WASTE ANESTHETIC GAS CONTROL:
SCAVENGING SYSTEMS
Scavenging Systems
An effective anesthetic gas scavenging system traps waste gases at the site of overflow from the breathing circuit and disposes of these gases to the outside atmosphere. The heating, ventilating, and air conditioning (HVAC) system also contributes to the dilution and removal of waste gases not collected by the scavenging system or from other sources such as leaks in the anesthetic apparatus or improper work practices.
A nonrecirculating ventilation system can reduce waste gas levels. Waste gas emissions to the outside atmosphere must meet local, state, and Environmental Protection Agency (EPA) regulatory requirements.
A scavenging system consists of five basic components (ASTM, F 1343 - 91):
1. A gas collection assembly such as a collection manifold or a distensible bag (i.e., Jackson-Rees pediatric circuit), which captures excess anesthetic gases at the site of emission, and delivers it to the transfer tubing.
2. Transfer tubing, which conveys the excess anesthetic gases to the interface.
3. The interface, which provides positive (and sometimes negative) pressure relief and may provide reservoir capacity. It is designed to protect the animal's lungs from excessive positive or negative scavenging system pressure. (Refer to OSHA Waste Anesthetic Gas Scavenging System for a more detailed description of how the scavenging interface works.)
4. Gas disposal assembly tubing, which conducts the excess anesthetic gases from the interface to the gas disposal assembly
5. The gas disposal assembly, which conveys the excess gases to a point where they can be discharged safely into the atmosphere. Several methods in use include a nonrecirculating or recirculating ventilation system, a central vacuum system, a dedicated (single-purpose) waste gas exhaust system, a passive duct system, and an adsorber.
Reference:
Safety & Health Topic: Waste Anesthetic Gases, Occupational Health & Safety Administration.