Negative Pressure Wound Therapy

Negative pressure wound therapy is also known as vacuum pressure therapy. It is a new technique; now, it is widely used in various countries. It is mainly used to treat acute and chronic wound and this method is specially used for Diabetic wound by delivering negative pressure to the wound and removing excess fluid from the wound, and it helps to heal the wound faster. This technique has more benefits and many research studies have been conducted. Here, an overview of the history, uses, indications range of pressure techniques mechanism recommended pressure contraindication and complication of negative pressure wound therapy are discussed.


INTRODUCTION
It is an upcoming new technique which is used for acute wound and chronic wound. Some advanced wound care method is needed to cure wound faster; here, this methods is getting popular. Firstly, it was more popular in U.S. Now, this method is used in many hospitals in India. It is a nonpharmacological method used to treat wound by applying sub-atmospheric; it stimulated the blood circulation and heals faster [1]. Many research studies has proven the good effect of negative pressure wound therapy.

HISTORY OF NEGATIVE PRESSURE WOUND THERAPY
In 1890, Dr. Gustav Bier used cupping system and glass cups in different shapes and sizes with tubing and bulb. It removes wound secretion from various parts of the body.
In 20 th century, Dr. Nail Bagaoutdinov a soviet surgeon started using negative pressure with foam dressing for infected wounds. Steps Read the device instructions and protocols of NPWT. Assess the wound site; assess the client nutritional status for adequate healing [7]. Provide complete details about negative pressure wound therapy to the client about this advanced technique.
Use some protective barriers such as petrolatum gauze to protect the sutured blood vessels. Don't over pack the wound too tightly with foam because while giving more compressing the foam prevents negative pressure from reaching the wound bed and it cause exudate to accumulate. Filler material is fitted to the contours of a wound and the overlaying foam is then sealed with a transparent film. A drainage tube is connected to the dressing through the opening present in the transparent film. Ensure that the tube in correct position to avoid skinfolds [8]. This therapy involves the controlled application of sub-atmospheric pressure to the local wound environment. After the dressing is sealed, the vacuum pump is ready to deliver continuous or intermittent pressures [9]. Negative pressure setting from 125mmHg for 15 minutes for 3 days according to patient tolerance. This therapy allows the arterioles to dilate, so it increases the local circulation, which assists in the proliferation of granulation tissue. This technique removes the excessive fluid from the area, so it reduce edema. Depending upon the type of wound, the negative pressure initially may be applied in a continuous mode for 48 hours to remove larger amounts of fluid and subsequently, an intermittent mode may be used to provide a more aggressive stimulus for promoting granulation.
During NPWT, we have to count and document all pieces of foam gauze and monitor the patient frequently for signs and symptoms of complications [4,10].  Pressure ulcers and acute wounds 125mmHg continuous negative pressure for 148 hours, later switched to intermittent intervals (5 minutes on and 2 minutes off) Chronic ulcers ( venous stasis, arterial insufficiency and neuropathies)

Mechanism of Action NPWT
Continuous therapy at 50 -75mmHg.
Compromised tissue flaps 125 mmHg of continuous therapy till base adhesion achieved.
NPWT dressing change 3 -5 days interval off or depending on the amount or characteristic of fluid withdrawn as well as the surrounding skin appearance eg: inflamed macerated etc.

How to reduce pain
Before NPWT, we have to apply topical lidocaine on the wound surface to reduce pain. (c) (d) Figure 1:(a) The necrotic tissue of right lower leg. The wound was circumferential and the lower leg and right foot was severely swollen.