OBJECTIVETo observe the effect of hyperbaric oxygen on the scar formation at the rabbit ears at an early stage.

METHODS16 New Zealand rabbits were used to establish the hypertrophic scar model on the ears, 4 wounds on each ear. The rabbits were randomly divided into hyperbaric group(n = 8) and control group (n = 8). The rabbits in the hyperbaric group received hyperbaric oxygen treatment, inhaling oxygen for 1 hour daily under 2ATA circumstance until the wounds were healed. The wound healing and the scar size, thickness, color and hardness in the ears were recorded. After healing, the scar was taken for histologic study with HE staining, Masson staining and trinitrophenol sirius red staining.

RESULTSIn hyperbaric oxygen group, the healing time of 64 wounds was (16.7 +/- 1.8) d, while it was (20.2 +/- 2.3) d in the control group, suggesting a significant difference between two groups (P < 0.05). The incidence of hyperplastic scar was lower (38/64, 59. 4% ) in hyperbaric oxygen group than that (52/ 64, 81.2%) in control group with significant difference between them (P < 0.05). Compared with the control group, the hyperbaric oxygen group had thicker corium layer and less fibroblasts, well-arranged but rare collagen and less collagen nodus and vortex-like structure under microscope. The hyperplastic index of scar was 3.48 +/- 0.94 in hyperbaric oxygen group and 4.65 +/- 0.76 in control group respectively (P < 0.01). The density of fibroblast in two groups were 186.5 +/- 27.3 (hyperbaric oxygen group) and 246 +/- 41.6 (control group) with statistically significant difference (P < 0.05). Furthermore, the area density of collagen fiber were (31.42 +/- 5.36)% in hyperbaric group and (43.62 +/- 7.36)% in control group (P < 0.05). The amount of collagen I and III was (71.42 +/- 5.36)% and (28.58 +/- 5.36)% in hyperbaric oxygen group, (62.46 +/- 7.32)% and (37.54 +/- 7.32)% in control group (P < 0.05). The ratio of collagen I to III was 2.499 in hyperbaric oxygen group, which was similar to the ratio (4:1) in normal skin, compared with the control group (1.664).

CONCLUSIONSThe hyperbaric oxygen can promote wound healing and effectively inhibit the early hyperplastic scar in rabbits ears.