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
How can you monitor waste gas levels
If required, done by an occupational hygienist with samples collected from multiple areas of the hospital and analyzed by infrared spectrometer at a cost of $250 - $700. Detector badges (passive dosimeters) or tubes may also be worn or placed in a specific area that are specific to a single chemical or to multiple chemicals. Results are given as a time-weighted average at $50 to $70 per badge.
What is the fire and safety precaution you have to take with compressed gas cylinders
Oxygen and N2O are not flammable but both support combustion and cause fuels to burn more readily. No sources of ignition should be in same room
describe use and storage of compressed gas cylinders
Ideally, wear protective goggles when connecting a gas cylinder to an anesthetic machine, and/or keep your head and face away from the valve outlet
Always turn the valve slowly to the full open position
If a cylinder leak occurs, never use your hand to try to stop the leak!!!
Sudden release of gas from cylinder (e.g. damage or regulator detaches) may cause the tank to become a rocket like projectile!!!
Thus, cylinders should always be upright and chained or belted to a wall etc.
Valve caps should be used on large cylinders that are not connected to gas line (to protect the valve from damage
They should also be out of emergency exits or heavy traffic areas
Use a handcart to move a cylinder to another location
Keep in order (first in, first out) and clearly labeled as to type and status
Use tear-off labels system
what are potential accidental methods of exposure
skin exposure, eye splash, oral ingestion of injectable drugs or inhalation agents, oral ingestion
Most concerns drugs are opiods used for restraint and capture of wildlife (10000X the potency of morphine!)
Why do we do paediatric spay and neuter
advantages for shelters
benefits for pet owner
advantages for breeders
faster/easier for vets
what are the advantages for shelters with paediatric spay and neuter
Tool for controlling pet overpopulation.
decrease return rate, decrease euthanasia
what are the benefits for owners with paediatric spay and neuter
more commitment, more socialized pets, better health care and persistent juvenile behaviour
what are the advantages for the breeders with paediatric spay and neutering
it is a real non breeding contract.
what are the advantages for vets with paediatric spay and neuters
faster, easier, less stress to the vet and to the animal, less expensive.
What are the medical advantages to doing paediatric spay and neuters
:decreased risk of pyometra, mammary neoplasia, behavioural changes, testicular neoplasia, perineal neoplasia, hernia.
:shorter surgery time
:shorter anesthesia episode
:shorter anesthetic recovery and healing
Does paediatric spay/neuter result in stunted growth
No, false.
Does paediatric spay/neuter result in obesity
No, obesity is multifactorial.
Does paediatric spay/neuter result in lethargy/inactivity
No, animals are naturally active. The dominant behaviour is unaffected.
Does paediatric spay/neuter result in reduced vaccine response
False.
How does paediatric spay/neuter affect the secondary sex characteristics
infantile vulva is more prone to medical problems, infantile prepuce and penis are present with prepubertal neutering.
Is estrogen linked to incontinence in cats
yes, it is estrogen responsive and easily treatable
what age is considered a neonate
birth to 2 weeks
what age is considered an infat
2-6 weeks
what age is considered pediatric
6-12 weeks avg. (8-16 wk)
what are some general characteristics about pediatrics
hypoAlb
increased permiability of blood brain barrier
low % body fat
What are the effects of anesthesia for neonates
makes them more sensitive to standard drug dosage
decrease tolerance to fluid load
what are the good strategies for dealing with neonates
decrease drug dosage
dont overhydrate
Describe neonates immature thermoregulatory system
large body surface area compared to body mass - leads to heat loss
have small fat reserve
decreased shivering reflex
what are the effects of anesthesia on neonates thermoregulatory system
hypothermia = delayed recovery hypothermia = increased O2 consumption
what are the thermoregulatory strategies to employ with neonates
keep them warm
describe neonates renal-urinary system
immature
what are the effects of anesthesia on neonates renal-urinary system
prolonged recovery time
decreased tolerance to fluid load
describe a neonates hepatic system
immature
what are the effects of anesthesia on neonates hepatic system
prolonged recovery time
**reduce drug dosage, or avoid drugs metabolized by the liver
describe a neonates respiratory system
high metabolic rate
limited pulmonary reserve
pliable rib cage
what are the effects of anesthesia on a neonates respiratory system
decreased respiratory reserve
what are the strategies to employ when working with neonates respiratory system
O2 and ventilation support
supervise induction
describe a neonates cardiovascular system
heart contraction not as efficient
limited cardiac reserve
what are the effects of anesthesia on neonates cardiovascular system
decrease cardiac reserve
what are the strategies to employ when working with neonates cardiovascular system
IV fluid (monitor closely) drugs that help contract the heart
What are two pieces of anesthetic equipment suited for pediatrics
temperature control device
pediatric bain system could be used
do we fast paediatrics?
no (max 2-4hr) due to risk of hypoglycaemia
What is part of the preanesthetic preparation for pediatriacs
weight gpe blood test \+/- vaccines/deworm \+/- pre-oxygenate
when does the fear imprint stage occur
at 7-8 weeks of age, reaction to painful stimulus is marked.
what is a necessary precaution to take when dealing with the fear imprint stage
smooth, gentle induction into anesthesia in mandatory or catecholamines are released that increase the liklihood of dysrhythmias.
What is the max fluid rate for pediatrics
3ml/kg/hour
why do we give pediatrics fluid
adapt poorly to hypovolemia
What do you need to do to ensure the patients stay warm
decrease contact with cold surface minimal shaving use warm pre-op solution use warm fluid use warming device limit body cavity exposure decrease surgery time use reversal agent.
What can you premedicate paediatrics with
opiods
acepromazine
alpha-2-agonist
what drug do you use to induce pediatrics
ketval or propofol
what analgesia do you give pediatrics
nsaid
describe recovery period for pediatrics
risky preventable continue fluid + active warming monitor glucose feed immediately upon anesthetic recovery
What is assisted ventilation
Assisted ventilation: anesthetist ensures that an increased volume of air is delivered to the patient…
◦ although the patient initiates each inspiration
what is controlled ventilation
Controlled ventilation: anesthetist forcefully delivers all of the air that is required by the patient…
◦ and the patient does not make any spontaneous respiratory efforts.
how do you administer controlled ventilation
any method by which anesthetist assists or controls the delivery of O2 + anesthetic gas to the patient’s lung
what is the goal of controlled ventilation
GOAL: ensure that patient receives adequate O2 and is able to exhale adequate amounts of CO2
describe ventilation when awake
Inhalation is initiated by the respiratory center (RC) of the brain
triggered by increasing levels of CO2 in arterial blood.
Above 40mmHg of CO2, RC initiate inspiration by:
stimulating intercostal muscles and diaphragm to move…
which results in expansion of the chest.
This create a negative P in the chest, pulling air into the lungs as they expand
When the lungs are adequately expanded….
…nerve impulses feed back to the RC to stop expansion.
Passive phase can begin as the diaphragm and intercostal muscles relax.
Normally, expiration lasts twice as long as inspiration
Why is ventilation in the anesthetized animal different
Tranquilizers and GA the responsiveness of the RC in the brain to CO2.
◦ Thus, inspiration does not occur as often despite significant elevations in CO2
Tranquilizers and GA relax the intercostal muscles and the diaphragm
◦ resulting in a decreased Tv
◦ With decreased RR and TV, Respiratory minute volume is decreased .
what are 3 potential problems with ventilation in the anesthetized animal
Hypercarbia
Hypoxemia
Atelectasis
what is hypercarbia
Hypercarbia:
◦ CO2 is not eliminated as rapidly (so PaCO2 increase)
◦ CO2 + H2O molecules in blood = HCO3 ˉ + H+
◦ Too much H+ = blood ph decrease
◦ Blood pH is decrease to as low as 7.2 relative to normal (7.38 to 7.42) = respiratory acidosis
how do you overcome hypercarbia
may have to assist or control ventilation
What is hypoxemia and how is it overcome
Hypoxemia: PaO2 may be if breathing room air as a result of respiratory minute volume
This is overcome by 100% O2 supply
What is atelectasis and how do you overcome it
may occur due to Tv
How to overcome?
◦ May have to assist or control ventilation
which patients are more at risk
Procedures that last greater than 30-60 minutes Obeses patients Preexisting lung disease Recent head trama Species differences
what are the two types of controlled ventilation
manual (bagging)
mechanical ventilation
How do you manually bag
◦ Periodic; 1-2 breaths ev. 2-5 minutes
◦ Intermittent mandatory: bagging throughout anesthetic period
How do you do mechanical ventilation
use a ventilator
what are the risks of controlled ventilation
Rupture alveoli if overinflated.
CO may be decreased with PPV throughout entire respiratory cycle
Excessive ventilation rate may result in excessive exhalation of CO2, resulting in a respiratory alkalosis
CONCLUSION: needs close anesthetic monitoring to ensure anesthetic depth and vital signs are maintained
what is laser surgery
L.A.S.E.R =
◦ Light amplification stimulated
emission radiation
What are the types of lasers in vet medicine
Types in med.vet:
◦ CO2 laser, diode laser in vet med
How does the laser work in laser surgery
How it works? Creates light absorbed transmitted into heat within tissue
Different T causes different changes
