Effect of fractional ablative carbon dioxide laser with lidocaine spray on skin flap survival in rats

Abstract

Background: Lidocaine spray is a local anesthetic that improves random-pattern skin flap survival. The fractional ablative carbon dioxide laser (FxCL) produces vertical microchannels that delivers topically applied drugs to the skin. In this study, we hypothesized that FxCL therapy would enhance the lidocaine effect to improve random-pattern skin flap survival in rats.

Methods: McFarlane random-pattern skin flaps were elevated in 48 rats, which were divided into four groups according to treatment: FxCL+lidocaine, FxCL, lidocaine, and nontreatment (control). On postoperative day 7, necrotic flap areas, the number of capillary vessels, and neutrophil count were evaluated. Anti-rat vascular endothelial growth factor (VEGF) and CD31 antibody activity were also evaluated by immunohistochemical staining.

Results: Flap survival rate was 53.41%± 5.43%, 58.16%± 4.80%, 57.08%± 5.91%, and 69.08%±3.20% in the control, lidocaine, FxCL, and FxCL+lidocaine groups, respectively. Mean neutrophil count in the intermediate zone excluding the necrotic tissue was 41.70± 8.40, 35.43± 6.41, 37.23±7.15, and 27.20± 4.24 cells/field in the control, lidocaine, FxCL, and FxCL+lidocaine groups, respectively. Anti-rat VEGF and CD31 antibody activity were the highest in the FxCL+lidocaine group.

Conclusion: FxCL with lidocaine had a positive effect on random-pattern skin flap survival in rats. Thus, FxCL with lidocaine spray should be considered as a new treatment option to improve flap viability.

Keywords: Lasers, gas; Lidocaine; Rats.

Fig. 1.

Elevation of random-pattern skin flap in this study. Caudally pedicled McFarlane-type 3×9-cm random patterns skin flaps were made on the dorsal skin.

Fig. 2.

Sutured random-pattern skin flap back to the donor bed. The sutured dorsal skin flap area was divided into three distinct zones equally (3×3 cm): proximal, intermediate, and distal zones.

Fig. 3.

Mean percentage of flap survival area (%) using photographs. The results were 69.08%±3.20% in the FxCL+lidocaine group, 57.08%±5.91% in the FxCL group, 58.16%±4.80% in the lidocaine group, and 53.41%±5.43% in the control group (mean±SD). The flap survival in the FxCL+lidocaine group improved significantly. FxCL, fractional ablative carbon dioxide laser. ^a)p<0.05.

Fig. 4.

Histologic findings (H&E, ×40) of random-pattern skin flap in the FxCL+lidocaine group. Blue arrows indicate MAZs by FxCL. FxCL, fractional ablative carbon dioxide laser; MAZ, microscopic ablation zone.

Fig. 5.

Mean neutrophil count in the intermediate zone except necrotic tissue under high-power fields (×200). The results were 27.20±4.24 cells/field in the FxCL+lidocaine group, 37.23±7.15 cells/field in the FxCL group, 35.43±6.41 cells/field in the lidocaine group, and 41.70±8.40 cells/field in the control group (mean±SD). The mean neutrophil count in the FxCL+lidocaine group was significantly lower than that in other groups. FxCL, fractional ablative carbon dioxide laser. ^a)p<0.05.

Fig. 6.

Immunohistochemical staining of anti-rat VEGF antibody (×400). The results showed more VEGF-positive staining cells (brown) in the FxCL+lidocaine group (A) than in the FxCL (B), lidocaine (C), and control groups (D). VEGF, vascular endothelial growth factor; FxCL, fractional ablative carbon dioxide laser.

Fig. 7.

VEGF-positive staining cells in the immunohistochemical evaluation. The number of VEGF-positive staining cells was significantly higher in the FxCL+lidocaine group than those in other groups (FxCL+lidocaine group, 121.64±19.38 cells/field; FxCL group, 92.45± 16.11 cells/field; lidocaine group, 98.12±17.83 cells/field; control group, 86.09±12.51 cells/field). VEGF, vascular endothelial growth factor; FxCL, fractional ablative carbon dioxide laser. ^a)p<0.05.

Fig. 8.

Immunohistochemical staining of anti-rat CD31 antibody (×400). The results showed more CD31-positive microvascular vessels (circular red-brown) in the FxCL+lidocaine group (A) than in the FxCL (B), lidocaine (C), and control groups (D). FxCL, fractional ablative carbon dioxide laser.

Fig. 9.

CD31-positive microvascular vessels in the immunohistochemical evaluation. The number of CD31-positive microvascular vessels in the FxCL+lidocaine group was significantly higher than those in other groups (FxCL+lidocaine group, 31.38±9.36 vessels/field; FxCL group, 22.52±3.99 vessels/field; lidocaine group, 24.66±8.25 vessels/ field; control group, 18.45±5.89 vessels/field). FxCL, fractional ablative carbon dioxide laser. ^a)p<0.05.