Premedication Flashcards
Sedation
induction of CNS depression and drowsiness by the use of drugs
Tranquillization
used somewhat synonymously to sedate
Analgesia
(antinociception) loss of reduction of pain sensation
General Anesthesia
controlled and reversible loss of consciousness, nociception, and mobility
Hypnosis and narcosis are sometimes used as synonyms
Balanced anesthesia
using multiple drugs to achieve the goals of general anesthesia with less side effects than using a single agent
Dissociative Anesthesia
a form of general anesthesia characterized by a catatonic state. These drugs dissociate the function of different parts of the brain; therefore, neural information is processed without proper coordination in space and time
Neuroleptanalgesia
a state similar to general anesthesia produced by sedative and an analgesia agent
Inhalational Anesthesia
general anesthesia using inhalational drugs
Total Intravenous Anesthesia (TIVA)
Achieved solely by injectable drugs
Partial Intravenous Anesthesia (PIVA)
a combination of injectable drugs and a lower concentration of inhaled anesthetic agent
Local Anesthesia
loss of sensation in a smaller, circumscribed body area
Regional Anesthesia
loss of sensation in larger but limited body area
What are the parts of the anesthetic procedure?
Premedication
Induction
Maintenance
Recovery
Anticholinergics
inhibit the parasympathetic nervous system
Antagonists on muscarinic acetylcholine receptors
Atropine
Lipid Soluble
Absorbs well IM, SC, PO
Crosses the BBB and placental barrier
Glycopyrrolate
Water soluble
Absorbs slowly IM, SC, PO
Does NOT cross the BBB or placental barrier
What are the indications of Atropine and Glycopyrrolate?
Increasing heart rate
Treatment of opioid induced bradycardia
decreasing salivation and bronchial secretion
What are the contraindications of Atropine and Glycopyrrolate?
Tachycardia
Hyperthyroidism
Heart Disease
Narrow angle glaucoma
What are the cardiovascular side effects of Atropine and Glycopyrrolate?
2 degree AV block bradycardia cardiac arrest Tachycardia hypertension
Medetomidine + Atropine
Vasoconstriction
Tachycardia
Hypertension
DO NOT COMBINE THESE DRUGS ROUTINELY
What are other side effects of anticholinergics?
Relaxes lower esophageal sphincter Mydriasis Bronchodilation Dries airway secretion Intestinal paralysis CNS toxicity
Why is it contraindicated for Atropine to be used in Rabbits?
They have high levels of Atropinase enzyme that break down atropine
What is the preferred anticholinergic for Rabbits?
Glycopyrrolate
What drugs are Alpha 2 agonists?
Xylazine
Dexmedetomidine
Medetomidine
Detomidine
What drugs are alpha 2 antagonists?
Atipamezole
Yohimbine
What are the strongest sedatives?
Alpha 2 agonists
What are the effects of alpha 2 agonists?
Sedation
Analgesia
Reduction sympathetic outflow from the brain
Reduction of stress response
Where are alpha 2 receptors located?
Wall of arteries and veins
causing vasoconstriction
Inhibition of lipolysis
inhibition of insulin release: hyperglycemia
What are the CNS effects of alpha 2 agonists?
Sedative effects : weak in pigs
some analgesic effect
Muscle relaxation
Cardiovascular effects of alpha 2 agonists?
Strong vasoconstriction
Leads to high SVR and BP
Reflex bradycardia develops due to high SVR and BP
Resulting in low CO and tissue perfusion
Respiratory effects of alpha 2 agonists
mild respiratory depression RR decreases but tidal volume increases Upper airway resistance increases V/Q mismatch in horses Bronchoconstriction lung edema hypoxemia
GI effects of alpha 2 agonists
Salivation decreases
Lower esophageal sphincter tone decreases
GI motility decreases
vomiting
Xylazine effects in cattle
uterine contractions and abortion
Alpha 2 agonist indications
Sedation of aggressive animals sedation in the ICU
Sedation to manage post operative airway
Prevention/treatment of seizures
Phenothiazines
acts as an antagonist on dopamine, seratonin, alpha 1, and histamine receptors
Phenothiazine CNS effects
Actions on dopamine and serotonin receptors
weaker sedative effects
no analgesia
Antiemetic effect
Phenothiazine Cardiovascular Effects
Antagonist on alpha 1 receptors
causing vasodilation and hypotension
Other Phenothiazine effects
Antihistamine
Antiarrhythmogenic
Inhibit platelet function
Penile prolapse
Phenothiazine indications
Mild sedation
prevention/treatment of opioid dysphoria
Prevention of emesis caused by morphine
sedation for dogs with laryngeal paralysis
Benzodiazepines
GABA receptor agonists Sedative Anticonvulsants muscle relaxant effects Minimal CV and respiratory effects No analgesia
GABA
inhibitory neurotransmitter in the CNS
Benzodiazepine agonists
Diazepam
Midazolam
Zolazepam
Benzodiazepine antagonists
Flumazenil
Sarmazenil
Benzodiazepine indications
Premedication : combined with opioids, alpha 2 agonist, or both
Induction: combine with dissociative anesthetics or Barbiturates or propofol
Treatment of seizures
What are the 3 Opioid receptors?
Mu
Kappa
Delta
What are the classifications of opioids?
Full agonists
Partial Agonists
Antagonists
Mixed agonist antagonist
Full agonists
activate receptors and trigger full tissue response
Partial agonists
activate receptors but do not trigger full tissue response even at high dose
Antagonists
bind to receptors but do not activate them
Mixed agonist antagonist
activate one receptor type and inhibit another one
Potency
tells you the dose
Efficacy
tells you the strength of the effect
Pharmacokinetics
onset, duration of effect, administration strategy
Opioid CNS effects
Analgesia
Decreasing the MAC of inhalants
Opioid GI effects
Defecation
Obstipation
Other effects of Opioids
Hypothermia
Myosis or mydriasis
Inhibition of urination
Noise sensitivity
Opioid Indication
Premedication
Preoperative analgesia
Treatment of acute and chronic pain
Morphine
Strong analgesic
May cause histamine release
Hydromorphone, oxymorphone
Strong analgesic
No histamine release
Fentanyl
Strong Analgesic
Fast onset short duration
No histamine release
Butorphanol
Weak and short acting analgesic
Antagonist on mu and agonist on kappa
Used for premedication in combo with benzodiazepine or alpha 2 agonists
Buprenorphine
Partial mu agonist
Strong analgesic than butorphanol but weaker than full mu agonist
Tramadol
Weak analgesic
inhibits NE and serotonin reuptake
