1 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Veterinary technicians must be familiar with the human safety considerations involved in veterinary anesthesia Workplace Safety Chapter 13

2 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Hazards of Waste Anesthetic Gas   Sources of waste inhalant anesthetic gas   Exhaled by patient or escaped from anesthetic machine during anesthetic period   Inhaled when emptying or filling anesthetic vaporizers   Inhaled after an accidental anesthetic liquid spill   Measurement of waste anesthetic gas in parts per million (ppm)

3 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Hazards of Waste Anesthetic Gas (Cont’d)   Short-term effects of exposure to high levels of waste anesthetic gas   Direct effect of anesthetic agent on brain neurons   Resolve spontaneously when area is left   Frequent occurrence indicates excessive waste gas levels

4 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.   Long-term effects of exposure to high levels of waste anesthetic gas   Serious health problems ReproductiveOncogenic HepaticRenal HematologicNeurologic   May be the result of toxic metabolites produced by the liver   Anesthetics eliminated through the lungs are less likely to produce long-term effects Hazards of Waste Anesthetic Gas (Cont’d)

5 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Long-Term Effects of High Level Exposure to Waste Anesthetic Gas   Reproductive effects   Risk of spontaneous abortion   Infertility   Congenital anomalies in children   Oncogenic effects   None of the commonly used agents are associated with an increased risk of developing cancer   Hepatic effects   Hepatotoxicity Rare, most common with halothane exposure

6 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Long-Term Effects of High Level Exposure to Waste Anesthetic Gas (Cont’d)   Renal effects   Possible renal toxicity with methoxyflurane exposure   Neurologic effects   Possible loss of motor skills and short-term memory   Possible increased incidence of neurological disease   Hematologic effects   Possible bone marrow abnormalities

7 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Measuring Waste Gas Levels   Highest levels are in surgery suites, surgical prep rooms, and anesthesia recovery rooms   Highest levels during the anesthetic period are nearest the anesthetic machine   Factors that determine levels   Duration of anesthesia   Flow rate of carrier gas   Anesthetic machine maintenance   Effective scavenging system   Anesthetic techniques used   Room ventilation (15-20 air changes per hour is ideal)   Anesthetic spills

8 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Reducing Exposure to Waste Anesthetic Gas   Use a scavenging system   Collects waste gas from the anesthetic machine and conducts it to a disposal site outside the building   Installation and consistent use are most important factors   Include exhaust from anesthetic machine, nonrebreathing systems, ventilators, anesthetic chambers, and capnometers   Active (high vacuum, low vacuum) or passive   Active system with dedicated vacuum pump is most efficient   Passive system is least expensive and is best used in rooms with exterior walls

9 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Active and Passive Scavenging Systems

10 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Potential Difficulties with a Scavenging System   Prevent the negative (vacuum) pressure on the breathing circuit   Reservoir bag will collapse   Negative pressure relief valve will open   Obstructions may block waste gas from entering the scavenging system   Anesthetic gas will accumulate in the anesthetic circuit   Excess pressure develops in circuit and patient’s lungs   Positive-pressure relief valve will open

11 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Alternative to Scavenging System   Activated charcoal cartridges   Used in rooms not set up for scavenging   Charcoal absorbs anesthetic vapors   Replace cartridge every 12 hours or when weight increases 50 g   Don’t absorb nitrous oxide vapors   Inefficient at flow rates >2 L/min   Masks with charcoal filters   Worn by personnel at special risk   Not effective for nitrous oxide   Don’t use masks designed for particulate matter

12 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Reducing Exposure to Waste Anesthetic Gas   Check equipment for leaks   Common sites for leaking equipment   Nitrous oxide connections not tightly secured   Rings, washers, other seals joining tanks to machine hanger yokes are missing, worn, or out of position   Covering of unidirectional valve is not tightly closed   Carbon dioxide absorber canister is not securely sealed   Pop-off valve/scavenger connection is not airtight   Holes in or loose connections for breathing hoses, reservoir bag, or ET tubes   Vaporizer cap missing

13 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Types of Leak Tests for Anesthetic Equipment   High-pressure tests   Check for leaks between the gas tanks and the flow meter   Gas pressure ≥50 psi   Only oxygen or nitrous oxide (the carrier gasses) is released through any leaks

14 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Types of Leak Tests for Anesthetic Equipment (Cont’d)   Low-pressure tests   Check for leaks in the anesthetic machine and breathing circuit   Gas pressure ≤15 psi   Oxygen, nitrous oxide, and anesthetic gas released through any leaks

15 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Reducing Exposure to Waste Anesthetic Gas   What type of leak test to perform   High-pressure and low-pressure: both nitrous oxide and oxygen carrier gasses   Low-pressure test alone: oxygen carrier gas alone   Low-pressure test: prior to machine use each day   High-pressure test: nitrous oxide tank weekly or when tank is changed   Leaks may be found by locating a hiss of escaping air or by using a detergent solution   Don’t use machine with a leak until the source of the leak has been identified and repaired

16 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Monitoring Waste Gas Levels   Important considerations   Hospital employee becomes pregnant   Odor of anesthetic gas is frequently detected   Special concerns about waste gas levels   Professional monitoring   Accredited industrial hygiene laboratory   In-house monitoring   Detector tubes or badge dosimeters

17 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Safely Handling Compressed Gases   Fire safety   Oxygen and nitrous oxide support combustion   Static electricity can cause fire when oxygen and combustibles are present   Eliminate all sources of ignition or flames from any room where cylinders are stored or used

18 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Safely Handling Compressed Gases (Cont’d)   Use and storage   Cylinders are storehouses of large amounts of energy   Wear impact-resistant goggles when connecting cylinders to anesthetic machine   Turn valve slowly and with proper wrench when turning on the cylinder   Chain or belt cylinders to wall   Store in an upright position to prevent damage   Store cylinders away from high traffic areas   Don’t drag or roll a cylinder   Keep full and empty cylinders separate   Label with tear-off labels   Use cylinders in the order they are received

19 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Labeling Compressed Air Cylinders

20 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Accidental Exposure to Injectable Agents   Opioids used for restraint and capture of wild animals   Etorphine (Immobilon, M99) and carfentanil (Wildnil)   More potent than morphine   Absorbed through mucous membranes or broken skin   Accidental exposure through accidental injection, eye splash, or oral ingestion

21 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Accidental Exposure to Injectable Agents (Cont’d)   Precautions   Become educated on potent opioids before using them   Don’t work alone and wear gloves when using potent opioids   Have reversal agents drawn up and ready for use   Have a treatment plan in place   Dispose of needles and syringes in a closed container immediately

22 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Accidental Exposure to Injectable Agents (Cont’d)   Cyclohexamines (ketamine, tiletamine)   Accidental eye splash may cause disorientation, excitement, dizziness, or unconsciousness   Alpha 2 -agonists   Xylazine, detomidine, medetomidine, dexmedetomidine   Accidental injection or skin contact may cause sedation, hypotension, bradycardia, respiratory depression, coma

23 Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc. Accidental Exposure to Injectable Agents (Cont’d)   Precautions   Personal protective equipment   Carefully load syringes   Properly dispose of needles and syringes   First aid, including eye wash, readily available