Negative-pressure wound therapy I: the paradox of negative-pressure wound therapy.
BACKGROUND
Does negative-pressure wound therapy reduce or increase the pressure of wound tissues? This seemingly obvious question has never been addressed by a study on living tissues. The aim of this study was to evaluate the nature of tissue pressure changes in relation to negative-pressure wound therapy.


METHODS
Three negative-pressure wound therapy dressing configurations were evaluated-circumferential, noncircumferential, and those within a cavity-on 15 human wounds, with five wounds in each category. Tissue pressure changes were recorded (using a strain gauge sensor) for each 75-mmHg increment in suction, up to -450 mmHg. In the circumferential and noncircumferential groups, tissue pressure was also measured over a 48-hour period at a set suction pressure of -125 mmHg (n = 10).


RESULTS
In all three groups, mean tissue pressure increased proportionately to the amount of suction applied (p < 0.0005). Mean tissue pressure increments resulting from the circumferential dressings were significantly higher than those resulting from the noncircumferential (p < 0.0005) or cavity group (p < 0.0005); however, there was no significant difference between the latter two groups (p = 0.269). Over the 48-hour period, there was a significant mean reduction in the (increased) tissue pressure (p < 0.04 for circumferential and p < 0.0005 for noncircumferential), but in only three of 10 cases did this reduce to pressures less than those before dressing application.


CONCLUSIONS
Negative-pressure wound therapy increases tissue pressure proportionately to the amount of suction, although this becomes less pronounced over 48 hours. This suggests that negative-pressure wound therapy dressings should be used with caution on tissues with compromised perfusion, particularly when they are circumferential.
Kairinos
Nicolas
N
Cape Town, South Africa From the Department of Plastic and Reconstructive Surgery and the Martin Singer Hand Unit, Department of Orthopaedic Surgery, Groote Schuur Hospital, and University of Cape Town.
Solomons
Michael
M
Hudson
Donald A
DA
D000075202:Contraindications; D006230:Hand Injuries / Q000628:therapy; D006801:Humans; D054843:Negative-Pressure Wound Therapy / Q000379:methods*; D011312:Pressure; D012867:Skin / Q000293:injuries*; D013314:Stress, Mechanical; D013848:Thigh; D014160:Transducers, Pressure; D014945:Wound Healing; D014947:Wounds and Injuries / Q000628:therapy*