title: Does a zone of increased perfusion exist around negative-pressure dressings?
abstract: BACKGROUND
  Although recent work has demonstrated that perfusion adjacent to a negative-pressure wound therapy dressing is decreased, laser Doppler studies have indicated that there is a zone of increased perfusion a couple of centimeters away. The existence of such a zone of increased perfusion is counterintuitive to the fact that negative-pressure wound therapy has been shown to increase tissue pressure. This study, using an alternative to laser Doppler, evaluated whether such a zone exists.
  
  
  METHODS
  Six volunteers were randomized into three groups to test different suction pressures (-75, -125, and -400 mmHg). Each volunteer would have two dressings applied on either side of the lower back. A thermal imaging camera was used to assess perfusion around the dressing during different phases (e.g., "Suction on" and "Suction off"). The mean area under the curve for each phase was compared with those of other phases by means of one-way analysis of variance. Each condition (phase) was compared in a systematic manner with every other by means of Fisher's least significant difference for post hoc comparisons. A Pearson's correlation was determined to test the effects of the different suction pressure groups.
  
  
  RESULTS
  No significant difference could be demonstrated for the area under the curve for the different phases. There was no significant correlation between the three suction pressures tested and the difference between the mean area under the curve for "Dressing on, no suction" and the two "Suction on" periods (Pearson correlation = 0.24; p > 0.4).
  
  
  CONCLUSIONS
  Thermographic evaluation of tissue around a negative-pressure dressing did not demonstrate a zone of increased perfusion, contrary to other studies, which used laser Doppler. This is in keeping with recent work demonstrating that negative-pressure wound therapy increases tissue pressure while the dressing is applying suction.
  
  
  METHODS
  Therapeutic, V.
authors.affiliation: Cape Town, South Africa From the Department of Plastic Surgery; Martin Singer Hand Unit, Department of Orthopaedic Surgery; and Department of Surgery, University of Cape Town and Groote Schuur Hospital.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Kairinos
authors.forename: William J M
authors.initials: WJM
authors.lastname: Holmes
authors.forename: Michael
authors.initials: M
authors.lastname: Solomons
authors.forename: Donald A
authors.initials: DA
authors.lastname: Hudson
authors.forename: Delawir
authors.initials: D
authors.lastname: Kahn
mesh_terms: D000328:Adult; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006940:Hyperemia / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D017078:Laser-Doppler Flowmetry; D008297:Male; D054843:Negative-Pressure Wound Therapy / Q000379:methods*; D012039:Regional Blood Flow / Q000502:physiology*; D012867:Skin / Q000098:blood supply*; D012881:Skin Temperature / Q000502:physiology; D013396:Suction / Q000379:methods; D013817:Thermography; D055815:Young Adult