The effect of alcohol swabs and filter straws on reducing contamination of glass ampoules used for neuroaxial injections*

We have investigated the incidence of contamination of the contents of glass ampoules used for neuraxial injections, and whether this was reduced by wiping the outsides of the ampoules with isopropyl alcohol or using a filter straw. One hundred fentanyl and diamorphine ampoules used for routine regional anaesthesia were either wiped or not wiped with alcohol before their contents were aspirated, and the residual contents were swabbed and incubated. None of the swabs from the wiped ampoules grew organisms compared with nine (18%) from non-wiped ampoules (p = 0.004). In a second, laboratory study, 100 glass ampoules of saline were coated with Staphylococcus aureus and divided into four groups: wiped/not wiped with alcohol and with/without a filter straw. The contents of the ampoules were aspirated; the remnants and the aspirate were swabbed and incubated as before. Most contamination occurred in the unwiped groups and although numbers were small, filtering appeared to reduce contamination further. As filter straws also reduce the risk of injecting glass particles (even if not contaminated), our results suggest that wiping glass ampoules with isopropyl alcohol and using a filter straw should be part of routine practice when performing regional anaesthesia.