test 1 Flashcards
what are six considerations that are crucial before anesthetic procedures?
- minimum patient database
- proper patient fasting
- pre-induction patient care
- supplies available
- equipment working
- pre-anesthetic medication
before the patient comes in for surgery, what 3 things do you need to ensure?
- full history has been collected
- patient fasted
- proper documentation completed
what is the purpose of the minimum patient database?
to make patient care decisions and uncover potential anesthetic risks
what does the minimum patient database include?
- patient history (incl. signalment
- complete PE findings
- results of preanesthetic diagnostic workup
when should the minimum patient database be completed? why?
the patient should be scheduled for an appointment several days before the planned procedure; if problems come up they can be addressed prior to surgery
why is it important to verbally confirm the scheduled procedure before beginning?
can prevent tragic accidents; anesthetizing the wrong patient, performing an unnecessary procedure, not performing a required procedure
as a technician, what do you need to obtain from the client regarding patient history?
- signalment
- current/past illnesses
- current medications
- allergies and/or drug reactions
- status of preventative care (vaccines, S/N, etc.)
why is the signalment so important to know before performing an anesthetic procedure?
there are unique species reactions and sensitivities to anesthetic agents
t/f - horses and cats are not sensitive to opioids
false - they ARE sensitive to opioids
t/f - cats produce excess airway secretions under anesthesia
true
what drug produces sensitivity in boxers and giant breeds?
acepromazine
what dog breed is resistant acepromazine?
terriers
what specific type of horse should you not administer acepromazine to?
contraindicated for use in stallions
xylazine is contraindicated for use in pregnant ___ and ___ ?
cows and ewes
what unique response can be seen in cats after administration of ketamine?
prolonged recovery
what might happen to a dog after being sedated with acepromazine?
may see behavioural changes
what details of past/current illnesses should be acquired with patient hx?
- preexisting disease
- changes in behaviour
- exercise intolerance
- weakness
- fainting and/or seizures
- unexplained bleeding
why would it be important to use a consistent technique when doing physical assessments?
to avoid missing any areas of the body - need to examine the entire patient
what four factors of patient appearance should be assessed?
- symmetry
- mentation
- posture/gait
- hydration status
t/f - patient dose is based on lean body weight
true
how can you assess the hydration status of a patient?
- skin turgor
- placement of eye in orbit
- mucous membrane colour, capp. refill time
- heart rate//pulse strength
once the hydration is assessed, what must be done before anesthesia?
must correct any hydration abnormalities
when taking TPR values, what is important to observe with patient respiration?
what the character of respiration is - how much effort are they exerting to breathe?
what exterior surfaces would you assess on PE?
- hair coat
- skin
- lymph nodes/mammary glands
- body openings (odours, discharge)
- eyes, ears, nose, throat
what is it called when the pupils are normally two different sizes?
anesicoria
why would you want to assess the patient’s haircoat?
hair loss can be proof of infectious and non-infectious conditions
how does thoracic auscultation differ from taking the heart rate?
listens for murmurs, arrhythmias, crackles, wheezes, etc.
t/f - thoracic auscultation is performed by an RVT prior to anesthesia
true - h/e the DVM should also perform prior to anesthesia
why is it important to listen over each valve of the heart?
there can be turbulence in blood flow through only one valve or multiple, need to assess all for heart murmurs
t/f - patient resps are proportional to body size
false - patient resps are inversely proportional to body size - small animal, higher resp rate
what is “stertor” ?
brachycephalic noise caused by their elongated/thickened soft palate
what is stridor?
brachycephalic laryngeal noise
what is dyspnea?
shortness of breath
what is cyanosis?
blueish colour to mucous membranes
what do crackles indicate? (in lung sounds)
moisture in the airways
how many quadrants need to be examined when ascultating the lungs?
four
what preanesthetic diagnostic tests/procedures need to be completed?
- CBC
- urinalysis
- blood chemistry
- blood coagulation screens
- electrocardiogram (ECG)
- radiography
how do you determine the physical status classification of a patient?
based on evaluation of the MPD
what does the physical status classification represent?
rates patient anesthetic risk
what are the levels of patient risk and what do they represent?
PS1 - minimal risk PS2 - low risk PS3 - moderate risk PS4 - high risk PS5 - extreme risk
define anesthesia
loss of sensation; one extreme in a continuum level of CNS depression
define general anesthesia
reversible state of unconsciousness, imobility, muscle relaxation and loss of sensation
define surgical anesthesia
analgesia and muscle relaxation; eliminates pain and patient movement
define local anesthesia
targets a small, specific area of the body; drug is infiltrated into desired area to cause loss of sensation
define topical anesthesia
applied to body surface or wound; produces a superficial loss of sensation
define regional anesthesia
loss of sensation to a limited area of the body; examples are nerve blocks and epidural anesthesia
what is balanced anesthesia?
using multiple drugs in smaller quantities for anesthesia
what are the two main advantages to balanced anesthesia?
- maximizes benefits of drugs
2. minimizes adverse effects
what is an RVT’s role as an anesthetist?
- prep/operate/maintain anesthetic machine
- administer anesthetic agents
- perform endotracheal intubation
- patient monitoring
what are some challenges and risks associated with anesthesia?
- dose calculation and rate adjustment
- vital signs and anesthetic depth
- assessing multiple pieces of information
- patient management
- accidents
why is it so crucial to monitor the patient’s cariovascular and pulmonary systems during anesthesia?
drugs may cause changes in the systems which can in turn be lethal
what is an endotracheal tube and what does it do?
flexible tube placed in the trachea; delivers anesthetic gases directly from the machine to the lungs
what are some advantages of using an endotracheal tube?
- opens airway
- less anatomical dead space
- precision administration of anesthetic agent
- prevents aspiration
- responds to respiratory emergencies
- monitors respirations
what are some different kinds of ET tubes?
- murphy tubes - beveled end and side holes; possible cuff
2. cole tubes - no side hole or cuff; used in birds and reptiles
why would a polyvinyl chloride ET tube be preferable over a red rubber?
the polyvinyl are clear and stiffer where the red rubber may kink or collapse in the patient
why would silicone ET tubes be a good choice?
it is pliable, strong, less irritating and resists collapse
how and why are tube cuffs used?
high volume/low pressure; used for short term intubation - pressure is distributed evenly along the cuff length
low volume/high pressure; potential tissue damage
why are cuffless tubes on non-inflated cuffs used?
used in small animals to reduce the risk of tracheal damage
what is a laryngoscope?
a tool used to increase visibility of the larynx while placing an ET tube
t/f - the same laryngoscope can be used for both small and large animals
false - small animals use 0-5 inch blade; large animals use up to an 18 inch blade
what does a subglottic airway device do?
allows airway management without invading the tracheal lumen
what are some advantages to a SAD?
- decrease in laryngospasm
- resistance to breathing
- decreased risk of airway trauma
- no post-op coughing
t/f - masks are used to administer oxygen and anesthetic gases to intubated patients
false - masks are used when the patient is not intubated
what are the four components of the anesthetic machine?
- compressed gas supply
- anesthetic vaporizer
- breathing circuit
- scavenging system
what oxygen level is required to maintain cellular metabolism under anesthesia?
30% oxygen
what purpose does the compressed gas supply (oxygen) serve?
used to increase inspired air to at least 30% O2
used to carry vaporizedd anesthetic to patient
what is the difference between E tanks and H tanks?
E tanks - small, attached directly to anesthetic machine
H tanks - large, attached remotely to anesthetic machine
where is the control valve located?
on top of the tank
what is the control valve used for?
an outlet port; can be loosened or tightened
what does the pressure reducing valve do?
reduces outgoing pressure to a usable level
when should the primary and secondary oxygen supplies be checked?
at the beginning and ending of every day
t/f - the compressed gas valve is turned counter clockwise to open
true
what happens when the valve stem is turned completely clockwise?
gas flow stops
how do you release line pressure?
depress the O2 flush valve or open the valve until all gas is vented
what are some safety issues associated with compressed gas?
- combustability
- yoke attachment
- high-pressure release
- storage
- colour coding (knowledge)
what colour are oxygen cylinders in canada?
white
what kind of gas is contained within a blue cylinder?
nitrous oxide
what is the tank pressure gauge used for?
to indicate the pressure of gas remaining in the cylinder; determines the number of liters remaining in a tank
what does the pressure-reducing valve do?
reduces gas pressure to a constant 40-50 psi
what is another name for the pressure-reducing valve?
pressure regulator
what does the line pressure gauge do?
indicates pressure in the gas line between the pressure-reducing valve and the flowmeter
what should the line pressure gauge read when the oxygen tank is opened?
40-50 psi
what must you do after turning the tank off?
evacuate line pressure until the gauge reads 0 psi using the oxygen flush valve
what does the flowmeter do?
- indicates gas flow expressed in liters per minute (L/min)
- reduces pressure of gas to 15 psi
who controls the flow rate during anesthetic procedures?
the anesthetist (RVT)
what is the purpose of the oxygen flush valve?
- delivers a short, large burst of pure oxygen directly into the rebreathing circuit or common gas outlet
- bypasses vaporizer and flowmeter
- used to refill breathing bag or to dilute anesthetic gas remaining in circuit at the end of anesthesia
when should you NEVER use the oxygen flush valve?
when the patient is hooked up to the breathing circuit
what does the anesthetic vaporizer do?
converts liquid anesthetic agent to a gaseous state; adds a controlled amount of vaporized agent to the carrier gas
how does the gas mixture leave the vaporizer?
through the outlet port
what is fresh gas?
mixture of vaporized anesthetic agent and carrier gas that enters the breathing circuit
how does the carrier gas (oxygen) get into the vaporizer to create fresh gas?
vaporizer inlet port; the oxygen exits the flowmeter into the inlet port
what are the different kinds of anesthetic vaporizers?
- non-precision
2. precision
t/f - non-precision vaporizers are safer, and used more often than precision
false - non-precision vaporizers deliver low pressure vapor based on estimation
how are precision vaporizers used?
deliver a precise amount of anesthetic to the patient; high vapor pressure that is controlled by the anesthetist
what factors affect vaporizer output?
- vaporizer setting
- carrier gas flow
- temperature (most modern vaporizers are compensated)
what color indicates isoflurane vaporizer?
purple
what colour indicated sevoflurane vaporizer?
yellow
what are the induction and maintenance rates of isoflurane and sevoflurane?
isoflurane - 3-5% induction; 1.5-2.5% maintenance
sevoflurane - 4-6% induction; 2-4.5% maintenance
what do you do to turn on the vaporizer?
- depress safety lock
2. turn dial to desired level (measured in percent concentration)
how full should the vaporizer be kept? what can happen if the level is incorrect?
should be at least half-full; if over full can result in overdose, if underfull can cause difficulty to keep patient anesthetized
what happens at hte vaporizer outlet port?
- oxygen/anesthetic exits vaporizer
2. connected to the common gas outlet or directly into breathing circuit
what happens at the common gas outlet?
fresh gas outlet; connected to the vaporizer outlet port and breathing circuit
what does the breathing circuit do?
- carries anesthetic and oxygen from the fresh gas inlet to the patient
- conveys expired gases away from the patient
what are the two types of breathing circuits?
- rebreathing
2. non rebreathing
how does a rebreathing system work?
- circle system
- not used on very small animals
- carbon dioxed is removed from exhaled air (in canister)
- exhaled air is inhaled again with added oxygen and anesthetic
how does air flow through a rebreathing system?
- inhalation unidirectional valve
- inhalation tube
- animal
- exhalation tube
- exhalation unidirectional valve
- carbon dioxide absorber canister
- past reservoir bag
- pop-off valve
- pressure manometer
- inhalation unidirectional valve
how is a closed rebreathing system different from a semi-closed rebreathing system?
closed is a total system; pop-off valve is nearly or completely closed; oxygen flow is low - used mostly for large animal
how is a semi-closed rebreathing system different from a closed rebreathing system?
partial system; pop-off valve is open and oxygen flow is high - excess air is released into scavenging system
t/f - it is rare to come across semi-closed rebreathing system in modern practice
false - semi-closed rebreathing is the most common configuration
what are the parts that compose a rebreathing system?
- fresh gas inlet
- unidirectional valves
- reservoir bag
- pop-off valve (pressure relief)
- carbon dioxide absorber canister
- pressure manometer
- air intake valve
- corrugated breathing tubes
- y-piece
what do unidirectional valves do?
- control the direction of gas flow (inspiratory, expiratory)
- open and close as patient breathes
- monitor respiratory rate and depth
- monitor for sticking due to condensation
what does the pop-off valve allow for?
- excess carrier and/or anesthetic gases to exit the breathing circuit and enter the scavenging system
- prevents excessive pressure or gas volume in the circuit
what position should the pop-off valve be in when manually ventilating a patient?
closed
what does the reservoir bag do?
- provides a flexible air storage reservoir
- indicates respiratory rate and depth
- confirms proper endotracheal tube placement
t/f - the reservoir bag can deliver anesthetic gases or pure oxygen to the patient
true
why would you manually ventilate a patient?
to force fresh gas into alveoli to normalize gas exchange; this normalizes the respiratory rate
t/f - manual ventilation minimizes atelectasis
true
how often should you ventilate the patient when bagging them?
every 5-10 minutes
what is contained within the carbon dioxide absorber canister? what happens when carbon dioxide is absorbed?
contains absorbent granules (calcium hydroxide) - granules react with carbon dioxide to form calcium carbonate
what should the capnograph read if the cannister is expired?
anything greater than zero indicates an expired cannister
what does the pressure manometer do?
indicates the pressure of gases within the breathing circuit
what unit does the pressure manometer express?
centimeters of water
how many centimeters of water are used when ventilating small and large animals, respectively?
small animals - 20 cm H2O
large animals - 40 cm H2O
what does the pressure manometer do when bagging a patient?
prevents excessive pressure in the lungs
what does the air intake valve do?
aka negative pressure relief valve - admits room air into the circuit if negative pressure is detected in the breathing circuit
what is a sure sign of negative pressure in the circuit?
collapsed reservoir bag
what will the patient develop if negative pressure enters the circuit ?
hypoxemia
t/f - negative pressure is sometimes okay when performing anesthesia
false - we NEVER want negative pressure
how many sizes do breathing tubes come in? what are they?
three; 50mm, 22mm and 15mm
what does the breathing tube connect to?
unidirectional valve and y-piece
what size patient requires a non-rebreathing system?
<7 kg
how does a semi-open system work?
exhaled gas is evacuated by the scavenging system, fresh gas is routed to the patient directly from the vaporizer - no carbon dioxide absorber canister, pressure manometer or unidirectional valves
components of a semi-open non-rebreathing sytstem?
endotracheal tube connector, fresh gas inlet, reservoir bag, overflow valve, scavenger tube and scavenger system
what are the two main configurations of non-rebreathing circuits?
- bain coaxial circuit
2. ayres t-piece
what is the benefit of a coaxial circuit?
exhaled gas comes through the outside tube - this warms the inhaled air slightly
what is the animal’s dead space?
the space from the mouth down to the lungs
what is considered the machine’s dead space?
all the way through the animal to the inspired gas
what is the danger with resistance?
any increased resistance to inspiration or expiration will cause an anaesthetized animal to breathe less effectively
what causes resistance on inspiration?
- gas level too low
2. tube is kinked
what causes resistance on expiration?
- kink in the tube
- wrong bag
- pop off isn’t open
- natural resistance through canister
t/f - smaller diameter greatly increases resistance
true
what is circuit drag?
the weight of hoses, machinery, etc. can cause the endotracheal tube to come out of the patient
t/f - when choosing an endotracheal tube you want to pick the smallest option
false - you want to place the largest tube possible without causing trauma
how do you calculate bag size?
tidal volume x 6
tidal volume - 10-20ml/kg
do non-rebreathing systems require high or low flow rates?
high flow rates based on patient body weight
calculate flow rate ?
200-300 ml/kg/min
what is the minimum flow rate?
500 ml/min
define an anesthetic agent
any drug used to induce a loss of sensation with or without unconsciousness
define adjunct
a drug that is not a true anesthetic but that is used during anesthesia to produce other desired effects such as sedation, muscle relaxation, analgesia, reversal, neuromuscular blockade or parasympathetic blockade
t/f - inhalants are the first drugs given during anesthetic procedures
false - inhalants are the last drugs administered
what happens if inhalants are used on their own?
patient recovery will be stormy, no pain control
what are some examples of inhalant anesthetics?
- isoflurane, sevoflurane and desflurane
- nitrous oxide
- halothane
- diethyl ether
is diethyl ether still used in anesthetic procedures?
no
t/f - halogenated organic compounds (like isoflurane) are stored as vapor at room temperature?
false - they are liquid at room temperature and vaporized in oxygen that flows through
what are some adverse effects of halogenated organic compounds?
- increased intracranial pressure (head trauma/brain tumors)
- hypothermia
- decreased blood pressure
- hypoventilation (dose dependent)
- carbon dioxide retention/respiratory acidosis
what are some important properties to consider with inhalant anesthetics?
- vapor pressure
- partition coefficient
- minimum alveolar concentration
- rubber solubility
what is vapor pressure?
the tendency of an inhalation anesthetic to vaporize to its gaseous state; how readily an inhalation anesthetic will evaporate in the anesthetic machine vaporizer
t/f - volatile agents require high pressure
true
what are some examples of volatile agents?
- isoflurane
- sevoflurane
- desflurane
t/f - volatile agents are delivered from a non-precision vaporizer
false - volatile agents are delivered from precision vaporizers only
what kind of vapor pressure is required for non-volatile agents?
low vapor pressure
what is the blood-gas partition coefficient?
the measure of solubility of an inhalation anesthetic in blood compared to air (alveolar gas)
what does the blood-gas partition coefficient indicate?
the speed of induction and recovery
t/f - a low blood-gas partition coefficient means a slower expected induction and recovery
false - low blood-gas is indicative for faster expected induction and recovery
is it more desirable to have a low blood-gas partition coefficient or a high blood-gas? why?
it is more desirable to have low blood-gas becuase the agent is more soluble in alveolar gas than blood - this means more drug is inhaled and less is absorbed by blood and tissues
why might a high blood-gas coefficient cause a slower induction and recovery?
because the drug is more soluble in the blood than alveolar gas, it takes longer for the patient to receive drug because more is being absorbed into the tissues
how does a low solubility coefficient work?
inhalant builds up to high concentrations in the pulmonary alveoli - steep diffusion gradient between alveoli and tissues - this causes a rapid entry into blood stream and passage into the brain - rapid induction and recovery
t/f - low solubility coefficient inhalants have a long time interval to change anesthetic depth
false - they have a short time interval to change anesthetic depth
what is an example of a low solubility coefficient inhalant?
isoflurane
why are high solubility coefficient inhalants less effective than low?
inhalant builds up quickly in blood and tissues but is widespread with less concentration in the brain
what does MAC stand for ?
minimum alveolar concentration
what is the MAC used for?
to measure a drug’s potency - used to determine the average setting on the vaporizer to produce anesthesia
t/f - a lower MAC would indicate a less potent agent and lower vaporizer setting
false - a lower MAC is indicative of a more potent agent (and lower vaporizer setting)
what two species is isoflurane approved for use in?
dogs and horses
what are the physical and chemical properties to be aware of for isoflurane?
- high vapor pressure; precision vaporizer
- low blood-gas PC; rapid induction/recovery
- MAC 1.3-1.63%
- low rubber solubility
- stable at room temp
- fewest adverse cardiovascular effects
- depresses respiratory system
- maintains cerebral bloodflow
- almost completely eliminated through the lungs
- induces adequate muscle relaxation
what might isoflurane producde if exposed to desiccate carbon dioxide absorbent?
carbon monoxide
what properties should be considered for sevoflurane?
- high vapor pressure; precision vaporizer
- low blood-gas
- high controllability of depth of anesthesia
- MAC 2.34-2.58%
how are anesthetic agents and adjuncts classified?
- route of administration
2. time of administration
what are agonists?
most anesthetic drugs; bind to and stimulate target tissue
what are antagonists?
reversal agents; bind to target tissue but don’t stimulate
how are opioids different than agonists or antagonists?
they can be partial agonists, agonist-antagonists and can block pure agonists
t/f - if a drug combination develops a precipitate when mixed in a syringe you can still administer it
false - never administer a drug if a precipitate forms
t/f - you can mix drugs in a single syringe if they are compatible
true
what drug can only ever be mixed with ketamine?
diazepam - it is not compatible with any other drug available
is diazepam water soluble?
no
is midazolam water soluble?
yes
what is the purpose of preanesthetic medications?
- calm or sedate excited animal
- minimize adverse drug effects
- reduce dose of concurrent drugs
- smoother induction and recovery
- analgesia
- muscle relaxation
what are preanesthetic anticholinergics?
parasympatholytic drugs - they work against the parasympathetic system to prevent and treat bradycardia - increases heartrate and decreases secretions
what do parasympatholytic drugs block?
acetylcholine
what are two examples of preanesthetic anticholinergics?
- atropine
2. glycopyrrolate
when might atropine be used?
when animal is arresting
what are some adverse effects of anticholinergics?
- cardiac arrhythmia
- temporary bradycardia
- thickened respiratory and salivary secretions
- intestinal peristalsis inhibition
what kinds of drugs fall under tranquilizers and sedatives?
- phenothiazines
- benzodiazepines
- alpha 2-adrenoceptor agonists
- alpha 2-antagonists
what species are approved for use of acepromazine?
horses, dogs and cats
what family of drug is acepromazine related to>
phenothiazines
t/f - acepromazine has a reversal agent
false
where is acepromazine metabolized? what patients might this be a concern for?
metabolized by liver; contraindicated for use in patients with liver disease
what is the half life of acepromazine in canines?
4.5 hrs
how does acepromazine effect the body?
- calming effect on CNS ; decreased interest in surroundings
- protects cardiovascular system against arrhythmias and decreases cardiac output
- mild antiemetic effects
what are some adverse effects of acepromazine?
- may produce aggression or excitement
- peripheral vasodilation (hypotension, increased heart rate, hypothermia)
- penile prolapse (horses)
what special consideration is given to drugs ending in -epam?
these are controlled drugs
what reversal agent is used for benzodiazepines?
flumazenil (limited availability)
t/f - benzodiazepines have a rapid onset of action
true
do all benzodiazpenes have the same duration of action?
no - duration varies with drug
what receptors do benzodiazepines act on?
gaba receptors
what are some effects of benzodiazepines?
calming and anti-anxiety, anticonvulsant
adverse effects of benzodiazepines?
- disorientation and excitement (young dogs) 2. dysphoria and aggression (cats)
t/f - diazepam can be given by rapid IV
false - diazepam must be given by IV slowly !
what can happen if cats are given oral diazepam?
fatal liver necrosis
what drug is commonly administered with diazepam to induce anesthesia in small animals?
ketamine
what makes midazolam unique from diazepam?
it is water soluble
does diazepam or midazolam have a shorter half life?
midazolam - 1 hr (vs. diazepam - 3 hrs)
are alpha 2 agonists controlled agents?
no; they are non-controlled
what effects do alpha 2 agonists produce?
- sedation
- analgesia
- muscle relaxation
what agents readily reverse alpha 2 agonists?
alpha 2 antagonists
what are some examples of alpha 2 agonists?
- xylazine
- dexmedetomidine (dexdomitor)
- detomidine (dormosedan)
- romifidine (sedivet)
how do alpha 2 agonists act on the body?
take away fight or flight response by decreasing the release of norepinephrine
where are alpha 2 agonists metabolized? excreted?
the liver; urine
do alpha 2 agonists cause rapid or slow sedation?
rapid; duration depends on species and drug of choice
how do alpha 2 agonists effect the cardiovascular system? (early phase)
- vasoconstriction and hypertension
- bradycardia
- arrhythmias
how do alpha 2 agonists effect the cardiovascular system? (late phase)
- decreased cardiac output
2. hypotension
t/f - alpha 2’s cause an immediate vomiting response in dogs and cats
true
what are some adverse effects of alpha 2’s ?
- change in behviour
- increased myocardial O2 consumption
- decreased cardiac output
- increased systemic vascular resistence
- respiratory depression
- increased urination
- bloat
- premature parturition (cattle)
- absorbed through skin abrasions and MM
- sweating (horses)
what patients should alpha 2’s be avoided in?
geriatric, diabetic, pregnant, pediatric or ill
t/f - dexdomitor (dexmedetomidine) is safer and more potent than xylazine
true
what antagonist is used to reverse dexmedetomidine?
atipamazole (antisedan)
can dexdomitor be safely combined with other drugs?
yes
what combination is commonly referred to as “kitty magic”?
- ketamine
- opioid (hydromorphone or butorphanol)
- dexdomitor
what species do we use detomidine in?
horses
is detomidine longer or shorter acting than xylazine?
longer - 2x duration
what is important to remember if administering an alpha 2 antagonist?
they reverse ALL effects of alpha 2 agonists - beneficial and detrimental
when should the dose of antagonist be reduced?
if more than 30 minutes has passed since administering the agonist
what is yohimbine used to reverse?
xylazine
how long does it take to see the effects of atipamezole (antisedan) after administration?
5-10 minutes
what are some commonly used opioids? what are their classifications?
- agonists
- morphine
- hydromorphone
- oxymorphone
- fentanyl
- meperidine - partial agonist
- buprenorphine - agonist-antagonists
- butorphanol
- nalbuphine - antagonists
- naloxone
- etorphine
- carfentenil
t/f - opioids do not have a wide margin of safety
false - they do have a wide margin of safety
where do opioids act on the body?
on mu, kappa and delta receptors; action on the receptors and spinal cord
what type of opioids act on mu and kappa receptors?
agonists
what level of pain is ideal for agonists?
moderate to severe pain
agonist-antagonists bind to mu and kappa receptors but only stimulate one - which is it?
agonist-antagonists stimulate kappa receptors
what effects do opioids cause in dogs?
- sedation
2. narcosis
what is narcosis?
narcotic-induced sleep
what effects do opioids have on cats/horses/ruminants?
- CNS stimulation
2. bizarre behaviour/dysphoria
what specific type of agonists are most effective against severe pain?
pure agonists
opioids can effect the pupils of dogs, cats and horses - what are their respective effects?
dogs - miosis (small pupils)
cats/horses - mydriasis (large pupils)
t/f - opioids can cause dogs to become hyperthermic
false - can cause dogs to become hypothermic
do opioids cause temperature changes in cats?
yes - can cause hyperthermia in cats
t/f - opioids cause increased urine production
false - cause decreased urine production
what are some adverse effects of opioids?
- anxiety/disorientation/dysphoria
- bradycardia
- decreased respiration
- ceiling effect (some agents)
- salivation and vomiting
what is the biggest respiratory concern with opioids?
respiratory suppression
t/f - intraocular and intracranial pressure are increased under opioids
true
define neuroleptanalgesia
use of a sedative and an opioid
what 2 uses do opioids have in surgical procedures?
- preanesthetic meds
2. analgesia
why is it important to know the half life of a drug you are reversing with naloxone hydrochloride?
if the half life of the drug you reversed is longer than the duration of action, you may see patient go down again depending on how much drug has been metabolized in their system
how long is the duration of action for naloxone?
30-60 minutes
what are some indicatiosn for use of trazodone?
- anxiety patients
- pre-op to reduce stress
- post-op to allow better recovery
what is the mode of action for trazadone?
serotonin antagonist; blocks serotonin reuptake at presynaptic neuorn
what unique situation may cause us to see aggression in patients once they are put on this medication?
if aggression has been suppressed due to fear - now the animal is at ease and the aggression can come out
why would trazodone be used with other behaviour meds?
it has a faster onset of action while waiting for other medications to start working (4-6 weeks)
what are the indications for use of gabapentin?
used for its analgesic and anxiolytic qualities
what is unique about gabapentin as an analgesic?
it works at the nerve level to relieve neurogenic pain
what can gabapentin be combined with to control patient pain?
gabapentin and an NSAID
what is the generic name for Cerenia?
maropitant
what are the indications for use of cerenia?
anti-emetic; prevents vomiting from premedication, helps patients eat faster post-op
t/f - cerenia has some effect on visceral pain
true
what does the acronym PISS stand for ?
pin index safety system
what does the acronym DISS stand for?
diameter index safety system
t/f - when giving injectable anesthetics we give the full dose in the syringe
false - iv anesthetics are administered “to effect”
t/f - injectable anesthetics can be used on their own to produce general anesthesia
false - must be used with other agents to produce complete effects of GA
what is propofol?
ultra short acting, non-barbituate anesthetic
what is propofol used for?
- induction
2. short term maintenance
what special exception is made for propofol IV ?
the solution is milky but it is okay to administer (it is fat soluble)
how long is the onset of action for propofol?
30-60 seconds
how long is the duration of action of propofol?
5-10 minutes
how does a patient’s plasma protein level effect administration of propofol? why?
propofol binds to protein so if plasma protein is low there will be more drug free-flowing and potency will be higher
t/f - propofol is rapidly removed from the brain by tissue redistribution
true
how does bloodflow affect the action of propofol on the body?
after iv administration the highest areas of blood flow will receive the most drug; this happens through tissue redistribution
how does propofol effect the CNS ?
- dose-dependent depression (sedation-GA)
- transient excitement/muscle tremors
- seizure-like signs
how does propofol effect the cardiovascular system?
- depressant
2. transient hypotension
how does propofol effect the respiratory system?
- possible apnea (post induction)
why do you need to ensure the patient is breathing in gas post-induction? (propofol)
if they are not breathing in gas, they can wake up within 5 minutes
what may happen if propofol is administered too slowly?
may cause excitement in the patient
how can you reduce the risk of apnea when using propofol?
use with another pre-medication (lower dose)
how long does it take for dogs and cats to fully recover from the effects of propofol?
dogs - 20 minutes
cats - 30 minutes
what are some general characteristics of alfaxalone?
- short duration of action
- wide margin of safety
- use IV for induction and maintenance
- use IM in cats for deep sedation/light anesthesia
what are some effects of alfaxalone?
- dose-dependent CNS depression
- can cause apnea
- hypotension
what are some risks associated with alfaxalone?
- patient can easily wake up
2. can cause hypoxia
t/f - alfaxalone does not require intubation
false - intubation is necesary
how long does alfaxalone last in dogs and cats?
dogs - 10-15 minutes
cats - 15-20 minutes
is it safe to combine alfaxalone with other injectable anesthetics?
no
what is the most commonly used barbituate?
thiopental (pentothal)
what are the characteristics of thiopental?
- high lipid solubility
2. rapid anesthetic effect, rapid recovery
how are the effects of thiopental terminated?
through redistribution of drug into body fat
what are some risks associated with thiopental?
- splenic enlargement
- avoided in sighthounds
- very rarely used
what are 2 examples of dissociative anesthetics?
- ketamine
2. tiletamine
t/f - dissociative anesthetics are used with other drugs to induce general anesthesia
true
are dissociatives controlled?
yes
t/f - dissociatives have no pain control
false - have good pain control at low doses
what does an animal look like when under dissociative anesthesia?
trancelike state; animal appears awake but is immobile and unaware of surroundings
t/f - dissociative anesthetics decrease windup through NMDA inhibition
true
are the patient’s reflexes intact when under dissociative anesthesia?
yes
how do dissociatives effect the cardiovascular system?
increased heart rate, cardiac output, and blood pressure
what is apneustic respiration? when might we see it?
animal inhales, looks like they hold their breath and then they exhale ; might see at higher doses of dissociatives
adverse effects of dissociatives?
increased intracranial and intraocular pressure
t/f - there is one effective reversal agent for dissociative drugs
false - there is no effective reversal agent
when does IV ketamine reach it’s peak action?
1-2 minutes after injection
when does IM ketamine reach it’s peak action?
10 minutes after injection
what is ketamine’s duration of effect?
20-30 minutes; increasing the dose will prolong duration but will not increase the anesthetic effect
KetVal is the trade name for what drug combination?
ketamine and valium (diazepam)
what is KetVal used for?
IV induction
t/f - KetVal has a rapid onset of action
true - 30-90 seconds
how long is the duration of action of ketval?
5-10minutes
how long does it take for patients to recovery after being under ketval?
30-60 seconds
what are some advantages to the ketamine diazepam combination?
- minimal cardiac depression
- good muscle relaxation
- superior recovery
- some analgesia
what are some disadvantages to ketamine/diazepam combination?
- possibility of respiratory depression is greater in combination
- cannot use IM (midazolam can be used in place)
what three drugs compose “kitty magic” ?
- dexdomitor
- ketamine
- opioid
how can you easily reverse the effects of dexdomitor?
administer a half of dose of antisedan
what is guaifenesin?
a non-controlled muscle relaxant
t/f - guaifenesin is an anesthetic drug
false - it is neither anesthetic or analgesic
at what point of the anesthetic procedure is guaifenesin used? what other drug is it combined with?
used with ketamine during induction protocol
t/f - guaifenesin is administered with a slow IV drip
false - administered rapidly IV until animal is ataxic
what species do we use guaifenesin for?
horses
what risks are involved if guaifenesin is used without premedication?
- may cause excitement
2. increased risk of side effects
can guaifenesin be used as a sole agent?
no; the sedation/analgesia are inadequate for surgery
what are the adverse effects of propofol? how can you prevent it?
- apnea
- bradycardia
- hypovolemia
minimize risk by titrating to effect
how many ET tubes should you set out to prepare for intubation? how do you pick?
3 tubes; one based on weight, one a half size smaller, one a half size larger
what position must your patient always be in for intubation?
sternal recumbency
t/f - it is best practice to preoxygenate for 3 minutes prior to intubation
true - especially for brachycephalic breeds
what should you always assess before intubating your patient?
depth of anesthesia
what do you need to be cautious of when intubating a cat?
largynospasm - can be avoided by using a local anesthetic
what is the opening called where you insert the endotracheal tube?
glottal opening
t/f - the endotracheal tube should be advanced on expiration
false - should be advanced on inspiration
how should you react to a patient coughing or resisting on intubation?
stop immediately and administer more induction agent
how can you confirm the placement of the ET tube?
- look for condensation in the tube
- watch reservoir bag for movement
- palpation of neck
how do you inflate the cuff?
use a syringe with 0.5ml increments until no leak is heard when reservoir bag is squeezed and pressure in the breathing circuit is 15cm H2O
