1. INTRODUCTION TO ANESTHESIA & PRE-ANESTHETIC AGENTS
CHAPTERS 1 & 3

2. TERMINOLOGY OF ANESTHESIA
_______________ may be defined as “loss of sensation”, but this only describes one of its effects.
It is used daily in most veterinary practices to provide sedation, tranquilization, immobility, muscle relaxation, unconsciousness, and pain control for a diverse range of indications including surgery, dentistry, grooming, diagnostic imaging, wound care, and capture/transport of wild animals

3. TERMINOLOGY OF ANESTHESIA
__________________ refers to drug-induced CNS depression and drowsiness that vary in intensity from light to deep.
Patient can be aroused by noxious stimuli
_______________________ is a drug-induced state of calm in which the patient is reluctant to move and is aware of but unconcerned about its surroundings.
Often used interchangeable with sedation

4. TERMINOLOGY OF ANESTHESIA
________________ is a sleeplike state from which the patient can be aroused with sufficient stimulation.
_____________________ refers to a drug-induced sleep from which the patient is not easily aroused and that is most often associated with the administration of narcotics.

5. TERMINOLOGY OF ANESTHESIA
__________________________________may be defined as a reversible state of unconsciousness, immobility, muscle relaxation, and loss of sensation throughout the entire body produced by administration of one or more anesthetic agents.
_______________________________ is a specific stage of general anesthesia in which there is sufficient degree of analgesia(loss of sensitivity to pain) and muscle relaxation to allow surgery to be performed without patient pain or movement.

6. Fully conscious
Awake
Light sedation
Moderate sedation
Sedation
Deep sedation
Border between
Consciousness and
unconsciousness
Hypnosis
Narcosis
Light surgical anesthesia
Unconscious
Moderate surgical anesthesia
General
anesthesia
Deep surgical anesthesia
Anesthetic overdose

7. TERMINOLOGY OF ANESTHESIA
__________________ anesthesia refers to loss of sensation in a small area of the body produced by administration of a local anesthetic agent in proximity to the area of interest.
_________________ 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.
_________________ anesthesia refers to a loss of sensation in a limited area (larger area than with local anesthetics)of the body produced by administration of local anesthetic agent in proximity to sensory nerves.

8. TERMINOLOGY OF ANESTHESIA
___________________ anesthesia refers to the practice of administering multiple drugs concurrently in smaller quantities than would be required if each were given alone.
Maximizes benefits of each drug
Minimizes adverse effects
Allows anesthetist to produce CNS depression, immobilization, and pain relief that is appropriate for the patient and the procedure.

9. PRE-ANESTHETIC AGENTS & ADJUNCTS
ANESTHETIC AGENT: any drug used to induce a loss of sensation with or without unconsciousness.
_________________: a drug that is not a true anesthetic but that is used during anesthesia to produce other desired effects such as sedation, muscle relaxation, analgesia, reversal, neuromuscular blockade, or parasympathetic blockade
Ex: muscle relaxants, neuromuscular blockers, reversal agents

10. PRE-ANESTHETIC AGENTS & ADJUNCTS
CHOOSING THE APPROPRIATE AGENTS
____________________: most clinics will not have the option of choosing from every drug on the market.
____________________: drugs are often chosen based on the veterinarian’s familiarity
____________________: drugs that are appropriate for one procedure may not be appropriate for another
Some drugs are short-acting and would not be appropriate for long surgeries
Some drugs may be appropriate for a spay but not a c-section

11. PRE-ANESTHETIC AGENTS
___________: It is ok to use a cheaper anesthetic as long as it is just as safe as the more expensive one.
______________________________: in emergency situations, fast-acting drugs may be necessary
The anesthetic protocol, dose, and route are chosen by the veterinarian
Many clinics have a routine protocol, but is important to consider all aspects of the patient’s minimum database

12. PRE-ANESTHETIC AGENTS
Drugs that are administered to an animal prior to general anesthesia
May be a single drug or combination of drugs
Do not mix two or more drugs unless you have reliable evidence that it is safe to do so.
REASONS TO ADMINISTER PRE-ANESTHETIC AGENTS
_________________________________________

13. PRE-ANESTHETIC AGENTS
REASONS TO ADMINISTER PRE-ANESTHETIC AGENTS
_______________________________________________
Ex: some anesthetic agents cause hypersalivation, we can use atropine or glycopyrrolate to counteract this effect.
________________________________________________
If the patient is already sedated, it takes less drug to bring them into the unconscious state. This is a safer practice than using large amounts of drugs
Using smaller amount of both pre-anesthetics and anesthetic agents in combination is known as balanced anesthesia.

14. PRE-ANESTHETIC AGENTS
REASONS TO GIVE PRE-ANESTHETIC AGENTS
_______________________________: some pre-anesthetic agents last long enough to be effective post-operatively

15. CLASSES OF PREANESTHETIC AGENTS
ANTICHOLINERGICS
TRANQUILIZERS and SEDATIVES
Phenothiazines
Benzodiazepines
Alpha-2 agonists
OPIOIDS
Agonists
Partial agonists
Agonist-antagonists
antagonists

16. ANTICHOLINERGICS
aka parasympatholytics
or sympathomimetics

17. ANESTHETIC & SURGICAL TECHNIQUES MAY STIMULATE THE VAGUS NERVE
The ______________ nerve provides parasympathetic innervation to numerous target organ such as:
Heart
Lungs
GI tract (viscerovagal reflex)
Secretory glands
Iris(oculovagal reflex)
The vagus nerve can stimulated by endotracheal intubation, GI traction, or manipulation of the eye

18. ANTICHOLINERGICS
Acetylcholine is the primary neurotransmitter in the PNS responsible for parasympathetic effects (cholinergic effects)
Ach
Ach

19. ANTICHOLINERGICS
These drugs are given to counteract the effects caused by vagal stimulation EXAMPLES: Atropine, Glycopyrrolate

20. ANTICHOLINERGICS
Ach
Ach
ANTICHOLINERGICS ONLY AFFECT _________________RECEPTORS
ON THE TARGET ORGANS

21. WHAT EFFECT DO ANTICHOLINERGICS HAVE ON THE VARIOUS BODY SYSTEMS?
EFFECTS:
ADVERSE EFFECTS:

22. WHAT EFFECT DO ANTICHOLINERGICS HAVE ON THE VARIOUS BODY SYSTEMS?
EFFECTS:
ADVERSE EFFECTS:

23. WHAT EFFECT DO ANTICHOLINERGICS HAVE ON THE VARIOUS BODY SYSTEMS?
EFFECTS:
ADVERSE EFFECTS:

24. WHAT EFFECT DO ANTICHOLINERGICS HAVE ON THE VARIOUS BODY SYSTEMS?
EFFECTS:
ADVERSE EFFECTS:

25. WHAT EFFECT DO ANTICHOLINERGICS HAVE ON THE VARIOUS BODY SYSTEMS?

26. WHAT EFFECT DO ANTICHOLINERGICS HAVE ON THE VARIOUS BODY SYSTEMS?

27. WHAT EFFECT DO ANTICHOLINERGICS HAVE ON THE VARIOUS BODY SYSTEMS?

28. ATROPINE vs. GLYCOPYRROLATE: A COMPARISON
Both drugs can be given SQ or IM (preanesthetic purposes) or IV (emergency treatment of bradycardia/cardiac arrest)
______________ is generally preferred for emergencies due to the quicker onset of action
Onset of Action/Duration of Action
Atropine IM: 5min, 10-20min, duration 60-90min
Atropine IV: 1 min, 3-4 min, duration several minutes
Glycopyrrolate IM: similar onset time to atropine, 30-45min, duration 2-3 hrs

29. ATROPINE vs GLYCOPYRROLATE: A COMPARISON
Glycopyrrolate causes less tachycardia
______________ is better at decreasing salivation
TOXICITY
With overdoses drowsiness, excitement, dry mouth, ataxia, muscle tremors, dilated pupils, hyperthermia, and tachycardia may be seen
REVERSED with PHYSOSTIGMINE
Reversal is uncommon
ANTICHOLINERGICS _____________CONTROLLED

30. TRANQUILIZERS and SEDATIVES
PHENOTHIAZINES
BENZODIAZEPINES
ALPHA-2 AGONISTS

31. GENERAL INFO ON TRANQUILIZERS/SEDATIVES
_________________ reduce anxiety, but may not decrease awareness
_________________ reduce mental activity and awareness and induce sleepiness
These terms are often used interchangeably
Patients that have received a tranquilizer/sedative may still be easily aroused and could potentially get aggressive or injure themselves

32. ACEPROMAZINE CHLORPROMAZINE
PHENOTHIAZINES
ACEPROMAZINE
CHLORPROMAZINE

33. GENERAL INFO on PHENOTHIAZINES
These drugs have no _____________ effects
These drugs are not controlled
These drugs do not have a ____________ agent
Examples: Acepromazine, Chlorpromazine

34. WHAT ARE THE EFFECTS THAT PHENOTHIAZINES HAVE ON THE VARIOUS BODY SYSTEMS?
ADVERSE EFFECTS:
EFFECTS:
ADVERSE EFFECTS:

35. WHAT ARE THE EFFECTS THAT PHENOTHIAZINES HAVE ON THE VARIOUS BODY SYSTEMS?
ADVERSE EFFECTS:
EFFECTS:
ADVERSE EFFECTS:

36. OTHER EFFECTS & ADVERSE EFFECTS of PHENOTHIAZINES:
ANTIHISTAMINE EFFECT
PENILE PROLAPSE
DECREASED PCV
Onset of action/duration of action
15min after IM injection, min
Duration: 4-8 hrs( could be up to 48hrs)

37. THINGS TO CONSIDER WITH PHENOTHIAZINES
Sedative effects can be overridden if patient is stimulated to a sufficient degree
Use a max of 3mg in dogs and 1mg in cats
Boxers and giant breed dogs by have increased sensitivity
Terriers and cats are more resistant to its effects
Chlorpromazine is used in veterinary medicine as an antiemetic, but not as an anesthetic adjunct.

38. DIAZEPAM MIDAZOLAM ZOLAZEPAM
BENZODIAZEPINES
DIAZEPAM
MIDAZOLAM
ZOLAZEPAM

39. GENERAL INFO ON BENZODIAZEPINES
Benzodiazepines depress the CNS by increasing activity of endogenous ____________________________, an inhibitory neurotransmitter in the brain.
These drugs are ________________
These drugs can be reversed
______________________ is the benzodiazepine antagonist. It is rarely used due to the very low incidence of adverse effects and the high cost.
These drugs provide no ______________
These drugs have unreliable sedative effects & could induce dysphoria, excitement, or ataxia in young, healthy animals, esp. when given alone
EXAMPLES: DIAZEPAM, MIDAZOLAM, ZOLAZEPAM

40. WHATEFFECTS DO BENZODIAZEPINES HAVE ON THE VARIOUS SYSTEMS OF THE BODY?
ADVERSE EFFECTS:

41. WHAT EFFECTS DO BENZODIAZEPINES HAVE ON THE VARIOUS SYSTEMS OF THE BODY?

42. THINGS TO CONSIDER ABOUT BENZODIAZEPINES
Diazepam is not __________-soluble and cannot be mixed with water- soluble agents except ketamine
Midazolam and zolazepam are water-soluble and can be mixed with other agents
Diazepam is painful and poorly absorbed when administered intramuscularly
Midazolam is more readily absorbed via IM and SQ routes
Zolazepam is available only mixed with tiletamine to produce the combination product ____________.
Diazepam is very soluble in plastic and over time is absorbed by syringes, IV bags, and IV tubing

43. THINGS TO CONSIDER ABOUT BENZODIAZEPINES
Diazepam and midazolam are light-sensitive
Onset of action/duration of action
Less than or equal to 15 min after IM injection
Duration: 1-4 hours

44. XYLAZINE DEXMEDETOMIDINE
ALPHA-2 AGONISTS
XYLAZINE
DEXMEDETOMIDINE

45. GENERAL INFO ON ALPHA-2 AGONISTS
These drugs ________controlled
These drugs ___________reversed
These drugs do provide _____________ effects
These drugs act on alpha-2 adrenergic receptors in the CNS and PNS causing a decrease in the neurotransmitter norepinephrine
The sedation is actually a paradoxical effect on the SNS. It decreases release of the neurotransmitter norepinephrine. The sedative effect is potent.
The analgesic effects are relatively short-lived (~20 minutes) and should be supported by other agents

46. WHAT EFFECTS DO ALPHA-2 AGONISTS HAVE ON THE VARIOUS BODY SYSTEMS?
ADVERSE EFFECTS:
EFFECTS:
CV: vasoconstriction with a reflex bradycardia followed by a decrease in cardiac output, hypotension, and further decrease in heart rate due to decrease in sympathetic tone.
Resp: depress respirations, effects are dose-dependent
MS: muscle relaxation
GI:vomiting esp in cats and xylazine>dexmedetomidine
Other drugs: increased effects of other anesthetic agents, reduce the amount of other drugs given
ADVERSE EFFECTS:
EFFECTS:

47. WHAT EFFECTS DO ALPHA-2 AGONISTS HAVE ON THE VARIOUS BODY SYSTEMS?
ADVERSE EFFECTS:
CNS:temporary behavior changes, aggression, excitement
CV: pronounced bradycardia; don’t use in debilitated animals or those with heart dz
RESP:pronounced depression esp when given with other agents and in brachycephalic breeds
Other: increased urination,gas distension of the stomach, premature labor, accidental absorption through the skin
EFFECTS:
ADVERSE EFFECTS:

48. OTHER EFFECTS OF ALPHA-2 AGONISTS
Hyperglycemia: alpha-2 agonists reduce the secretion of insulin by the pancreas
Hypothermia: alpha-2 agonists decrease thermoregulation and shivering
Premature parturition
Can be absorbed through the skin and abrasions – as little as 0.1ml of dexmedetomidine can cause hypotension and sedation in humans.

49. THINGS TO CONSIDER ABOUT ALPHA-2 AGONISTS
Xylazine is largely reserved for use in large animals
Cattle are sensitive and only require 1/10 of the dose used in horses
___________________ is largely used in small animals and is _______ potent than xylazine
Both drugs are commonly mixed with other drugs such as ketamine, and an opioid such as butorphanol or morphine
Animals can undergo minor and major surgical procedures with these combinations

50. THINGS TO CONSIDER ABOUT ALPHA-2 AGONISTS
These drugs can be reversed with Yohimbine (reverses xylazine) and ______________ (reverses dexmedetomidine)
Atipamezole is sold in combination with dexmedetomidine and is given in a __________ ratio
It is not recommended to treat bradycardia with anticholinergics, but rather the appropriate reversal agent
Reversal takes only 5-10min

51. AGONISTS PARTIAL AGONISTS AGONIST-ANTAGONISTS ANTAGONISTS
OPIOIDS
AGONISTS
PARTIAL AGONISTS
AGONIST-ANTAGONISTS
ANTAGONISTS

52. GENERAL INFO ON OPIOIDS
MODE OF ACTION
3 Primary receptor in the brain and spinal cord
Mu, kappa, delta
SEDATION
ONSET OF ACTION:15min after IM administration
DURATION: 1-3 hrs for most (buprenorphine 6-8 hrs)
ANALGESIA
*excellent somatic and visceral analgesia
Agonists their effects on the mu and kappa receptors; partial agonists only partially stimulate the receptors; agonist-antagonists do not stimulate the mu, but stimulate the kappa; pure antagonists bind to but do not stimulate the mu & kappa receptor

53. WHAT EFFECTS DO OPIOIDS HAVE ON THE VARIOUS BODY SYSTEMS?
ADVERSE EFFECTS:
CV: bradycardia, esp with other agents
RESP: minimal resp depression, panting due to effect on thermoregulatory center
EFFECTS:
ADVERSE EFFECTS:

54. WHAT EFFECT DO OPIOIDS HAVE ON THE VARIOUS BODY SYSTEMS?
EFFECTS:
ADVERSE EFFECTS:
EFFECTS:
ADVERSE EFFECTS:

55. OTHER EFFECTS OF OPIOIDS
Allergic reactions: morphine for example may cause facial swelling and hypotension after rapid Iv administration
Changes in body temperature: there is a resetting of the thermoregulatory center in the brain resulting in the dog panting and possibly lowering the body temperature
Cats may have an elevated body temperature for unknown reasons.
Miosis in dogs; mydriasis in cats
CNS: anxiety, disorientation, dysphoria, increased response to noise
CV: pronounced bradycardia
RESP: dose dependent respiratory suppression, esp with other agents
GI:initally vomiting, salivation, diarrhea, flatulence, followed by prolonged constipation
ALLERGIES: morphine, meperidine, facial swelling, hypotension

56. GENERAL INFO on OPIOIDS
These are controlled substances with human abuse potential
Opioids used in combination with a tranquilizer achieve a state of profound sedation and analgesia termed ________________________
These drugs can be reversed with the opioid antagonist _________________ (works within 2 min IV and 5 min IM)
Agonist-antagonists such as butorphanol can also be used to reverse the effects of pure agonists
These will be discussed further and in more detail in week 5-6