The Experimental Study Of Lidocaine And Poloxamer-188 On Deepening Of Deep Second-Degree Burn Wounds At The Early Stage

Object:To evaluate the preventive and therapeutic role of topical application of lidocaine and intravenous injection of Poloxamer 188 (P188) in early progressive injury of deep partial-thickness burn wounds.Methods:Wistar rats with a weight range 220 to 250g were used as object of study in which a deep second-degree burn model was set up. With deep second-degree burn wounds at the backs, Wistar rats were randomly divided into control group, lidocaine treatment group, and P188 treatment group,32 wistar rats in each group. The Wistar rats in the I idocaine treatment group was scalded and immediately treated with lidocaine gel on burned area (apply lidocaine gel to the burn every 6 hours after, each time 1 mL containing lidocane 20mg); the Wistar rats in P188 treatment group after being scalded was immediately treated with intravenous injection of Poloxamer 188 within isotonic saline solution (200mg/Kg, dissolved in isotonic saline 1mL, injected every 24 hours after) and the wistar rats in control group were injected with same volume isotonic saline The activity of Na-K-ATPase, myeloperoxidase (MPO), the value of malonaldehyde (MDA) and succinic dehydrogenase (SDH) in the wound tissue were tested at 2h,24h,48h and 72h after being burned (each time,8 wistar rats from each group). The progressive change degree of the wound biopsy displayed by HE staining and Proliferating cell nuclear antigen (PCNA) immunohistochemistry staining were also determined. A healthy group not exposed to thermal trauma served as normal control.Result:In all the three groups, SDH content and Na-K-ATPase activity reached the lowest values after 24h when burns occurred, followed by gradual increases, but still far lower than the normal level. After 24h, the SDH and Na-K-ATPase activity of both treatment groups were higher than that those of the control group (P<0.05); the activity of MPO of control group reached the highest after 24h, wherea the M PO activity of the two treatment groups peaked after 48h. After the MPO activity of three groups dropped down, but still higher than the normal level. A comparison of the highest values of the activity of MPO showed that the MPO activity of the control group was higher than that of two treatment groups (P<0.05); the value of MDA of three groups kept rising from 2h to 72h after being burned, and that of the control group showed higher than that of two treatment groups(P<0.05).The HE staining demonstrated that the burn wound depth after being burnt 48h later was deeper than that after a period of 2h. Compared to control group, skin appendages of Wistar rats in the P188 treatment group and lidocaine treatment group had more residual cells with slight collagen denaturation and collagen necrosis and a slower and less progression of burn wound depth. Similar with HE staining, PCNA staning also revealed the progression of burn wound depth. Epidermal cells sampled from control group and treatment groups appeared no brown staining, a signal of PCNA negative, indicating that epidermal cells stopped proliferation completely. Compared with control group, P188 treatment group and lidocaine treatment group showed that the residual cells of follicle had a brown staining, notifying a better proliferation in the burnt tissue and a slighter progression of burn depth.Conclusion:Progression of burn wound depth exists at the early stage of deep second-degree burns; lidocaine administered topically at the early stage was able to prevent progressive injury of the burn wound; injecting Poloxamer 188 in the case of early stage of deep second-degree burns can slow down the process of wound deepening.