Swine anesthesia Flashcards
(36 cards)
1
Q
Important points to emphasize regarding swine:
Behavior?
Physical exam?
A
- Behavior–not amiable for restraint, difficult to grab
- PE difficult to do sometimes
- Observe before handling
- If part of herd: questions about its interactions
- History of porcine stress in herd?
- Pet
- Better history
- Thoracic auscultation–PE can still be difficult
2
Q
Important oints to emphasize regarding swine
Veins/arteries?
Injection sites?
Intubation?
Alpha2’s?
Stress?
A
- Veins and arteries not readily accessible
- Limited sites for injections (fat)
- Intubation can be very difficult
- Swine = most resistant species to sedative effects of alpha2’s
- Stress–> trigger to porcine stress syndrome
3
Q
Restraint
Easy?
Equipment involved?
Which pigs are easiest?
A
- Not very amiable to restrain–stress easily
- Not much to grab
- Adults can be very strong
- Can use snare (if needed)
- Stanchion = good control
- Baby pigs and small, mini breeds easier
- May squeal when restrained
4
Q
Injections
Needle?
Sites?
A
- IM injections necessitates using needles at least 2-3in long to avoid injections into fat
- Sites
- IM injection behind the ear-neck muscle
- Using ‘butterfly’ avoids restraint (good small pigs)
- SQ injection in skin fold of rear leg
- IM injection behind the ear-neck muscle
5
Q
Venous puncture
6 sites
A
- Cranial vena cava–site is proximal to manubrium
- Used for large volumes
- Cephalic vein proximal–young/small pigs
- Jugular–deep in jugular groove
- Medial caudal vein–at the first movable tail joint–ventral midline
- Subcutaneous abdomen vein
- Ear vein
6
Q
IV catheter placement
Difficulty?
Requires what?
Sites?
A
- Tough skin, veins deep, not readily accessible
- Almost always requires sedation
- Difficult to restrain
- Squealing
- Must avoid stress
- Ear veins
- Auricular vein
- Small ears more difficult
- Lateral saphenous
7
Q
Preparation for anesthesia
Fasting?
A
- Adults = 12-24hrs
- Improper fasting–> gas accumulation producing distention; inc. pressure on diaphragm impeding ventilation
- Inc. risk of vomiting/regurg/aspiration
- Piglets = held from suckling 3-4hrs, but prone to hypoglycemia
- Mini pigs = fast up to 12hrs
8
Q
Sedation
Azaparone
A
- Butyerophenone (similar to phenothiazines)
- Only tranquilizer approved for swine in US
- Used primarily to decrease fighting and anxiety amongst pigs (lower dosages)
- Sedation at higher dosages
- IM
- Boars– >1mg/kg = penile prolapse
9
Q
Xylazine
A
- Most resistant species to xylazine and other alpha2’s
- Does not produce good sedation when used alone
- May cause vomiting
- 2-3mg/kg IV may produce rapid but short sedation that is readily abolished as soon as handler approaches/touches pig
- Add ketamine IM–short-term restraint (20-30min)
10
Q
Anticholinergics
A
- Usually not given routinely unless bradycardia warrants
- Ketamine (usually) and telazol (might) produce salivation–> makes visualizing the larynx difficult and may occlude airway or tube
- Low doses atropine may minimize secretions (unless suction is available at intubation)
11
Q
Benzodiazepines
A
- May produce some sedation when used alone (small/young pigs)
- Usually combined with other drugs, BUT
- 0.5mg/kg medazolam IM alone can produce moderate sedation
- Can also give medazolam intranasal
- Lab piglets–rapid and reliable sedation
12
Q
Tiletamine/zolazepam (telazol)
A
- “Super ketamine/diazepam”
- Reconstitute powder w/ 5ml sterile water
- Very reliable sedation and good muscle relaxation
- Potent–so small volume
- 4mg/kg IM good for IV catheter placement but not enough for intubation and may produce long recoveries (zolazepam)
- Tiletamine = responsible for restraint/anesthesia
- Zolazepam = muscle relaxation and sedation
- Prolonged recoveries using higher doses
13
Q
TKX (Telazol, ketamine, xylazine)
Reconstitue with?
Ketamine added–>
Xylazine added–>
T&Z?
Route?
A
- Reconstitute w/ 250mg ketamine + 250mg xylazine = 5ml total
- Ketamine adds more restraint, ‘anesthesia’
- Xylazine provides more sedation, muscle relaxation w/ improved analgesia
- T&Z diluted down to use smaller dosage of mixture
- IM
14
Q
Opioids
Sedation?
Used as? Example?
Post-op pain?
A
- Not very good for adding sedation to other sedatives for premedication
- Used as an adjunct to analgesia during anesthesia
- Fentanyl–bolus or infusion
- Post-op pain:
- Fentanyl patches
- Buprenorphine IV (if poss.) or IM
15
Q
Induction (if not intubatable w/ premedications)
Mask?
Drugs?
A
- Mask w/ iso or sevo if close, just not quite intubatable
- Propofol (amount depends on how sedated w/ premeds)
- Alfaxalone
- Thiopental
- If using ear vein: dilute in syringe to 1:1–avoid irritating vein
16
Q
Intubation
When?
Why?
Positioning?
Oxygen?
A
- Should always intubate unless very short procedures (<30-45 min)
- Protects airway from poss. aspiration
- Long soft palate–may obstruct airway
- Allows for ventilation to avoid hypercapnia and minimize chance of hypoxemia
- Sternal (but some feel dorsal works best)
- Pre-oxygenate before/during induction (mask or flow) at nose
- Lidocaine–sprayed on larynx using long urinary catheter–>depress spasms
- Extend head (do not over-extend)
17
Q
Why are pigs difficult to intubate?
A
- Difficult to visualize larynx
- Difficult to open mouth wide
- Narrow glottis and trachea; long soft palate
- Thick tongue, fat cheeks
18
Q
Name the labeled structures
A
- dp = pharyngeal diverticulum
- ct = long thyroid cartilage on the floor of the larynx
- pc = pharyngeal recess above larynx
- Places where the tube can get ‘stuck’
- e = epiglottis
19
Q
Intubation
Steps
A
- Carefully extend the stylet through the glottis, into the trachea (a small distance)
- ‘Thread’ the T tube over the stylet into the trachea WHILE retracting the stylet
- Must use care to avoid trauma to trachea: hematoma
- Must turn tube upward once past the glottis
- Lidocaine airway again, prior to extubation, when pig starts to swallow/chew tube
20
Q
How do you verify proper RT placement?
A
-
ET CO2 wave form
-
Waveform and CO2–only comes from the lungs
- Only reliable sign
-
Waveform and CO2–only comes from the lungs
- Condensation in the tube
- Breathing moves rebreathing bag
- “Normal” chest excursion with IPPV
21
Q
Endotracheal tube sizes?
A
- <10kg = 3-4
- 10-15 = 4-6
- 20-40 = 6-8
- 50-100 = 8-10
- >100 = up to 16
22
Q
Maintenance and monitoring
Rates?
Head signs?
A
- O2 flow rate ~50-100ml/kg/min initially, then decrease to 10-30ml/kg/min
- Iso 2.5-3% then maintenence usually 1.5-2%
- Head signs not very helpful IMO
- Want loss of palpebral with deviated eyeball
- Monitor autonomic signs
23
Q
What is monitored during pig ax?
A
- ECG–rhythm
- BP–indirect (doppler and/or oscillometeric)
- Direct pressure–auricular artery in center of pinna
- Need to cutdown for other arteries
- Pulse oximetry
- Capnography
- Temperature
24
Q
Maintenance
What is important to remember?
MAP?
Systolic?
A
- Anesthesia depresses ventilation–and in large/heavy animals hypoventilation is significant
- Hypoventilation = hypercarbia
- Hypercarbia will dec. the PaO2
- Must be ventilated IPPV–to maintain ETCO2 in acceptable range (<50-55mmHg)
- Keep MAP > 60mmHg
- Kee systolic > 85mmHg
25
**Expected vital parameters: mini and market pigs**
Normal life span
Rectal temp
Heart rate
Resp rate
Blood pressure
ETCO2
26
What 4 things should be done during recovery?
* Extubate when pig is swallowing/chewing
* May be prone to spasms once removed
* If laryngeal edema/spasms suspected: lidocaine w/o dilute phenylephrine drip into larynx (before extubation) is helpful
* Keep warm (esp. for surgery)--wrap legs
* Reverse alpha2 agonists if necessary
27
Potential complications (5)?
* Hypoventilation--provide IPPV
* Hypotension--assess depth
* Reduce inhalent if poss.
* Fluids: dobutamine; dopamine
* Airway obstruction; laryngeal edema
* Porcine stress syndrome
* Striated muscle deterioration
* Malignant hyperthermia
28
What breeds are associated with porcine stress syndrome/malignant hyperthermia?
* Pietran
* Landrace
* Large white
* Poland China
* Duroc
29
Porcine stress syndrome/MH: pathophysiology
* Inherited--autosomal recessive mutation in the ryanodine gene (Ca release channel)
* Ca cannot exit sarcoplasmic reticulum
* Leads to muscle rigidity
* Hyper-metabolic state--inc. temp
* Inc. CO2 (prod. exceeds elimination)
* Can be fatal
30
**MH**
Triggers?
* Stress (called capture myopathy in wild animals)
* Halothane; succinycholine 'classic' triggers assoc. w/ anesthesia
* Has occurred w/ all the inhalents
* **Must have the gene**
* Not all pigs will get MH
31
**MH**
Signs?
* Rapid onset of tachycardia, tachypnea
* Hyperthermia (\>107 F)
* Myoglobinuria
* Inc. K, inc. ionized Ca
* Unstable BP
* Muscle rigidity
* **Rapid rise in ETCO2 (despite increases in RR/volume)**
* Hypermetabolic state--overproduction of CO2
* Dysrhythmias lead to cardiac arrest
32
**MH**
Antidote?
Problem?
* Dantrolene
* Suppresses Ca release but doesn't inhibit uptake of Ca by muscle cells
* Aids in Ca removal from SR
* Direct relaxing effect on skeletal muscle
* Problem--most likely won't have it
* Call medical center in town to get it fast
33
**MH**
Treatment?
* Discontinue inhalent anesthesia; change to fresh machine (w/ new equipment)
* Use propofol or alfaxalone to keep asleep (if necessary) w/ midazolam
* Institute body cooling--ice baths or alcohol
* Cool IV fluids
* Hyperventilate to dec. ETCO2
* Blood gas--for pH, BE, PaCO2, PaO2
* Metabolic acidemia can/will occur
* If PCO2 is still high, Na bicarbonate will only increase CO2
* Still might be necessary (small amounts) if BE \> 10-12 mEq/L
34
Anesthesia for MH susceptible pig?
* Pre-treat w/ dantroline 5mg/kg PO 8-12 hours before surgery
* May need to repeat pre- and post-operatively
* Use injectables (propofol and opioids/medazolam) if necessary to avoid inhalants
35
**Lumbosacral epidural**
Use?
Process?
* Facilitate C-section, repair rectal, uterine, vaginal prolapse, other 'hind-end' procedures
* Lumbosacral anesthesia
* Retrain--chute, sanction, w/ or w/o sedation
* Palpable depression midline between and just caudal to iliac wings at L6-S1
* Needle length 2-4cm
* Up to 4-10cm \> 100kg
* 20mg (1ml) lidocaine/4.5-7kg
36
What drug is used for castration?
Lidocaine 2% w/ equal volume saline (for more volume) injected into center of each testicle
