Negative-Pressure Wound Therapy (NPWT)

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Capture Meditech SAC Machine

Negative-Pressure Wound Therapy (NPWT)

Negative-pressure wound therapy (NPWT) or Suction Assisted Closure (SAC) is a mode of therapy used to encourage wound healing. This therapy has been widely and successfully used over the last 20 years although the physiologic basis of its effects is not yet fully understood. NPWT has dramatically changed the treatment of chronic and complex wounds. It can be also used as an adjunct treatment for temporary closure and wound preparation preceding surgical procedures such as skin grafts and flap surgery. Randomized controlled clinical trials have shown that NPWT increases the wound healing rate. NPWT decreases tissue oxygenation in wound beds by the external compression exerted by the foam and pad of the connecting tube. Moreover, the foot is the most sensitive region in the body to ischemia, and diabetes is often accompanied by atherosclerosis. Therefore, when an NPWT is applied to a diabetic foot ulcer, care should be taken to minimize compression pressure.

NPWT Benefits and Contraindications

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. Sterile tubing then connects the sponge to a vacuum producing device. Controlled negative pressures of 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. 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.

Mechanism of action: NPWT acts by,

  1. Increased blood flow
  2. Reduced edema
  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 homeostasis
  4. Exposed large vessels in wound bed
  5. Malignancy

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