Negative-pressure wound therapy II: negative-pressure wound therapy and increased perfusion. Just an illusion?
BACKGROUND
A recent study demonstrated that negative-pressure wound therapy increases underlying tissue pressure. This finding is incongruous with studies using laser Doppler that show that perfusion is immediately increased on initiation of suction. This study investigated perfusion in negative-pressure wound therapy using two alternative modalities.


METHODS
Radioisotope perfusion imaging was used to determine perfusion beneath circumferential negative-pressure wound therapy dressings on 20 healthy hands (n = 20). Ten hands received suction pressures of -400 mmHg and 10 received -125 mmHg, with the contralateral hand used as a control without any suction. Transcutaneous partial pressure of oxygen was used to determine perfusion beneath noncircumferential negative-pressure wound therapy dressings on 12 healthy legs (n = 12), with each volunteer being sequentially randomized to receive suction pressures of -400 and -125 mmHg, respectively.


RESULTS
Tissues undergoing circumferential negative-pressure wound therapy demonstrated a mean reduction in perfusion of 40 +/- 11.5 percent (p < 0.0005) and 17 +/- 8.9 percent (p < 0.0005) at suction pressures of -400 mmHg and -125 mmHg, respectively. Perfusion reduction at -400 mmHg was significantly greater than at -125 mmHg (p < 0.015). In the noncircumferential negative-pressure wound therapy group, there was a mean reduction in transcutaneous partial pressure of oxygen of 7.35 +/- 7.4 mmHg (p < 0.0005) and 5.10 +/- 7.4 mmHg (p < 0.0005) at suction pressures of -400 mmHg and -125 mmHg, respectively. There was a tendency for greater reductions in the -400 mmHg group, but this was not significantly different from the -125 mmHg group (p = 0.07).


CONCLUSIONS
These findings demonstrate that perfusion beneath negative-pressure wound therapy decreases for increasing suction pressure. Thus, it is suggested that negative-pressure wound therapy should be used with caution on tissues with compromised vascularity, particularly when used circumferentially.
Kairinos
Nicolas
N
Cape Town, South Africa From the Department of Plastic Surgery, the Department of Nuclear Medicine, the Department of Surgery, and the Department of Orthopaedic Surgery, University of Cape Town.
Voogd
Anda M
AM
Botha
Pieter H
PH
Kotze
Tessa
T
Kahn
Delawir
D
Hudson
Donald A
DA
Solomons
Michael
M
D000328:Adult; D005260:Female; D006225:Hand / Q000098:blood supply; D006801:Humans; D017078:Laser-Doppler Flowmetry; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D054843:Negative-Pressure Wound Therapy / Q000379:methods*; D010100:Oxygen / Q000097:blood; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012039:Regional Blood Flow; D013670:Sodium Pertechnetate Tc 99m; D013396:Suction; D014947:Wounds and Injuries / Q000000981:diagnostic imaging* / Q000628:therapy*
D019275:Radiopharmaceuticals; D013670:Sodium Pertechnetate Tc 99m; D010100:Oxygen