COMPARISON OF NEGATIVE PRESSURE WOUND THERAPY COMBINED WITH INSTILLATION OF TOPICAL PHENYTOIN VERSUS SALINE IN HEALING OF EXTREMITY ULCERS- A RANDOMIZED CONTROL TRIAL

All the patients with extremity wounds included in the study will undergo debridement either under local/regional block in minor procedure room or under general anesthesia in main operation theatre.

A tissue bit sample from the edge of the wound will be sent for aerobic culture and sensitivity will be sent on admission. Wounds will be managed initially with surgical debridement and cleaning of the wound. Injection Ceftriaxone (one gram twice daily) and Metronidazole (500mg thrice daily) intravenous will be started empirically in all cases at admission and will be changed to appropriate antibiotic therapy based on the antimicrobial culture sensitivity pattern. A wedge of tissue of size approximately 2-3 mm will be taken from the edge of the wound for assessing histopathological parameters as well as for qualitative and quantitative bacterial cultures on day 1 of initiating NPWT.

A photograph of the wound will be taken. The surface area of the wound was measured using the smartphone based app(imito measure)6. The NPWT will be applied using sterile foam arranged in 2 layers over the wound with a drain tube placed in between the two layers of the foam. This system will be sealed using a sterile transparent plastic sheet with an adhesive surface on one side. Drain tube will be  connected to suction device and pressure set at - 125 mm Hg. Change of dressing will be done once every 48 hours. Patients in group 1 receiving NPWT with instillation topical phenytoin(2%) and group 2 received instillation with normal saline. 2 vials of phenyotin (100 mg) will be diluted with saline and will be instilled once daily for a period of 14 days. Instillation of the wound will be done four times a day at an interval of 4 hours with a dwell time of 10 minutes. Volume of saline for instillation was determined by the amount just enough to visibly saturate the foam as indicated by a darker color change in of the foam.

A repeat biopsy will be taken from the wound edge on 14th day of initiating NpWT  or earlier if the wound is ready for final closure, and sent for histopathology and bacteriology. A photograph of the wound will be taken again on day 14 following initiation of NPWT and wound surface area was measured using Imito measure smartphone based app to assess the percentage reduction in the size of the wound.

The primary outcome will be measured in terms of days from time of initiation of negative pressure wound therapy to the stage where the treating surgeon decides it is fit for wound closure. Secondary outcomes will be measured by assessing the bacterial burden of the wound, pathological strength of granulation tissue in terms of changes in surface epithelium, histological appearance of granulation tissue, changes in inflammatory cells, changes in proliferating blood vessels and fibroblastic reaction and changes in adnexal structures.