Leakage and absorption of isoflurane by different types of anaesthetic circuit and monitoring tubing

Abstract

SummaryConductive rubber anaesthetic circuit tubing both absorbs volatile agents and leaks these agents through its walls. We quantified the leakage and absorption properties of the most commonly used plastic materials used to make breathing circuit tubing, relative to conductive rubber. We then compared two different types of plastic tubes used to carry gas to volatile agent monitors; one made of polyvinyl chloride, the other made of polyvinyl chloride lined internally with a thin layer of polyethylene. We found that the three commonly used plastic types used to make anaesthetic circuit tubing all leak less volatile anaesthetic through their walls than conductive rubber. Polyethylene and polypropylene tubing absorb significantly less volatile anaesthetic than conductive rubber; however, this is not the case with polyvinyl chloride tubing. Differences in the leakage and absorption properties of polyvinyl chloride monitoring tubing are not significantly changed by the addition of a thin internal layer of polyethylene. It is therefore not worthwhile incorporating this feature into production.

Preparation of the Dräger Fabius GS™ workstation for malignant hyperthermia-susceptible patients

“…Anesthetic solubility in rubber, including silicone, exceeds that in most plastics. [8][9][10] The breathing system circuitry internal to the Dräger Fabius GS TM workstation comprises silicone and is probably a site of considerable anesthetic absorption. Whereas flushing is effective in removing volatile anesthetics from latex and polysulfone tubing, only autoclaving has been found to be effective in removing volatile anesthetics from silicone.…”