Objective To compare the air permeability,water absorption and water locking properties of two different foam dressings,thus to provide theoretical and experimental evidence to alternative optimization for acute and chronic wound.Methods Five Mepilex foam dressings(group 1) and PermaFoam Comfort dressings(group 2) each was selected.Simulated wound exudation was made by NaCl and CaCl·H2O.The water-absorbing rate of dressings at post immersion 24 h (PIH),the water-absorbing speed of dressings at post immersion 1,5,10,20 min,the diffusion diameter of exudation dripped on the surface of dressings for 5 min,the beaker filled with exudation was sealed tightly by dressing for 24 h,and the weight was gotten before and after 24 h.Statistical analysis was performed.Results (1) The water-absorbing rate:the group 1(616±19)% was significantly higher than (313±13)% of the group 2 (t=29.137,P<0.01);(2) The water-absorbing speed:the group 1 (119.68±2.59)g·s-1·m-2,(24.39±0.62)g·s-1·m-2,(12.33±0.29)g·s-1·m-2,(12.33±0.29)g·s-1·m-2 were significantly higher than those of the group 2[(65.85±4.37)g·s-1·m-2,(13.82±1.03)g·s-1·m-2,(7.16±0.41)g·s-1·m-2,(3.66±0.12)g·s-1·m-2,t=23.704,t=19.708,22.947,31.764,all P<0.01];(3) The water holding capacity:the group 1 (5.66±0.15)cm was significantly higher than (2.2±0.12)cm of the group 2,(t=39.089,P<0.01);(4) The air permeability:there was no statistically significant difference between the two groups(t=0.189,P>0.05).Conclusion The Mepilex foam dressing is more suitable for the early stage of acute wound with large exudation in short time,while the PermaFoam Comfort dressings is better for chronic wound or the later period of acute with less exudation in a relative slow seepage velocity.

Objective: To explore the influence of different inner dressings in negative-pressure wound therapy (NPWT) on escharectomy wound of full-thickness burn rabbits. Methods: Eighteen Japanese white rabbits were inflicted with full-thickness burn on unilateral back. They were divided into polymer dressing group (PD), biological dressing group (BD), and silver biological dressing group (SBD), according to the random number table, with 6 rabbits in each group. On 3 days post burn, the wounds were performed with escharectomy, and then wounds of rabbits in group PD were covered with polyurethane foam. Wounds of rabbits in group BD were covered with porcine acellular dermal matrix (ADM) and wounds of rabbits in group SBD were covered with silver porcine ADM. Then continuous NPWT was performed on rabbits of the three groups for 7 days. Immediately after surgery and on post surgery day (PSD) 7, general observation of wound was conducted and tissue around the wound was harvested for determination of dry to wet weight ratio. The content of bacteria was counted and the content of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and IL-6 in wound was determined by enzyme-linked immunosorbent assay. Fibroblasts in wound were counted after Masson staining and number of microvessels was counted after CD31 antibody immunohistochemical staining. Data were processed with analysis of variance for repeated measurement, LSD-t test, paired samples t test, and Bonferroni correction. Results: (1) Immediately after surgery, there was no granulation tissue in basal wound of rabbits in the three groups, with rich blood supply and obvious edema. On PSD 7, much granulation tissue was found in basal wound of rabbits in the three groups, with no or mild edema and no obvious redness and swelling in wound edge. (2) There were no significant differences in dry to wet weight ratios of tissue around the wound among and within the three groups immediately after surgery and on PSD 7 (with F values respectively 0.70 and 0.09, t values from 0.17 to 0.52, P values above 0.05). (3) Immediately after surgery, the content of bacteria in wounds of rabbits in groups PD, BD, and SBD was respectively (603.0±146.0) ×10^4, (573.0±63.0) ×10^4, and (590.0±100.0)×10⁴ colony-forming unit (CFU)/g, with no significant difference among them (F=0.13, P>0.05). On PSD 7, the content of bacteria in wounds of rabbits in groups PD, BD, and SBD were respectively (5.4±0.8) ×10^4, (4.6±0.9) ×10^4, and (3.5±0.9)×10⁴ CFU/g. Among them, the content of bacteria in wounds of rabbits in group SBD was lower than that in groups PD and BD, respectively (with t values respectively 3.78 and 2.29, P<0.05 or P<0.01). The content of bacteria in wounds of rabbits in the three groups on PSD 7 was decreased compared with that immediately after surgery (with t values from 10.05 to 21.81, P values below 0.01). (4) There was no significant difference in content of TNF-α, IL-1β, and IL-6 in wounds of rabbits in the three groups immediately after surgery and on PSD 7 (with F values from 0.10 to 1.89, P values above 0.05). The content of TNF-α in wounds of rabbits in the three groups on PSD 7 was significantly higher than that immediately after surgery (with t values from 2.93 to 5.01, P<0.05 or P<0.01). (5) There was no significant difference in amount of fibroblasts in wounds of rabbits in the three groups immediately after surgery and on PSD 7 (with F values respectively 0.01 and 0.81, P values above 0.05). The amount of fibroblasts in wounds of rabbits in the three groups on PSD 7 was larger than that immediately after surgery (with t values from 4.78 to 11.58, P values below 0.01). (6) There was no significant difference in number of microvessels in wounds of rabbits in the three groups immediately after surgery and on PSD 7 (with F values respectively 2.42 and 2.49, P values above 0.05). The number of microvessels in wounds of rabbits in the three groups on PSD 7 was larger than that immediately after surgery (with t values from 7.17 to 11.14, P values below 0.01). Conclusions SBD is better at inhibiting the growth of bacteria. PD, BD, and SBD have almost the same effects on reducing tissue edema and inflammatory reaction, and on promoting the accumulation of collagen fibers and tissue vascularization.