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Flashcards in Anesthetic drugs 2 Deck (29):
1

What is the use of anesthetic drugs?

to induce &/or maintain general anesthesia (state of complete unconsciousness)

2

Can general anesthesia be interrupted?

cannot be interrupted by stimulation

3

Injectable anesthetics

Used for short procedures, but not as a single agents
• Rapid induction
• Not easy to control depth
• Slow recovery
- Lipid soluble
- Redistribution --> Action terminated --> metabolism

4

Barbiturates
• MOA
• admin
• Precautions

MOA
- Facilitate GABA-binding to receptors
--> Cl- influx --> hyperpolarization
• controlled substances
• Anesthetic / poor analgesia

• IV Only!
- necrosis if extravascular
• Small safety margin
• Profound resp. depression
• Cardiac arrhythmia
• Don't us alone in Sighthounds
• Stormy recovery?

5

Clinical use of Barbiturates in Small animal vs Large animal

Small
- induce general anesthesia
- Titration effect

Large
- Used in combo w/ guaiacolate

6

Ultrashort acting Barbiturates

Thiopental
- Induce anesthesia
** redistributes away from brain quickly! But not quickly metabolized

** lasts 2-3 minutes in brain
--> redistributed to muscles & fats

7

Propofol

non-barbiturate
• Enhances GABA effects
• Only IV (emulsion)
• induce & maintain general anesthesia

• Titrated to effect

• Preferred to barbiturates bc rapid metabolism

• Used when endotracheal intubation not suitable

8

Precaution of Propofol

Hypotension & Respiratory depression
- Apnea (especially horse)
- NO analgesia
- Lipid metabolism disorders can be aggravated

9

Etomidate

non-barbituate
• Induce & maintain anesthesia
• Bradycardia
• Hypotension
• PVCs
• Bradypnea to apnea
• IV hemolysis
(propylene glycol = high osmolarity)

10

Non-barbiturate drugs

1. Propofol
2. Etomidate
3. Chloral hydrate

11

Dissociative drugs

Controlled substances
1. Ketamine (Cats/primates)
2. Tiletamine

• P seems to be dissociated from environment
• Analgesia & light unconsciousness, but reflexes maintained

MOA
- NMDA receptor antagonist

12

Precautions of dissociative drugs

• ↑ muscle tone & secretions
• spontaneous muscle movement
• tachycardia
• Slow / stormy recovery in dog
- slow metabolism
- faster & smoother than in cat
(no metabolism)
• Ketamine = use w/ pre-anesthetic drugs in dogs & horse
--> prevents cataleptoid anesthesia

• Ketamine
- induces amnesia & nightmares (in humans)

13

Inhalation anesthesia

Major elimination route = Respiratory tract

-All depress cardiopulmonary function in a Dose-dependent manner

1. Methoxyflurane
2. Halothane
3. Isoflurane
4. Sevoflurane
5. Nitrous oxide

14

What is MAC

Minimal alveolar conc of anesthesia @ which 50% of P population will not respond to painful stimuli

15

What is Second gas effect?

Nitrous oxide (low solubility) is used to facilitate rate of induction & change of anesthetic doth in combo with 1° anesthetic (halothane / servoflurane)

16

What is a rxn to inhalation anesthetics in swine?

Malignant hyperthermia
- life threatening myopathy due to hyper metabolic rxn in skeletal muscles

17

What affects the potency of an inhalant anesthetic?

- lower MAC = more potent
- Sx - requires 1.2 -1.35 MAC
- Weakest = Nitrous oxide
- ↑ solubility, slower rates, & ↑ Amt of inhalant is needed to ↑ partial pressure in blood & longer it takes to reach equilibrium & anesthetic depths in the brain

18

Methoxyflurane

• High blood/gas solubility

19

Halothane

• Rapid induction & recovery
- low enough blood/gas solubility
• highly volatile
- requires precision vaporizer

20

Isoflurane

• Low blood/gas solubility
- rapid induction & recovery
• gold standard in inhalant anesthesia

21

Sevoflurane

• Smaller safety margin than isoflurane
• Cannot be used for extended periods
- dose & time dependent nephrotox

22

Nitrous Oxide

Used for 2nd gas effect

23

Clinical use of Inhalants

Used for induction & maintenance of general anesthesia
• Reversible by ventilation
- 1° route for inhalant elimination
• Depth of anesthesia = easily controlled
• Rapid recovery compared to injectable anesthesia

24

What risks are assoc'd with inhalant anesthetic in the air?

• Headache to personnel
• Risk of fetal anomaly

25

Maintenance of general anesthesia w/ inhalant drugs

Conc reduced by pre-meds w/ tranquilizer or opioid & concurrent use of NO

26

Anesthesia of Lagomorphs

• watch for stress, compression of thoracic cavity, upper respiratory, & renal infection
• Do NOT use Telozol
- Risk of renal failure

27

Anesthesia of Guinea pigs

• Watch for
• stress,
• obstruction of glottis by food / chewed paper,
• regurgitation,
• bronchial secretion during anesthesia

28

Anesthesia of Small rodents

• Irritating agents
--> self mutilation
• Watch for hypothermia

29

Anesthesia of Ferrets

Watch for
• hypoglycemia
- monitor BG
• hypothermia
• hypotension