Premedication Flashcards
Aims of premedication (6)
• Relieve anxiety,/,fear, • Facilitate,handling, • Counteract side effects of anesthetic agents, – Nausea/Vomiting/Salivation, – Excessive mm tone – Bradycardia • Reduce the dose of anesthetics • Contribute to perioperative analgesia • Contribute to smooth recovery
5 types of PMs
- sedatives and tranquilizers
- analgesics
- anticholinergics
- anti-emetics and GI protectants
- hypnotics
3 sedative/tranquilizer examples
- phenothiazines
- benzodiazepines
- alpha 2 adrenergic agonists
2 analgesic categories
- opiods
- NSAIDs
Anti-emetics and GI protectants (6)
- NK-1 antagonists
- D2 antagonists
- 5-HT antagonists
- PPIs
- Anti-H2
- buffers
3 hypnotic examples
- alfaxalone
- ketamine
- tiletamine
Anticholinergic MOA
competative antagonist M AchR
2 anticholinergics
- atropine
- glycopyrrolate
anticholinergic side effects
- paradoxical bradycardia
- ↑ HR
- bronchodilation
- ↓ secretions (increased viscosity)
- Mydriasis
- ileus
- antisialogue
- sedation/hallucinations
Which anticholinergic does NOT cross the BBB and placenta
Glycopyrrolate
atropine metabolism
- Dog and human = hydrolysis + excreted unchanged
- Cat + small ruminants = hepatic and renal esterases
- Atropinase: 30% of rabbits
glycopyrrolate metabolism
excreted unchanged in urine
Why use anticholinergics as PM (3)
- prevent bradycardia
- reduce salivation
- reduce bronchial secretions
Why not use anticholinergics as PM?
- Thickening, of, saliva, and, bronchial secretions,
- Decreased ,GI motility,
- Increased, myocardial, oxygen consumption /arrhythmias
- No study to prove benefit
Effects of Phenothiazines
- tranquilization
- ↓ MAC
- vasodilation
- hypothermia
- antiemetic
- relax LES
- ↓ HCT and PLT aggregation
- antihistaminic
Phenothiazine MOA
D2, alpha 1, H1, and M Ach R antagonists
Acepromazine should be avoided in what patients?
- pediatric
- geriatric
- debilitated
- hepatic dysfunction
Can ace be antagonized?
no
________ can cause priaprism in breeding stallions and bulls
acepromazine
benzodiazepine MOA
allosteric modulator of GABA a receptors
effects of benzodiazepines (4)
- sedation
- anxiolysis
- anticonvulsant
- mm relaxants
benzodiazepines are reliable sedatives in what patients?
- very young
- very old
- very sick
- small ruminants
- pigs
benzos need to be associated with _________ or ________ for reliable sedative effect
- opioids
- hypnotics
side effects of propylene glycol (found in Diazepam)
- hemolysis
- pain
- thrombophlebitis
- erratic IM/SQ absorption
- hepatic failure w/ chronic PO use
Benzodiazepines
- Diazepam
- Midazolam
- Zolazepam
- Flumazenil
_______ and ______ experience a smooth recovery with Telazol (Zolazepam) but _____ and ______ have a rough recovery
- cats and pigs
- dogs and horses
_______________: competative antagonist of benzodiazepines
Flumazenil
What is the drawback of Flumazenil?
Can cause seizures
Effects of alpha-2 adrenergic agonists
- sedation
- MAC reduction
- emesis
- ileus
- CO reduction
- decreased ability to thermoregulate
- biphasic CV effects
- mild respiratory depressant
- cyanosis
- uterine ecbolic effect
- ↑ urine production
- suppression of stress response
- insulin suppresion (hyperglycemia and hyperkalemia in large felids?)
advantages of alpha-2 agonists
- reliable sedatives
- can be reversed
- analgesics
- not controlled
- variety of administration routes
do NOT give alpha 2 agonists to ______ or _______
- neonatal patients (rely on HR for CO maintenance)
- sheep/goats (fulminant pulmonary edema)
_______ is used as a pro-emetic in cats
xylazine
__________ causes fulminant pulmonary edema in sheep/goats (mediated by macrophages)
alpha-2 agonists
_________ is an alpha 2 agonist avaliable as an oral gel
Detomidine
alpha-2 agonist which may be used as a CRI
Dexmedetomidine
3 uses of alpha 2 antagonists
- to terminate sedation
- to treat overdose
- after capture of wild animals
Considerations before using alpha-2 antagonists
- analgesia will be reversed too
- ketamine convulsive action may be revealed
- CV side effects
3 alpha-2 antagonists
- Tolazoline
- Yohimbine
- atipamezole
_________ alpha-2 antagonists is licensed IM only
Atipamezole
Tolazoline side effects
- fasciculations
- hypotension
- ventricular arrhythmias
- death
3 antiemetics
- Maropitant
- Metoclopramide
- Ondansetron
3 antiacids
- Famotidine
- Omeprazole
- Na citrate
_________ antacid must be given orally
Na citrate
Need to be careful with Na citrate as an antiacid in patients with __________ or __________
- CKD (metabolic alkalosis)
- cardiac disease (risk of CHF due to Na overload)
Opioids undergo hepatic metabolism, with the exception of _________
Remifentanil
3 places opioids act on
- dorsal horn
- supra-spinal
- peripheral nerves
Sedation effects of opioids
- may cause dysphoria (horses) or euphoria (cats)
- MAC sparing
effects of opioids
- mild respiratory depression
- anti-tussive
- bradycardia/AV blocks
- miosis (mydriasis in cats)
- both anti-emetics and pro-emetics
- ileus
- urinary retention
- immune suppression
- histamine release
- hypothermia in dogs
- hyperthermia in cats, ferrets, swine, and horses
the more_______ an opioid is , the faster they reach the emetic center and the less likely they are to cause vomiting
lipophilic
____________ is an opioid antagonist
Methylnaltrexone
9 common side effects of opiods
- dysphoria
- respiratory depression
- bradycardia
- N/v
- aspiration pneumonia
- ileus
- urinary retention
- hyper/hypothermia
- can induce hyperalgesia
4 reasons to use opioids as PM
- sedatives
- contribute to intra-operative analgesia
- MAC sparing effects
- minimal CV effects
- can contribute to a smooth, pain-free recovery
full mu agonist opiods
- morphine
- hydromorphone
- oxymorphone
- methadone
- fentanyl
- remifentanil
- tramadol
- Etorphine
- Carfentanil
________is an opioid that also acts as an NMDA antagonist
Methadone
__________ is an IV only opiod used in patients with severe liver disease
Remifentanil
Does Tramadol work better in cats or dogs?
dogs
________ is 4,000 times more potent than morphine and is antagonized with Diprenorphine
Etorphine
________ is 10,000 times more potent than morphine and is antagonized with Naltrexone
Carfentanil
_________ is a partial mu agonist
Buprenorphine
_________ is an opioid agonist-antagonist
Butorphanol
benefits of Butorphenol
- good sedative
- good anti-tussive
- does not cause emesis
3 opioid antagonists
- Naloxone
- Naltrexone
- Diprenorphine
________ and ___________ can be used to reverse the side effects of full mu agonists while retaining analgesia
- Butorphanol
- Buprenorphine
NSAIDs inhibit _______ production by inhibiting COX
- eicosanoids
Side effects of NSAIDs
- GI injury (gastritis, enteritis, ulceration, perforation)
- kidney injury
- hepatotoxicity
- coagulation
Contraindications for NSAID therapy
- pre-existing GI disease
- pre-esisting kidney disease
- hepatic insufficiency, increased LEs?
- ↓ effective circulating volume
- concurrent or recent corticosteroid administration
- concurrent or recent administration of a different NSAID
- concurrent use of other potentially nephrotoxic drugs
- MCT
- coagulopathies
- pediatric patients
NSAIDs
- carprofen
- meloxicam
- Robenacoxib
- Firocoxib
- Deracoxib
- Flunixin meglumine
- Phenylbutazone
Signs of adequate sedation in horses
- head is lowered, below the shoulder (5 legged stance)
- not interested in their surroundings
- ptosis
- glazed eyes
- don’t protest if you stick your fingers into their mouth
- don’t attempt to withdraw their tongue if you pull it out
what will happen to cows once you give them xylazine (unlike horses)
they are likely to go down
