Block 1 Flashcards
What is the physical status?
This is the assessment of systemic risk in relation to ASA standards
What is level 1 ASA?
Healthy patient
What is level 2 ASA
Patient with mild system disease
What is level 3 ASA?
Severe systemic disease but well controlled
What is level 4 ASA?
Severe systemic disease but threat to life
What is level 5 ASA?
Not expected to live for more than 24h without intervention
What is level 6 ASA?
Patient is being used for organ donation
What do agonists do?
Activate that specific receptor
What do antagonists do?
Block that specific ligand
What are 4 mechanisms of action of acepromazine?
Blockade of dopamine receptors in forebrain
Serotonin antagonist (5-HT1, 5-HT2)
Blockade of alpha-1 adrenergic receptors in vasculature
Inhibitory effect on P-glycoproteins and alter uptake of other drugs into brain
What a potential genetic issue with acepromazine?
Dogs with MDR1 mutation may increase toxicity due to ATP-binding transporters
What is dopamine 1 receptor?
Post-synaptic and causes vasodilation of splenic and renal circulations
What is dopamine 2 receptor?
Pre-synaptic and causes norepinephrine release
What causes vasodilation with acepromazine?
alpha 1 adrenergic receptor blockade
How long will vasodilation with acepromazine last?
Longer than the sedation because the alpha-1 receptor affinity is greater than the dopamine receptor affinity. So sad
What is the horse penis side effect of acepromazine
Paraphimosis
What kidney issue may occur due to acepromazine
Decreased systemic vascular resistance causes increased renal perfusion
What happens with the spleen with acepromazine?
Splenic engorgement causing a decrease in PCV by 20-30%
What happens with histamines with acepromazine?
Antihistaminic effect due to an H1 receptor blockage
Where is acepromazine metabolized?
The liver
Does acepromazine have analgesic effect?
No but can enhance analgesic effect of other drugs
What happens to the muscles during acepromazine?
Muscle relaxant, may see 3rd eyelid prolapse
How can you administer acepromazine?
Any way
Is acepromazine reversible?
NOT REVERSIBLE!
What is the time to clinical effect of acepromazine IM and IV?
IM: 30min
IV: 10-15min
Is acepromazine an antiemetic?
Yes!
What are the 2 most common alpha-2 agonists?
Xylazine and dexmedotomine
What is the main mechanism of action of alpha 2
Bind to alpha 2 and 1 receptors in CNS and PNS
Activation causes hyper polarization of cells causing decreased cellular activity
What is the ligand for alpha 2?
norepinephrine
Which receptor specifically causes sedation and supra spinal analgesia for alpha 2 receptor?
Alpha 2A (maybe alpha 2D in certain species)
How are alpha 2 agonists metabolized?
Liver and excreted in urine
What are the 4 cardio effects of alpha 2 agonist?
Vasoconstriction and hypertension (alpha 2B) then vasodilation (alpha 2A)
Peripheral vasoconstriction (alpha 1 receptor)
HR decreases (baroreceptor reflex)
Decreased CO (30-50%)
What are 2 respiratory effects of alpha 2 agonists?
Decreased respiratory rate
Stridor or dyspnea from muscle relaxation
What are 2 musculoskeletal effects of alpha 2 agonist?
Great muscle relaxers
Base-wide stance in horses
What happens to salivation with alpha 2 agonists?
Decreased salivation but a suppressed swallow reflex (more saliva in mouth)
What happens to blood glucose with alpha 2 agonist?
Increased due to a suppression of insulin release
What are 2 urinary effects of alpha 2 agonists
Anti-ADH and decreased tubular reabsorption of sodium causing low urine specific gravity
Decreased renal perfusion due to vasoconstriction
What is the main contraindication of alpha 2 agonist?
Heart disease (vasoconstriction)
What is the ratio of tolazoline with alpha1:alpha2
1:1
What happens if you reverse tolazoline in a camelid
Death
How are alpha 2 agonists reversed?
With alpha 2 antagonists
What is the alpha 2 antagonist used for xylazine?
Yohimbine
What is the alpha 2 antagonist used for dexmeditomidine/
Atipamezole
Who is most and least sensitive to xylazine?
Most: Ruminants (100x)
Least: Pigs
What is a stronger alpha 2 agonist for horses?
Detomidine (dormosedan)
What are 5 main affects of benzodiazepines?
Sedation
Relaxation (anxiolytics)
Anticonvulsants
Muscle relaxant
Amnesia
What receptor do benzos work on?
GABA
What subunit does the sedative effects come from on the GABAa?
Alpha-a
What subunit does the anxiolytic effects come from on the GABAa?
Alpha-b
What subunit does the muscle relaxation effect come from on the GABAa?
Either a or b
Which benzodiazepine has a shorter onset and a more potent effect due to greater affinity for receptor?
Midazolam
Which benzo is more lipid soluble?
Diazepam (brain?)
How is midazolam metabolized?
hepatic, intestinal
Is midazolam excretion affected by renal failure?
NO!
How is diazepam metabolized?
Hepatic (excreted in urine)
What is the toxicity associated with diazepam?
Long term use of diazepam has seen hepatic necrosis
What are the cardiovascular effects using benzodiazepines
None
What are the respiratory effects using benzodiazepines
Depression of swallow reflex
What are the musculoskeletal effects using benzodiazepines
Muscle relaxation
What are the GI effects using benzodiazepines
appetite stimulant in cats and goats
delayed gastric emptying in cats
What behavioral thing can be seen in benzodiazepines?
Paradoxical effect - excitement
Is there analgesia with benzodiazepines?
No!!!
What is the reversal (antagonist) for benzodiazepines
Flumazenil
How is flumazenil metabolized?
Hepatic
How can you administer midazolam?
IV, IM, or PO
How can you administer diazepam?
IV or PO
What is neuroleptanalgesia
Combination of an opioid with a sedative or tranquilizer
What is the benefit of neuroleptanalgesia?
Increase sedative and analgesic effect
Decrease dosage of both
What is the main effect of opioids?
Analgesia
What are the 2 opioid receptors?
Mu and Kappa
What are the 4 classifications of opioids?
Opioid agonists
Opioid partial agonists
Opioid agonist-antagonist
Opioid Antagonist
What classification of opioids stimulate all types of receptors?
Opioid agonists and partial agonists
What classifications of opioid receptors stimulate some receptors and block others?
Opioid agonist-antagonists
What classification of opioid receptors block all receptors?
Opioid antagonists
What are 4 opioid agonists?
Fentanyl
Hydromorphone
Morphine
Methadone
Of the full agonists, which one is not used for premed because it is short acting?
Fentanyl
Which opioid classification provides the highest level of analgesia but also the highest incidence of side effects?
Full agonists
How long does fentanyl last?
20 minutes
How long do other full agonists last?
3-4 hours
Why do partial agonists last longer?
Bind very tightly to mu receptor causing longer lasting effects
How long does buprenorphine last?
6-8 hour (roughly 2x as long as full)
What are the receptors of a agonist/antagonist?
Kappa agonist / Mu antagonist
What is the length of kappa/mu?
Short duration (1-2h)
What species are kappa/mu usually used in?
Large animal
What happens to full agonist with kappa/mu?
Bind tightly to mu receptor and will reverse full mu agonist (because its an antagonist)
What are some side effects to dogs on opioids?
Miotic pupils, hypothermia, dysphoria
What are some side effects to cats on opioids?
Dysphoria, hyperthermia
What are some side effects to horses on opioids?
Stall pacing, dysphoria
What are the 4 opioid agonists?
Morphine
Hydromorphone
Fentanyl
Methadone
What is the relevant partial agonist?
Buprenorphine
What is the relevant opioid agonist-antagonist?
Butorphanol
What is the relevant opioid antagonist?
Naloxone
What is the main effect of opioids on the cardiovascular system?
Bradycardia
Blood pressure
How to reduce bradycardia associated with opioids?
Anticholinergics
What causes some blood pressure decreases with opioids?
Morphine causes histamine release resulting vasodilation
What is the respiratory affect of opioids?
Depressed, primarily if animal is unconscious (rate and tidal volume)
Why do opioids reduce respiratory function?
Higher paCO2 is tolerated before respiration is increased
Cough is suppressed
What are 3 very important GI affects of opioids?
Increased salivation
Emetic (except methadone)
GI slows down -> ileus
Why should you use caution with opioids in horses?
Since GI slows down, increase chance of colic
What is the main effect of opioids on urinary system?
Increased release of ADH causing a decrease in urination
How are opioids metabolized?
In the liver
What are 2 benefits of a partial agonist or a agonist-antagonist?
Less addictive
Less hard on cardiopulmonary system
What does a partial agonist or agonist-antagonist look like?
Analgesia remains but sedation is lessened and cardiopulmonary depression is lessened
What happens when an opioid antagonist is given?
Sedation is reversed but analgesia remains
Rank ace, alpha 2 agonist, and bentos in order of how much sedation you expect to be given
1 alpha 2
#2 Benzo
#3 Ace
Of the sedatives, dex and xylazine produce the highest level of sedation
What is the purpose of neuroleptanalgesia?
Mix a sedation with a tranquilizer
When is the use of epidural opioids an option?
When the patient is inpatient
What is the best opioid to use for epidurals?
Preservative free morphine
How long does a opioid epidural take to kick in?
1-2 hours
How long with an opioid epidural last?
8-12 hours
Where is the epidural in a small animal placed and what are the landmarks?
Between L7 and S1
Between ileal wings
What species is Zorbium used in?
Cats!
What are the 4 things that anesthesia can be used for?
Surgery
Diagnostics
Long term ICU ventilation
Physical exam if needed
What is the anesthesia triad?
Muscle relaxation
Unconsciousnes
Analgesia
What are the 3 big things to be assessed prior to anesthesia?
Cardio
Pulmonary
CNS
What are 2nd tier things to be assessed for anesthesia?
Renal and hepatic
What is the minimum required at OSU CVM before put under general anesthesia?
PCV TP
What are the 6 components to anesthetic plan?
physical exam
premed
induction
maintenance
monitoring
recovery
What are the 3 reasons to premed?
Easier induction
Easier placement of IV catheter
Smoother recovery
Remember:
Ace is not reversible
Dex is reversible
Ace increases blood flow to kidneys
Ace is dose dependent
Remember:
Ace is a vasodilator
Dex is a vasoconstrictor
Dex provides analgesia
Dex increases sedation level
Remember:
In horses, xylazine lowers head. Detomadine is a great premed in them
Ace is a muscle relaxer, dex is an emetic
In dogs with heart disease, dont use drugs that cause bradycardia (opioids and alpha 2)
What premed drugs can cause bradycardia?
Opioids and alpha 2
What do you see in older patients in terms of dosing?
Less drug needed
What is different about greyhound pre med?
Take longer to wake up
Lower heart rate so don’t use drugs that will decrease HR too much
What is the most common drug sedative to cause hypoventilation?
Alpha 2
What is the most common drug sedative to cause hypotension?
Ace
What drug should you avoid if you are worried about histamine release?
Morphine (histamine release)W
what is an additional anesthetic concern with horses under general?
Hypoxemia
Remember when using a full mu agonist with horses (morphine), it will slow GI and may cause colic
Reminder:
Methadone is not an opioid emetic, good for patients at risk of vomiting
When should you throw away a propofol bottle?
6-12 hours after opening
What channels does propofol work on?
GABA receptor (same as benzos and same mechanism I think)
How long does propofol last?
5-15 min
How is propofol metabolized
Both hepatic and extra hepatic
How can you infuse propofol?
IV ONLY
How can you decrease side effects with propofol?
Injection over a long period of time
What is another way you can use propofol for total IV anesthesia?
CRI IV
What are the 4 cardio effects of propofol?
Hypotension
Vasodilation
Compensatory increase in HR
Decrease in myocardial contractility
What patient should you be cautious about giving propofol to?
Hypovolemic patients (due to hypotension and vasodilation)
What are 2 respiratory affects of propofol?
Severe respiratory depression
Apnea or hypoventilation (dose dependent)
Does propofol have analgesia?
No
What does propofol cause in cats in the blood?
Heinz bodies
What urine outcome of propofol happens that is not a concern?
Green urine
How long will alfaxalone last in the container?
28 days
Is alfaxalone a controlled drug?
Yes
What is the mechanism of alfaxalone?
Binds GABAa cell surface receptors and modulates neuronal chloride ion transport
How long does alfaxalone last?
5-20 min
How is alfaxalone metabolized?
Liver
How is alfaxalone excreted?
Bile and urine
What are the cardiovascular side effects of alphaxalone?
Dose dependent!
Hypotension
Vasodilation
What are the respiratory side effects of alphaxalone?
Dose dependent respiratory depression
Severe hypoventilation and apnea if a lot given
Tell me about alphaxalone in c sections
Alphaxalone saw better puppy vigor after c section than propofol
Is there analgesia with alphaxalone
No!
What type of steroid is alfaxalone?
Neuroactive (nonhormonal)
Etomidate is ______ soluble at acidic pH
water
Etomidate is _______ soluble at physiologic pH
lipid
Etomidate is classified as a _____
Hypnotic
What is the mechanism of action of etomidate?
GABAa selective modulator
How is etomidate metabolized?
Liver
How is etomidate excreted?
Urine and bile
How fast do propofol, alfaxalone, and etomidate cause unconsciousness?
Immediately
How is the induction of etomidate?
Rapid but can be rough
(Smooth recovery tho)
What are the cardiovascular side effects of etomidate?
Minimal to no effects on blood pressure, cardiac output, or heart rate!
Great for heart patients
What are respiratory side effects of etomidate?
Minimal to no respiratory effect!
What is an important side effect of etomidate?
Decrease in cortisol, corticosterone, and aldosterone (adrenal suppression)
What dog do you NEED to avoid giving etomidate?
Addison dogs!
What are 2 other common side effects of etomidate?
Myoclonus (twitching)
Retching during induction
What is the original cyclohexylamine and most potent?
Phencyclidine
What is the least potent?
Ketamine
What is telazol?
Tiletamine + zolazepam
How does dissociative anesthesia work?
An interruption from the unconscious to conscious parts of the brain
Describe the dissociative state in 4 ways
Cataleptoid state
Opened eyes
dilated pupils
Palpebral reflex
What are the 2 carbon atoms in ketamine bottle?
S(+) and R(-)
Which carbon is more potent and just better?
S(+)
What is the mechanism of action of ketamine?
Non-competative antagonist of NMDA receptor preventing binding of glutamate and glycine. Results in depressed activity
Where are NMDA receptors
In nerve cells
Ketamine has what affect on bronchials?
Bronchodilation
It is a muscarinic with sympathomimetic action!!
Does analgesic outlast anesthetic effect?
Yes!
Ketamine wears off faster than its excreted
Duration of action related to redistribution to lean body tissues and fat
How is ketamine metabolized?
In liver
Norketamine is metabolized in which species?
dogs and horses
Norketamine is not metabolized (and just excreted) in which species?
Cat
What ways can you administer ketamine?
IV or IM
What must be combined with ketamine to give muscle relaxation?
A muscle relaxant (maybe midazolam, propofol)
By itself, it has 0 muscle relaxation
What are the 2 cardiovascular effects of ketamine?
Causes an increase in BP, HR, and CO due to the sympathomimetic effect
Eventually it wears off to a myocardial depression
What is the respiratory side effect of ketamine?
Mild respiratory depression
What does ketamine always need to be used with?
A muscle relaxant
What is an additional side effect of ketamine (2 actually)?
-Increased brain and eye pressure
-Increased salivation
What type of patient should ketamine not be used on?
Brain tumor patient
What is telazol a mixture of?
1:1 mixture of tiletamine and zolazepam
In cats, does tiletamine or zolazepam last longer?
Zolazepam
In dogs, does tiletamine or zolazepam last longer?
Tiletamine
What type of induction is telazol usually associated with?
Rough inductions
What species are telazol commonly used in?
Horses, dogs, cats, pigs
What is the mixture in large animal that involves telazol?
TKX = Telazol, ketamine, xylazine
What cardiovascular side effects does telazol have?
Similar increase of HR, CO, and BP as ketamine
What side effect does telazol not have that ketamine does?
Increase in brain and eye pressure
What type of breathing pattern does ketamine cause?
Apneustic (large breaths, then short breaths, then large breaths, etc) breathing pattern
What happens to excretion of alfaxalone in cats?
Has a potential to accumulate
What are the 4 basic components to an anesthesia machine?
Gas source
Vaporizer
Flow meter
Pressure regulator
What is the letter for a small tank?
E
What is the letter for a large tank?
H
When should you replace the oxygen tank?
When it falls below 200psi
How do you calculate the volume in an oxygen tank?
Volume = pressure (psi) / 3
How many psi are in a full tank?
1900 psi
How many liters are in a full tank?
660L
When are you in the high pressure system?
In the tank, manometer
What transitions gas from high pressure system to intermediate pressure system?
The pressure reducing valve (regulator)
What transitions gas from intermediate pressure to low pressure system?
Flow control valve
When does the house pipeline come in?
In the intermediate pressure system
What is the flow control valve and what system is it in?
It is the knob on the flowmeter.
Knob is in the intermediate system but the flowmeter is in low system
What system is the oxygen flush valve in?
Intermediate system!
Where do you read the sphere?
In the middle
Where do you read the diamond?
At the top
How often should a machine be services?
Once a year
How does the soda lime work in rebreathing system?
CO2 is an acid and soda lime is a base so when air flows through, CO2 is removed and gas is recycled
How do you determine how big your reservoir bag should be?
5 x TV
Or (50-100 mL/kg)
How do you know if it is a rebreathing system or not?
If there is a canister -> rebreathing
If no sodalime canister -> Not rebreathing
What do you need to ensure on the one way valves?
That they are dry and not warped (especially on CO2 rebreathing)
What happens if there is an incompetent one way valve?
Movement of CO2 up the inspiratory limb and then there will be consumption of CO2 on next breath from that limb
How can you tell if a one way valve is bad?
Can see both opening at the same time
What does new sodalime feel like?
Moist and crumbly
What does exhausted sodalime feel like?
Dry and hard
Color is not reliable
How should the pop off valve be left?
OPEN!!!
When should you use non-rebreathing system?
in smaller patients (<5kg)
What is the minimum volume to meet vaporizer fresh gas flow needs in a rebreathing system?
500mL/min
What is the fresh gas flow rate of rebreathing system?
20mL/kg/min
What is the fresh gas flow rate of non rebreathing system?
200mL/kg/min
Where is gas waste vented from?
APL valve
What is active scavenging?
Negative pressure is generated by vacuum pump and gases are actively removed from exhausted port
What is passive scavenging?
Into charcoal canister and released
Veterinarians are at higher risk of pregnancy loss
Make sure ETT cuff is always properly inflated
Only turn vaporizer on after cuff is inflated
Make sure appropriate scavenging is used
Make sure anesthesia machine is checked before each case
After breaking iso, evaluate area, ventilate area, treat as hazardous waste, wash area with water, avoid skin and eyes, collect in plastic bags with respirators and gloves
Small spills can let evaporate, ventilate area, evacuate personnel
Which induction drug is least likely to cause apnea?
Etomadine and ketamine
Which induction drug does not require hepatic metabolism
Propofol
Is propofol 28 labeled for cats?
NO!!!
What patient might you be worried about using propofol in?
A puppy with a non developed liver
A portosystemic shunt dog
What drug should you avoid in heart diseased patients?
Ketamine!
What is physiological pain?
Pain where no or minimal tissue injury occurs (ouch pain - protective warning system)
What is pathologic pain?
Pain following tissue injury
What is spontaneous pain?
Pathologic pain in absence of noxious stimulus
What is allodynia
Pathologic pain in response to normally innocuous stimulus
What is hyperalgesia?
Exaggerated pathologic pain in response to a noxious stimuli.
Pain may be ______ or ________
Somatic or visceral
What are the phases of nociception in order?
Transduction
Transmission
Modulation
Projection
Perception
What are the 2 types of fibers peripherally?
A-delta
C fibers
Which is responsible for fast pain and which long pain?
A-delta (myelinated) short pain
C fibers (unmyelinated) long pain
Where are the nerve bodies for transmission?
In the spinal cord dorsal root ganglia
What are the areas of the brain that are responsible for perception of pain?
Periaqueductal grey matter
Reticular activating system
Thalamus
What does CNS plasticity do?
Cause hypersensitivity to acute and chronic pain
What is sensitizing soup and what does it do?
A bunch of inflammatory cells and nerve growth factors and substance P that increase sensitivity to nociceptors
What is wind up also known as?
Temporal summation
What is the cellular physiology being temporal summation (wind up)
Unblocking of NMDA-receptors leading to hypersensitivity
What is the definition of an animal that is enduring pain?
Suffering
What are the 3 types of visceral pain?
Stretch
Hypoxemia
Inflammation
What is neuropathic pain
damage of the nervous system leading to hypersensitivity and Spontaneous Activity to non-noxious, non-painful stimuli
What are some things in the inflammatory soup?
Prostaglandins (released by COX1 and 2), histamine, serotonin, nerve growth factor, cytokines
What are the 3 A’s of evaluating pain?
Attitude, appetite, activity
What is the downside of relying on HR, BP, and RR for pain?
Will level with chronicity
What are the 4 parts of taxonomy of pain?
Location (somatic-deep or superficial /visceral)
Severity
Mechanism (inflammatory, neuropathic, or idiopathic)
Severity
What is the visual analogue scale?
Graph with no pain to worst pain
What is simple descriptive pain?
Check boxes that define your pain pre and post op as none, mild, moderate, or severe
What is the scale for the Colorado Pain Scale?
0-4
What is Glasgow Composite Pain Scale? (GCPS)
Pain score from 0-20 from 7 different domains
When should you give analgesia?
As preemptive analgesia
What do opioids decrease the release of in pain management?
Glutamate
What 3 things do opioids provide?
Analgesia, sedation, euphoria
What 3 things do alpha 2 agonists provide?
Analgesia, muscle relaxation, sedation
Which species are alpha 2 agonists good for?
Equine
What part of pain does NMDA antagonists (ketamine) act on?
Treats wind-up pain (central sensitization)
How do local anesthetics work?
Block nerve transmission by blocking inflow of Na+ - sodium channel blockers
What are the 4 types of local anesthetics?
Lidocaine, ropivacine, bupivacain, mepivicaine
What is known as kitty magic?
Dexmedetomidine
Ketamine
Butorphanol
What 3 things can NSAIDs do?
Anti inflammatory
Antipyretic (lowers fever)
Analgesic
What 4 things are activated during inflammation?
Phopholipase A
COX
LOX
Nuclear factor kappa beta
How do NSAIDs act?
Act against COXs
COX-1 is constitutive
COX-2 is constitutive and inducible
Mostly inducible tho
COX-3 is inducible
What are the 4 side effect of NSAIDs?
Antithrombic
Gastric defect
Renal damage
Hypersensitivity runs
(chance of hepatopathy in dogs)
When should you NOT USE NSAIDS?!
Patient is concurrently on steroids
Which NSAID is toxic to animals?
Acetaminophen
What NSAID does not inhibit COX? What does it target?
Galliprant
Prostaglandin EP4 receptor
What type of local anesthetic is not metabolized in the liver?
Amino esters (procaine)
Why do local anesthetics not work well at inflamed tissues?
Venules and capillaries are dilated in inflamed tissues causing increased blood flow to the area which promotes absorption and removal of the local anesthetic
What local anesthetic lasts the shortest and the longest?
Lidocaine the shortest
Bupivacaine the longest
What local anesthetic takes the longest to start working?
Lidocaine shortest
Bupivacaine longest
What can cause a local anesthetic to last longer?
Adding a vasoconstrictor like epinephrine
What needs to be considered when the patient is pregnant with local anesthetics?
There is a lot of placenta transfer from mother to fetus
What decreases transfer of local anesthetic from mother to fetus?
High protein binding
What local anesthetic should be used?
Bupivacaine
Longest protein binding
What local anesthetic has the highest risk of toxicity if it goes IV?
Bupivacaine
Lidocaine can go IV
Lidocaine causes vasodilation
What local anesthetic is used in horses?
Mepivacaina aka carpocaine
For local anesthetics, will CNS or cardiovascular toxicity appear first?
CNS!
For bupivacaine, will CNS or cardiovascular signs appear first?
Cardio can show first
How much higher does dose need to be to cause myocardial toxicity with local anesthetics?
4x
How do you treat cardiovascular toxicity of local anesthetic?
Ventilation
Epinephrine
How do you treat cardiovascular toxicity of bupivacaine?
CPR
Intralipid bolus**
What local anesthetic should you use for an instratesticular block?
Lidocaine
Scrotal approach - cat
Prescrotal approach - dog
Where does lidocaine go with the intratesticular block?
Somatic chord
Do local anesthetics delay healing or increase risk of infection?
NO!
What can you do if the maximum dose is reached on a line block?
Add saline
What does the infraorbital block block? lol
Infraorbital nerve and rostral maxillary alveolar nerve
Where is the needle inserted in the infraorbital block?
doral to the 3rd premolar
What teeth are blocked in infraorbital block?
Premolars forward
What needs to be considered when doing infraorbital block on cats or brachycephalic dogs?
Puncturing the orbit
what is a different technique that can be used on brachycephalic and cats?
Perpendicular approach
What does the maxillary block block?
Maxillary branch of trigeminal
What does the maxillary branch innervate?
Nose, upper lip, upper teeth, maxilla
What is the approach for maxillary block?
Behind last molar perpendicular
What does the inferior alveolar (mandibular) block block?
Mandibular branch of trigeminal
What structures are blocked with the inferior alveolar block?
Lower teeth
What does the mental block block?
Just the chin…
Not teeth!
What is most preferred epidural drug?
Opioid - preservative free morphine
What is the tallest spinous process that should be used for locating L7?
L6
What are the 3 indications that you are in the right spot when placing the epidural?
- You feel a pop, meaning you passed through the ligamentum flavum
- Saline is sucked
- You feel a change in resistance
What if there is CSF or blood in hub?
Too lateral, reposition
What are the 3 nerves blocked in a nerve block?
Radial
Median
Ulnar (doral and palmar)
What nerves are blocked in the proximal paravertebral nerve block?
L1, L2, L3
What nerves are blocked in the distal paravertebral nerve block?
L1, L2, L4
For food animal epidural, where do you block between?
Co1 and Co2
Where does the spinal cord end in cows, goats, sheep, and pigs?
S1
Where does the spinal cord end in horses?
S2
Where does the spinal cord end in dogs?
L6-L7
Where does the spinal cord end in cats?
L7-S3
What is the mechanism of action of inhaled anesthetics?
Inhibiting GABA and glycine receptors and slowing acetylcholine and glutamate receptors
What is the solubility represent?
Speed of induction and recovery
What does lower solubility represent?
faster induction and recovery
What does MAC stand for?
Minimal alveolar concentration
What is MAC equal to?
how much should I use
How does solubility change with temperature?
4% increase per celsius
What happens with hypothermic patients?
Solubility is increased which causes them to take longer to wake up from anesthesia
What should you start a patient at?
2 x MAC
What level are most patients adequately anesthetized at?
1.2-1.5x MAC
What species has a higher MAC?
Cats
What are a couple factors that decrease MAC (less anesthetic)
Hypothermia
Pregnancy
Old
What is a factor that increases MAC (more anesthetic)?
Hyperthermic
Excited animals (high catecholamines)
MAC is not affected by sex, hypertension, or duration of anesthesia
What is MAC for most dogs and horses on Iso?
1.3
(sevo = 2.3)
What is MAC for most cats on iso>
1.6
What pressure produces the anesthesia?
The brain
What is most important factor from producing anesthesia?
Blood:gas solubility
What happens with high CO2?
Takes longer to induce patient. Excited patients producing a lot of CO2 will take longer to induce
How does most inhalant leave the body?
Through breathing it out
What are the side effects of inhalants on respiratory and cardio systems?
Respiratory depression
Increase in intracranial pressure
Vasodilation
Decrease in cardiac output due to myocardial contractility
Are inhalants nephrotoxic?
NO!
Where does central sensitization occur?
In the spinal cord
Avoid alpha 2 with heart disease
Ketamine alone has no muscle relaxant
Medazolam is a good muscle relaxant
Ketamine not used in HCM cats???
What 3 things need to be monitored under anesthesia?
Depth of anesthesia
Cardiovascular system
Respiratory system
How many stages are in the Guedel Classification?
4
What is stage 1?
Analgesia and amnesia. Induction to loss of consciousness
What is stage 2? Not commonly seen
Delirium and unconsciousness. From loss of consciousness to onset of automatic breathing
What is stage 3?
Surgery anesthesia. Automatic respiration to respiratory paralysis
What is stage 4?
Respiratory paralysis to death
What are the CNS changes in response to depth?
Movement in response to surgery
Ocular reflex
Pedal reflex (flex to move away from pain)
Anal tone
What are the muscle relaxation changes associated with anesthesia plane?
Jaw tone
What does palpebral reflex tell us?
Too light = blink response
Just right = no blink
Too deep = no blink
Where should dog and cat’s eyes be under surgical plane?
Ventromedially
Where should a horse’s eye be in surgical plane?
One rostral, one central
If waking up, maybe nystagmus
What happens if the animal is too deep?
Eyes are central with dilated pupils
Can you check for surgical planes with jaw tone (too deep, too light, and appropriate depth)
Yes!
What does a high HR and BP mean for the plane?
Too light
What does a high HR and low BP mean for the plane?
getting deeper
What does a low HR and BP mean for the plane?
Deep
What are 2 other ways to check cardiovascular system?
Mucous membrane color
Capillary refill time
What lead is usually read on ECG?
lead II
What does hyperthyroidism due to heart rate under anesthesia?
Increases (tachycardia)
What are the 2 stages of Cushings reflex
Stage 1 = tachycardia + hypertension
Stage II = bradycardia + hypertension + abnormal respiration pattern
What are 2 devices to monitor BP noninvasive?
Doppler
Oscillometric (cuff)
What is hypotension in SA?
below 60
What is hypotension in horses?
Below 70
Which 3 types of drugs cause hypotension
Ace
Inhalants
Propofol
What 3 types of drugs cause hypertension
Ketamine
Alpha 2
Catecholamines
What is capnometry?
Continuous measurement of inspired and expired gases of CO2
Non-diverting or diverting (takes a little longer) are available
Need to look at screenshot of capnograph on iPad
What is phase 1 of capnograph?
Inhalation phase
What is phase 2 of capnograph?
CO2 coming from upper airways (breathing out)
What i phase 3 of capnograph?
CO2 coming from the alveoli
What is phase 4 of capnograph
Beginning of inhalation (breathing in)
What is the CO2 measurement that should be considered?
PaCO2
What might exhausted sodalime cause?
Hypercarbia
What is the minimum PCV?
20%
What are some factors that may interfere with pulse oximeter?
Vasoconstriction
Shivering
Pigmentation
How long do you have to intubate before desaturation in healthy animals?
3 minutes
What is normal tidal volume?
10-15ml/kg
During inhalation, blood flows into the thorax due to a decreased intrathoracic pressure (just like air does)
What happens to blood flow to chest with assisted ventilation?
Less blood flow due to lack of negative intrathoracic pressure
When should ventilation be considered?
When PaCO2 is greater than 60
What is after load
Aortic pressure
What is a PEEP used for?
Help prevent collapse of the dependent lung
Decrease work of breathing
What do all preganglionic neurons secrete?
Acetylcholine
parasympatholytics = AntiSLUD
SLUD is salivation urination and defication
What is the definition of hypotension in mean and systolic?
Systolic <80
Mean < 60
Which machine only monitors systolic BP?
Doppler
What is the most common complication in veterinary anesthesia?
Hypotension
What 5 meds cause hypotension?
Ace
Propofol
Alphax
Inhalants
Phenoxybenzamine
Can severe hypercapnia cause hypotension?
Yes
What are the 4 basic causes of hypotension?
Vasodilation
Bradycardia
Decreased inotropy
Hypovolemia
Do histamines cause hypotension?
Yes!
What drug can you use to treat vasodilation?
Norepinephrine
In which patients is hypotension more of a concern?
Renal patients
What is definition of hypertension?
Systolic above 180
Mean above 140
What drug may cause hypertension?
Alpha 2 agonists (also renal disease)
What can hypercapnia cause?
Hypertension
What is the most common arrhythmia in patients under anesthesia?
Sinus bradycardia
What drugs can cause bradycardia?
Alpha 2 agonist
Opioids
Inhalants
How to treat bradycardia?
Atropine (anticholinergic)
What drug can cause tachycardia?
Ketamine
Anticholinergics
How are temperature signals transmitted? (Same as pain)
A delta and C fibers
Cold through A delta
Warm through C
What is the definition of hypothermia?
Below 98
What are the 4 mechanisms of heat lost?
Radiation
Conduction
Convection
Evaporation
What is radiation?
Heat loss from skin
What is conduction?
Heat to surrounding, like a cold surface
What is convection?
Air currents
What is evaporation?
In feces and urine
What are the 2 most common ways to lose heat?
Convection
Radiation
What is the definition of hyperthermia?
Above 102.2
What is the complication with hyperthermia?
Organ failure
What is the definition of hypoventilation (hypercapnia)
PaCO2 greater than 60
Et greater than 55
What is weird about hypercapnea?
It can lead to both hypertension and hypotension
How to treat hypoventilation?
Decrease anesthetic depth
Increase O2 flow rate
What is definition of hyperpnea?
Abnormal increase in rate and depth
What is definition of tachypnea?
Rapid, shallow respiration
What does hypocapnia cause?
respiratory alkalosis
What does hypoxemia cause?
Lactic acidosis
Causes blue mm, increase in HR, increase in RR
What are causes of hypoxemia?
Hypoventilation
R-L shunt
V/Q mismatch
What is something easy you can do to reduce hypoxemia?
Pre-oxygenation
Should low Sp02 be treated by increasing O2?
No, already breathing 100% O2
Need to be within 4cm for flu-by oxygen to have nay affect
Getting the tongue wet does not increase accuracy of pulse oximetry
44% of dogs die within 3 hours of anesthesia and 62% of cats
What are the 3 main reason for small animals to have a rough recovery?
Emergence delirium (wake up and freak out)
Opioid-induced dysphoria
Pain
What is the affect on preload when the patient is vasodilated?
Blood is pooling in areas of the body so this decreases preload
What is the dose of xylazine compared to that of horse?
1/10
What should you do in a patient if their PaO2 is low?
Give a bronchodilator
What should you do in a patient if their PaCO2 is high?
Ventilate
Does propofol cause vasodilation or vasoconstriction?
Vasodilation
Which of the induction drugs dont metabolize fully in the liver?
Just propofol
What is apeneic?
Involuntary pause in breathing
What can a 2nd degree AV block be caused by?
When dex is given
What should be considered when irregular rhythms are seen?
Anticolanergic
What should not be done in renal disease patients to treat hypotension?
Be given a fluid bolus quickly
True or false: Most animals do not need fluids under anesthesia
True
What are the 2 common types of drip sets?
10 drops/mL
60 drops/mL
What crystalloid fluid does not have Ca: LRS, plasmalyte, saline
Plasmalyte
What are common crystalloid fluid rate for dogs and cats?
Dogs: 5mL/kg/hour
Cats: 3mL/kg/hour
What does OSU require before every surgery at <5 within 24 hr?
PCV/TP
What does OSU require for patients >5 within 30 days and then within 24 hours?
CBC/Chem
PCV/TP
How do you calculate the size of the reservoir bag?
10 x kg x 5
What is the maintenance for a dog?
10-40 mL/kg/min
How do you calculate the amount of liters left in a tank based off of the psi?
psi/3 = L
Calculate maintenance for a 50kg dog?
~20 x 50kg = 1000mL = 1L
If the tank has 466L and the maintenance is 1L/min, how many minutes doe the tank have left?
466-200L (always leave 200 left in it) = 266 minutes
What is the maintenance rate for a non-rebreathing tube?
100-400. so use 200 (10x more than rebreathing)
How long should adult cattle be fasted?
18-24 hours
Why should you not starve a ruminant more than 24 hours?
Development of ketosis
What are the top 2 worries for ruminant with anesthesia?
Bloat
Aspiration
How much saliva do cattle produce a day?
50-150L
Why are anticholinergics not indicated to reduce saliva in ruminants?
It reduces only the watery part of saliva and leaves the viscous part which is worse
Where should the head be during sedation of cows?
Head down
Leave in sternal when possible
Why should you never tie the endotracheal tube over the nose in ruminants?
It will stop breathing
Head elevated but nose down
What are 3 reasons endotracheal tube placement in ruminants is hard?
Small opening of the mouth
Lingual torus
Narrow and long oral cavity
What is the most sensitive species to xyalzine?
Goats
Where can you go to find recommendations for drugs off label?
FARAD
What is a unique concern in some breeds of pigs for anesthesia?
Malignant hyperthermia
What triggers malignant hyperthermia?
Inhalants and stress
What is common in pigs during endotracheal intubation?
Laryngospasm (use lidocaine)
What is sedation commonly used in pigs?
TKX
Telazol
Ketamine
Xylazine
What should be watched in all species in neonates?
Hypoglycemia!
What are 4 things that a make anesthesia of horses difficult?
Flight animals
Colic potential
Obligate nasal breathers
Depth of anesthesia may change quickly
What is the best drug to use for equine sedation?
Alpha 2
What are the 3 criteria for properly sedated horses?
Reluctant to move
Not interested in surroundings
Head down
What is important to never to with horse sedation?
NEVER induce anesthesia in a horse that is not adequately sedate
How are induction drugs given, different from other animals?
Rapidly
Horses get nervous and try to run around if not
How do you put a horse back to the surgical depth if it begins to wake up?
Injectable needed on hand
Inhalation is too slow
How can you prolong anesthesia in the field for horses (what drug can you use on a drip)?
Guaifenesin, Ketamine, Xylazine back
What do you need to do post-recovery for horses?
Muzzle for 1-3 hours to prevent esophageal obstruction
What drugs are collies, herding breeds sensitive to and what is the mutation?
Ace and butorphinol
MDR1
Do overweight patients need more or less dosage?
LESS!
**What are the 4 parts of BOAS?
Elongated soft palate
Stenotic nares
Hypoplastic trachea
Everted saccules
What is the equation for mean arterial pressure?
CO x SVR
What are the 3 things that depend on stroke volume?
Preload, after load, contractility
What does low after load mean
high after load?
Low = easier to pump blood forward
High = harder to pump blood forward
What may cause a high after load?
Vasoconstriction
What type of dog is most likely to get mitral valve disease?
Old small breed dogs
What type of dog is most likely to get DCM?
Large breed dogs
What are cardioprotective sedatives and analgesics?
Benzos and opioids
What induction drug is bad for dogs with Addison’s?
Etomidate
How should you premed a HCM cat?
Low dose dex or midazolam
How many minutes should you pre oxygenate?
3 min
What do you fill when you pre oxygenate?
FRC
What does FRC stand for?
Functional residual capacity
What 2 things make up the FRC?
Expiratory reserve volume
Residual volume
What happens if you have low albumin in a patient?
Low albumin means less proteins for the drug to bind to and thus more free proteins to activate causing higher affect
What do you reverse a benzodiazepines with?
Flumazenil
What should not be used in patients with renal disease?
Vasodilators
May decrease renal blood flow
Does vomiting increase brain pressure?
Yes, be careful during intubation
What are the 3 contents of the skull?
Brain matter
CSF
Blood
What is the Monro-Kellie Doctrine
If one of the 3 things in the brain increase, something else must decrease
What table position should nervous system patients be in?
Reverse trendelenburg position
