This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNB 2018, Subject name: Surgery
[{'content': 'Negative pressure wound therapy (NPWT) is used in: \nSelect and explain. \nA. Bedsore in sacrum after debridement, B. After amputation negative suction, C. Osteomyelitis, D. Unexplored fistulas', 'role': 'user'}, {'content': 'Answer: A \nExplanation: VACCUM ASSISTED CLOSURE/ NEGATIVE PRESSURE WOUND THERAPY (NPWT) NPWT Promotes wound healing by applying a vacuum through a special sealed dressing. Continued vacuum draws out the fluid from wound & increases blood flow to the area. Vaccum may be applied continuosly or intermittently, depending upon the types of wound being treated & clinical objectives. Negative pressure of -125 mm Hg is used Dressing should be changed 2-3 times/week Primary Effects of NPWT on Wound Healing Macrodeformation Drawing the wound edges together leading to contraction Stablization of wound environment Wound protected from outside micro- organisms in a warm & moist envirnoment Reduced edema With removal of soft tissue exudates Microdeformation Leading to cellular proliferation on the wound surface Contraindications for NPWT Use Malignancy in the wound Untreated osteomyelitis Non-enteric & unexplored fistula Necrotic tissue with eschar', 'role': 'assistant'}]