26 January 2012

UCT researcher develops self-regulating vacuum dressing for wounds

A UCT researcher has made a significant advance in the field of wound care by developing a self-regulating vacuum dressing for wounds.


A UCT researcher has made a significant advance in the field of wound care by developing a self-regulating vacuum dressing for wounds.

University of Cape Town (UCT) doctoral student Dr Nicolas Kairinos’s thesis (The biomechanics of negative-pressure wound therapy) has found that, contrary to common perception, negative-pressure wound dressings do not reduce tissue pressure but increase it, resulting in reduced blood supply. Despite this they result in accelerated wound healing.

His research resulted in the concept of a new type of vacuum dressing that regulates its own suction pressure so that wound pressures are always optimal for healing.

Explains Kairinos: “Negative Pressure Wound Therapy (NPWT) has been around for about 20 years. Its mechanism of action, however, had never been adequately explained.

“Many assumed that it dilates the blood vessels in a wound and by increasing the blood supply it promotes healing. For the last 15 years or so, it was taken for granted by most that -125 mmHg was the ideal pressure to use, based on seminal papers that were written in 1997 by Morykwas and Argenta et al. This suction pressure is therefore used commercially worldwide.

“However, to everyone's surprise, our research findings demonstrated that these dressings increased pressure in the tissues and as a result reduced blood supply. So the mechanism of action (that was thought to be increased blood supply) was clearly incorrect.”

Safer wound dressings

Kairinos also found that the tissue pressure changes that occurred were different in different people’s wounds, despite the same suction pressure being used.

“Based on these findings I realised that the suction needed to be regulated to suit each individual wound's blood supply. My invention was therefore to have a device that detects what the blood supply is in a wound and then automatically regulate the suction pressure so that it is not too high or too low. This will make these dressings safer, in that it won’t allow a suction pressure which results in tissue pressures that are so high that they are occluding [blocking] that particular wound's blood vessels.

“Similarly, if a wound has a very good blood supply, it will allow the dressing to apply higher suction pressures than usual, which will reduce swelling of the wound and improve wound healing.”

According to Kairinos the new self-regulating vacuum dressing for wounds could be available for use in about three years’ time.

“We are currently working closely with the NanoSciences Innovation Centre in the Physics Department at UCT who have developed and patented a novel sensor which can detect blood supply on a wound using a paper-thin sensor. Having such a thin sensor is crucial for this dressing.”

Authority in field of NPWT

It will be possible to have these dressings applied in and out of hospital. “A trained nurse or GP will also be able to apply a NPWT dressing so patients will not have to see a specialist all the time. However, the initial instruction to apply the dressing would have to come from a plastic surgeon ideally.”

Kairinos presented his research at a number of congresses, both locally and internationally. Though it was received well locally, it did raise some eyebrows initially in the international community as it “went against the grain of what was already out there”.

“However, the more research I did and the stronger our case became, the more the scientific community sat up and listened - particularly after we published my two human studies back to back in 2009 in Plastic and Reconstructive Surgery [the world's number one plastic surgery journal],” Kairinos recalls.

The University of Cape Town is now regarded as an authority in the field of NPWT with the largest human studies on NPWT. Dr Kairinos’s PhD was supervised by Professor Donald Hudson of the Department of Surgery.

- (Birgit Ottermann, Health24, January 2012)

(Photo credit: Monday Paper, University of Cape Town)


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