Anesthesia Flashcards
What are the four classes of opioids and give an example of each.
- Full agonists - Morphine, hydromorphone, oxymorphone, fentanyl, alfentanyl, sufentanyl, remifentanyl, methadone
- Partial agonist- Buprenorphine
- Agonist/antagonist- Butorphanol
- Antagonist- Naloxone
What are the uses of Anticholinergics (2)
a. Prevention and/or treatment of bradycardia.
b. During cardiopulmonary resuscitation (CPR).
What is the mechanism of action of anticholinergics?
a. Competitive antagonist of acetylcholine at the muscarinic postganglionic
receptors in the autonomic nervous system.
What are the contraindications of anticholinergics? (4)
a. Patients with preexisting tachycardia or cardiac diseases where increase
in heart rate is contraindicated (e. g., hypertrophic cardiomyopathy)
b. When the existent bradycardia was caused by an alpha-2 agonist
c. Animals with narrow angle glaucoma and synechia
d. In Horses UNLESS severe bradycardia (HR < 20) is present and
unresponsive to other treatment options.
Anticholinergics should be avoided in horses EXCEPT in what SPECIFIC circumstance.
d. In Horses UNLESS severe bradycardia (HR < 20) is present and
unresponsive to other treatment options.
What systems does Atropine sulfate effect
Cardiovascular, Respiratory, and CNS
What are the cardiovascular effects of Atropine (5)
- Increases heart rate
- Increases myocardial work
- Decreases myocardial perfusion if degree of tachycardia significantly reduces ventricular filling time
- +/- affect blood pressure
- Low doses may cause transient bradycardia & 1st or 2nd degree AV block due to presynaptic muscarinic receptor blockade that normally inhibit release of acetylcholine
What are the respiratory effects of Atropine
Decreases oral, pharyngeal, and respiratory tract secretions. and * Bronchodilation
What are the CNS effects of Atropine
- Crosses the blood brain barrier
- Overdosage can stimulate the CNS and cause seizures
What special considerations need to be taken for horses when administering atropine sulfate
Decreases motility and secretory activity of the gastrointestinal tract. Can result in gastrointestinal stasis (Colic) in horses.
What is the duration of atropine when given IV and IM
Duration: IV: 30 min, IM: 1 – 1.5 hours
What is the use of Tranquilizers / Sedatives
Commonly used to induce sedation and decrease anxiety before the induction of
anesthesia. They can also be used prior to physical examination, diagnostic
procedures, or to transport animals.
What are some uses for Acepromazine
- Sedation
- Antiemetic
- Anti arrhythmogenic
- Antihistaminic
- Antipruritic
What is the mechanism of action of Acepromazine
- Block post synaptic dopamine receptors in the basal ganglia and limbic system
- May also inhibit the release of, and increase the turnover rate of dopamine
- Block the action of serotonin
- Block alpha-1 adrenergic receptors
What are the cardiovascular effects of Acepromazine
- Causes dose dependent vasodilation, that may lead hypotension, due to depression of vasomotor reflexes mediated by the hypothalamus and brainstem, peripheral alpha-1 adrenergic blockade, direct relaxing effect on vascular smooth muscle, and direct cardiac depression (negative inotrope)
- Hypotension may lead to a reflex sinus tachycardia
What are the respiratory effects of acepromazine
The respiratory effects are minimal
What CNS affects does acepromazine have
-CNS depression and sedation by affecting the basal ganglia, hypothalamus, limbic system, brain stem, and reticular activating system
-Depresses the thermoregulation center
-Potentiates the sedative effects of opioids
What is the duration of acepromazine in dogs, cats, and horses
3 – 6 hours in dogs and cats
1-2 hours in horses.
2 Benzodiazepines
Reasons for administration of benzodiazepines are what?
Mild sedation, muscle relaxation, and anxiolysis,
and as an anticonvulsant
What is the mechanism of action of Benzodiazepines?
Binds to specific benzodiazepines GABAA receptor in
the brainstem reticular formation and spinal cord.
What are the two systems that see minimal effects from Diazepam?
Cardiovascular and Respiratory
What happens if you rapidly administer diazepam IV?
When infused rapidly, it can cause hypotension due to the high concentration of propylene glycol.
* Rapid intravenous infusion may cause pain and venous thrombosis
What is diazepam dissolved in and why?
It is dissolved in 40% propylene glycol because it is not water soluble.
What organ metabolizes diazepam?
Liver
