Inhalation Anesthesia Machine/Vaporizer/Waste Gas Maintenance
IACUC Policy: 049-05, Effective Date: 08/16/2013, Last Revision: 03/18/2026
Overview/Purpose
To ensure animal safety and reduce risk of personnel anesthetic gas exposure, proper maintenance of anesthesia equipment, appropriate waste scavenging systems, and safe administration techniques must be employed. Anesthesia machine training is available, free of charge, through University Laboratory Animal Resources (ULAR). The purpose of this policy is to outline the required preventative maintenance and performance evaluations for anesthetic machines used for animal research on campus.
Definitions
- Anesthesia machine: The vaporizer and associated equipment (regulators, flow meters, breathing circuits, and scavenge system) that is used to deliver precise amounts of inhaled anesthetic gas and/or a carrier gas.
- Breathing circuit: The tubing that delivers the gas mixture from the machine to the patient.
- Induction chamber: A transparent box or container that animals can be placed within to induce anesthesia by enveloping the animal with the anesthetic gas.
- Precision vaporizer: A component of the anesthesia machine used to regulate the delivery of the volatile anesthetic gas.
- Scavenge system: A system to remove halogenated waste gas from the anesthetic system so it does not return to the patient or increase exposure to personnel.
- Active scavenge system: incorporates a vacuum to pull off waste gas.
- Passive scavenge system: passive flow carries the waste gas through a charcoal canister which adsorbs the waste gas.
- Vaporizer calibration: A process of taking apart the precision vaporizer, cleaning the components, replacing worn gaskets and verifying gas outputs with a refractometer. Such an evaluation must be performed by a qualified vendor (e.g., Patterson and Henry Schein).
- Vaporizer verification: A process of verifying the percentage of volatile gas that the vaporizer puts out at each setting. This may be done by ULAR or a qualified vendor.
Requirements
Before each use, the entire machine should be checked by the operator for proper function and integrity.
- All tubing must be connected and free from leaks and kinks including breathing circuits, scavenge tubing, and rebreathing bags (if used). Note: A rebreathing bag and circuit should only be used in animals weighing >3.5 kg.
- The carrier gas tanks must fit snugly onto the regulator yoke with no leaks and have sufficient levels for the duration of the procedure.
- A scavenge system must be in place and functioning properly.
- A scavenge system using charcoal canisters requires a record of the duration of use or weight of the canister before each use to identify when it needs to be replaced. All exhaust holes on the canister must be unobstructed.
- When using an active system, ensure that the vacuum is turned on and working at an appropriate flow.
- Personnel must take all measures to avoid breathing in anesthetic gases.
- Induction chambers should be connected to an active scavenge system or used inside of a biosafety cabinet/fume hood.
- Nosecones must fit snugly to avoid the potential for leakage of gas around the nose, and work should be done inside a biosafety cabinet/fume hood.
- If using an endotracheal tube, ideally it should be cuffed, but if no cuff is available then ensure the proper size is being used to acquire a snug fit.
- Vaporizers must be verified every three years or based on manufacturer's recommendation and calibrated based on performance. If the vaporizer delivers an amount >20% outside the settings during verification, it must be taken out of service and sent out for calibration.
- Investigative staff are responsible for ensuring appropriate verification and calibration of all investigator-owned machines. Requests for validation can be made through ULAR – see Surgical and Technical Services.
Revision History
- 049-00 – new policy approved 08/16/2013
- 049-01 – The vaporizer validation percentage was changed from 10% to 20% of the metered concentration to reflect industry standard. 05/16/2014
- 049-02 – The vaporizer must be validated annually or calibrated at least once every 3 years unless the manufacturer indicates otherwise. 03/27/2015
- 049-03 – This policy was reformatted. Revisions reflect definitions, a performance evaluation, and the expectations for verification and calibration of anesthesia machines. Approved 01/20/2017
- 049-04 – Revisions reflect the change in frequency for verifying and calibrating vaporizers. A table listing the types of breathing systems and frequency to verify vaporizers was removed. Approved 01/17/2020
- 049-05 – Revised to include checklist as an appendix. Approved 03/17/2023
- 049-06 – Updated definitions, updated requirements, anesthesia machine checklist removed, 3 year review. Approved 03/18/2026
Article ID: 36
Created: May 1, 2024
Last Updated: May 8, 2026
Online URL: https://ohiostateresearch.knowledgebase.co/article/inhalation-anesthesia-machine-vaporizer-waste-gas-maintenance-36.html