About Negative Pressure Wound Therapy (NPWT)

​Negative pressure wound therapy is an increasingly popular technique to treat difficult wounds. It involves the application of a negative pressure or vacuum to wound environment to expedite wound healing. 

Technique: An interface such as open pore sponge or gauze is placed on a clean wound bed. This is then sealed with a transparent film so that the wound exterior is separate from the external environment. A sterile tubing then connects the sponge to a vacuum producing device. Controlled negative pressures of 75 to 120 mm of Hg are applied to the wound. 

Negative pressures are applied in a continuous or intermittent mode. The NPWT dressings are removed and reapplied after a few days until the treatment endpoints are achieved. 

Mechanism of action: NPWT acts by, 

1. Increased blood flow 
2. Reduced oedema 
3. Increased angiogenesis and granulation
4. Mechanical deformation

When done using proper technique on appropriate wounds NPWT leads to lowering of bacterial loads and increased granulation tissue formation. NPWT is ideal in those situations when the patient is at a greater risk for conventional reconstructive procedures. 

Contraindications for NPWT: 
These include, 

1. Osteomyelitis
2. Infective wounds
3. Abnormal hemostasis 
4. Exposed large vessels in wound bed
5. Malignancy 

The benefits of NPWT include faster healing and reduction in the complexity of reconstruction. It is especially useful in situations when conventional methods are ineffective or risky.