Final Flashcards
Waste anesthetic gas includes what vapours
Includes all anesthetic vapors……
breathed out by a patient (in recovery)
that escape (leak) from the anesthetic machine
during filling or emptying of anesthetic vaporizers
due to accidental spill of liquid anesthetic.
what unit are waste gas concentrations expressed in
ppm
33ppm = level at which average person can smell the odor of halothane which is how many times the recommended max concentration
= 15X the recommended max concentration!
What are the short term effects of breathing in waste anesthetic gasses
direct effect on brain neurons causing fatigue, headache, drowsiness, nausea, depression and irritability
if occur frequently, may be indicator of excessive waste gas levels with a potential for long-term toxicity effects
What are the long term effects of breathing in waste anesthetic gasses
Long-term inhalation of waste gas may be associated with several health problems
Mechanism? Not fully understood. Probably due to toxic metabolites produced by the breakdown if anesthetic gases within the liver and their subsequent excretion by the kidney
The more an anesthetic agent is retained by the body and then metabolized (versus those quickly eliminated through the lungs), the more likelihood toxic metabolites will be produced.
How do you assess risk for waste anesthetic gas exposure
It is difficult to determine a clear-cut assessment of risk because many studies are contradictory within themselves or across studies
It is not established in the majority of studies that the waste anesthetic gases are the causative factor in some of the increased health risks
Many studies did not measure the level of waste gas present which makes interpretation of the validity of the study difficult
In general, avoid exposure to high levels of waste anesthetic gas and reduce exposure as much as possible
What does waste anesthetic gas levels depend on
Iso levels vary between 1 to 20ppm (if presence of scavengers) Highest level immediate to anesthetic machines but depends on: Duration of anesthesia Flow rate of carrier gas Anesthetic maintenance Use of an effective scavenging system Anesthetic techniques used Room ventilation Anesthetic spills
How do you reduce exposure to waste anesthetic gas
Use of a scavenging system
equipment leak testing
anesthetic techniques and procedures
What is the definition of a scavenging system
tubing attached to the anesthetic pop-off valve (or in case of a non-rebreathing system, to the outlet port or tail of the reservoir bag)
What is the function of a scavenging system
to collect waste gas from the machine and conduct it to a disposal point outside the building
what is the employers responsibility involving a scavenging system
install adequate engineering controls to ensure that occupational exposure to any chemical never exceeds the permissible exposure limit
what are the two types of scavenging system
active system
passive system
What is the active scavenging system
Active system (fig. 13.2 p.357) uses suction created by vacuum pump or fan to draw gas into the scavenger most efficient system but more expensive more maintenance ..and must turn on system each day!!
What is the passive scavenging system
Passive system (fig. 13.1 p. 357) uses gravity and positive pressure of gas in the anesthetic machine to push gas into the scavenger
most commonly, passive systems discharge through a hole in the wall
suitable for rooms adjacent to the exterior of the building
distance to the outlet should be less than 20 feet
Another type of passive system: may place end of transfer hose adjacent to room ventilation exhaust or nonrecirculating air conditioning system.
waste gas should be totally confined within scavenger hose until discharge and must not be recirculated within the building
transfer hose may not be more than 10 feet in length
What is an activated charcoal canister and filter mask used for
Activated charcoal canister: system used of no scavenging into the room
Activated charcoal filter mask: for personnel at special risk
What is the negative pressure system
Negative pressure: if using an active scavenging system, you should prevent negative pressure (vacuum) from the scavenger from being excessively applied to the breathing circuit,
particularly if machine is not equipped with a negative pressure relief valve
If occurs, reservoir bag will collapse!!
ensure that reservoir bag is at least partially inflated with air at all times (if no neg. P relief valve present)
What is the disadvantage to using a scavenging system
Potential for blockage of the entry of waste gas into the system which is analogous to a closed pop-off valve
Why is equipment leak testing so important
Leakage is a significant source of operating room pollution and is not reduced by scavenging
Where can leakage occur from
Leakage may occur from any part of the machine in which N2O or anesthetic is present including:
Connections for N2O lines
rings, washers, seals etc.
Connections between flowmeter and vaporizer
Unidirectional valves
CO2 absorber canisters
Holes in the reservoir bags/ hoses
Pop-off valve and scavenger is not airtight
Connection sites of the hoses, reservoir bag or endotracheal tube
Vaporizer cap not replaced after the filling
What is a high pressure leak test
High pressure tests for N2O or O2 leakage arising between the tanks and the flowmeter (to do only if use N2O)
What is a low pressure leak test
Low pressure tests for escape of anesthetic gas from the anesthetic machine
To do every day!
Why are good anesthetic techniques so important
Faulty work practices were found to account for 94% to 99% of waste anesthetic gas released in scavenged operating rooms in one survey of human hospitals
How many air changes per hour are needed
at least 15.
how often should anesthetic machines be serviced
1/2x per year