Pre-Application Evaporation of Surgical Preparation Solutions: Does It Matter?

Abstract

Introduction: Surgical site infections (SSIs) remain the most common health care associated infections in the surgical population. Preoperative surgical preparation solutions containing alcohol are believed to be best at eradicating skin microorganisms. The efficacy of alcohol is concentration dependant, with a concentration of greater than 60% most bactericidal. Surgical antisepsis guidelines do not stipulate how long alcoholic preparation solutions can be left out prior to use. Method: 30 ml of Alcoholic Iodine (Iodine 1% in Alcohol 70% (v/v)) and Alcoholic Chlorhexidine (Chlorhex-idine 2% in Alcohol 70% (v/v)) were left to stand in gallipots in an operating theatre equipped with laminar flow. Sam-ples were taken at 0, 30, 60 and 120 minutes and the alcohol content was analyzed. The experiment was repeated 3 times for each time interval. Results: The Alcoholic Iodine group demonstrated significant decrease in alcohol concen-tration, from a mean of 76% (SD 3.6) to a mean of 37.7% (SD 2.9) in only 30 minutes. This effect was sustained, reaching a mean concentration of 26% (SD 2.9) alcohol at 120 minutes. The Alcoholic Chlorhexidine group did not exhibit the same degree of concentration drop, the concentration dropped marginally to 71.5% (SD 2.7) at 120 minutes from 83.4% (SD 0.4). Conclusion: Alcoholic Iodine exhibits significant evaporation under operating room conditions after 30 minutes. Alcoholic Chlorhexidine does not appear to undergo similar losses in concentration. We recommend that alcoholic surgical preparation solutions must be poured immediately prior to use, and must be discarded if left un-covered for more than a few minutes.