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  6. IACUC Policy on Use of Isoflurane
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    IACUC Policy on Use of Isoflurane

    Purpose:         

    In order to ensure appropriate use of Isoflurane, UConn Health’s Institutional Animal Care and Use Committee (IACUC) has implemented a policy on the use of this drug.  Isoflurane is a halogenated anesthetic gas commonly used to anesthetize research animals.  Researcher exposure occurs primarily through the inhalation of waste anesthetic gases that are unintentionally released into the laboratory environment if equipment is not setup or functioning properly or the waste anesthetic gas is not properly exhausted.  Short term overexposure may result in irritation of the eyes, skin and respiratory tract, cough, sore throat, and may impair consciousness and motor skills. Adverse effects on the liver and kidneys are possible as a result of overexposure. As a volatile anesthetic gas, it must be used with a vaporizer to ensure its safety for use in survival surgery.

    Any proposed deviation from these guidelines must be fully explained and justified to the IACUC in the research proposal.

     

    Action:

    Anesthesia for Survival Surgery

    1. Isoflurane must be used via a vaporizer designed for its use. The laboratory may choose to own its own vaporizer or rent a vaporizer for occasional use from the Center for Comparative Medicine.
    2. Vaporizers must be calibrated on a yearly basis; please review the IACUC Policy on Vaporizer Calibration and Maintenance.

    Anesthesia for Terminal procedure using the “Drop Method”

    1. The IACUC will allow the “Drop Method” for use with isoflurane for terminal procedures; however, this requires continuous monitoring of the animals.
    2. Use of isoflurane via this method must be performed in a chemical fume hood or equivalent (e.g., down draft table) to control the anesthetic waste gas.
    3. A chamber can be used that is large enough to accommodate the animal for anesthesia. A small amount of anesthesia liquid is placed in either a reservoir or on an absorbable material (such as gauze, cotton balls, etc.).  The reservoir or absorbable material must be positioned so that the animal cannot come in direct contact with the isoflurane.
    4. There are two ways to use isoflurane in the drop method:
      1. Diluted. A mixture of 20% v/v anesthetic in propylene glycol is recommended for mice and a 30% v/v liquid anesthetic in propylene glycol is recommended for rats.  A general guideline for the amount of diluted mixture is approximately 1.0cc for every 500cc volume of the chamber to be used.
      2. Undiluted. If undiluted gas is used, it is extremely important to use the appropriate amount to prevent over-anesthetizing the animal.  This should be based on the volume of the chamber. Anesthesia usually will be adequate at 1.0-1.5%.
    ml per liter volume of container Equals %
    0.05 1
    0.10 2
    0.15 3
    0.20 4
    1. For a short procedure prior to euthanasia, once the anesthetic has been loaded into the chamber, the animal is placed inside and monitored for unconsciousness. A deep plane of anesthesia is indicated by lack of movement to a firm toe pinch.  Once the animal is adequately anesthetized, the animal can be removed from the chamber.
    2. For a slightly longer period of anesthesia, a tube (e.g., 15-ml conical tube for mice or a 50-ml conical tube for rats) can be loaded with gauze containing several drops of anesthesia liquid. The animal should be restrained and the nose held to the tube until the anesthesia takes effect.

    Sedation for non-surgical procedures

    1. Use of isoflurane for non-surgical procedures must be performed in a chemical fume hood or equivalent (e.g., down draft table) to control the anesthetic waste gas.
    2. A chamber can be used that is large enough to accommodate the animal for anesthesia. A small amount of anesthesia liquid is placed in either a reservoir or on an absorbable material (such as gauze, cotton balls, etc.).  The reservoir or absorbable material must be positioned so that the animal cannot come in direct contact with the isoflurane.
    3. The animal can be removed once a sedative effect has taken place. Care must be taken to watch the animal closely as over-anesthetizing, and thereby euthanizing the animal, can happen.

     

    References:

    1. Johns Hopkins University IACUC policy “Use of Anesthetic Gasses:  Drop Method”

    2. Bodnar, M., et al. “Mouse Isoflurane Anesthesia using Drop Method”. Laboratory Animals, May 2023.

     

    Effective Dates:            December 21, 2023 through December 31, 2026

    This policy has been approved by a majority vote of the IACUC Members