Assessment of a simplified NPWT device in pre-clinical studies

Background: The purpose of this study was to evaluate the mechanisms of action of a new single-use NPWT device.  The device has been developed to radically simplify NPWT for wounds at the lower end of the current NPWT acuity scale by providing disposable, easy to use, patient-friendly NPWT.  The device is constructed to operate without an exudate canister at a single set point of -80 mmHg. 

Methods: Wounds 6 cm in diameter and 2 cm deep were created on the backs of 8 anesthetised pigs.  Measurements were taken of pressure at the wound bed, tissue contraction and blood flow through Laser Doppler filament probes inserted at 0.5 cm and 2.5 cm from the wound edge in normal skin.   

Results: Mean pressure at the wound bed was -77 (±1) mmHg with the new single-use NPWT system which was similar to the pressures detected with full sized NPWT devices and dressings (between -75 mm Hg and -79 mm Hg).  Mean tissue contraction 91 (±1) % of original wound area by the new single-use NPWT device and dressing was comparable to full-sized NPWT device contraction of foam and gauze filled wounds at 90% and 91% respectively.  Close to the wound edge (0.5 cm) laser Doppler blood flow was reduced in all combinations of full-sized NPWT device and new single-use devices and dressings by between -40 and -20%.   Further away from the wound edge laser Doppler blood flow was increased by between 20 and 40%. 

Discussion: The new single-use NPWT device sets up exactly the same patterns of tissue contraction and blood flow as existing durable, multi-use mains-powered NPWT devices.  It follows therefore that subject to deployment on wounds of modest size and exudate flow, the new single-use NPWT device is predicted to deliver similar clinical results to conventional full sized NPWT devices.