Workplace Safety

1. Veterinary technicians must be familiar with the human safety considerations involved in veterinary anesthesia Chapter 13 Workplace Safety

2. 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. 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. Long-term effects of exposure to high levels of waste anesthetic gas Serious health problems Reproductive Oncogenic Hepatic Renal Hematologic Neurologic 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. 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. 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. 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. 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. Active and Passive Scavenging Systems

10. 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. 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. 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. 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. 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. 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: nitrousoxide 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. 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. 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. 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. Labeling Compressed Air Cylinders

20. 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. 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. Accidental Exposure to Injectable Agents (Cont’d) Cyclohexamines (ketamine, tiletamine) Accidental eye splash may cause disorientation, excitement, dizziness, or unconsciousness Alpha2-agonists Xylazine, detomidine, medetomidine, dexmedetomidine Accidental injection or skin contact may cause sedation, hypotension, bradycardia, respiratory depression, coma

23. 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