Safe Use Of Anesthetic Gases. Department of Environmental Health & Safety Safety Training for Researchers Updated April 7, 2009

Transcription

1 Safe Use Of Anesthetic Gases Department of Environmental Health & Safety Safety Training for Researchers Updated April 7, 2009

2 Contents Background Health Effects Exposure Limits Signs of Overexposure Waste Gas Scavenging Methods 1. Building Exhaust Ventilation with Anesthesia Machine and Intubation 2. Localized Exhaust System 3. Fume Hood 4. Nose cones with Charcoal Scavenging Canisters Safe Use of Vaporizers Safe Use of Induction Chambers

3 Background Commonly used as anesthetic in animal research because of extremely rapid induction and recovery times Waste anesthetic gas (WAG) becomes occupational health concern for researchers and lab staff Scavenging methods must be implemented to protect researchers against overexposure

4 Health Effects Central Nervous System Effects Adverse Reproductive Effects Congenital Abnormalities Adverse Liver and Kidney Effects Source: OSHA Fact Sheet No

5 Exposure Limits NIOSH has established the following recommended exposure limit (REL) for several halogenated anesthetic gases: 2 ppm or 15.1 mg/m 3 as a ceiling limit (average over 1 hour) The University of Minnesota has adopted this NIOSH REL as the University of Minnesota Exposure Limit for any halogenated anesthetic gas:

6 Signs of Overexposure Commonly, the odor threshold for anesthetic gases is greater than the exposure limit; therefore, odor is not an adequate indication of overexposure. In other words: If you can smell the anesthesia, you are probably being over exposed! Acute symptoms of overexposure: Nausea Skin irritation Nose/throat/respiratory irritation Headache Dizziness Drowsiness

7 Waste Gas Scavenging Methods 1. Building Exhaust Ventilation with Anesthesia Machine and Intubation 2. Localized Exhaust System 3. Fume Hood 4. Nose Cones with Charcoal Scavenging Canisters Not all scavenging systems are created equal!

8 1. Local Building Exhaust Ventilation with Anesthesia Machine and Intubation Anesthetic gas delivery machines with scavenging hoses connected directly to building exhaust Common in large laboratories or operating rooms Ensure connections are tight and intubation is correct Leaks have been detected at hose connections and near intubation site Test regularly for leaks in connections and hoses

9 2. Localized Exhaust System Must exhaust directly to the outside Examples: Elephant Drop Slot exhaust Elephant Drop Slot Exhaust Downdraft Table 100% exhausted biosafety cabinet (Class II, Type B2 ONLY) Downdraft Table

10 3. Fume Hood Yes Placement of entire gas mixing and delivery system inside fume hood is ideal Filtering fume hoods NOT allowed No! Require high degree of attention and maintenance Thorough training required on use and maintenance Hazardous chemicals could exhaust back into room Poor warning properties of anesthetic gases will provide no indication if filters become overloaded

11 4. Nose Cones with Charcoal Scavenging Canisters Set-up and maintenance of effective canister scavenging system can be tedious Therefore, use must be limited to situations where other means of scavenging are not practicable. Can only be used with systems that actively move gas (e.g., from pressurized tanks or a vacuum system); systems cannot use gravity

12 4. Nose Cones with Charcoal Scavenging Canisters Canister users must routinely check for leaks Canister users must keep log of: Starting weight of canister Date of first use and subsequent use dates Weight of canister before each use discard canister when gain reaches manufacturer s limit Expiration date of canister

13 4. Nose Cones with Charcoal Scavenging Canisters Exhaust ports on bottom Exhaust ports on top Canisters with exhaust ports on the top work better than those with exhaust ports on the bottom Both should be used in upright position f/air canister should be suspended so that bottom ports are not covered

14 Safe Use of Vaporizers Must be calibrated annually Must be filled in a fume hood or by using a keyed filling system Pour Fill (must be done in a fume hood) vs. Key Fill

15 Safe Use of Vaporizers Use the lowest necessary oxygen flow rate and concentration of anesthetic to achieve anesthesia Typical induction for rodents: 5% anesthetic in O 2 with flow rate set at about 0.25 L/min of O 2 Typical maintenance for rodents: about 2% (range is 1% to 3%, but there are many variables that change conditions of anesthesia) Anesthetic gas delivery systems must be placed inside a fume hood; except under the following conditions: Anesthesia machine is connected to building exhaust Local exhaust ventilation is provided over the delivery system Work is done on back draft or down draft table

16 Safe Use of Induction Chambers Induction chamber (knock-out box) procedures must be performed inside a fume hood

17 For more information. Anesthesia and Analgesia in Laboratory Animals, ed. American College of Laboratory Animal Medicine University of Minnesota Research Animal Resources OSHA Fact Sheet Number (Waste Anesthetic Gases) OSHA Guidance Document Anesthetic Gases: Guidelines for Workplace Exposures For help with anesthesia delivery systems and techniques contact a Research Animal Resources (RAR) veterinarian at 612/ For help with waste anesthetic gas scavenging system set-up contact DEHS at 612/