Week 8 - Injectable and Dissociative Anesthetics Flashcards
1
Q
Anesthesia is a ______ process resulting in the ___ loss of sensation in a body ____ or the ____ body.
A
reversible, total, part, whole
2
Q
Anesthesia is induced by a drug or drug combination that depresses ______ nervous tissue activity (_____ and ______) or _____ (general anesthesia).
A
peripherally, local, regional, centrally
3
Q
Under general anesthesia (GA) the animal is experiencing?
A
- unconsciousness
- hyporeflexia
- analgesia
- skeletal muscle relaxation
4
Q
General anesthesia (GA) uses _______ and _____ agents to allow adequate surgical access to the operative site.
A
intravenous, inhaled
5
Q
Name the four classifications of Anesthesia.
A
- Principal effect
- Chemistry (structures and actions)
- Route of administration
- Time of administration
6
Q
What falls under the category of principal effect?
A
Principal effect:
* Local vs general
* Sedative and tranquilizers vs analgesics
* Neuromuscular blockers
* Anticholinergic agents
* Reversal agents
7
Q
What falls under the category of routes of adminstration?
A
Route of administration:
* Inhalation
* Injectable (IM, IV)
Less common:
* Oral
* Topical
* Rectal
* Intraperitoneal (i.p.)
8
Q
What falls under the category of chemistry (structures and actions)?
A
Chemistry (structures and actions):
* Barbiturates
* Non-barbiturates
* Cyclohexylamines (Dissociative agents)
* Inhalant Anesthetics
Injectable agents
9
Q
What falls under the category of time of administration?
A
Time of administration:
* Pre-anesthetic
* Induction
* Maintenance
10
Q
List the actions of anesthetic drugs
A
- Pharmacokinetics
- Pharmacodynamics
- Drug distribution
- Target tissues and stimulation (CNS: depression or stimulation)
11
Q
Agonists ____ to and ____ target tissue (CNS)
* Most _____ and _____ are agonists.
A
bind, stimulate, anesthetics, adjuncts
12
Q
Antagonists bind to target tissue but don’t ______
________ agents act as antagonists.
A
stimulate, Reversal
13
Q
What is the purpose of combined anesthesia?
A
No single agent provides all desirable properties both rapidly and safely, therefore several categories of drugs are combined to produce optimal anesthesia
14
Q
Combined or Balanced Anesthesia refers to the practice of administering ______ drugs concurrently in _____ quantities than would be required if each were given alone.
A
multiple, smaller
15
Q
Combined or Balanced Anesthesia
* _______ benefits of each drug
* ______ adverse effects
* Allows anesthetist to produce CNS _______, ________,
and ___ relief that is appropriate for the patient and the procedure.
A
Maximizes, Minimizes, depression, immobilization, pain
16
Q
Drug Combinations:
* Don’t mix drugs in a ____ syringe unless they are _____.
* Don’t administer a drug combination if a _____ develops when the drugs are mixed
A
single, compatible, precipitate
17
Q
- Exact mechanisms of anesthetic effects are ______.
- No ______ receptor has been identified
- The fact that chemically unrelated compounds produce anesthesia
argues against the existence of a _____ receptor.
A
unknown, not known, single
18
Q
Injectable Anesthetics ______ the CNS at ___ levels in a ____-dependent manner. Mainly used in ________ and treatment of ______.
* Can produce _____ when given alone.
* Used with ____ agents
* In general, don’t provide _____ or muscle _____
* IV administration: “to ____” ( _______ method)
A
depress, all, dose, anesthesia, seizures, unconsciousness, other, analgesia, relaxation, effect, titration
19
Q
List the categories of Injectable anesthestics
A
- Barbiturates
- Non-barbiturates
- Dissociative agnets
20
Q
List four examples of barbiturates used as injectable anesthetics.
A
Thiopental
Methohexital
Pentobarbital
Phenobarbital
21
Q
List four examples of non-barbiturates used as injectable anesthetics.
A
Propofol
Etomidate
Alphaxalone
22
Q
List four examples of dissociative agents used as injectable anesthetics.
A
Ketamine
Tiletamine
23
Q
Barbiturates are derivates of ?
A
Barbituric acid
24
Q
Barbiturates are _____ substances. They do not provide ______ and there is no known _____ agent.
A
controlled, analgesia, reversal
25
Barbiturates are a group of _____- _______ medications used for treatment of ?
sedative, hypnotic, seizures,
preoperative anxiety, and inducing anesthesia
26
Name the classifications of Barbiturates based on time until onset.
| Dr. Levenson said this was important
1. Ultra short
2. Short
- Intermediate -
3. Long-acting
27
Name two examples of ultra short barbiturates. Which species can these medications be used on? For what purpose?
Thiopental
Methohexital
Dogs, cats, horses
Induce general anesthesia
28
Name two examples of short barbiturates. Which species can these medications be used on? For what purpose?
Pentobarbitol
Lab animals
Induce general anesthesia
Treat epilepsy in small animals
29
Name two examples of long-acting barbiturates. Which species can these medications be used on? For what purpose?
Phenobarbital
Used as an anticonvulsant
& sedative
30
Barbiturates can be further classified into ____________ and __________.
Oxybarbiturates, Thiobarbiturates
31
Barbiturates can be further classified into ____________ and __________.
Oxybarbiturates, Thiobarbiturates
32
List some examples of Oxybarbiturates.
methohexital, phenobarbital, and pentobarbita
33
List some examples of Thiobarbiturates.
thiopental and thiamylal (more lipid soluble)
34
These are the chemical structures of?
35
These are the chemical structures of?
36
# Characteristics of Barbiturates:
Barbiturates are potent _______ but weak ______. They have a high ___ solubility, which allows them to ______ enter the ___ and _____ its function. Redistribution occurs very ____ to other tissues ( _____ muscle & ____ tissue)
* They can cause ?
anesthetics, analgesics, lipid, quickly, CNS, depress, rapidly, skeletal, adipose, apnea (stop breathing for more than 20 seconds = classified as Apnea), coughing, chest wall spasm, laryngospasm, and bronchospasm
37
# Barbiturate MOA
Barbiturates MOA
* Not fully understood (bind to ____-gated ___- channels resulting in ________ of the neurons)
* Mimics the inhibitory effects of ______.
* Causes CNS _____ and loss of _______.
Termination of effect: agents leave _____ and are (3) ?
GABA, Cl, hyperpolarization, GABA, depression, consciousness, brain, metabolized, excreted, or redistributed
38
Barbiturates
Uses: ______ anesthetic induction
To allow _____ (meds used for this? )
Sustain with inhalation anesthetic (_______)
Sustain with _____ doses or _____ infusion (_______)
Used alone for _____ procedures
Rapid, intubation, thiopental and methohexital), thiopental, repeated, continuous, methohexital, short
39
Factors that affect potency, onset, and duration of action of Barbiturates include:
* Ionization --> non-ionized
* Protein binding --> unbound drug, i.e., drug that's not bound to plasma proteins
* Lipid solubility --> lipid-soluble
* Redistribution --> Blood carries drug to brain and other tissues
40
Lipid Solubility
* Tendency of the drug to dissolve in _____, ____, and ____
* Affects the ability to penetrate the _____ _______.
* High solubility feature results in ultra-____-acting drug
* High solubility results in _____ tissue ______.
* Short acting drugs are _____ lipid soluble
* Long-acting drugs have ____ lipid solubility
fats, lipids, oils, cell membrane, short, rapid, redistribution, moderately, low
41
Redistribution
* Drug is distributed fastest to _____-rich tissues
* Drug enters tissue based on _____ solubility
* Effect occurs when drug is in the tissue (____)
* Drug leaves the tissue when _____ level drops (animal _____)
* _____ carries drug to other tissues
* Drug is released by ___ and eliminated by?
vessel, lipid, brain, blood, recovers, Blood, tissues
42
Barbiturate Redistribution
How it works ?
_______ acting drug is given ___
It then travels to the ___ (______ rich)
It is _____ lipid soluble and crosses into brain cells _____.
Dog is now _______ ~___ seconds
Once the levels in the brain are _____ than in the blood, the molecules will move back ____ the concentration gradient
Drug re-enters _____
Redistributes to _____, ___ and other body _____
Patient begins to recover in ___ - ____ minutes
Over the next couple of hours drug is released from ____ and ___ and
Eliminated from the body by ____ metabolism and excretion of _______ in the ____
Ultrashort, IV, brain, vessel, highly, quickly, unconscious, 30, higher, down, circulation, muscle, fat, tissues, 10, 15, muscle, fat, liver, metabolites, urine
43
Pharmacological Effects of Barbiturates on the CNS?
Mild sedation to unconsciousness
Possible excitement at low doses
44
Pharmacological Effects of Barbiturates on the cardiovascular system?
Cardiac depression
Increased cardiac sensitivity to epinephrine
Cardiac arrhythmias (thiopental)
45
Pharmacological Effects of Barbiturates on the respiratory system?
Decreased respiratory rate and tidal volume
Brief apnea (thiopental)
Shallow breaths (pentobarbital)
respiratory acidosis
poor tissue oxygenation
46
Pharmacological Effects of Barbiturates on other parts of the body?
Initial decreased motility
Later increased motility
Sneezing, coughing, laryngospasm
Incomplete muscle relaxation
47
Adverse effects of Barbiturates on the cardiovascular system?
Cardiac arrhythmia
Bigeminy (the heart skipping a beat)
48
Adverse effects of Barbiturates on the respiratory system?
Related to dose and rate of administration
Initial apnea (< 1-2 min)
Neonate respiratory depression (C-section using barbiturates)
49
Other adverse effects of Barbiturates on the body?
* Exaggerated potency in Sighthounds, critically ill patients,
hypoproteinemic or acidotic patients
* Tissue irritation and sloughs (if not IV)
* Intra-arterial injection: vasoconstriction, pain, tissue necrosis
* Death from overdose
50
Barbiturates should not be used on which canine species?
Greyhounds
51
During induction, barbiturates can cause?
* ________ injection
* Very ____ rate of _______
* Stage ___ excitement
* _______ concentration in brain to induce stage ____
* Action: Administer ____ drugs
Perivascular, slow, administration, II, Insufficient, III, more
52
During recovery, barbiturates can cause?
* Pentobarbital
* Paddling and vocalization
* Action: Administer IV diazepam or
pre-anesthetic medications
53
Barbiturate-Drug Interactions
* Enhance muscle _____
* Increase _____ enzyme activity
Prolonged use
Shorter duration of activity of drugs metabolized in the liver (opioids and diazepam)
* Administration with chloramphenicol (enhanced effects of pentobarbital and phenobarbital)
relaxants, hepatic
54
Thiopental is _____-____ acting and can be used on ______ animals and ______. Once administered, thiopental has a ____ onset and ____ duration of action; patient completely recovers in ?
Ultra-short, small, horses, rapid, brief, 1-2 hr
55
Thiopental is a _____ powder in multidose vials that must be ______ with _____ water, ____ saline, or __% dextrose in water.
1. What % concentrate should be used in small animals? Horses?
| Not being tested on this
crystalline, reconstituted, sterile, normal, 5
1. 2-2.5% solution (small animals)
5% solution (horses)
56
Thiopental has a shelf life of __ ____ refrigerated of 3 days at RT. Don’t use if a _____ is present
| Not being tested on this
1 week, precipitate
57
Dosing Thiopental ____ with protocol and procedure.
- Reduced up to ___% in debilitated animals
- Reduce dose in ____ sedated animals
- Give to ___
- Repeat doses are ______ leading to ______ recovery
- Don’t use for _____ maintenance
- Various protocols for administration.
varies, 80, heavily, effect, cumulative, prolonged, anesthetic
58
Methohexital is ____-_____ acting and is similar to thiopental but _____ lipid solubility.
- Can be useful on an _____ animal
- _____ induction and intubation
- Decreased risk of ______ aspiration
- Safe for use during __-____.
- Safe to use in ______ and other _______
- A powder that must be ______ with _____ water.
- ___-___% solution (small animals)
- Shelf life: ?
ultra-short, higher, unfasted, Rapid, vomitus, C-section, greyhounds, sighthounds, reconstituted, sterile, 1-2.5, 6 weeks at RT
59
Pentobarbital is ____-acting
* Largely replaced by ______
* Administered IP to _____ for general anesthesia
* Status epilepticus – treatment
Administer ___ to stop seizures and produce ____ sedation
______ margin of safety
* Euthanasia
short, propofol, rodents, IV, heavy, Narrow
60
Propofol is the ______ ______ used anesthetic in Vet Med (safe drug but expensive)
* ____-___ acting (highly lipophilic)
* Good for ______ cases (onset is ___ and ____, ~ ?)
* Can be used on which species?
most commonly, Ultra-short, outpatient, smooth, rapid, 40 sec)
Small animals, small ruminants, exotic animals, neonates of all species
61
Propofol MOA: Activates _____ receptors (similar to _______)
GABAA, barbiturates
62
Propofol
Uses:
___ bolus and ____ to treat status epilepticus in dogs and cats.
_____ lipid soluble, highly _____ bound, ____ onset & __-____, and rapidly _____.
(good for _____ procedures or prior _____ anesthesia)
Only good for ___ hr
Onset of action: ___-___ sec
Duration of action: _-__ min
Complete and quick recovery (dogs: ___ min: cats___ min, faster than _____)
Safe to use in animals with ___ trauma or increased ______ pressure
___ may not tolerate prolonged infusion
IV, CRI, Highly, protein, rapid, re-distribution metabolized, short, inhalant, 6, 30-60 , 5-10, 20, 30. barbiturates, head, intracranial, Cats
63
Propofol
1. Available in what forms? What are the cons of this?
2. When handling, you must use _____ technique.
3. Discard unused drug within ___ hr of opening
4. __-year shelf life if unopened
5. It is more expensive than ?
1. egg lecithin/glycerin/soybean oil aqueous emulsion Egg lecithin, glycerol, and soybean oil support bacterial growth
2. Aseptic
3. 6
4. 3
5. ketamine-diazepam or thiopental
64
Pharmacological Effects of Propofol on the CNS?
Dose-dependent depression (sedation is part of induction GA)
Poor or no analgesia
Euphoric feelings
65
Pharmacological Effects of Propofol on the cardiovascular system?
Cardiac depressant
Transient hypotension
66
Pharmacological Effects of Propofol on the respiratory system?
Depressant with possible apnea
Administer slowly to effect
Monitor patient carefully
67
Pharmacological Effects of Propofol on the other parts of the body?
Twitching during induction (dogs)
Muscle relaxation
Safe to use in animals with liver or kidney disease
Appetite stimulant (low doses)
Antiemetic
Decreases intraocular and intracranial pressure
68
Adverse Effects of Propofol on the CNS?
Transient excitement and muscle tremors (induction)
Paddling, muscle twitching, nystagmus, opisthotonus (resembles seizures)
69
Adverse Effects of Propofol on the cardiovascular system?
Hypotension - transient
70
Adverse Effects of Propofol on the respiratory system?
Apnea (rapid injection, high dose)
71
Adverse Effects of Propofol on the other parts of the body?
Seizure-like signs (treat with diazepam)
Pain with injection (perivascular injection does not produce tissue damage (compare to barb)
Cats: multiple doses: anemia, diarrhea, anorexia, blindness, aggression, even death.
Prolonged recovery
72
Etomidate is a _______ ______ non-_______ drug of ____-___ duration with ____ margin of safety. Shows ____-like effects
sedative hypnotic, barbiturate, ultra-short , high, GABA
73
Etomidate is used as an alternative to _____ or ______ in animals with ________ ______ dysfunction, _____ trauma, or that are _____ ill
thiopental, propofol, preexisting cardiac, head, critically
74
Etomidate
MOA: binds to ____ receptor and allosterically enhances the affinity of _____ to its receptor
GABA, GABA
75
Etomidate
PK: _____ hepatic hydrolysis, does not ______
Adverse effects:
* ____ and _____ upon IV injection
* May inhibit myocardial _________
Rapid, accumulate, Pain, hemolysis, contractility
76
Pharmacological Effects of Etomidate on the CNS?
Clinical significance is unknown; Decreases cerebral blood flow, metabolic rate, and oxygen consumption
77
Pharmacological Effects of Etomidate on the cardiovascular system?
Minimal depression
78
Pharmacological Effects of Etomidate on the respiratory system?
Minimal depression
79
Pharmacological Effects of Etomidate on the other parts of the body?
inhibits adrenal steroidogenesis reducing the normal
increase in plasma cortisol levels during anesthesia and surgery
80
Alphaxalone is a ______ _______ _____ with rapid, ____-acting general ______ effects
synthetic, neuroactive, steroid, short, anesthetic
81
Alphaxalone MOA
GABAa receptor agonist
82
Alphaxalone can be administered via?
IV or IM injection
