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We determined whether propofol, thiopental, or 0.9% saline would serve as a growth medium for Candida albicans. In Part I, we investigated whether opening 20 propofol ampules would cause glass particles from the exterior of the ampule to fall into the emulsion and contaminate it. Each ampule was painted with red fingernail polish and its contents were passed through filter paper after it was opened in a routine manner. In Part II, a sample from a colony of C albicans was added to sterile vials containing 20 mL of either 0.9% saline, 1% propofol, or 2.5% thiopental. A 1-microL sample from each vial was then plated onto Sabaroud's dextrose plus brain-heart infusion (SABHI) agar at the following times after inoculation: 0, 3, 6, 16, and 24 h. The plates were incubated at 35 degrees C for 24 h and the number of colony-forming units counted. The filtration of two of the painted ampules in Part I revealed red glass fragments. In Part II, the saline and thiopental solutions did not increase the number of colonies of C. albicans by 24 h. However, the propofol, after a latent period between 6 and 16 h, supported the growth of C. albicans at a rapid rate. Our investigation shows that glass particles from the exterior of a propofol ampule can contaminate its contents when the ampule is opened in a routine manner. Furthermore, propofol provides an excellent growth medium for C. albicans. Thiopental and saline showed no growth. We conclude that the ability of propofol to grow C. albicans necessitates rigorous standards of sterility in its handling.

Patient infections related to the use of propofol have been reported. To investigate the growth of Staphylococcus aureus in propofol, thiopental, methohexital, etomidate, and 0.9% saline containing no bacteriostatic drug, these preparations were inoculated and samples were plated onto blood agar at 0, 3, 6, 21, 24, and 27 h. The number of colony-forming units (CFU) on the plates was then determined after 24 h of incubation. Samples from the inoculated etomidate solution showed zero CFU at 3 h and thereafter, whereas 21 h were required by the methohexital and thiopental solutions to reduce the number of CFU to zero. For normal saline, no significant change in CFU was seen before the first 6 h, then the number of CFU gradually declined, although some S. aureus CFU were still present at 27 h. Inoculation of the propofol emulsion resulted in a substantial growth of S. aureus between 6 and 21 h after inoculation. We conclude that, of the preparations tested, only propofol was an excellent medium for the rapid growth of S. aureus. Meticulous sterile technique, therefore, is advised when handling it.

The potassium-titanyl-phosphate laser is being used for airway surgery and could cause an endotracheal tube fire. To determine whether five different metallic foil tapes or the Laser-Guard protective wrap would protect polyvinylchloride (PVC) endotracheal tubes from this laser, it was set to a power of 18 W and aimed at the wrapped endotracheal tube under study for up to 1 min while 5 L/min of oxygen flowed through the endotracheal tube. A plain (unwrapped) PVC endotracheal tube was studied also. The plain PVC endotracheal tube was ignited by the laser after 14 s. Potassium-titanyl-phosphate laser radiation did not significantly affect the nonadhesive sides of the foil tapes tested or the Laser-Guard covering. However, potassium-titanyl-phosphate laser radiation caused ignition or melting of underlying PVC endotracheal tubes when it was applied to the endotracheal tubes with the adhesive side of the foil tapes facing outward. It is concluded that only the Laser-Guard protective coating adequately protected the PVC endotracheal tubes tested under the conditions of this experiment.

The combustibility of Xomed LaserShield endotracheal tubes was compared to that of polyvinylchloride (PVC) and rubber endotracheal tubes at 15, 17, and 20 watts (W) of power from a CO2 laser. Oxygen, 5.0 L/min, flowed through the tubes during the investigation. The laser was aimed perpendicularly at the shaft of the endotracheal tube under study and actuated until an intraluminal fire occurred. The times to blow torch combustion of the PVC tubes were 1.7, 1.8, and 1.5 s at 15, 17, and 20 W, respectively. For the Xomed tube, the times to combustion were 85.9, 42.5, and 20.3 s at 15, 17, and 20 W, respectively. Intraluminal (blow torch) fires of the rubber endotracheal tubes occurred after 24.5, 25.4, and 21.9 s at 15, 17, and 20 W. The times to combustion of the PVC and Xomed tubes were significantly different at 15 and 17 W. The times to intraluminal combustion of the rubber tubes were significantly different from those of the Xomed tubes only at 15 W. We conclude that the Xomed tube does not offer consistently better resistance to laser-induced combustion than the PVC or rubber endotracheal tubes tested.

To assess the possibility of indirect damage by CO2 laser reflection from specialized or modified tracheal tubes, four different tracheal tubes were studied. They were (1) a Rusch red rubber tracheal tube wrapped with 3M No. 425 aluminum foil tape, (2) a Rusch red rubber tracheal tube wrapped with Venture copper foil tape, (3) a polyvinylchloride tracheal tube wrapped with Laser-Guard protective coating, and (4) a Mallinckrodt Laser-Flex tracheal tube. The tracheal tubes were straightened and centered within cardboard cylinders and the laser set to 40 W was aimed to reflect from the tracheal tubes onto the cardboard. The times to combustion perforating the cardboard cylinders because of laser reflection were 1.41 +/- 0.54 (mean +/- SD), 1.73 +/- 0.93, 3.70 +/- 2.18, and 9.26 +/- 3.40 s for tracheal tubes 1, 2, 3, and 4, respectively. The differences between the times to combustion with tracheal tubes 3 and 1, 3 and 2, 4 and 1, 4 and 2, and finally, 4 and 3 were statistically significant. We conclude that the Laser-Guard-wrapped polyvinylchloride tracheal tube and the Mallinckrodt Laser-Flex tracheal tube were less reflective of incident CO2 laser radiation than the copper or aluminum-foil-wrapped red rubber tracheal tubes.

To determine whether the filling of tracheal tube cuffs with saline would decrease their combustibility during laser surgery, 20 polyvinylchloride tracheal tubes were studied. The cuffed end of each tracheal tube was inserted into the neck of an empty flask, and the tube and flask were flushed with oxygen for 5 min before cuff inflation. Ten tracheal tubes had their cuffs inflated with air, and 10 were inflated with saline. A Lasersonics LS880 CO2 laser, set to 5 W for five of each of the two types of filled cuffs and to 40 W for the other pair of five tubes, was fired continuously at the cuffs for up to 1 min. No combustion occurred at the 5-W setting. The times to cuff perforation when the laser was set at 5 W were (mean +/- SD) 1.00 +/- 0.83 and 4.21 +/- 3.91 s for the air- and saline-filled cuffs, respectively, a difference that was not statistically significant. The time to deflation of the saline-filled cuff (104.6 +/- 67.5 s) was, however, significantly longer than that of the air-filled cuff (2.59 +/- 1.97 s). When the tracheal tube cuffs were exposed to 40-W laser radiation, the cuff and adjacent tube shaft ignited in all cases when the cuffs were inflated with air, but only in one of five cases when the cuffs were filled with saline (P less than 0.05). The filling of tracheal tube cuffs with saline provides simple, moderately effective partial protection of the cuff of endotracheal tubes during CO2 laser airway surgery.