Impact of active thermoregulation on the microcirculation of free flaps.

BACKGROUND: While it is a known fact that warming increases blood flow in healthy tissue, little is known about the impact of active thermoregulation on the altered microcirculation of free flaps. The objective of the study was to identify the impact of postoperative active thermoregulation on free flap microcirculation. METHODS: Tissue temperature was assessed in 25 free perforator flaps using an implanted probe. Active thermoregulation was achieved using a water circulation based system. Changes in microcirculation were evaluated at the day of surgery and throughout the first three postoperative days after passive cooling (room temperature), passive warming (wound dressing), active warming (38 °C) and active cooling (15 °C) using laser Doppler flowmetry and remission spectroscopy. RESULTS: Active warming increased flap temperature by 7.7% to 36.4 °C ± 0.5 °C in comparison to the initial values of flaps without dressing (P < 0.001). As a result, the blood flow increased by 77.7% of the base value (P < 0.001). A significant correlation between all microcirculation parameters and tissue temperature was observed with a 5.52 AU blood flow increase per degree temperature increase (r = 0.7; P < 0.001). All microcirculation parameters showed a statistically significant increase after both passive and active warming, whereby active warming showed significantly higher values than passive warming. CONCLUSIONS: Active thermoregulation using water-based circulation is an effective and safe procedure to improve microcirculation in free flaps and is superior to conventional passive warming strategies.

The ideal split-thickness skin graft donor-site dressing: a clinical comparative trial of a modified polyurethane dressing and aquacel.

BACKGROUND: The almost single disadvantage of conventional polyurethane film dressings, uncontrolled leakage, is probably as often described as its numerous advantages for split-thickness skin graft donor sites. This shortcoming can be overcome by perforating the polyurethane dressing, which permits controlled leakage into a secondary absorbent dressing. The study was conducted to compare the polyurethane dressing system and Aquacel, a hydrofiber wound dressing, which also seems to fulfill all criteria of an ideal donor-site dressing. METHODS: This prospective, randomized, double-blind clinical trial included 50 adult patients. Skin graft donor sites were divided equally for the application of Aquacel and polyurethane dressing. The dressings were kept unchanged for 10 days. After removal of the dressing at day 10, the epithelialization rate of both sites was evaluated. Pain scores were assessed according to a 0 to 5 numeric pain scale every postoperative day and during dressing removal. RESULTS: On postoperative day 10, 86.4 percent of the polyurethane dressing donor sites showed complete reepithelialization compared with 54.5 percent of the Aquacel-treated donor sites (p<0.001). Polyurethane dressing was significantly less painful until and during removal of the dressing (p<0.001). There was no significant difference with respect to scar formation. CONCLUSIONS: Overall, polyurethane dressing was superior to Aquacel. Further attributes of the polyurethane dressing such as ease of application, low labor input, high patient comfort, and protection against secondary wound infection qualify this dressing system as an ideal wound covering for donor sites. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.