Premeds Flashcards by Brooke Michelle

What is the MOA of Atropine and Glycopyrrolate

Anticholinergics. Competitive Antagonists of MAchR (anti-muscarinics) increase HR by blocking muscarinic receptors

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Effects of Anticholinergics

Increase HR-used to treat bradycardia. Bronchodilation, reduced, thicker secretions. Mydriasis, increase IOP. dec motility/ileus. Sedation, hallucinations

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Atropine Metabolism

Excreted unchanged in dogs. Hepatic and renal esterase’s in cats, small ruminants. Will not affect 30% of rabbits so use Glycopyrrolate.

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Advantages and Disadvantages Anticholinergics (Atropine, Gylcopyrrolate) as pre-meds?

Ad: Used to treat bradycardia + hypotension, reduce salivation, reduce bronchial secretions

Disadv: Thickening of secretions (risk for airway obstruction), decrease GI motility, increase myocardial O2 consumption/arrhythmias

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Phenothiazine (Acepromazine) MOA

D2, a1, H1 MachR antagonists
CNS: tranquilization, Neuroleptoanalgesia (if given with opioids) decreased MAC
Vasodilation
Hypothermia (will loose heat)
Antiemetic, relaxes LES, delay gastric emptying
Dec. HCT, dear. PLT aggregation

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Acepromazine uses

Use in healthy, normal patients
Good Antiemetic
Lasts long (don’t use if patient needs to go home)
CANT be REVERSED
Giving more won’t increase sedation, use low doses
DON’T use in: young,old, hepatic dysfunction patient
Less reliable (Don’t use in aggressive/excited)
Decreases BP (Don’t use in hypovolemic)
Causes Priapism (Don’t use in breeding stallions, bull)
CV collapse in boxers

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Benzodiazepine MOA/effects

GAGA receptor agonist, makes less excitable

Effects: sedation, anxiolysis, anticonvulsant, MM relaxants

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What type of patient should you use Benzodiazepine for?

Good sedative for young, old, sick, small ruminants, pigs

Don’t use in healthy patients, may cause excitement

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3 Benzodiazepines

Diazepam, Midazolam, Zolazepam

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Benefits of Benzodiazepines

min CV effects, dose dependent respiratory depressant, reduced anesthetic required, CAN REVERSE/antagonize, must give with opioids/hypnotic, undergo hepatic metabolism

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Diazepam ingredients

35% propylene glycol
ONLY IV
Insoluble in water
light sensitive-cant leave out in syringe

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Midazolam ingredients

IM, SQ or IV
water soluble (only at ph 3.5)
lipid soluble (at physiologic pH)
Comes alone, no propylene glycol

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Zolazepam ingredients

\+tiletamine=Telazol
Powder-reconstituted
Smooth recovery in cats, pigs
Rough recovery in dogs, horses
Used for wild, aggressive animals
*Tigers experience prolonged recovery, ataxia, seizures, death*

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What is Flumazenil?

Antagonist of Benzodiazepines. Reversal drug

can cause seizures

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Alpha-2 Agonists MOA

Mimic negative feedback
Decrease NE release, Dec Ca conductance
Also act on a1 receptors & imidazoline I2 (not xylazine)
Medetomidine (most selective)> Detomidine> Xylazine(least selective)

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a-2 Agonists effects

Sedation, analgesia, MAC reduction
causes vomit, dec. motility 
Biphasic: hypertension then hypotension
up to 66% CO reduction
dec. thermoregulation
Cyanosis
hyperglycemia, insulin suppression
Hyperkalemia in big cats

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What causes Fulminant pulmonary edema in ruminants?

Alpha-2 Agonists (don’t use)

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What causes hyperkalemia in large cats (they can die)

Alpha-2 Agonists

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Advantages of a-2 Agonists

reliable does-dependent sedatives -the more given, the more sedated (unlike ACE)
horses stay on their feet
REVERSIBLE
Analgesic
Not controlled
Can be administered all routes (IM, IV, SQ, oral, neuraxial)

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What are the side effects of a-2 Agonists

Bradycardia, hypotension, dec. CO
Do not use in neonates, only healthy patients!
Dec. temp
Emesis
Dec. GI motility
Hyperglycemia (suppresses insulin production)

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Xylazine uses

a-2 Agonist (not commonly used in small animals)
Pro emetic in cats
Seizures in horses if injected via carotid

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Detomidine uses

a-2 agonist
Used in horses, pigs
more potent than xylazine, longer lasting

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Romifidine uses

a-2 agonist
Licensed for horses
Lasts longer than xylazine

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Medetomidine uses

a-2 agonist

For wild animal capture

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Dexmedetomidine

a-2 agonist Dexter-rotatory isomer Twice as potent as medetomidine (doses are half) Used as CRI-analgesia, sedation

a-2 Antagonists uses

ends sedation, treats over-dose, to reawaken wild animals Reverses analgesia too Side effects: CV effects, seizure w/ ketamine, will not help bradycardia from a2-antagonists

What are three a-2 adrenergic antagonists

Tolazoline Yohimbine Atipamezole (IM ONLY)

Do a-2 antagonists have side effects?

Yes Tolazoline can cause hypotension, arrhythmias, death Atipamezole can cause sudden death, CV collapse, H release

If after giving Dexmedetomidine (a-2 agonist) your patient is bradycardia + hypertensive, what do you do?

Nothing, increase halogenate, or reverse

If after giving Dexmedetomidine (a-2 agonist) your patient is bradycardia + normotensive, what do you do?

nothing

If after giving Dexmedetomidine (a-2 agonist) your patient is bradycardia + hypotensive, what do you do?

Give Anticholinergic! Atropine or Glycopyrrolate

Maropitant MOA

Antiemetic, NK1 antagonist Give PO before premed to reduce a-2 agonist induced vomit Don't give SQ, painful

Metoclopramide MOA

Antiemetic 5H3 (serotonin) antagonist, D2 (Dopamine) antagonist Pro kinetic & antiemetic may be used as CRI

Ondansetron MOA

Antiemetic | 5H3 antagonist

Name 3 Antacids

Famotidine Omeprazole Na Citrate

Famotidine use

Antacid | H2 antagonist

Omeprazole use

Antacid Proton Pump inhibitor increases pH

NA Citrate uses

buffer, antacid Oral ONLY Don't use in patients with CKD (can cause metabolic alkalosis), or heart problems

Opioids undergo what type of metabolism?

Hepatic metabolism (except Remifentanil)

Where are opioid receptors located?

CNS +peripheral (almost everywhere in the body)

3 Analgesia effects of Opioids

1. Dorsal horn 2. Suprea-spinal 3. Peripheral

Which Full u agonist can be given all routes and can cause vomiting and H release so give it slowly?

Morphine

Name 4 drugs that can be used to pre-medicate calm, sick dogs. (Can also be used in combo with ACE or a2 agonist)

Morphine Hydromorphone Oxymorphone Methadone

Which Full u Agonist is also a NMDA antagonist?

Methadone

What is an opioid, Full u agonist, that is given IV, epidurally, or trans-dermal patches?

Fentanyl

Which opioid is most commonly associated with hyperalgesia, and can be given IV only through CRI (lasts 3-5 min)

Remifentanil

Which Full u agonist opioid is mostly used post-anesthesia and is a NE & serotonin reuptake inhibitor?

Tramadol

What are two ultra potent opioids used for capture?

Etorphine (antagonized w/ diprenorphine) | Carfentanil (antagonized w/ naltrexone)

Partial Agonist used for mild pain procedures. Good for post-op pain management.

Buprenorphine

Agonist-Antagonist used for non-painful procedures (imaging, endoscopes, bronchoscopy, BAL) in horses

Butorphanol

Name 3 Antagonists & what they reverse

Naloxone -reverses Full u Agonists Naltrexone- reverses Carfentanil Diprenorphine- reverses Etorphine

What do you give a healthy ASA I or II ?

1. a2 agonist or Acepromazine (tranquilizer) to sedate 2. Opioid 3. + Hypnotic if aggressive

What do you give a ASA >III (neonate or geriatric)

1. Don't need sedation to place IVC | 2. Pick a combo of opioid + benzodiazepine with minimal CV effects

What happens to adult cattle when given hyaline as part of the premeds with an opioid.

Cows will go down! (as opposed to horses)

Swine sedate well using what?

Benzodiazepines (Dexmedetomidine, Ketamine, Midazolam)

What are the three most important distribution tissues?

Splanchnic viscera, muscles, fat

Fast acting injectable Anesthetic, can give perivascular Short CV depression Apnea, respiratory depression Protects brain (CNS friendly) Must throw away after 6hrs of opening Benzyl Alcohol prolongs shelf life to 28 days

Propofol

``` Injectable Anesthetic Increases sympathetic tone (inc. HR, BP) Poor muscle relaxant Often combined with Benzos for induction Increases myocardial work load Increases ICP, CBF, IOP (don't use in glaucoma patients) Rough recoveries Apneustic breathing, apnea Maintained reflexes ```

Ketamine

Injectable anesthetic stimulates sympathetics (inc. HR, BP) Similar effects as ket/diaz. Smaller volume Rough recoveries Can be reconstituted with Ketamine and alpha2

Telazol

Injectable anesthetic used in patients with CV disease Minimal cardiovascular changes so good for cardio patients Adrenal suppression Poor muscle relaxant Combine with opioid or benzo for induction Expensive

Etomidate

What are two Opioids used as injectable anesthetics? Dec. HR and ventilation No myocardial depression Reversible, analgesic

Fentanyl (short acting) | Hydromorphone

``` Fast acting injectable anesthetic Can give perivascular and IM Cardiovascular depression Apnea, respiratory depression CNS friendly ```

Alfaxalone

Can you be hypoxic without being hypoxemic?

Yes. | Examples: Thrombus, vasoconstriction, hypotension, low cardiac output, arrhythmia, low BP

Below normal oxygen levels in blood

Hypoxemia

Below normal oxygen levels in tissues

Hypoxia

Causes of Hypoxemia

Low FiO2 Hypoventilation ventilation: profusion mismatch AV shunt (PDA)

Why is it easy to become hypoxemic during the recovery period?

1. Going from 100% FiO2 to room air 21% FiO2 (low FiO2) 2. Drugs (opioids, propofol) cause hypoventilation 3. Untreated pain may cause hypoventilation (high PaCO2)

2 causes of Atelectasis (deflated alveoli)

1. Absorption (from using 100% O2 with no N to keep alveoli open) 2. Compression

What causes High V/Q

Hypotension (alveolus ventilated but not perfused)

What causes low V/Q

Atelectasis (alveolus perfused but not ventilated)

If pop-off valve (APL) is left closed during surgery, what should you do?

Tell someone & | Monitor for pneumothorax hours after anesthesia is over!

What is a drug used to treat malignant hyperthermia?

Dantrolene

What should a capnograph read to indicate adequate chest compressions?

>10 mmHg

What three things should you have for advanced life support (ALS)?

Drug administration + monitoring | ECG, Doppler, Capnograph

Which drugs can be administered during advanced life support

Atropine (in case vagal arrest) | Epinephrine (low dose)

What is an important reason for selecting Glycopyrrolate over atropine?

Gylcopyrrolate does not cross the BBB or placenta

Morphine, if given quickly IV, may potentiate hypotensive crisis by causing...

the release of Histamine

An apneustic breathing pattern can be seen after giving...

Ketamine

The anesthetic with the least cardiovascular affects in the dog is

Etomidate

What happens if you give a local anesthetic in an infected area. Ex: Lidocaine

The drug will become less lipid soluble, ionized, ion trap in the acidic environment and won't work

What is EMLA cream used for?

Skin desensitization A topical anesthetic mixture of lidocaine and prilocaine for venipuncture or small mass removal long onset of action, short duration

What is a common complication of an inferior alveolar n. block (mandibular n.)

May block the lingual nerve! (Dog will chew on tongue)

What are the target nerves of the Lumbar paravertebral block?

T13, L1, L2

Interarcuate ligament (flavum)

the roof of the epidural space | Epidural space is between this and dura matter

What space do you approach to give an epidural in large animals?

the Sacrococcygeal space

What are 5 clinical signs of hypovolemia?

``` Tachycardia hypotension weak pulses prolonged CRT cool extremities ```

Pre-Op: Alfaxan, Dexmedetomidine, opioid+benzo | Intra-Op: Etomidate, isoflurane, Phenylephrine

HCM

Pre-Op: Atropine, Acepromazine, opioid +benzo | Intra-op: Etomidate, isoflurane, ketamine, dopamine, dobutamine

Degenerative Valve Disease

Butorphanol, Acepromazine Induce with propofol only Dexamethasone, cerenia

Respiratory disease

Reversible opioids + bentos morphine, ketamine Inotropes to inc. CO

Chronic renal insufficiency

Remifentanil, propofol, isoflurane

Liver Disease

Midazolam, Mannitol, cerenia, Propofol only

Elevated ICP

What are two things hypoventilation causes?

Hypoxemia | Hypercapnia