Topical acidification promotes healing of experimental deep partial thickness skin burns: a randomized double-blind preliminary study.

The effects of three buffered solutions with pH values of 3.5, 7.42 and 8.5, respectively, on the healing rate of deep partial skin thickness burns, was followed for 21 days in 16 guinea-pigs. Two symmetrical burns were inflicted on the back of each animal and then each individual wound was dressed with an irrigation disc dressing; solutions were coded (no. 1 to no. 3) and the animals were randomly divided and blindly treated as follows: Group A, solution no. 1 v. solution no. 2 (n = 4); Group B, solution no. 2 v. solution no. 3(n = 4); Group C, solution no. 1 v. solution no. 3(n = 4); Group D, non-irrigated disc dressings (n = 4). The solutions were applied to the surface of the burn wounds at a rate of 0.15 ml/cm2. Dressings were changed every 7 days to assess contraction and epithelialization by a sonic digitizer. On post-burn day 21 the newly formed scar tissue was measured in all wounds. After computation of the healing rate at the end of the study, the data were then related to the coded treating agent. Contraction did not differ in all test groups during the study. Epithelialization was significantly faster in the pH 3.5-treated burns than in the other treated wounds (P less than 0.001). The present study indicates that topical acidification of experimental deep partial skin thickness burns promoted healing. The precise mechanism should be elucidated.

Drug-loaded synthetic dressings: effect on contraction, epithelialization, and collagen synthesis of deep second-degree experimental burns.

The effect of drug-loaded synthetic dressings on the contraction, epithelialization, and collagen synthesis of deep second-degree burns was followed for 21 days in 44 guinea pigs. Two symmetrical burns were inflicted on the back of each animal; the animals were then divided at random into the following test groups: Group 1 (n = 10), a prefabricated, precut, pliable, and noncracking dressing designated as Dimac (DM), versus Dimac plus 2% silver sulfadiazine (DM+); Group 2 (n = 10), Hydron loaded with 2% silver sulfadiazine (HAgS) one versus fine mesh gauze and 1% silver-sulfadiazine cream (GAgS); Group 3 (n = 12), Hydron (Hyd) versus fine mesh gauze (G); Group 4 (n = 4), fine mesh gauze versus Telfa (Tel); Group 5 (n = 6), Telfa versus Telfa; Group 6 (n = 2), gauze versus gauze. Epithelialization and contraction rates were measured at dressing changes on postburn days 6, 12, 18, and 21, with a computerized sonic digitizer. Collagen biosynthesis was measured from the wound scar on PBD 21 and expressed as relative collagen biosynthesis. Contraction on PBDs 18 to 21 was significantly lower (p less than 0.05) in the DM and DM+ treated burns. Epithelialization of the DM and DM+ treated groups on PBD 21 was significantly (p less than 0.05) higher than in the Hyd, HAgS, GAgS, and Tel treated burns, and did not differ from the G treated wounds. The relative collagen biosynthesis method was inapplicable to this burn wound model.

The salutary effects of the bed on the survival of experimental flaps.

The present study indicates that the distal, random segment of an axial pattern experimental flap can be partially salvaged by employing local pressure, which provides favorable contact with the bed. This portion of the flap could be considered as a composite skin graft. Serial India ink injections demonstrated that its physiological take resembles that of a split-thickness graft, dominantly depending on the blood vessels emerging from its bed, and to a lesser extent on those provided by its proximal segment and adjacent skin edges. Increasing the topical flap humidity hindered, rather than improved, its survival.

Tobacco smoking: impairment of experimental flap survival.

The survival rate of experimental flaps as affected by exposure to inhaled tobacco smoke has been investigated in rats subjected to different smoking regimens. A distally based dorsal flap was raised and reattached in each animal. Evaluation of the flaps on postoperative day 8 showed a mean rate of necrosis of 28.5% in 25 control animals, 32.2% in 21 rats postoperatively smoking for 7 days, 41.3% in 18 rats preoperatively smoking for 7 days, and 45.7% in 21 rats smoking for 7 days both before and after the surgical procedure. Histological sections from the lungs of the smoking animals revealed a pattern compatible with mild smoke inhalation injury. Arterial oxygen tensions were lower in the tobacco smoking animals. It is assumed that the multiple effects of tobacco smoking contributed to the impairment of experimental flap survival.

The disc dressing for local irrigation of experimental burn wounds.

The newly designed disc dressing permits the surface of experimental burn wounds to be irrigated with liquid therapeutic agents without the need for frequent dressing changes. This approach is simple to handle, reduces the risk of trauma or contamination of the wound, and is not time consuming.

The sonic digitizer: a rapid and accurate method to assess the size of experimental flaps.

Two methods for measuring area, the sonic digitizer and the polar-planimeter, were compared for speed, accuracy, and efficiency. The sonic digitizer was significantly (p less than 0.001) faster than the planimeter (97.2 +/- 9.5 versus 206.3 +/- 14.8 seconds per flap) and more efficient. The accuracy of both methods in measuring areas of 5 to 30 cm2 was comparable; however, for areas of 5 to 13 cm2 the sonic digitizer gave more reproducible results (p less than 0.001). These differences were not reflected in the computed rate of necrosis of the present flap model.