Bacteria are more likely to grow when propofol is injected through IV extension tubing. (Image source: Thinkstock)

Bacteria are more likely to grow when propofol is injected through IV extension tubing. (Image source: Thinkstock)

Inject propofol through the stopcock of IV extension tubing and some residual drug will remain.  How long does it take for bacterial growth to occur?  Dr. Nikolaus Gravenstein, Department of Anesthesiology, University of Florida College of Medicine, Gainesville, Florida, and colleagues compared bacterial contamination after propofol and nonpropofol anesthesia at 6, 24, and 48 h after surgery.  The results of their study are discussed in the article “Leaving More Than Your Fingerprint on the Intravenous Line: A Prospective Study on Propofol Anesthesia and Implications of Stopcock Contamination,” to be published in an upcoming edition of Anesthesia & Analgesia.

The authors collected IV stopcock extension sets after they were used for propofol (same-day ambulatory surgery) and nonpropofol anesthesia (often methohexital, used for cataract extraction or electroconvulsive therapy).  The propofol used contained preservative EDTA.  Fifty samples were taken at each interval (6, 24, and 48 h) and analyzed.

Cultures were positive in 17% of propofol anesthesia stopcocks and 19% of non-propofol stopcocks.  Six hours after surgery, if propofol was visible there were 44 colony forming units/mL (CFU/ml), if propofol was not visible there were 41 CFU/mL, and if no propofol was used there were 37 CFU/mL.  Average bacterial counts at 48 hours across all samples were 472 CFU/mL for the propofol stopcocks compared to only 4 CFU/mL in the tubing where propofol was not used.  Significant predictors for number of bacteria included propofol vs no propofol and time. Gram-positive cocci were the most common type of bacteria.

The time of IV tubing set replacement is variable across institutions.  Based on this study’s results, IV extension tubing sets should probably be changed six hours after propofol anesthesia.  It is unclear whether the presence of bacteria was associated with a change in patient outcome. One can speculate that lines should be changed six hours after the use of propofol in immunocompromised patients with increased risk of sepsis.