week 3, mean percentage of wound contraction was 90.9% in NPWT therapy as compared to 74.54% in conventional group patients. The difference was statistically significant (p<0.05).

Table 4: Wound contraction rate

Decrease in wound dimensions was significantly faster in NPWT group patients as compared to conventional group. The difference was statistically significant from week 2 (p<0.05).

Table 5: Wound contraction rate

Closure by secondary intention was achieved in 85.7% and 71.4% patients of NPWT and Conventional group while skin grafting was required in 14.3% cases of NPWT group as compared to 28.6% cases in conventional group respectively (p<0.05).

Table 6: Wound closure

Mean healing time in days was significantly less in cases managed by NPWT compared to conventional group (7.33 versus 12.12 days; p<0.01). Mean hospital stay was significantly more in cases managed by conventional dressing as compared to NPWT (17.23 versus 11.13 days; p<0.05). Mean cost incurred by cases managed by conventional dressing was slightly lower than incurred by cases managed by NPWT (Rs 920/- Vs 1140/-; p-0.12). The difference was however non-significant.

Table 7: Other characteristics

DISCUSSION

Negative Pressure Wound Therapy (NPWT) has been advocated as a novel method in the healing of chronic ulcers by stimulating the chronic wound environment in such a way that it reduces bacterial burden and chronic interstitial wound fluid, increases vascularity and cytokine expression and to an extent mechanically exploiting the viscoelasticity of periwound tissues.^6,7 One concerned with the branded VAC appliances used for NPWT was their cost. As most of our patients are from poor socio-economic background, financial viability of the VAC is an issue. Hence, we planned to use an economical modification for NPWT for the treatment of chronic ulcers and compare its results with conventional dressing. Mean age of study subjects was 52.8 and 53.6 years in Conventional and NPWT group respectively. The incidence being higher age group can be well explained by fact that most of the chronic ulcers are diabetic ulcers, which is a complication of diabetes mellitus. Complications of diabetes increase with age. Also diabetes is disease of mostly elderly. Similar finding of highest incidence of diabetic ulcers being in age group of 45 to 64 years in the national health department survey (N.H.D.S) at USA.⁸ In another similar study by Lone AM et al.,⁶ mean age in NPWT group was 53.79 years and in Conventional group was 54.57 years. Male Preponderance was observed in both groups (64.3% in Conventional and 57.1% in NPWT group respectively). This was similar to that observed in review of literature by Rieber et al.,⁹ India being a male dominated country and lack of medical care given to females may also be a contributing factor. In a study by Lone AM et al.,⁶ women constituted approximately one third and men around two third of study participant in a NPWT and Conventional group. Application of negative pressure over the wound bed allows the arterioles to dilate, increasing the effectiveness of local circulation, promoting angiogenesis, which assists in the proliferation of granulation tissue.¹⁰ We observed that patients on NPWT therapy had early appearance of granulation tissue as compared to patients treated by Conventional dressing (p<0.05). The wound contraction rate was also significantly faster with NPWT therapy Mean healing time in days was significantly less in cases managed by NPWT compared to conventional group(7.33 versus 12.12 days; p<0.01). In a study by Lone AM et al.,⁶ granulation tissue appeared in 26 (92.85%) patients by the end of Week 2 in NPWT group in contrast to 15 (53.57%) patients by that time in conventional group. Armstrong and Lavery¹¹ also observed that the use of negative pressure therapy resulted in an increased rate of granulation tissue formation and a higher proportion of healed wounds compared to saline gauze dressings. Eginton MT et al.,¹² compared the rate of wound healing with the NPWT to conventional moist dressings in the treatment of large diabetic foot wounds. NPWT dressings decreased the wound volume and depth significantly more than moist gauze dressings (59% vs. 0% and 49% vs. 8%, respectively). The study concluded that Negative-pressure wound treatment may accelerate closure of large foot wounds in the diabetic patient. In a study by Moues CM et al.,¹³ patients were included (NPWT vacuum n = 29, conventional n = 25). The authors observed that wound surface area reduced significantly faster with NPWT vacuum therapy. Vuerstaek et al.,¹⁴ noted that patients in the NPWT group healed faster (29 days x 45 days, p<0.01), also reaching more quickly the time of wound bed preparation (7 days x 17 days, p<0.01) [80] . Egemen et al.,¹⁵ applied NPWT in 20 patients with venous ulcers and found a rapid preparation of the bed, as well as an optimization of the subsequent integration of the skin graft. Ford et al.,¹⁶ noted mean percentage reduction in ulcer volume was higher in the NPWT group (51.8% vs. 42.1%, p=0.46), NPT promotes healing and neo-vascularisation. Ashby et al.,¹⁷ noted superior benefits of NPWT in comparison with moist dressing in regards to rapid development of granulation tissue and wound contraction. In present study, mean hospital stay was significantly more in cases managed by conventional dressing as compared to NPWT (17.23 versus 11.13 days; p<0.05). The decreased stay can be attributed to rapid healing and wound contraction rate in cases of NPWT therapy, which allowed an earlier reconstruction and reduced the days of hospitalization. Similar findings were noted by Moues CM et al.,¹³ Petzina et al.,¹⁸ Assenza et al.,¹⁹ Closure by secondary intention was achieved in 85.7% and 71.4% patients of NPWT and Conventional group while skin grafting was required in 14.3% cases of NPWT group as compared to 28.6% cases in conventional group respectively (p<0.05). In the study by Lone AM et al.,⁶ most of the cases required skin grafting owing to large ulcers, the healing by secondary intention was higher in cases of NPWT as compared to Conventional dressing (23% versus 7%). Our observations were consistent with those of Prabhdeep et al.,²⁰ who also reported more cases requiring skin grafting in conventional group. Llanos et al.,²¹ in their study on traumatic wounds, observed that need for second coverage procedure was less common in the NPWT group (5 [16.7%] vs. 12 [40.0%] patients, p = 0.045). Mean cost of the therapy by using branded VAC appliances is approximately Rupees 3000/- for 48 -72 hours session which is very high, especially for patients requiring multiple sessions as in our study. If we superimpose this cost for the approximate of 5 days in present study, it will amount to Rupees 10,000/-. In present study, however, mean cost incurred by cases managed by NPWT was Rs 1,140/-. When we compare the cost to conventional dressing, the cost is slightly higher (Rs 920/-), but if we compute the shorter hospital stay in NPWT patients and faster recovery, meaning early return to work; the overall therapy is much more cost effective than conventional dressing. Thus Negative Pressure Wound Therapy with its modification appears to be superior compared to conventional dressings in terms of early appearance of granulation tissue, rapid contraction and decrease in hospital stay. Overall healing rate was also faster than conventional dressing while the cost was comparable. We thus recommend use of Negative Pressure Wound Therapy in chronic wound management as first line therapy. We also recommend further studies with larger sample size to validate our observations in each specific type of chronic wounds viz. venous, diabetic and pressure ulcers.

CONCLUSION

Present study concludes that the Negative Pressure Wound Therapy with its modification appears to be superior compared to conventional dressing in terms of early appearance of granulation tissue, rapid contraction, overall faster healing, decrease in hospital stay and much more cost-effective.

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