Standard for Inhaled Anesthetics


University of North Carolina at Chapel Hill Standard for Inhaled Anesthetics



The standards and procedures described below provide guidance to all researchers and animal handlers administering and handling inhaled anesthetics (e.g., isoflurane).


This Standard applies to all personnel engaged in the use of inhaled anesthetics in studies involving research animals.

The University of North Carolina at Chapel Hill ("UNC-Chapel Hill" or "University") Institutional Animal Care and Use Committee (IACUC) expects that anyone involved in animal work at the University will comply with this Standard. Requests for exceptions to this Standard must be reviewed and approved by the IACUC.


New researchers seeking certification in the use of an isoflurane vaporizer are first required to review IACUC, Environment, Health, & Safety (EHS) and Division of Comparative Medicine documents, complete an online EHS/DCM training Powerpoint, then complete the hands-on training. Details about vaporizer training and links to the required documents can be found on the DCM training page.  

Please review the EHS Standard Operating Procedure for Isoflurane.


Maintenance and Use

All anesthetic vaporizers must be serviced by a trained professional on an established schedule consistent with the manufacturer’s recommendations. A copy of the manufacturer’s recommendations should be available to the IACUC for review. At a minimum, vaporizers must be calibrated every two (2) years to ensure that the vaporizer is delivering the amount of anesthetic reflected by the setting on the vaporizer. All calibrations should be documented and readily available during IACUC laboratory inspections. A certification sticker applied to the vaporizer may serve as documentation and should indicate the name of the servicing agent and the date of service.

Additional indications of the need for vaporizer service includes the following:

  1. Discoloration (yellowish brown) in the "Fill" sight glass of a vaporizer
  2. Sticking valves or knobs
  3. Subjects not responding (as anticipated) to the level of anesthesia provided
  4. Cracked or damaged hoses

Users should assess the vaporizer for these changes prior to each use and contact the manufacturer for service if any abnormalities are found.  

[Note: The National Institute for Occupational Safety and Health (NIOSH) (Health Care Workers Guidelines, Chapter 5) states that all anesthetic equipment must be regularly monitored for leakage, improper design, or defects. This includes the anesthesia machine as well as the vaporizer since anesthetic machines can develop improperly functioning components such as flutter valves, gaskets, and scavenging equipment.]

Induction Chamber

The induction chamber should be an appropriately-sized container for the species. Researchers should ensure the rubber seal remains pliable, the seal’s integrity prevents any leaks from the chamber, and the chamber has no cracks.

Opening the isoflurane induction chambers without the use of active scavenging can release vapors into the air. For this reason, researchers should flush the line with oxygen prior to opening the chamber. Ideally, induction chambers should be used in a hood, with a vacuum, or another system of active scavenging. If only passive scavenging is possible (e.g., charcoal canister), researchers should arrange for EHS to measure isoflurane levels during a typical procedure.

Vaporizer with Nosecone

When using a nosecone to administer isoflurane, it is important to ensure an adequate fit. To maintain an adequate anesthetic plane, an appropriately-sized nosecone should be used that covers the animal’s nose and mouth. Rubber diaphragms may be used in combination with a  scavenging system to minimize the release of vapors into the air.

Drop Method

The ‘drop method’ is a rapid method to anesthetize rodents for very short procedures or to perform euthanasia via isoflurane overdose. Glass or plastic desiccators may be purchased from vendors or a customized version can be crafted. It is essential that the container be appropriately sized to prevent the need for large volumes of isoflurane or overcrowding of animals, which slows induction time. The container lid must be easily sanitizable and tight fitting to prevent potential isoflurane leaks. A protective layer (such as a perforated platform in a desiccator) is required inside the container to prevent direct contact of the animals with isoflurane-soaked materials. Contact with the anesthetic can cause skin irritation and potential overdose since isoflurane is absorbed through the skin.

Due to potential risk to human health, the use of the ‘drop method’ must occur in a fume hood, a ducted biosafety cabinet, or with a properly functioning active scavenging system. If this cannot occur, EHS must be contacted to measure the air quality. The investigator must receive EHS approval to use the ‘drop method’ on a bench top. Once bench top use is approved, the investigator must post a copy of the approval in the area.

For instructions on how to perform this procedure, please see the Standard Operating Procedure for Isoflurane Drop Method.


Requests for exceptions to this Standard must be reviewed and approved by the IACUC.


NIOSH: National Institute for Occupational Safety and Health

Related Requirements

External Regulations and Consequences

University Policies, Standards, and Procedures

Contact Information

Contact Information Table
Subject Contact Telephone

Animal Health

DCM Vet Services


Annual on campus calibration service

DCM Vet Services


Important Dates

  • Effective Date and title of Approver: 10/2018; UNC IACUC
  • Revision and Review Dates, Change notes, title of Reviewer or Approver: 04/2018; UNC IACUC

Approved by: UNC IACUC

100% helpful - 1 review
Print Article


Article ID: 132186
Thu 4/8/21 9:25 PM
Fri 4/19/24 9:22 AM
Responsible Unit
School, Department, or other organizational unit issuing this document.
Research-Institutional Animal Care & Use Committee
Issuing Officer
Name of the document Issuing Officer. This is the individual whose organizational authority covers the policy scope and who is primarily responsible for the policy.
Issuing Officer Title
Title of the person who is primarily responsible for issuing this policy.
Vice Chancellor
Next Review
Date on which the next document review is due.
10/18/2024 12:00 AM
Last Review
Date on which the most recent document review was completed.
10/18/2023 12:00 AM
Last Revised
Date on which the most recent changes to this document were approved.
04/20/2022 12:00 AM
Effective Date
If the date on which this document became/becomes enforceable differs from the Origination or Last Revision, this attribute reflects the date on which it is/was enforcable.
04/20/2022 12:00 AM
Date on which the original version of this document was first made official.
09/05/2019 12:00 AM