Diffusion of anaesthetic gases through different polymers

Area of Science:

• Anesthesiology
• Materials Science
• Environmental Health

Background:

• Reducing anesthetic gas leaks in closed systems is vital for improving working conditions.
• Gas permeation through plastic components is a key source of contamination.
• Polymer properties like molecular structure, solubility, and diffusion coefficient influence gas permeation.

Purpose of the Study:

• To quantify permeation rates of anesthetic gases through various materials used in breathing circuits.
• To assess the impact of silicone, latex, rubber, and PVC on anesthetic gas leakage.

Main Methods:

• An experimental setup was developed to measure permeation rates.
• Nitrous oxide, enflurane, and isoflurane permeation were tested through silicone, latex, rubber, and PVC.
• Components like reservoir bags, ventilation tubes, and endotracheal tubes were analyzed.

Main Results:

• Silicone materials exhibited the highest anesthetic gas permeation rates, exceeding other materials by over 10,000 times.
• Silicone component use increased anesthetic system leakage by 4 ml/min (18% in ventilators, 31% in closed systems).
• Nitrous oxide showed high permeation through silicone despite its low solubility in plastics, highlighting diffusion's role.

Conclusions:

• Silicone's high gas permeability significantly contributes to anesthetic gas leakage.
• Leakage rates are dependent on the material's diffusion coefficient.
• Minimizing total leakage in minimal-flow anesthesia systems requires using plastics with low solubility and diffusion coefficients.