Faculty and Staff

Safe Use of Anesthetic Gases in Research Environments

Last updated September 4, 2009 10:31:26 PM PDT
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Follow these guidelines to control the risk of exposure to waste anesthetic gases.

Anesthetic gases are used to prevent pain and other sensations during surgery. Anesthetic gases and vapors that leak into the workplace are considered waste anesthetic gases and may pose health hazards.

Note: These guidelines are intended for use in a veterinary research environment.

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Accident and emergency response

Be prepared to respond to accidents and emergencies.

Common problems that cause exposure

Be alert for these common issues that contribute to anesthetic gas exposure:

  • Poorly fitted face masks
  • Use of uncuffed endotracheal (ET) tubes or improper inflation of cuffs on ET tubes
  • Turning on flow meters or inhalents before attaching the breathing system to the subject
  • Disconnecting subjects from the anesthesia machine before waste anesthetic gases have been adequately scavenged
  • Leaks in the anesthetic delivery system
  • Benchtop delivery of inhalent anesthetic without benefit of adequate scavenging or sufficient room ventilation

Control the hazards

Minimize or eliminate the possibility of workplace exposure by doing the following:

  • Use these engineering controls:
    • Handle inhalants, whenever possible, in a certified chemical fume hood, certified hard-ducted biosafety cabinet, downdraft table, or other local exhaust that allows rapid elimination of waste gases from the workplace.
    • Work in a well-ventilated room with at least 10 air changes per hour. (UCSD research laboratories are generally required to have at least 10 air changes per hour.)
    • Use a reliable scavenging system to collect, remove, and properly dispose of waste anesthetic gases and vapors that leak into the work environment.
    • Wear personal protection equipment:
      • Lab coat
      • Safety glasses
      • Disposable surgical-type gloves
      • Closed-toe shoes
  • Use the least hazardous product and delivery system available for the task. Examples include:
    • Open drop versus precision vaporizers
    • Induction box versus mask versus uncuffed ET tube versus cuffed ET tube
  • Keep container sizes and quantities as small as possible in the work area.
  • Avoid techniques that make scavenging difficult or impossible, including:
    • Open drop delivery of anesthetics (periodically dripping liquid volatile anesthetic onto a gauze sponge)
    • Insufflation (delivery of a relatively high flow of anesthetic in oxygen into the trachea or pharynx through a catheter)
    • Mask inductions and maintenance
    • Use of induction boxes
    • Use of cuffless ET tubes or not adequately inflating cuffs on ET tubes
    Conduct the techniques above, when unavoidable, in a chemical fume hood, hard-ducted biosafety cabinet, downdraft table, or other local exhaust that allows rapid elimination of waste gases from the workplace.
  • Follow these best practices:
    • Restrict access to the work area.
    • Turn on flow meters and vaporizers only when needed, and turn them off when finished.
    • Use the lowest flow of fresh gas as is safely possible for the subject and the machine.
    • Ensure a tight seal around the muzzle of animal subjects when using an anesthetic mask.
    • Maintain a reasonable distance between yourself and the source of the inhalant.
  • Take care to avoid spilling liquid agent when filling the vaporizer.

Equipment and system maintenance

  • Check anesthesia machines, breathing systems, and scavenging systems for leaks before each use.
  • Have equipment and systems regularly serviced and maintained to ensure reliable performance.

Evaluate hazards

Evaluate the possible hazards of the materials and processes you intend to use before you begin work.

Hazardous waste disposal

Dispose of waste properly.

Note: All charcoal canisters should be processed as hazardous waste when complete.

Identify anesthetic gases

Anesthetic gases commonly used at UCSD include:

  • Halogenated
    • Halothane (no longer being manufactured in the U.S.)
    • Desflurane
    • Sevoflurane
    • Isoflurane
    • Enflurane
  • Non-halogenated
    • Ether
    • Nitrous oxide

Obtain approval

Request approval from your principal investigator (PI) before beginning any new project involving anesthetic gases.

Purchasing and storage

  • Buy the least amount of product the work requires. Do not buy in large quantities to "save money."
  • Label all containers with this information:
    • Name of the material
    • Concentration
    • Warnings
    • Date, when appropriate
    • Preparer's initials, when appropriate

Safety training

Anesthetic gases are to be used only by trained staff. The PI or a knowledgeable designee must provide appropriate safety training.

  • Inform employees about specific hazards and possible health effects.
    • Explain possible routes of exposure:
      • Skin contact
      • Eye exposure
      • Inhalation
    • Describe the signs or symptoms of exposure.
  • Educate employees about appropriate work practices that will minimize exposure.
  • Review emergency procedures in the lab and make sure everyone who works with anesthetic gases is familiar with them.
  • Keep training records on file, including:
    • Information covered
    • Date
    • Names
    • Employee signatures

Scavenging systems

Use a reliable, properly maintained scavenging system. Acceptable scavenging systems must:

  • Control the concentration of trace anesthetics in ambient air
  • Be maintained to ensure they do not leak
  • Not be discharged to the outside air in areas near building air intakes

Scavenging systems can be passive or active; however, active scavenging is far more effective and should be the primary method of exposure control.

  • Passive scavenging systems have positive pressure in the gas disposal tubing. Examples include:
    • Non-recirculating ventilation systems that allow discharge of waste gases through an exhaust vent or grill.
    • Discharging waste gases directly to the atmosphere outside the building.
    • Adsorption devices, such as canisters containing activated charcoal. Adsorption methods of scavenging are recommended only if other, more reliable, methods are not available. Consider these safety issues before using canister disposal systems:
      • Use canisters containing activated charcoal, in lieu of other types of scavenging systems, when portability is an issue. Note: Activated charcoal will not adsorb nitrous oxide. Charcoal canisters only adsorb halogenated anesthetics (e.g., isoflurane, halothane).
      • Be aware that some variation in effectiveness occurs with different brands of canisters and with changes in the rate of gas flow through the canister.
      • Do the following when using a canister for waste gas disposal:
        • Do not block vent holes.
        • Weigh the canister before and after each use to evaluate the remaining adsorption capacity.
        • Dispose of canisters as hazardous waste.
    Note: Passive systems that simply vent gases to floor level or the open room, relying on inhalant anesthetic gases being heavier than air, are prohibited.
  • Active scavenging systems have negative pressure in the gas disposal tubing. Examples include:

Signs or symptoms of exposure

  • Be alert for these signs or symptoms of exposure associated with anesthetic gases:
    • Headaches
    • Irritability
    • Nausea
    • Fatigue
    • Motor skill, perceptual, cognitive impairment
  • Act quickly if an exposure occurs.
    • Seek medical attention immediately at an emergency room.
    • Call Campus Police at (858) 534-4357 (534-HELP), and request an ambulance if transportation is necessary.
    • Call the Poison Control System, (800) 876-4766, if you need additional information.

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For more information, contact an EH&S Research Assistance Program specialist.