Smalltest nr 3 part 2 Flashcards
1
Q
Definitions:
General Anaesthesia
A
- Injectable or inhalation
- Injectable has 1 exception, in which it has a painkiller effect and can be used as a premed: ketamine
- But remember! Ketamine causes muscle rigidity!!! Mustn’t be given on its own!
(BDZ and ⍺-2 agonist combined with ketamine)
- Also, remember that its analgesic effect isn’t strong as e.g. fentanyl
2
Q
Definitions:
Balanced anaesthesia
A
There is no one substance that can provide all 3 requirements of surgery
- Total unconsciousness
- Total muscle relaxation
- Total analgesia
Balanced = a combination of drugs
3
Q
Definitions:
TIVA
A
- Total intravenous anaesthesia
- Must maintain pressure because ↓ BP during anesthesia, which can lead to:
- acute renal failure (must keep BP above a certain level, 90mmHg. This can be done via catheter)
- Can also inject certain injectable anaesthetics via IM,
- however, it will give you a less safe anaesthesia
4
Q
Definitions:
Neuroleptanalgesia
A
- Tranquilisers + opioids
- Muscle relaxation and analgesia
- Ø total unconsciousness!
- Used in minor procedures
5
Q
Definitions:
Ataranalgesia
A
- Benzodiazepine + opioid
- Less deep than neuroleptanalgesia
6
Q
Anesthesia during surgery
Premedication
AIMS
A
- Sedation
- Potentiation (Lowers needed dose for anesthesia and painkillers used later on)
- Avoidance of pre-excitmentation
- Avoidance of histamine (HA) release
7
Q
Anesthesia during surgery
Induction
AIMS
A
- Get rid of reflex so that you can put an endotracheal tube down the trachea to provide oxygen during surgery as well as
- maintain trachea diameter (some breeds are more prone to trachea collapse during surgery)
8
Q
Anesthesia during surgery
Maintenance
AIMS
A
Fulfill the 3 requirements
- Total unconsciousness
- Total muscle relaxation
- Analgesia
Once fulfilled → can begin the procedure
9
Q
Anesthesia during surgery
Premedications
SUBSTANCES
A
- Tranquilizers → potentiate analgesics and anti-HA (acepromazine)
- ⍺-2 agonists → analgesia potentiation, some analgesic effect
- BDZ → pre/post narcotic effect
- Opioids → analgesia
- Ketamine → premed (subhypnotic dose) and maintenance, potentiates anaesthesia and has analgesic effect (desensitization of pain)
10
Q
Anesthesia during surgery
Induction
SUBSTANCES
A
- Injectables
- Propofol
(use lower dose because of premed potentiators)
- Thiopental (eq)
- Inhalations
- Sevoflurane → doesn’t cause irritation
11
Q
Anesthesia during surgery
Maintenance
SUBSTANCES
A
- Inhalation (isoflurane, sevoflurane, etc)
- Injectables (IV)
Use combinations, e.g.
Ketamine + BDZ
Ketamine + ⍺-2 agonists
12
Q
Anesthesia during surgery
Premedication
IMPLEMENTATION COMMENTS
A
- ⍺-2 agonists have painkilling effect, but not enough for maintenance (potentiate analgesic effect)
- Morphine → must wait ~30 min before beginning the procedure
-
Buprenorphine and butorphanol are not enough for painful surgeries. They’re also partial agonists!!
- Mustn’t be used if you’re planning to use full agonists (morphine/fentanyl) later on!!
- Fentanyl → not used as premed
13
Q
Anesthesia during surgery
Induction
IMPLEMENTATION COMMENTS
A
- Isoflurane → nephrotoxic and causes irritation
(due to irritation, it’s not used for this step since animals, especially rabbits, will be too irritated to inhale)
14
Q
Injectable anaesthetics and opioids can be given as bolus dose
A
→ repeat bolus when required to maintain depth of anaesthesia (otherwise the animal will wake up on the surgery table).
15
Q
Injectable anaesthetics
More safe
A
More safe would be to use the continuous rate infusion
( dose per hour/BWkg), however, keep in mind that if it’s stopped suddenly, it’ll be eliminated much faster
16
Q
Anticonvulsants
Definitions:
A
- Sudden
- Transient
- Repetitive brain malfunction
- Convulsions or tic
- Depends on severity and area of brain affected
17
Q
Anticonvulsants
Epilepsy
A
- Malfunction of motor neuron
- Can be due to several different causes
- - Toxicosis
- - Liver failure
- - Metabolism disease
- - Trauma (lesions)
18
Q
Anticonvulsants
Idiopathic epilepsy
A
Idiopathic epilepsy → seen in dogs <6 years
19
Q
Anticonvulsants
Aim of treatment
A
→ to eliminate or decrease frequency/gravity of epileptic episodes
20
Q
Anticonvulsants
When to start treatment:
A
- Convulsions last longer than 5 minutes
- 3+ generalised convulsions in 24 hrs
- 2+ convulsions within 6 months
- When postictal symptoms can still be seen for more than 1 day after an epileptic episode
= (vocalization and/or other strange behaviours)
21
Q
Active agents for status epilepticus treatment
A
- Diazepam
- Phenobarbital
- Pentobarbital
- Levetiracetam
- Propofol
- Isoflurane, (sevoflurane)
- Ketamin
22
Q
Diazepam
Administration
A
- *IV or rectal**
- *Diazepam** solution → vehicle’s absorption via IM is bad
23
Q
Diazepam
Comment
A
Midazolam, lorazepam
→ can be given IM (better absorption, but onset = longer)
24
Q
Phenobarbital
Administration
A
IV (onset = 20-30 min)
25
Pentobarbital
Administration
* **IV**
* **Trace amount used (micrograms!)**
26
Levetiracetam
Administration
* **IV**
* **Rectal**
27
Propofol
Administration
* **IV**
* **Bolus**, or
* **continuous infusion**
28
Isoflurane, (sevoflurane)
Administration
**Inhalation**
29
Ketamin
Comment
**In certain cases
Causes muscle rigidity, use after diazepam, phenobarbital**
30
What is If seizures proceed even afterwards
* Then give continuous rate infusion of **diazepam** or **propofol**, (ketamine?)
* keep the animal sedated as long as needed.
* Withdrawal drugs from time to time to see if the animal can manage,
* if seizure comes back,
* sedate the animal again.
31
Active agents to prevent epilepsy, epilepsy control:
Test type I
**Phenobarbital (A)
Imepitoin (A)
Potassium bromide (B)**
I= controlled trials;
II= case-control or cohort study;
III= case reports or series;
IV= expert opinion
Recommendation levels
A= high;
B= moderate;
C= low;
D= not recommended
32
Active agents to prevent epilepsy, epilepsy control:
Test type II
**Primidone (D)**
I= controlled trials;
II= case-control or cohort study;
III= case reports or series;
IV= expert opinion
Recommendation levels
A= high;
B= moderate;
C= low;
D= not recommended
33
Active agents to prevent epilepsy, epilepsy control:
Test type III
**Zonisamide (C)**
I= controlled trials;
II= case-control or cohort study;
III= case reports or series;
IV= expert opinion
Recommendation levels
A= high;
B= moderate;
C= low;
D= not recommended
34
Active agents to prevent epilepsy, epilepsy control:
Test type IV
**Levetiracetam (C)**
I= controlled trials;
II= case-control or cohort study;
III= case reports or series;
IV= expert opinion
Recommendation levels
A= high;
B= moderate;
C= low;
D= not recommended
35
What if you want to change drug
* To change drugs, you must do it **gradually**!
* **New drug**, begin with a **low dose** and **increase until therapeutic range**, and at the same time,
* You **decrease the dose of the current drug.**
36
Phenobarbital
in general
administration
* *First line!**
* *Success: ~80%**
* *Administration:**
* **IV or**
* **Orally** (Po absorption is good with slow onset of reaction)
37
**Phenobarbital**
On set of action
Measure of blood levels
Half life
1. **Onset** = **slow** (20-30 min); takes **2-3 weeks to reach steady plasma state**, thus have to **wait 2-3 weeks to evaluate its effectiveness** (must warn the owner about this)
2. **Measure blood levels:**
* If phenobarbital blood level is **below range** → **↑dose**
* If **above the range** and the patient is still **experiencing seizures,** then **phenobarbital ≠ effective**. Either **combine** or **change drug**
* It there’s **no epileptic episode** for **6-12 months** and **phenobarbital blood level** is **above range**, then you can **↓ dose**
1. **Half-life = 2-3 days** (admin. 2x daily)
38
**Phenobarbital**
General
* **Anticonvulsant** at **subhypnotic doses**
* **Enzyme inducer of CYP450!**
(responsible for the metabolism of other drugs!! Thus, have to increase their doses) → **autoinduction** (induces its own metabolism via activating liver enzymes → increases the rate of metabolism)
* Does **not exert its effects immediately** → so if the dog has a seizure the following day of 1st administration, do not change the drug immediately (2-3 weeks)
39
**Phenobarbital**
Side effects
Side effects:
1. **Sedation & ataxia** → last only a few days after admin.
2. **Polyphagia** → increase appetite ⇒ **weight gain**
3. **Polyurea** → increase drinking ⇒ increase urine volume
4. **Ca → sensitivity (liver damage) → idiosyncratic reaction**
40
Potassium Bromide
General
**Potassium bromide**
* **Ø fe! (lethal lung oedema)**
* **Success: 50-70%**
* Can be a **first line drug**
* Failure → combination (phenobarbital as a combination partner)
* **It’s a salt,** so there is **no metabolism in the liver**
* **Elimination → via kidney**
If the patient **suffers from kidney failure**,
* **lower dose (by 25%)** to avoid the **accumulation of salt**
* Can **induce vomiting**, can reduce this by s**plitting the dose to 2x a day with food**
**Half-life = 35-46 days** (admin. 1x daily),
**Plasma steady-state = 3 months**
41
Potassium Bromide
Side effectss
Side effects:
1. **Polyphagia**
2. **Pruritus (itchy)**
3. **Paraparesis (weakness of HL)**
4. **Pancreatitis (pancreas inflammation)**
42
Imepitoin
1. **First line**
2. **Failure → combination**
3. **Quite safe**
4. **Kidney failure → lower dose**
43
Levetiracetam
1. **Second line** (in combinations
2. **Oral tablet** (3x a day, sometimes 4x)
Side effects:
1. **Sedation**
2. **Ataxia**
3. **Loss of appetite**
44
Diazepam
* **Ø recommended long term in fe**
(individuals can be very sensitive! **It’s hepatotoxic** and can **induce irreversible liver damage** if given ~7 days)
* **Ca → appropriate dose can be effective**
Side effects:
1. **Polyphagia (fe, ca)**
2. **Ø depth perception**
3. **Sedation**
45
Zonisamide
* Success: **limited date (~60%),** used mostly in Humans
* **Second line (in combinations)**
Side effects:
1. **Sedation**
2. **Ataxia**
46
Other alternatives
1. **N. vagus stimulation** → **implant** (Hu), placed near or on N. vagus so that it doesn’t stimulate repetitive muscle contractions
2. **CBD, Gabapentin → supportive**
3. **The ketogenic diet** (high fat, moderate protein, low carbohydrates)
* **Not proven to be safe and effective**
* **Pancreatitis**!! (Ø recommended)
1. . **Acupuncture, homeopathy: NO!**
47
Not recommended substances
1. **1. Primidone**
2. - Very hepatotoxic
3. **2. Lamotrigine**
4. - Hepatotoxicity
5. **3. Phenytoin**
6. - Myocardial damages
7. **4. Carbamazepine**
8. - Bad pharmacokinetics
9. **5. Oxcarbazepine**
10. - Bad pharmacokinetics
11. **6. Vigabatrin**
12. - Not enough data
13. **7. Tiagabine**
14. - Not enough data
48
Situation task 1
Dog with severe trauma
Stabile general condition (3 years old, no known disease)
Amputation inevitable
Which drugs should we use?
* *Phenothiazine** → potentiate analgesic effect
* *⍺-2 agonist** → increase pain killing efficacy
* *Benzodiazepines** → can prevent pre & post anesthesia excitement
* *Ketamine** → IV & has analgesic effect (NMDAr antagonist), given at a continuous rate (at subanesthetic dose), decreases sensitization of pain
* *Lidocaine** → local anaesthetic, use around nerve where you’re going to cut the leg off
49
Situation task 2
Dog with severe liver failure
Idiopathic epilepsy
Phenobarbital was administered earlier
What kind of agents can be used for monotherapy of epilepsy control?
Potassium bromide
**Potassium bromide**
