Intro to Anesthesia & Pre-Anesthetic Agents Flashcards
Sedation
Sedation is a drug-induced CNS depression and drowsiness that vary in intensity from light to deep
Anesthesia
May be defined as “Loss of sensation” but this only describes one of its effects
Tranquilization
Tranquilization is a drug-induced state of calm in which the patient is reluctant to move and is aware of but unconcerned about its surroundings
Hypnosis
Hypnosis is a sleep-like state from which the patient can be aroused with sufficient stimulation
Narcosis
Refers to a drug-induced sleep grime which the patient is not easily aroused and that is most often associated with the administration of narcotics
Which is deeper? Sedation or Hypnosis?
Hypnosis is deeper than sedation
General Anesthesia
General anesthesia is a state of unconsciousness, immobility, muscle relaxation, and loss of sensation throughout tue entire body produced by administration of one or more anesthetic agents
Surgical Anesthesia
Surgical anesthesia is a specific stage of general anesthesia in which there is sufficient degree of analgesia and muscle relaxation to allow surgery to he performed without patient pain or movement.
Analgesia
Loss of sensitivity to pain
Topical Anesthesia
Topical anesthesia is the loss of sensation of a localized area produced by administration of a local anesthetic directly to a body surface or to a wound
Regional anesthesia
Refers to a loss of sensation in a limited area of the body produced by administration of local anesthetic agent in proximity to sensory nerves
(Ex. Epidural)
Balanced anesthesia
Refers to the practice of administering multiple drugs concurrently in smaller quantities than would be required if each were given alone
Anesthetic agent
Any drug used to induce a loss of sensation with or without unconsciousness
Adjuncts
A drug that is not a true anesthetic but that is used during anesthesia to produce other desired effects such as muscle relaxation, analgesia, reversal, neuromuscular blockade, or parasympathetic blockade
Pre-anesthetic agents
Drugs that are administered to an animal prior to general anesthesia
Reasons to administer pre-anesthetic agents
To calm or sedate an excited or fractious animal
Reduce stress, pain, amount of drugs needed to anesthetize the animal
Vagus nerve
Provides parasympathetic innervation to numerous target organs such as heart, lungs, GI tract, secretory glands, iris
Acetylcholine
The primary neurotransmitter in the PNS responsible for parasympathetic effects
These drugs are given to counter the effects caused by vagal stimulation
Anticholinergics
Anticholinergics only affect these receptors on the target organs
Only affect Muscarinic receptors
Pre-anesthetic agent groups
Anticholinergics
Tranquilizer and Sedatives
Opioids
The Anticholinergic drugs
Atropine
Glycopyrrolate
The Tranquilizer/Sedative drug class
Phenothiazines
Benzodiazepines
Alpha-2 Agonists
The Opioid drug types
Agonists
Partial Agonists
Agonist Antagonist
Antagonists
Anticholinergic prevent this
Bradycardia
Opioids provide this
Pain relief
These drugs can be given Endotracheal (NAVEL)
Naloxone Atropine Vassopressin Epinephrine Lidocaine
The Phenothiazine drugs
Acepromazine
Chlorpromazine
The Benzodiazepine drugs
Diazepam
Midazolam
Zolazepam
The Alpha-2 Agonist drugs
Xylazine
Dexmedetomidine
The opioid antagonist
Naloxone
Why is atropine preferred over glycopyrrolate for emergencies?
Quicker onset of action, but does not last as long as glycopyrrolate
What is the reversal for Anticholinergics?
Physostigmine
What are the effects of tranquilizers?
Reduce anxiety, but may not decrease awareness
What is the effect of sedatives?
Reduce mental activity and awareness and induce sleepiness
Do phenothiazines have analgesic effects?
No
Are phenothiazines controlled?
No
Reversal agent for phenothiazines?
No reversal agent
Boxers and giant breed dogs have an increased sensitivity to this drug class
Phenothiazines
What effect do anticholinergics have on the heart?
Increase HR (prevents bradycardia)
What effect do anticholinergics have on salivation?
Decrease salivation
What effects do anticholinergics have on the respiratory system?
Causes bronchodilation
Adverse effect: thicken mucus secretions in the lungs
What effects do anticholinergics have on the GI?
Decreases peristalsis
Decreases GI activity
Avoid use in Equine, large animals (can cause bloat)
What effect do anticholinergics have on the eyes?
Mydriasis (pupil dilation)
What effect do anticholinergics have on secretions?
Decreases tearing
Need to apply eyelube
(Can cause dry eye)
Which drug is better at decreasing salivation? Atropine or Gylcopyrrolate?
Glycopyrrolate
What effects do phenothiazines have on the heart?
Vasodilation➡️Low blood pressure (hypotension)➡️Heat loss➡️Reflex tachycardia
What effects do phenothiazines have on the brain?
Sedation (CNS Depression)
Adverse: Decreases seizure threshold
What effects do phenothiazines have on the GI?
Antiemetic
What effects do antiemetic a have on the lungs?
No significant decrease in RR
Adverse: could worsen respiratory depression cause by other drugs
The sedative effect of this group of drugs can be overriden if patient is stimulated to a sufficient degree
Phenothiazines
Which phenothiazine is used in veterinary medicine as an antiemetic, but not as an anesthetic adjunct?
Chlorpromazine
Are benzodiazepines controlled?
Yes
Reversal for benzodiazepines?
Flumazenil
Do benzodiazepines provide analgesia?
No
What effects do benzodiazepines have on the heart?
No significant effects
What effects do benzodiazepines have on the lungs?
No significant effects
What effects do benzodiazepines have on the brain?
CNS depression by increase activity of GABA
Anticonvulsant
Adverse: Can cause dysphoria, excitement when used alone in young healthy animals
What effects do benzodiazepines have on the GI?
Stimulates appetite in cats (when given IV)
What effects do benzodiazepines have on the muscles?
Muscle relaxant
Painful IM injection, and not absorbed very well that route
This benzodiazepine is not water soluble
Diazepam
Diazepam cannot be mixed in the same syringe as water-soluble agents except with this drug
Ketamine
Zolazepam is only available mixed with this drug
Tiletamine
Together they make Telazol
This drug is very soluble in plastic
Diazepam
These benzodiazepines are light sensitive
Diazepam and Midazolam
These drugs decrease the release of norepinephrine
Alpha 2 agonists
Are alpha-2 agonists controlled?
No
Can alpha-2 agonists provide analgesic effects?
Yes
What are the reversal drugs for alpha-2 agonists?
Yohimbine reverses Xylazine.
Atipamezole reverses Dexmedetomidine.
What effects do alpha-2 agonists have on the heart?
Early on Vasoconstriction
⬆️BP=⬇️HR=⬇️BP
What effects do alpha-2 agonists have on the lungs
Decrease RR, decrease tidal volume
What effects do alpha-2 agonists have on the brain
Potent sedation
What effects do alpha-2 agonists have on the GI
Xylazine is an antiemetic
What effects do alpha-2 agonists have on the muscles
Muscle relaxation
Why can alpha-2 agonists cause hypothermia?
They decrease thermoregulation and shivering
Which alpha-2 agonists an be absorbed through the skin and abrasions?
Dexmedetomidine
Which alpha-2 agonists is used in small animals? In large animals?
Dexmedetomidine- small animals
Xylazine- large animals
Types of opioids
Agonists
Partial agonists
Agonists-antagonists
Antagonists
