Intradermal lignocaine injections increase blood cell flux but not flap survival in rats.

In four groups of six rats a random dorsal flap was raised, and 5, 20, or 200 mg/ml lignocaine or 0.9% sodium chloride, were injected intradermally. Cutaneous laser Doppler blood cell flux was measured at 12 time points over 130 minutes. In six other groups 5, 20, 100, 200, or 400 mg/ml lignocaine concentrations, or sodium chloride were tested. Blood cell flux was measured at the time that the flap was raised and 30 minutes after the injections. The area of the flap that survived was measured on day 10. Raising of the flaps resulted in a significant reduction in blood cell flux, which was followed by a significant increase at 10 minutes (p < 0.05) after the injections with all lignocaine concentrations tested. Injections of 5, 20 and 100 mg/ml lignocaine elicited a significant increase (p < 0.05) in blood cell flux compared with baseline values. There was no reduction in blood cell flux values at any concentration of lignocaine tested. Compared with sodium chloride, injections of lignocaine had no significant effect on flap survival. We conclude that, despite an increase in blood cell flux, lignocaine had no effect on flap survival in this model.