In Reply

We thank Tafelski et al. for making some interesting points about our recent study¹  and asking for clarification of some issues.

We agree that for various reasons, our results may be an underestimate, and we discussed these in some length in our article.

With respect to the Hawthorne effect, we agree that our findings may reflect an underestimation of the actual rate of syringe contamination. Indeed, in the article, we indicated that “anesthesiologists were encouraged to behave ‘normally’ in respect of their aseptic practice,” but that “the open-label nature of the study may have influenced them to be more fastidious.”

We also agree that the exclusion of propofol from drugs injected through the filter unit in our study may have contributed to an underestimation of the rate at which microorganisms were injected into patients, and this too was mentioned. On the other hand, the used propofol syringes were included in the analysis of syringe contamination.

Our institution has no formal policy concerning disinfection of vial septa with alcohol in the context of anesthetic practice, although guidelines from the Australian and New Zealand College of Anaesthetists²  are considered applicable, and these guidelines recommend this practice. We made no attempt to evaluate compliance with any aspect of the safe injection of intravenous medications in this study, but in a previous study³  in a highly realistic simulated anesthetic environment, none of our participants wiped the vial septa.

We did not measure the time taken between drug preparation and injection into the intravenous lines, and so cannot comment on this. However, we believe that these times were reflective of the normal clinical practice of the participants.

The mean (range) time taken from collecting to analyzing our syringes was 3.6 h (0.75 to 22.5 h). We could find no apparent relationship between length of time and the number of microorganisms found.

We appreciate this interest in our work because we believe that more reflection and research is warranted to inform effective initiatives to improve this aspect of patient care in anesthesia.