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254 Cards in this Set
- Front
- Back
what are the three most common complications under inhalant anesthesia?
|
1. hypotension
2. hypoventilation 3. hypothermia |
|
what is the most common complication under injectable anesthesia?
|
hypoxia
|
|
when do you treat arrhythmias under anesthesia?
|
- if it is causing hemodynamic instability
- if it is going to cause further complications - if the cause or the arrhythmia are treatable |
|
what two physiological parameters contribute to tissue oxygen delivery?
|
1. arterial blood pressure
2. arterial blood O2 content |
|
what two physiological parameters contribute to arterial blood pressure?
|
1. systemic vascular resistance
2. cardiac output |
|
what two physiological parameters contribute to cardiac output?
|
1. heart rate
2. stroke volume |
|
what three physiological parameters contribute to stroke volume?
|
1. preload
2. afterload 3. myocardial contractility |
|
what are three agents/conditions that can stimulate sinus bradycardia?
|
1. opioids
2. hypothermia 3. vagal stimulation (push on eye, distend stomach with air) |
|
why can sinus bradycardia be bad under anesthesia?
|
because it can cause hypotension → low perfusion
|
|
what are two ways to treat sinus bradycardia under anesthesia?
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1. anticholinergics
2. warming |
|
why can sinus tachycardia be bad under anesthesia?
|
- reduces ventricular filling time → ↓CO → hypoxia
- could indicate pain because anesthetic plane is too low |
|
how is sinus tachycardia under anesthesia treated?
|
- find the cause (low plane?)
- analgesia - increased depth |
|
what is a type 1 and type 2 2nd degree AV block?
|
- Type 1: Wenckebach (beat-beat-pause-beat-beat-pause…)
- Type 2: a "regular" 2nd degree AV block |
|
when is a 2nd degree AV block normal under anesthesia?
|
it is common in very fit horses
|
|
what are two classes of anesthetics that can induce a 2nd degree AV block?
|
1. α2 agonists
2. opioids |
|
how and when is 2nd degree AV block treated under anesthesia?
|
- only if appropriate (e.g. hemodynamic effects)
- anticholinergics |
|
how is a 3rd degree AV block treated?
|
pacemaker (will come up on a pre-op exam)
|
|
what drug is bigeminy associated with?
|
thiopental
|
|
if you have to treat VPCs or V-tach, what is the drug of choice?
|
lidocaine
|
|
what drug is contraindicated with the presence of ventricular escape beats? What is the indicated drug class?
|
- lidocaine contraindicated
- use anticholinergics to reestablish sinus rhythm |
|
what is an acceptable MAP for small animals? Large animals in recumbency?
|
- small animals: 60 mmHg
- large animals: 70 mmHg |
|
what pAO2 is the in the danger zone
|
60 mmHg
|
|
what are three things in surgery that may cause hypotension?
|
1. inhalent anesthetic agents
2. excessive depth 3. hemorrhage |
|
what are three clinical signs (without instruments) of hypotension?
|
1. Tachycardia
2. Weak pulses(maybe) 3. Pale MM |
|
what are three things that you can administer to a patient to correct hypotension during anesthesia?
|
1. fluids (crystalloids/colloids)
2. ± inotropes 3. ± vasopressors |
|
what SpO2 is mild hypoxia? What is severe?
|
- mild: < 95%
- severe: < 90% |
|
when are the two most common times that we would see hypoxia?
|
beginning and end of anesthesia
|
|
what are three circumstances that you would see hypoxia in the maintenance phase of anesthesia?
|
- tank runs out
- disconnected from breathing circuit - obstruction |
|
what must happen to see cyanosis?
|
5 g/dL of deoxyhemoglobin
|
|
what are two circumstances when a cyanotic patient is well-ventilated?
|
1. polycythemic patient (they have more blood and can easily overcome the 5 g/dL threshold)
2. anemic patients (especially small patients) may always be cyanotic |
|
what are four signs of hypoxia (and the cause) other than cyanosis and instrument measurements?
|
1. Tachycardia (they need faster circulation to get oxygenated)
2. Arrhythmias (heart muscle deprived of oxygen) 3. Bradycardia (heart is deprived) 4. “Gasping” (agonal) |
|
what are five causes of hypoxemia?
|
- Low FiO2 (fraction of inspired oxygen)
- V-Q mismatch (ventilation-perfusion mismatch; atelectasis) - Shunt - Hypoventilation (needs to be profound) - Diffusion impairment |
|
what are five things to do when hypoxemia is suspected/confirmed?
|
- Check your patient!
- Supply oxygen - Intubation (do it / check it) - Attempt to ventilate - Check your machine |
|
why do oxygen levels not correlate with CO2 levels?
|
oxygen levels do not correlate with CO2 levels, especially when the animal is being given supplemental oxygen. The animal has to be BREATHING to get rid of the CO2. The animal does not have to be breathing to have a good SpO2 if they are being supplied oxygen
|
|
what are five ways to assess ventilation?
|
- Respiratory rate
- Respiratory depth - Respiratory pattern - Blood gas (PaCO2) - Capnography (EtCO2) |
|
what are two basic reasons why CO2 levels may be elevated in the blood?
|
1. poorly eliminated
2. produced excessively |
|
- what is a normal pCO2?
- what is an "acceptable" high range of pCO2? |
- 35-45 mmHg (normal)
- 50-55 mmHg (acceptable) |
|
what are five clinical signs of hypercapnia/Hypercarbia?
|
- Increased respiratory rate
- Tachycardia - INCREASED BP - Dark pink MMs - Eventually, narcosis (sleepiness) |
|
what are five reasons why hypothermia is important?
|
- DECERASES MAC OF INHALANT
- SHIVERING IS PAINFUL AND PHYSIOLOGICALLY EXHAUSTING - Arrhythmias - Delayed wound healing - Prolonged recovery |
|
what are the four mechanisms of heat loss?
|
1. conduction
2. convection 3. radiation 4. evaporation |
|
what are three characteristics of emergence excitement?
|
1. disorientation
2. dysphoria 3. pain |
|
what are the three most important things to do to treat emergence excitement?
|
1. TREAT PAIN
2. handle with care! 3. reassess |
|
what are the three organic functional groups of a typical local anesthetic?
|
1. lipophilic portion (e.g. aromatic ring with a p-amino and carboxyl group)
2. hydrocarbon chain (e.g. ester or amide) 3. hydrophilic segment (e.g. tertiary amine) |
|
what are five ester local anesthetics?
|
1. Procaine
2. Benzocaine 3. Chloroprocaine 4. Tetracaine 5. Cocaine |
|
what are three commonly used amide local anesthetics and four others?
|
1. lidocaine
2. mepivacaine 3. bupivacaine - etidocaine - prilocaine - levobupivacaine - ropivacaine |
|
which local anesthetic has a fast onset (15 min) and moderate duration (1-2 hours)
|
lidocaine
|
|
which local anesthetic has a fast onset (15 min) and longer duration (1-2 hours), and is commonly used in lameness evaluation of the horse and not in small animals?
|
mepivacaine
|
|
which local anesthetic has a slow onset and long duration (1-2 hours), and is the primary local anesthetic used in the VTH for small animals and horses?
|
bupivacaine
|
|
what is the mechanism of local anesthetics?
|
- blocks the ACVITVELY FIRING nerves of nerves ("frequency-dependent blockade")
- blocks the CLOSED and INACTIVATED Na channels - prevents neuronal depolarization |
|
what aspect of a nerve determines its sensitivity to a local anesthetic?
|
the amount of myelination. Less myelinated nerves are more sensitive than heavily myelinated nerves
|
|
in what acid/base form are solutions of local anesthetics?
|
in the protonated (i.e. hydrochloride salt) form
|
|
why is the rate of absorption important with local anesthetics?
|
Local anesthetics act locally, so absorption usually signals the end of their action
|
|
if you do a ring block, what drug do you not want to mix with the local anesthetic and why?
|
epinephrine, because it will vasoconstrict and cause the limb distal to the block to become ischemic
|
|
why do ester local anesthetics generally last for a much shorter period of time than amide local anesthetics?
|
- because pseudocholinesterases (ubiquitous) rapidly metabolize them
- amides are metabolized by hepatic CYP450 enzymes, which is a slower process |
|
why can amide based local anesthetics cause allergic reactions?
|
because they are metabolized to PABA
|
|
why shouldn't you give bupivacaine IV?
|
because it is severely cardiotoxic
|
|
which local anesthetic is neurotoxic?
|
lidocaine
|
|
what is the result of cardiotoxicity with a local anesthetic? How is it treated?
|
- malignant arrhythmias
- treated with IV lipid administration |
|
which local anesthetic has been especially associated with methemoglobinemia?
|
procaine (Cetacaine™)
|
|
what are two good places where local anesthetics are absorbed when applied topically?
|
- mucous membranes such as cornea and larynx
|
|
local anesthetics absorb poorly through skin. What are two exceptions?
|
1. EMLA cream
2. Lidoderm patch |
|
what should you always do before injecting local anesthetic into a patient?
|
ASIPRATE
|
|
how do you perform a "Bier block?"
|
- Place IV Catheter
- Place Tourniquet - Inject lidocaine - Block is gone shortly after removal of tourniquet - Time limited by tourniquet - don't use bupivacaine! |
|
where are three sites to perform a regional block with local anesthetics?
|
1. Epidural
2. Intrathecal 3. Brachial Plexus |
|
which local anesthetic is indicated for CRI? What animals is this contraindicated and why?
|
- lidocaine
- not in cats because it lowers cardiac function |
|
why is intra-articular local anesthesia controversial?
|
because it may be toxic to chondrocytes
|
|
What is the definition of allodynia?
|
Pain caused by a stimulus that does not normally provoke pain
|
|
What is the definition of analgesia?
|
Absence of pain in the presence of stimuli that would normally be painful
|
|
What is the definition of hyperalgesia?
|
An increased response to a stimulation that is normally not painful
|
|
What is the definition of hypoalgesia?
|
A diminished sensitivity to noxious stimulation
|
|
What is the definition of inflammatory pain?
|
Spontaneous pain and hypersensitivity to pain in response to tissue damage and inflammation
|
|
What is the definition of multimodal analgesia?
|
The use of multiple drugs with different actions, which may act at different levels of the nociceptive pathways, to produce optimal analgesia
|
|
What is the definition of neuropathic pain?
|
Pain originated from an injury or that involves peripheral or central nervous system and is described as burning or shooting, possibly
associated with motor, sensory, or autonomic deficits |
|
What is the definition of nociception?
|
The reception, conduction and central nervous system processing of nerve signals generated by the stimulation of nociceptors. This process leads to the perception of pain
|
|
What is the definition of physiologic pain?
|
Protective mechanism to make individuals move away from the cause of potential tissue damage or to avoid movement or contact with external stimuli during a reparative phase
|
|
What is the definition of preemptive analgesia?
|
Administration of analgesics drugs before stimulation to prevent sensitization of neurons and windup, thus reducing postoperative pain
|
|
What is the definition of somatic pain?
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Pain originated from injury of bones, joints, muscle, or skin and is usually localized, constant, sharp, aching and throbbing
|
|
What is the definition of visceral pain?
|
Pain originated from stretching, distention or inflammation of the viscera, and is usually deep, cramping, aching or gnawing, and poorly localized
|
|
What is the definition of windup?
|
Sensitization of nociceptors and peripheral and central pain pathways in response to an overwhelming quantity of afferent nociceptive impulses resulting in expanded receptive fields and an increased rate of discharge
|
|
Pain caused by a stimulus that does not normally provoke pain is called what?
|
allodynia
|
|
Absence of pain in the presence of stimuli that would normally be painful is called what?
|
analgesia
|
|
An increased response to a stimulation that is normally painful is called what?
|
hyperalgesia
|
|
A diminished sensitivity to noxious stimulation is called what?
|
hypoalgesia
|
|
Spontaneous pain and hypersensitivity to pain in response to tissue damage and inflammation is called what?
|
inflammatory pain
|
|
The use of multiple drugs with different actions, which may act at different levels of the nociceptive pathways, to produce optimal analgesia is called what?
|
multimodal analgesia
|
|
Pain originated from an injury or that involves peripheral or central nervous system and is described as burning or shooting, possibly associated with motor, sensory, or autonomic deficits is called what?
|
neuropathic pain
|
|
The reception, conduction and central nervous system processing of nerve signals generated by the stimulation of nociceptors. This process leads to the perception of pain" is called what?
|
nociception
|
|
Protective mechanism to make individuals move away from the cause of potential tissue damage or to avoid movement or contact with external stimuli during a reparative phase is called what?
|
physiologic pain
|
|
Administration of analgesics drugs before stimulation to prevent sensitization of neurons and windup, thus reducing postoperative pain is called what?
|
preemptive analgesia
|
|
Pain originated from injury of bones, joints, muscle, or skin and is usually localized, constant, sharp, aching and throbbing is called what?
|
somatic pain
|
|
Pain originated from stretching, distention or inflammation of the viscera, and is usually deep, cramping, aching or gnawing, and poorly localized is called what?
|
visceral pain
|
|
Sensitization of nociceptors and peripheral and central pain pathways in response to an overwhelming quantity of afferent nociceptive impulses resulting in expanded receptive fields and an increased rate of discharge is called what?
|
windup
|
|
what is the three-fold chain of neurons in the nociceptive pathway and where do these neurons project?
|
1. First order neuron: starting at the periphery and projecting to the spinal cord
2. Second order neuron: cross the spinal cord and ascend to the brain 3. Third order neuron: projects into the cerebral cortex and other supraspinal structures |
|
which types of neurons are involved in nociception?
|
Free A-delta and C nerve endings
|
|
A-delta nociceptors:
- what types of stimuli are they sensitive to? - what are the two types? - how fast do they discharge compared to C-fiber nociceptors? - what type of information do they provide to the CNS? - what is an example of they painful feelings they transduce? |
- Composed of mechanoreceptors and mechanothermal receptors
- Low-threshold (<75%); High-threshold (<25%): respond only to tissue-damaging stimulation - Discharge at a higher rate than C-fiber nociceptors - Provide more discriminative information to the Central Nervous System - Responsible for pricking and sharp qualities of “First Pain” |
|
C-fiber nociceptors:
- comment on the threshold and type of stimuli they are responsive to - what type of pain do they produce? - what is an example of the painful feelings they transduce? - what higher-level behaviors in the CNS do they activate? |
- Almost all are High-threshold and respond to different types of stimulation (polymodal)
- Activation is responsible for slow-onset (“second”) pain that occurs after the initial insult. - Burning and aching qualities - Signals tissue damage and inflammation that initiates self-preservation behaviors such as avoidance and guarding and disuse. |
|
What are the four steps of the pain pathway?
|
1. transduction
2. transmission 3. modulation 4. perception |
|
A-delta fibers:
- diameter - myelination - conduction speed - type of pain - timing of the pain with respect to other pathways |
- Small diameter 1-4 μM
- Myelinated - Fast conduction - Transmit well localized pricking, sharp pain - “First pain”. |
|
C-fibers:
- diameter - myelination - conduction speed - type of pain - timing of the pain with respect to other pathways |
- Smaller diameter 0.4 – 1.2 μM
- Unmyelinated - Slow conduction - Transmit poorly localized dull or aching pain - “Second pain” |
|
amplification or suppression of the peripheral sensory nerve impulses at the level of the spinal cord is called what?
|
modulation
|
|
what is pain modulation?
|
amplification or suppression of the peripheral sensory nerve impulses at the level of the spinal cord
|
|
What is end result of neuronal activity of pain transmission, where pain becomes a conscious multidimensional experience?
|
perception
|
|
what is pain perception?
|
end result of neuronal activity of pain transmission. Pain becomes a conscious multidimensional experience
|
|
what are the three cortical areas involved in pain perception?
|
1. reticular system
2. somatosensory cortex 3. limbic system |
|
what are three neurotransmitters involved in peripheral sensitization of pain (primary hyperalgesia)?
|
1. Substance P
2. Neurokinin A 3. Calcitonin gene related peptide (CGRP) |
|
what are four physiologic responses to neurotransmitters involved in peripheral sensitization and primary hyperalgesia?
|
1. Excitability of sensory and sympathetic fibers
2. Vasodilation 3. Extravasation of plasma proteins 4. Recruitment of inflammatory cells |
|
what is the "sensitizing soup"
|
a group of cytokines, neurotransmitters, and other autacoids involved in secondary hyperalgesia
|
|
what is secondary hyperalgesia?
|
a lower response threshold for A-delta and C-fiber activation (activation of silent nociceptors) in an expanded area around the site of primary pain sensitization
|
|
what is the physiologic process of "wind-up"? (4 steps)
|
1. NMDA receptor activation
2. Ca influx 3. Activation of protein kinase C 4. Increased sensitivity to glutamate |
|
where does "wind-up" occur?
|
dorsal horn of the SC
|
|
how does pain affect the immune system?
|
Increased cortisol levels impair wound healing and decrease immune system function
|
|
how does pain affect the neuroendocrine system? (3)
|
- Activated by Pain
- Gluconeogenesis is favored - Impaired metabolism results in catabolism and cachexia |
|
how does pain affect the GI system?
|
Sympathetic stimulation can cause shunting of blood, decreased motility, and decreased mucosal integrity
|
|
how does pain affect the CV system?
|
Activation of RAAS:
- fluid retention - elevated blood pressure - decreased renal perfusion - Increased HR, SV, CO and myocardial O2 consumption. |
|
what are some clinical signs in animals that have loss of normal behavior due to pain?
|
- Decreased ambulation or activity
- lethargic attitude - decreased appetite - decreased grooming (cats) - Harder to assess in the hospital |
|
what are some examples of abnormal behaviors associated with pain?
|
- Inappropriate elimination
- Vocalization - Aggression - Decreased interaction with other pets or family members - Altered facial expression - Altered posture - Restlessness - Hiding (especially in cats) |
|
generally, how does an animal in pain react to touch?
|
Increased body tension or flinching in response to gentle palpation of injured area and palpation of regions likely to be painful, e.g., neck, back, hips, elbows
|
|
what are four physiologic parameters that may be elevated as a result of pain?
|
1. Heart rate
2. Respiratory rate, 3. Body temperature 4. Blood pressure |
|
when an animal is in pain, what do their pupils do?
|
dilate
|
|
what are six types of scales for pain assessment?
|
1. simple descriptive scale
2. visual analog scale 3. numerical rating scale 4. dynamic and interactive visual analog scale 5. University of Melbourne Pain Scale (UMPS) 6. Glasgow Composite Measures Pain Scale |
|
what are the four steps in the Dynamic and Interactive Visual Analog Scale (DIVAS) of pain assessment?
|
1. Observation from a distance undisturbed
2. Approached, handled, encourage to walk 3. Palpation of surgical incision and surrounding area 4. Final overall assessment of sedation and pain |
|
what is considered to be the most accurate scale of pain assessment in animals?
|
The Glasgow Composite Measures Pain Scale
|
|
what are the six parameters assessed in the SHORT FORM Glasgow Composite Measures Pain Scale?
|
1. vocalization
2. mobility 3. demeanor/response to humans 4. attention to wound 5. response to touch 6. posture and comfort |
|
how do you differentiate pain from dysphoria?
|
- pain with interaction: can be temporarily distracted or calmed; doses of opioids help; there is an identifiable source of pain
- dysphoria: difficult to distract or calm; DOSES OF OPOIDS DO NOT HELP; no identifiable source of pain |
|
what are four basic ways to modify the nervous system to provide analgesia?
|
1. inhibit perception
2. modulation of spinal pathways (inhibit central sensitization) 3. inhibit transmission (inhibit impulse conduction) 4. inhibit transduction (inhibit peripheral sensitization of nociceptors) |
|
what are four drug classes that inhibit pain perception?
|
1. anesthetics
2. opioids 3. α2-agonists 4. benzodiazepines |
|
what are two classes of drugs that inhibit transmission of pain through the nerves?
|
1. local anesthetics
2. α2-agonists |
|
what are three classes of drugs that inhibit pain transduction (i.e. inhibits peripheral sensitization of nociceptors)
|
1. NSAIDs
2. opioids 3. local anesthetics |
|
what are seven classes of drugs that inhibit modulation of spinal pathways of pain (inhibit central sensitization)?
|
1. local anesthetics
2. opioids 3. α2-agonists 4. tricyclic antidepressants 5. cholinesterase inhibitors 6. NMDA antagonists 7. NSAIDs |
|
what severity of pain are treated with opioid:
- mu-agonists? - partial mu-agonists? - agonists-antagonists? |
- mu-agonists: moderate to severe
- partial mu-agonists: mild to moderate - agonists-antagonists: mild |
|
name six mu agonists used as analgesics
|
1. morphine
2. oxymorphone 3. fentanyl 4. hydromorphone 5. methadone 6. meperidine |
|
name a partial mu agonist used as an analgesic
|
buprenorphine
|
|
name an opioid agonist-antagonist used as an analgesic for mild pain
|
butorphanol
|
|
name six COX-2 NSAIDS
|
1. Meloxicam (Metacam)
2. Carprofen (Rimadyl) 3. Etodolac (Etogesic) 4. Deracoxib (Deramaxx) 5. Firocoxib (Previcox) 6. Tepoxalin (Zubrin) |
|
what are six contraindications of NSAID administration?
|
1. renal or hepatic insufficiency
2. low effective circulating volume (dehydration, hypotension, shock) 3. active GI disease 4. coagulopathies 5. concurrent use of corticosteroids or other NSAIDs 6. pregnancy |
|
what are two cons of using α2-agonists as analgesics for long-term use?
|
1. low doses still have a CV effect
2. short duration of drug (CRI may be needed) |
|
lidocaine as an IV analgesic
- site of action - mechanism of action - what animal (disease) is this commonly used? - complications of lidocaine under anesthesia |
- inhibits spontaneous impulses from injured nerve and from dorsal root ganglion
- NMDA receptor antagonism (neuropathic pain) - good visceral analgesia in horses (colic) - decreases MAC about 25% for inhalant anesthetics |
|
low dose ketamine as an analgesic
- mechanism of action - why is this good for burn victims? - routes of administration |
- blocks glutamate at NMDA receptor
- good for burns because it treats central sensitization and hyperalgesia - IV, SQ, IM, epidural |
|
when is it appropriate to give analgesia to prevent hypersensitivity and the lowest amount of post-operative pain?
|
before, during, and after surgery
|
|
what is an advantage of CRI opioid administration over bolus?
|
pain relief without the sedation/euphoria/dysphoria at the peak and without the returning pain/hypersensitization/tolerance at the trough
|
|
what opioid is commonly given transmucosally?
|
buprenorphine
|
|
what is an advantage of giving opioids transmucosally versus orally?
|
no first-pass effect
|
|
which opioid is commonly given transdermally?
|
fentanyl
|
|
which two types of analgesics are given intraarticularly?
|
local anesthetics and opioids
|
|
what are four nerves in the head to block when you would want to do dental work?
|
1. infraorbital
2. maxillary 3. inferior alveolar 4. mental |
|
what is a common analgesic drug cocktail that is given intraoperatively and also post-operatively?
|
FLK: fentanyl, lidocaine, ketamine
|
|
what are four opioids commonly given pre-operatively?
|
morphine, hydromorphone, oxymorphone, fentanyl
|
|
in chemical restraint, what is required for ruminants to become recumbent? Horses?
|
- ruminants: sedation
- horses: they need anesthesia |
|
chemical restraint comment on fasting for field procedures in:
- equine - bovine - alpaca/llama/ovine/caprine |
- equine: not necessary
- bovine: if prolonged recumbency, 48-72h or solid food and 24h of liquid restriction; short recumbency: 24h of fasting - alpaca/llama/ovine/caprine: 24h of food and 13h of water restriction |
|
what are two reasons why are large animals (except horses) fasted before chemical restraint?
|
1. risk of regurgitation/aspiration
2. tympanism/hypoventilation/hypoxemia |
|
what are five signs of sedation in large animals?
|
- Head drop
- Droopy eyes - Droopy lips - Increase distance between feet - Ataxia |
|
what is the major mechanism of action of acepromazine with regards to using it for standing restraint in large animals?
|
inhibits dopamine receptors in the brain
|
|
why is acepromazine good for sedation (i.e. chemical restraint), but not for anesthesia, when used alone?
|
because it has a "ceiling effect", where you reach a maximum efficacy, but the side-effects keep increasing with increasing dose.
|
|
what is the onset and duration of acepromazine when used as chemical restraint?
|
- onset: 20-30 min
- duration, up to 5 hours |
|
what is the reversal agent for acepromazine when used for standing restraint?
|
there is none
|
|
what is a problem with acepromazine in stallions?
|
priapism
|
|
which large animal chemical restraint drug produces less ataxia than α2-agonists and is good for transporting animals?
|
acepromazine
|
|
acepromazine is not effective in what species?
|
swine
|
|
which sedative also can be used as a vasodilator to improve hoof circulation?
|
acepromazine
|
|
what is the biggest problem with oversedation in large animals (e.g. using α2 drugs in chemical restraint)?
|
it is harder to move the animal
|
|
comment on the use of α2 agonists in standing restraint on its effects on:
- muscles - pain - coordination - GI - renal |
- muscle relaxation
- analgesia - ataxia - decreased GI motility - diuresis |
|
what is the most common reversal agent in standing restraint used with xylazine?
|
yohimbine
|
|
what are three α2 reversal agents used in standing restraint?
|
yohimbine, atipemazole, tolazoline
|
|
what are three important side effects of α2 agonists when used in standing restraint?
|
1. hypertension
2. bradycardia 3. arrhythmia |
|
what is the only FDA approved α2 reversible agent for use in veterinary patients?
|
tolazoline
|
|
for standing restraint in field procedures, by what route of administration is xylazine administered to:
- horses? - cattle? |
- horses: IV
- cattle: IM |
|
what is an important side-effect of xylazine in cows?
|
induces abortion in late gestation
|
|
what is a good sedative to control pain in severe colics?
|
xylazine
|
|
which α2 agonist can be given through the oral mucosa in aggressive or needle-shy horses?
|
detomidine
|
|
what is a good way to cause a seizure in a horse with α2 drugs?
|
inject into their carotid artery by mistake instead of the jugular
|
|
what is an important side-effect of xylazine in sheep?
|
acute pulmonary edema
|
|
detomidine in standing restraint of horses:
- compare to xylazine with respect to sedation and analgesia effects - onset and duration - what is a disadvantage post-op? - what side-effect is stronger in this drug versus xylazine? |
- better sedation, and sedation lasts longer than analgesia
- onset: 5-7 min; duration ≈ 45 min - can mask surgical colic - more CV depression than xylazine |
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what are two advantages of romifidine over other α2 drugs in standing restraint of the horse?
|
1. less head drop than xylazine and detomidine
2. less ataxia than other α2 drugs |
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what is the proper route to give xylazine reversal agents and why?
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IM, because IV administration can cause CV instability
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which opiod in standing restraint is most commonly used and is good for visceral pain?
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butorphanol
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butorphanol in standing restraint:
- what is a side-effect in horses that are not painful and/or not sedated? - which receptors does it interact with and how? - why might it be used with morphine? - what is an advantage of giving this drug IV versus morphine? - compare to morphine with respect to GI tract stasis |
- can cause excitement in not sedated/not painful horses
- kappa-agonist; mu-ANTAGONIST - used with morphine to antagonize some of the μ-effects while preserving some analgesia - does not release histamine with IV injection; morphine does - less GI tract stasis versus morphine |
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why is guaifenesin only used IV with chemical restraint?
|
because extravascular injection causes tissue necrosis
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guaifenesin for chemical restraint:
- effects on CV and respiratory - degree of analgesia - risk if too concentrated - route of administration |
- minimal CV and respiratory effects
- no analgesia - can cause hemolysis if concentration is too high - administered IV only (necrosis) as a fast bolus and/or CRI |
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what is the most common agent used in horses for field procedures?
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ketamine
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what is a common analgesic drug cocktail that is given to horses for field procedures or a triple-drip during anesthesia?
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KGX: ketamine, guaifenesin, xylazine
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what are two complications of large animals in recumbency?
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1. myopathy
2. tympanism in ruminants that have not been adequately fasted |
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what is the mortality rate of horses under general anesthesia?
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1%
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what are three common sedative/analgesic combinations used for horses pre-op?
|
1. Acepromazine ± alpha-2 agonists ± opioid
2. Acepromazine + opiod 3. Alpha-2 agonists ± opioid |
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why should you give morphine diluted and slowly, while observing the BP of a horse?
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because it can cause histamine release when given IV
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why should morphine be given with an α2 drug in horses for pre-op sedation?
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because morphine alone can cause excitement
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what is the most important thing to be sure of before you give horse anesthesia?
|
ADEQUATE SEDATION
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what two injectable anesthetics should you not use in horses?
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propofol and etomidate
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what class of drugs is most commonly given to horses to induce anesthesia?
|
dissociatives (e.g. ketamine)
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what happens if you accidentally inject ketamine perivascularly?
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nothing
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how do horses differ from donkeys and mules with injectable anesthetics?
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donkeys and mules require more frequent dosing
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comment on the depth of anesthesia in the horse if the horse is/has:
- blinking - fast nystagmus - slow nystagmus - a strong palpebral reflex |
- blinking: too light
- fast nystagmus: too light - slow nystagmus: ok; assess other parameters - strong palpebral reflex: this is normal under adequate anesthesia |
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Telazol:
- onset and duration - induction quality - use maintenance - recovery quality |
- onset: up to 2 minutes; duration 15-45 minutes
- good induction quality: smoother drop to ground, which is especially good for orthopedic patients - usually you would re-dose with ketamine - recovery can be rough due to excitement; re-dosing with ketamine will give a smoother recovery |
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what horses can you use propofol as induction agents?
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foals
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what is a long list of induction drug combinations for horses?
|
- Telazol (tiletamine + zolazepam)
- Ketamine + diazepam (or midazolam) - Ketamine + GG - Ketamine (with high dose xylazine sedation) - Thiopental - Thiopental + GG - Propofol (foals) - Propofol + Ketamine (foals) |
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inhalants in horse anesthesia
- advantages - degree of muscle relaxation - degree of analgesia - CV and respiratory effects - why is this tough to do in the field? |
- advantages: Easier to control depth of anesthesia, Very little metabolisation
- Good muscle relaxation - NOT analgesics - Profound CV and respiratory depression - field: Require anesthesia machine, which is not feasible |
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what is a big difference between an anesthesia machine that you would use on a dog versus a horse?
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the horse anesthesia machine must be capable of much higher flow rates
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what is the most popular analgesic used with horse inhalant general anesthesia? Why is it so popular?
|
- lidocaine
- enhances the anesthesia (e.g. ↓MAC) and ↑GI motility |
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what are five drugs that are used as analgesics and enhancers of inhalent anesthesia in the horse?
|
1. morphine
2. lidocaine 3. butorphanol 4. xylazine 5. ketamine |
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describe the following signs of LIGHT anesthesia in the horse:
- corneal reflex - palpebral reflex - lateral nystagmus - unstimulated blinking - eyeball position - tear production |
- corneal reflex: brisk
- palpebral reflex: brisk - lateral nystagmus: present - unstimulated blinking: present - eyeball position: centered - tear production: present |
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describe the following signs of ADEQUATE anesthesia in the horse:
- corneal reflex - palpebral reflex - lateral nystagmus - unstimulated blinking - eyeball position - tear production |
- corneal reflex: present
- palpebral reflex: slowed - lateral nystagmus: absent - unstimulated blinking: absent - eyeball position: rotated (not in every horse) - tear production: absent |
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describe the following signs of DEEP anesthesia in the horse:
- corneal reflex - palpebral reflex - lateral nystagmus - unstimulated blinking - eyeball position - tear production |
- corneal reflex: absent
- palpebral reflex: absent - lateral nystagmus: absent - unstimulated blinking: absent - eyeball position: centered - tear production: absent |
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what are four reasons why you want to use an invasive blood pressure monitor in horses under general anesthesia?
|
- leading cause of death is CV collapse
- high incidence of myositis in horses - keep above 70 mmHg - blood pressure spikes before eye changes when they wake up |
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what is an advantage and a disadvantage to providing positive pressure ventilation to the horse during anesthesia?
|
- prevents atelectasis
- causes CV depression |
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what is the preferred positive inotrope type to use in horses under general anesthesia?
|
β-agonists (versus α1 agonists)
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what is the preferred specific positive inotrope given to horses under general anesthesia
|
dobutamine (versus dopamine, vasopressin, or norepinephrine)
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what are six things to do/give to the horse during recovery from general anesthesia?
|
1. Sedation
2. Oxygen 3. Airway support (Oral or nasal tube) 4. Empty bladder 5. Cover eyes 6. Nasal decongestion (vasoconstrictors) |
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what are eight complications of general anesthesia in the horse?
|
1. Hypotension/CV collapse
2. Hypoventilation 3. V/Q mismatch 4. Myopathy 5. Nerve paralysis 6. Fractures 7. Airway obstruction (nasal swelling) 8. Excitement |
|
fasting for bovine anesthesia:
- adults - milk-fed calves |
- Adults 18-24 hours if possible
- Milk-fed calves just a few hours |
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what are three common sedation protocols for bovine pre-op?
|
1. Alpha-2 agonist – REMEMBER LOWER DOSE
2. Alpha-2 agonist + butorphanol 3. Alpha-2 agonist + ketamine |
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what are the two most common local anesthetics given to bovines?
|
1. lidocaine
2. bupivacaine |
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what are five bovine injectable anesthesia protocols?
|
1. Ketamine
2. Ketamine + Diazepam 3. Ketamine + GG 4. Thiopental 5. Thiopental + GG |
|
normal parameters of bovine inter-operative anesthesia:
- HR - RR - eye position - BP |
- HR: 60-80 beats per minute
- RR: 20-30 breaths per minute - Eye position: Ventral rotation indicates surgical anesthetic depth; Central position could indicate too light OR too deep (!) - Blood pressure: same as other mammals; Normotension is important to prevent myopathy |
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what are five potential complications during bovine general anesthesia?
|
1. tympany
2. regurgitation (don't use atropine) 3. hypoventilation 4. movement 5. hypotension |
|
comment on using dobutamine in the bovine during anesthesia
|
they are VERY sensitive to it's tachycardic effects
|
|
bovine recovery from general anesthesia:
- optimal position - excitement - when do you extubate? |
- sternal ASAP
- little to no excitation on recovery - extubate only when they have good airway control |
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what are five things that make small ruminant general anesthesia a pain in the ass?
|
1. very narrow dental arcade
2. relatively long face and thick tongue 3. they regurgitate often 4. they may bloat 5. eye position is less useful than pupil size and shape |
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comment on the problem of regurgitation of small ruminants under anesthesia:
- plane of anesthesia at induction - type of tube - use of atropine |
- you may need to make them "deeper" at induction to reduce regurgitation
- use a cuffed ET tube - don't use atropine; it just makes secretions thicker |
|
what are three common complications of small ruminant general anesthesia?
|
1. hypoxia
2. rumen tympany 3. hypotension |
|
what are two sedation/analgesia protocols for the small ruminant?
|
1. Alpha-2 agonist
2. Alpha-2 agonist + opioid |
|
what are four injectable induction protocols in the small ruminant?
|
1. Ketamine + Diazepam
2. Telazol 3. Thiopental 4. Propofol (smaller animals) |
|
what is the best way to make sure that a small ruminant is properly intubated?
|
capnograph
|
|
small ruminant recovery from general anesthesia:
- optimal position - excitement - when do you extubate? |
- maintain sternal recumbency
- usually no excitation - extubate when they are swallowing effectively |
|
which two types of large animals are obligate nasal breathers?
|
horses and camelids
|
|
what is an extremely important thing to be sure of when anesthetizing a camelid?
|
accurate weight
|
|
what is the preferred sedation/analgesia protocol for camelids, what are two others?
|
- α2 and buprenorphine (preferred)
1. xylazine 2. α2 + butorphanol |
|
what two injectable drugs can cause perivascular necrosis?
|
thiopental and guaifenesin
|
|
what are three injectable induction protocols for camelids?
|
1. Ketamine + Diazepam
2. Propofol (smaller animals) 3. Thiopental |
|
camelid anesthesia maintenance:
- HR - RR - BP - eye position |
- HR: 40-80 bpm
- RR: 20 bpm - BP: same as other mammals - eye position: less useful; pupil size and shape are more indicative |
|
comment on eye position with camelids under general anesthesia:
- palpebral reflex - spontaneous blink - nystagmus |
- palpebral reflex: maintained at adequate depth
- spontaneous blink: too light - nystagmus: not usually visible |
|
what do camelids tend to do during recovery that is weird?
|
Curl necks backward and swing head during recovery
|
|
how long should an adult pig be fasted before anesthesia?
|
12-24 hours
|
|
where is an IV catheter placed in a pig?
|
ear vein
|
|
what is different about the trachea of a pig (with regard to intubation) versus other animals?
|
it makes a dorsal bend at the level of the laryngeal vestibule, so the tube must be manipulated to get good intubation
|
|
what are the four steps of intubating a pig?
- position - arytenoid visualization and treatment - ET tube specifics - technique to pass the tube |
- Sternal recumbency, neck stretched up, mouth open with gauze
- Laryngoscope to visualize arytenoids, & spray lidocaine - ET tube with stylet bent at tip into a curve - Pass tube until you meet resistance, then turn 180 up, advance, and turn back down |
|
what are two breeds of pigs predisposed to malignant hyperthermia?
|
Landrace and Duroc
|
|
what triggers malignant hyperthermia in pigs?
|
stress, depolarizing muscular blockers, inhalants (esp. halothane)
|
|
how do you treat malignant hyperthermia in the anesthetized pig?
|
- remove all inhalant
- actively cool the pig - ventilate - ± dantrolene (supposedly stabilized Ca release from the SR) |
|
what are four complications of anesthesia in the pig?
|
1. malignant hyperthermia
2. regurgitation 3. hypothermia (no hair!) 4. hypotension (same likelihood as other animals) |
|
comment on recovery of swine from anesthesia:
- temp - smoothness |
- monitor temperature closely; warming often needed
- recovery is generally smooth |
|
which sedative is not very good for use in swine?
|
acepromazine
|
|
what are four premed/sedative protocols for swine general anesthesia?
|
1. Telazol
2. Telazol + xylazine 3. Ketamine ± midazolam ± butorphanol 4. Also Telazol, ketamine, xylazine (TKX) – but this takes them deeper, in between premed and induction |
|
what are four injectable induction protocols used in swine?
|
1. Ketamine ± diazepam
2. Propofol (smaller animals) 3. Telazol 4. Thiopental – phlebitis in small vessels |
|
what are two physiologic characteristics of the cat that complicates anesthesia in them versus dogs?
|
1. hepatic enzyme deficiencies
2. laryngospasm |
|
fasting for general anesthesia in the cat:
- adults - young kittens |
- adults: 8-12 hours
- kittens: 1-2 hours |
|
why is UA important in the feline pre-op exam?
|
because renal failure is common
|
|
how long does it take lidocaine to relax the arytenoids?
|
30 sec - 1 minute or so
|
|
if you apply lidocaine to a cat's arytenoids and after about 2 minutes, you are still getting laryngospasm, what are two things you can do other than applying more lidocaine to help intubation?
|
1. use a stylet
2. use more induction drug |
|
normal parameters of feline inter-operative anesthesia:
- HR - RR - eye position - BP |
- HR: 120-160 bpm
- RR 10-20 bpm - eye: ventro-medial - BP: same as other mammals |
|
what are three potential complications during feline general anesthesia?
|
1. hypothermia - small or skinny patients
2. hypotension - very sensitive to volume overload, so watch your drip rate 3. bronchoconstriction - underlying asthma, reactive airway |
|
how can you tell if a cat may be having bronchoconstriction during general anesthesia?
|
squeeze the reservoir bag; if bronchoconstriction, the bag may be stiff
|
|
what are three complications of feline general anesthesia during the recovery phase?
|
1. HYPERthermia - "cats get hot"; young healthy animals
2. HYPOthermia: common; warming PRN (don't use a heat lamp) 3. slow recovery - delayed metabolism? Reversal? |
|
what comprise a "kitty bomb" or "kitty magic"?
|
ketamine, dexmedetomidine, opiod (e.g. butorphanol or buprenorphine)
|
|
what are three sedation protocols for feline general anesthesia?
|
1. "kitty bomb": ketamine, dexmedetomidine, opiod
2. acepromazine + opiod (slow - 20 minutes) 3. ketamine + midazolam ± opiod (not common; 5 minutes) |
|
what are three injectable induction protocols for feline general anesthesia?
|
1. propofol
2. diazepam + ketamine 3. Telazol |