A histological comparison of acute inflammatory responses with a hydrofibre or tulle gauze dressing

This study analysed the physical properties of Aquacel hydrofibre dressing in rat partial-thickness wounds, focusing on the acute inflammatory infiltrate of granulocytes and macrophages in the wound and the dressing.

Partial-thickness wounds (2 x 2 cm) were made on the back of 60 anaesthetised male Wistar rats and covered with Aquacel (n = 30) and tulle gauze (n = 30). The rats were killed on postoperative days one, two, three, four, seven and 10 (10 animals per day and five per dressing). Re-epithelialisation and Polymorphonuclear (PMN), fibronectin and macrophage activity were then analysed.

PMN leucocytes (granulocytes) were captured in the dressing and remained active there, resulting in a reduced number in the wounds when compared with tulle gauze. A fibrin layer formed between the dressing and the wound, creating a physical barrier. Macrophages infiltrated the wound bed but could not be detected in the dressing. Little inflammation was observed in the wound bed and the macrophages operated primarily in the repair mode. Active PMNs in the dressing provided an appropriate antimicrobial environment. Tulle materials became embedded in wounds and were associated with a more disturbed pattern of epithelial outgrowth. Aquacel stayed 'on top' of wounds, with only minimal incorporation into the superficial epidermis.

The observations of the physical properties of different materials and their histological consequences correlate well with published clinical results, particularly in relation to the speed of re-epithelialisation and the level of scarring.