.: Negative Pressure Wound Therapy

NEGATIVE PRESSURE WOUND THERAPY (NPWT), also called topical negative pressure therapy, is a method of treating acute or chronic wounds using subatmospheric pressure in the wound area.

It promotes wound healing by removing edema, prevents infection by removing bacteria & exudates, and enhances tissue growth by mechanical stress. The NPWT system basically consists of the following:

1. The vacuum pump;

2. Tubings and reservoir (for the suctioned fluids); and

3. Dressings (airtight film/seal and foam)

As the benefits of NPWT became more widely known, several NPWT systems appeared in the market. Although these systems boast that these can actually save healthcare costs by promoting rapid healing, the cost of a single system is still too high for hospitals in the third world to afford.

The first experience we had with NPWT was when one of our consultants used it in his patient, 2-3 years ago. We did not have any commercial NPWT system available, so we simply -- crudely-- improvised.

We used the common suction pump found in hospital wards in our locality:

This pump is commonly used for suctioning secretions of intubated patients and those on ventilators. Unlike newer generations of suction machines, these are loud, and heat up pretty fast. They were not designed for continuous use, and will burn out when left running for too long. So we turned it on for 2 hours, then off for an hour (for older suction pumps more prone to overheating, we used the 1 hour on, 1 hour off schedule). What is nice is that these pumps have their own fluid reservoirs, and some even have built-in pressure gauges.

As for dressings, we initially used watertight barrier dressings (Opsite, Tegaderm). These dressings work very well; their only downside is the high cost of these commercial dressings. So we frequently resorted to "Robin Hood" tactics: keeping leftover dressings from Pay patients and using them on Charity patients (Hey, we did TRY to maintain sterility). For the foam, we used common upholstery foam scraps. We found a few some 1" thick pieces included in knee immobilizers. We cut them up into smaller pieces then sterilized them using steam autoclave.

Despite the crude equipment and methods, wounds healed well. Still, it left much to be desired. Our hospital ward can't spare any of the suction machines for extended periods of time, so we just can't aply NPWT anytime we need to.

Then an Organization introduced us to an elegantly simple vacuum pump: a converted aquarium aerator.

It is cheap, available, silent, and can work continuously for days or weeks on end. Conversion of the pump from a positive pressure pump into a negative pressure (suction) takes less than an hour.

Another orthopod, Bhaskar Pant, then proceeded to describe a novel airtight dressing: clear foodwrap (e.g., Clingwrap). A few rolls around the limb makes a good airtight seal. Strips of tape seal the ends of the dressing. It may look that this setup will cause strangulation of the limb, but from our experience, apart from discomfort in some patients, no adverse event was noted.