ECP 4 Flashcards
What are the 6 main special physiological considerations for equine anaesthesia
1) large muscle mass
2) myopathy on recovery
3) Hyperkalemic periodic paralysis
4) Respiratory concerns
5) additional respiratory concerns
6) effect of GI tract in dorsal recumbency
In terms of large muscle mass for horses how does this affect equine anaesthesia and the two main forms of issues
- Risk for neuropathy ○ Must provide adequate padding ○ Special attention to surface nerves (i.e. Facial) 1) Facial nerve paralysis 2) radial nerve paralysis
Facial nerve paralysis in equine anaesthesia what due to, how to avoid and does it resolve
○ Often due to pressure on nerve from halter in lateral recumbency
§ Remove halter for procedure
§ Avoid halters with metal buckles on dependent side during recovery
□ Place a towel or pad between the buckle and the face if unavoidable
○ Can resolve spontaneously over a few days but not always
§ Affect ability to eat and drink
Radial nerve paralysis in equine anaesthesia what due to, how to avoid and does it resolve
○ Can be caused by prolonged lateral recumbency
§ Pull dependent limb forward -> unstacks the shoulders so brings body weight of the radial nerve
May resolve spontaneously over several days
Myopathy on recovery in equine anaesthesia why occurs, how to prevent and the worse result
- Due to poor perfusion intraoperatively
○ Blood flow to both dependent & “up” limbs decreased @ 1.5 x MAC Isoflurane (AJVR 1987)
§ Other drugs can affect this too!
○ Maintain MAP = 70 mmHg (80 mmHg for heavily muscled breeds) - need to perfuse the butt of the horse - Can develop rhabdomyolysis (muscle death)
○ Supportive care + treatment for potential myoglobinuric renal failure - can be death sentence or reduced function
Hyperkalemic Periodic Paralysis for equine anaesthesia what is it, caused by, how to prevent
○ genetic disorder of Quarter Horses
- Stress of sedation & anaesthesia can cause attack
- Quarter Horses: test for presence of gene in America and possibly do in Australia
○ Pre-treat both hetero- & homozygotes w/ acetazolamide (promote insulin production drive Na back into cells) prior to anaesthesia
- Careful intraoperative monitoring for signs of high K+ - for all standard breeds that haven’t tested
○ BRADYCARDIA first clinical sign
What is an important respiratory concern with equine anaesthesia, why does this occur
- At risk of development of hypoxemia & hypercapnia w/out ventilatory support
General anaesthesia leads to V/Q mismatch in the horse!! (↑ shunt fraction)
Due to: - Horses preferentially perfuse dorsocaudal lung fields
- Positioning changes ventilatory patterns
○ Lateral recumbency causes atelectasis of dependent lungs = decreased ventilation
What are the 2 other important respiratory concerns of equine anaesthesia why occur and how to prevent
1) Hypoventilation
§ Positional, weight of chest wall, muscle weakness from drugs, GI tract impeding diaphragmatic movement (fall onto diaphragm)
§ Assisted ventilation should be provided for procedures longer than 45-60 mins
2) Obligate nasal breathers
§ Nasal edema can occur (esp. in dorsal)
□ Consider nasotracheal tube &/or phenylephrine for recovery
§ Confirm nasal air flow after extubation
Effect of GI tract in dorsal recumbency in equine anaesthesia what occurs and what can lead to
○ Stomach/intestines rarely fully emptied
○ Weight of on abdominal vena cava ↓ venous return & cardiac output
§ May see tachycardia to compensate
○ Will push on diaphragm → ↓ diaphragmatic excursion → Hypoventilation
What are the 3 main special pharmacologic considerations with equine anaesthesia
- Anticholinergics:
Decrease GI motility = Ileus = Risk of Colic - Opioids:
○ Can cause excitement when given alone - not given alone
○ All opioids decrease equine GI motility!! - not first line of defence for pain
§ Butorphanol “theoretically” less so than pure mu’s - only lasts for an hour -> redosing issue - Alpha-2 Agonists: - use in sick horses
○ Provide visceral analgesia - significant pain relief
§ Better than opioids or NSAIDs
○ Xylazine = significant contributor to colic therapy
○ Other systemic effects (↓CO, etc.) as in other species
What are the 2 main venous access in an adult horse, what needle and what used for
1) Jugular vein ○ 18-20 gauge needle for injections - can tell the difference between carotid (high blood flow) and jugular (trickle) ○ Most common vein accessed in horse ○ Carotid artery just dorsal to vein! 2) Cephalic Vein ○ Good for short term catheters ○ Some horses do not tolerate ○ Impractical for injections or blood draws 3) Others ○ Femoral, Lateral Thoracic
What are the 4 main important equine patient preparation for anaesthesia
- Physical Exam
- Include respiratory & cardiac auscultation
- TPR, MM colour & CRT - Bloodwork
- PCV, TS (+/- Creatinine) every time
- Others as needed dictated by patient/procedure - Clean/Pick feet + wrap
- Remove shoes if possible - Wash out mouth!
What are 2 main equipment needed for equine anaesthesia
1) Mouth gag ○ Typically PCV or metal dental gag - to stop the horse from chewing the tube (high jaw tone) 2) Choosing an Endotracheal Tube ○ 26-30 mm ID ○ 20 mL cuff syringe Test cuff!
What is the goal of equine premedication, what combination of medications generally used
- Goal is moderate sedation
○ Usually an alpha-2 agonist +/- opioid
○ +/- acepromazine - not enough for pre-medication by itself BUT study suggest that will reduce risk of dying
§ Needs 30mins to work -> not used in emergency situation
§ Stallion -> risk of priapism -> consider positives and negatives
What are the 4 main clinical signs of sedation in the horse
○ Dropped head
○ Droopy lower lip
○ Relaxed ears
○ Relaxed posture
Equine anaesthesia induction what is the goal, most common combination of medication, what is important to consider and the 2 types
- Goal is controlled “fall” to recumbency
○ Diazepam/Ketamine (most common), Thiopental, Guaifenesin/Ketamine, Xylazine/Ketamine, Zolitel - Safety of personnel is priority!
Make sure everyone in area knows that horse has drugs “on board”
1) Field induction
2) Stall induction
Stall induction for equine anaesthesia what are the 2 main types
1) Assisted induction
○ Horse against wall with personnel holding to wall - eases them down
- Safer to use “swing gate” to hold horse against wall if possible
2) Pneumatic Lift Table
○ Horse must be sedated prior to “strapping” to table
Intubation of horses what are the 2 types how to intubate and when don’t you need to
1) Endotracheal intubation is “blind”
○ Place mouth gag between incisors
○ Slide tube through gag and slowly advance into trachea (feel like butter, oesophagus more tissue)
○ Confirm tracheal placement
§ EtCO2 ** - see carbon dioxide movement
§ “Feeling” air
§ Palpating neck
2) Nasotracheal intubation sometimes performed
○ Typically 20-22 mm ID
○ Technically more difficult
- Field Anaesthesia – horse may not be intubated
Equine Anaesthesia maintenance what used for different length procedures
1) Balanced crystalloids @ 10 mL/kg/hr
2) TIVA Triple Drip - = 45 mins to 1 hr as need ventilation support for larger procedure
3) Maintain on inhalants - > 1 hr
○ Iso MAC – 1.3-1.4%
○ Sevo MAC – 2.3-2.8%
Blood pressure monitoring during equine anaesthesia what are the 2 types and goal in terms of level
- Goal of MAP >/= 70 mmHg
○ 80 mmHg in heavily muscled breeds/drafts
1) Can use non-invasive
○ Doppler
○ Oscillometric
2) Invasive (arterial) is gold standard - common for surgery
○ Facial, Mandibular, Transverse Facial, Lateral Metatarsal aa.
What are some options for intraoperative analgesia for equine anaesthesia
○ Intermittent opioid boluses ○ Local and regional anaesthetics ○ Intra-articular morphine ○ CRI’s § Lidocaine § Alpha-2 agonists § Butorphanol? § Ketamine
Recovery from equine anaesthesia what are important considerations
- Place in lateral recumbency in quiet, dim stall
- Provide supplemental oxygen
- Extubate when breathing spontaneously and well
○ No need to wait for swallowing - no risk of regurgitation - Can be very eventful/rough
○ Consider assisted recovery
• Hand - not recommended for adults
• Rope - assistance
• Sling - to help protect limbs
• Pool - Consider light sedation while inhalant wears off
Foal anaesthesia what to do with mare
○ Let her accompany the foal for as long as possible
○ She may need sedation
○ Let her see the foal as soon as possible afterwards - make sure can stand properly
Foal anaesthesia what are 4 main considerations in terms of physiological differences
1) Immature Liver ○ May not maintain normoglycemia ○ Altered/slow drug metabolism 2) Immature thermogenesis ○ May need external heating support 3) More compliant chest and high RR 4) Immature SNS
Foal anaesthesia premedication examples
- Benzodiazepine (sedative in foals) + Butorphanol – great sedation/premedication for very young &/or sick foal
- Alpha 2 Agonist for older/robust foals
Foal anaesthesia induction protocols
- Facemask or NT tube Inhalant in oxygen
○ But CEPEF showed that injectable reduced mortality - Propofol or Alfaxan (+/- muscle relaxant)
- Ket/Val (ketamine/diazepam) - in older animals
- KetoFol! -> ketamine and Propofol
Typical endotracheal tube sizes 8-16 mm ID - special foal ones
Foal anaesthesia what maintain on, monitoring and recovery
Maintain on Inhalants or TIVA
Monitoring important as with adults
- Direct ABP may be technically more difficult
- May need external heat support
- Should check perioperative blood glucose
Recovery usually assisted by hand (1-2 people depending on size/age)
Heat requirements for reptiles what are the two main types and the important instruments for this
Poikilothermic
- PBT: preferred body temperature varies for every body function
- POTZ: preferred optimal temperature zone varies between taxa/species
○ Tank need to provide this!!!!
- Heat source preferences vary between taxa
Thermostats vs thermometers
What are the 3 different light requirements for reptiles and what reptiles need what
○ UVA,B and C - A = activity, B = bone, C = cancer
○ UVA debate
○ UVB essential for chelonians, lizards other than geckos, crocodiles
§ Most snakes don’t need it
Ultraviolet light for reptiles what are important considerations
- 30cm or less from basking area -> larger animal needs longer length globe
- Change globe every 6 months
- Full spectrum is visible UVA spectrum only
- Fluorescent, mercury vapor, compact UVB
- Blocked by glass and plastic
Humidity for reptiles what does it affect how to get high and low humidity and how do some reptiles access water
- Enclosure humidity affects hydration, hygiene, health of sin, lungs and gut and behaviours
○ Low humidity: small water bowl at cool end, rare bathing and misting, dry substrates, excellent drainage
○ High humidity: large shallow water source near heat, foliage, frequent misting, bathing allowed
§ Good ventilation essential for both - Some reptiles drink from containers, other from foliage or misting
- Too much access to water can be as unhealthy as too little from some taxa
Space requirements for reptiles what are 3 important considerations
1) Enough space to stretch out, climb or swim and to behave normally
○ Spread out from one corner to the other diagonally
2) Enable retreat from companions
○ Give multiple hides, basking spots etc.
3) Designed to provide an appropriate temperature mosaic
What are some important considerations with substrates and furnishings
Substrates
- Consider hygiene, thermal properties, absorbency, abrasiveness
- Turf, newspaper, commercial litters, stones, slate tiles (can hold heat), bark, sand
Furnishings
- Logs, rocks, tiles, plants, artificial works
- Hides, burrows, screening
What are 4 important things that cause stress in reptiles in terms of the envionment
- Handling reptiles usually takes them out of their POTZ
- Socialising with mammalian carnivores is usually stressful
- Being under constant surveillance by us or other pets is very stressful
- Vibrations through their tanks also cause stress
What are general diets for snakes, chelonians, lizards and crocodiles and what is important to consider with diets
- Snakes: whole prey, never live prey
- Chelonians: tortoises are terrestrial and herbivores, turtles are aquatic, fresh water turtles eat invertebrates with varying proportions of plants
- Lizards: very wide range of dietary niche
- Crocodiles: carnivores
The quality of the diet is only as good as the quality of raising of the prey items
what are important aspects of hygiene in an aquatic tank and vivarium
Aquatic - Water quality monitoring ○ Nitrogen cycle, water hardness, Ph - Filtration ○ In tank vs external, under gravel - Partial water changes Vivarium - Daily spot cleaning, 3-6 monthly scrub F10 - Mite prevention and treatment
What are the 3 important tank set up considerations when asking a client
- Poikilotherms with individual POTZs
○ Heat source management, basking opportunities, insulation, ventilation - Light (visible and UVB)
○ UVB globe type, position, age of globe
○ Day length - Humidity
Water source, misting, furnishings, ventilation
Rabbit physiological characteristics what makes them different
- Small lung volume
- Obligate nasal breathers
- Narrow gape in a crowded mouth
- Cannot regurgitate and must eat very often
○ Caecal fermenters -> gut status - DON’T FAST RABBITS - Prey animal mask their fear and pain
Rabbit patient examination what are 5 important parts
- Patency of nasal passages
- Hydration
- Gut fill and faecal consistency
- IV catheterisation marginal ear vein
- DO NOT FAST patient at all
Rabbit anaesthesia what is involved withe premedication, induction and maintenance
Premedication
○ Opioid and sedation
○ Oxygenation before give drugs - IMPORTANT
○ Quiet, calm, be gentle but restrain well, turn light of to work
Induction
○ IV or IM
Maintenance
○ Gaseous per tube (intubate) or mask (harder to ventilate, but positive pressure ventilation on the nose)
○ Circuit for patients less than 10Kg/5Kg
