One vs two applications of chlorhexidine/ethanol for disinfecting the skin: implications for regional anaesthesia

Chlorohexidine/ethanol is commonly used for skin disinfection before neuraxial procedures. Two applications of this solution have been advocated but no evidence exists to support this. Our aim was to ascertain whether two applications of chlorohexidine/ethanol solution are more effective than one for skin disinfection before neuraxial anaesthesia. A 4-cm diameter soya agar contact plate was applied to the skin of the lumbar region of 309 healthy volunteers, followed by a single spray application of chlorhexidine gluconate 0.5% w/v in 70% v/v denatured ethanol. This was allowed to dry and a second contact plate applied. The disinfectant was re-applied and after drying, a third contact plate applied. Agar plates were incubated at 37°C for 24 h. No growth occurred in any plates after the first or second spray (p < 0.0001). We feel reassured that the current practice of using a single application of chlorhexidine/ethanol solution is sufficient to disinfect the skin before regional anaesthesia, particularly in the emergency situation when waiting for a second application to dry may add needless delay and risk translocation of excess chlorhexidine into the subarachnoid space.