Anaesthesia and analgesia Flashcards
Define nociception
lack of awareness of painful inputs
Why do we give a premed ?
-reduce dose of inducing agent
-reduce dose of maintenance agent
-pre-emptive analgesia
-smooth recovery
List pre med drugs
acepromazine ACP
alpha 2 agonist -medetomidine
benzodiazepine - midazolam
alfaxalone
opiod
Describe the use of ACP as a pre med
-usually with opiod
-sedation
-cause vasodilation - not good for sick animals
-SC,IM,IV and oral
What alpha 2 agonists do we use for small animals ?
medetomidine or dexmedetomidine
What alpha 2 agonists do we use for horses ? ( fast-slowest to kick in )
xylazine - fastest
detomidine - middle
romifidine - slowest
What alpha 2 agonists are used in cattle ?
xylazine
detomidine
Describe alpha 2 agonist as a pre med
-cardiovascular effects
-analgesia
-increase urine production - no blocked cats
-effects glucose - diabetic patients
-not in sick patients
-has reversal agent ( atipamezole )
List examples of benzodiazepines
midazolam
diazepam
Describe the action of benzodiazepines as pre meds
-no analgesia
-ASA 3 - can use in sick animals
-wide therapuetic index
-avoid in excitable animals
-works on GABA
-reversal ( flumazenil )
- usually combined opiod, ketamine or alfaxalone
Describe the action of alfaxalone
-IV and IM
-usually combined opiod
-minimal cardiovascular effects
-painful in large animals IM - large amount
List some examples of opiods
methadone (dog , cat , horse )
fentanyl ( dog, cat )
butorphanol ( used lot in equine )
buprenorphine ( horse , dog , cat )
Describe the action of opiods as pre med
-analgesia
-limited cardiovascular effects
TRUE/FALSE ASA 5 is a healthy animal
false
TRUE/FALSE no alpha 2 agonists in sick patients
true
List some induction agents
propofol
alfaxalone
ketamine
TRUE/FALSE volatile agents are mainly used for maintenance
true
What does propofol target ?
GABA receptors
State disadvantages and advantages of propofol
-rapid uptake
-rapid smooth recovery
-resp and cardiovascular depression - Good to have IPPV breathing system
-no analgesia
What does alfaxalone target ?
-GABA receptors
Advantages and disadvantages of alfaxalone as a induction agent
-rapid onset of action
-rapid and smooth recovery
-licensed for rabbits too
-resp and cardiovascular depression
-no analgesia
What does ketamine target ?
-NMDA receptor antagonist
Advantages and disadvantages of ketamine as an inducing agent
-analgesia
-licnesed ruminants,rodents,rabbits ,primates and horses as well as cat and dog
-poor muscle relaxation ( combine with alpha 2 or BZD)
-schedule 2
What in feline triple
opiod,ketamine and alpah 2
What in a feline quad ?
opiod , alpha 2 , midazolam and ketamine
How do you measure an ET tube ?
nares to point of shoulder
TRUE/FALSE = gags are usually required for large animal intubation
true
What is a supraglottic airway device ?
v-gel
use cats, rabbits
Name some non rebreathing systems .
-lack
-bain
-T piece
Name the weight , circuit factor and IPPV ability of a lack and mini lack
-10 kg
- 1
-not long term IPPV
Mini lack same as above but for 2-10 kg
State the weight, CF and IPPV ability of a bain.
-7-30 KG
- 2.5
-really good IPPV
State the weight , CF and IPPV ability of a T piece .
-less than 10kg
-2.5
-IPPV
lacks full name
parrallel lack
How to do fresh gas flow calculation ?
fresh gas flow per minute=MV x CF
TV= 10mls/kg ( so need to x 10 by weight )
MV = TV x RR (20 bpm) = usually 0.2 L
CF - of what breathing system you select
Name a rebreathing system with weight and IPPV ability .
-circle
-10-150 kg ( 30-1000kg in LA )
-IPPV
How to calculate fresh gas flow for a circle
-first 10-15 min - 100mls/kg/min(2-4L/min)
-then 50ml/kg/min ( 1-2l/min)
What is a minimum alveolar conc and how does it help ?
-minimum alveolar conc
-how much needed in order to not respond to surgery if didn’t have pre med
TRUE/FALSE a patient with more fat will have a longer recovery
true - anaesthetic will redistribute into fat and this will act as a reservoir for anaesthetic
What do we use to maintain anaesthesia ?
inhalation agents
Name some advantages and disadvantages of isoflurane
-less mortality than halothane
-licensed - dog, cat, horse, exotics
-lower solubility -not washed away as quick
-cardiovascular and resp depression
Name some advantages and disadvantages of sevoflurane.
-faster induction and recovery
-more expensive
-not licensed horses
-cardiovascular and resp depression
What is TIVA and how is it achieved ?
-total intravenous anaesthesia
-top up bolus injections (propofol,alfaxalone, ketamine )or continuous rate infusions ( triple drip use equine ,propofol,alfaxalone )
What is the triple drip in equine ?
detomidine , guaifenesin , ketamine in fluid bag
What is PIVA ? what are the main goals of it ?
-Partial intravenous anaesthesia
-reduce MAC , cardiopulmonary depression
-additional analgesia
-balanced anesthesia
e.g use of inhalation agent and lidocaine , ketamine , alpha 2 agonist , opiods - continuous rate infusion or top-up boluses
Name ways to establish depth of anaesthesia.
-jaw tone ( brachy maintain some jaw tone, ketamine increase muscle tone )
-eye position
-palpebral reflex
How can we monitor temperature during surgery ?
-oesophageal temp probe
-rectal thermometer
What does SpO2 tell us ?
percentage of haemoglobin that is saturated with oxygen
normal is about 95%
What does capnograph measure ? what does this tell us ?
ventilation
-expired (EtCO2 level of CO2 released at end of expired breath ) and inspired CO2 levels
-problem ventilation, metabolism(will be impacted by perfusion ) , perfusion
Normal EtCO2 in cats and dogs
dog - 35-45mmHg
cats- 28-45 mmHg
What can low CO2 indicate ?
hyperventilation - CO2 exhaled faster than being produced
What can high CO2 indicate ?
hypoventilation - CO2 exhaled slower than its being produced
Why treat pain ?
effects us on a sensory , motivational and cognitive level
How can measure pain ?
-physiological measurements
-pain scales -composite measure pain scale (feline, dog ) , equine pain scale or equine composite pain scale
-pain faces and grimace scale ( cats , muzzle tension , orbital tightening ,ear positioning )
What drugs can we use to manage pain ?
-NSAIDs -galiprant - joint specific
-paracetamol
-opiod -preventative analgesia
-local anaesthetics -easy to overdose
-Alpha 2 agonists - pre medy
-ketamine - more for perioperative analgesia , good zoo ,exotics
Name some chronic pain scales
helsinki chronic pain index
guvquest
How do local anaesthetics work ?
-ionised
-interact with sodium channels
Name local anaesthetics used in vet med .
-procaine
-lidocaine
-bupivacaine
-mepivacaine
-proparacaine
State some advantages and disadvantages of use of procaine
-rapid
-last 40-60 minutes
-low toxicity
-cattle
-low potency
State some advantages and disadvantages of lidocaine
-rapid
-1-2 hr
-low toxicity
-all species
-low potency
Some advantages and disadvantages of bupivacaine
- last 4-6 hours
-very high potency
-small animals
-slow
-very high toxicity
What species is mepivacaine used in ?
equine
Name some blocks
-preincisional
-castrate - pre incisional , intra testicular
-ovariohysterectomy - direct infiltration of mesovarium ligament , lavage peritoneal cavity with local
-eye - retrobulbar (curved or straight needle )
-epidurals - lumbosacral , sacrococcygeal
-dental - rostral maxillary ( soft tissue ) , caudal maxilary, mandibular block ( and rostral mandibular )
-IVRA intravenous regional analgesia
What’s a nerve locater ?
use it to find nerve to administer nerve block
TRUE/FALSE only use pure lidocaine IV
true
Name 3 local anaesthesia techniques for flank surgery
-line block
-inverted L block
paravertebral anaesthesia
What gauge and length needle would you use for large animal nerve blocks ?
18 gauge , 1 1/2 inch
Describe how to do a line block and some properties
-local at varying depths along incision site
-unrealiable anaesthesia of peritoneum
-slow
Describe how to perform an inverted L block and some properties
like a line block but in inverted L shape - block both routes to the flank area
-unrealiable anaesthesia of peritoneum
-slow
Describe how to perform paravertebral anaesthesia .
-T13 , L1, L2 (L3 for caesarean )
-once deep to transverse processes insert local then pull up insert more before coming out
-fast
-anaesthesia in most of flank - include peritoneum
Name some blocks for foot surgery in cattle
-ring block
-IVRA
What local do we use for cattle ?
procaine
What local do we use for horses ?
lignocaine
What are the 5 sensory nerve blocks of the head in a horse ?
-supraorbital - frontal nerve 9 branch optic )
-lacrimal -lateral canthus
-zygomatic - (zygomatic nerve )
-infratrochlea - Medial canthus
-retrobulbar - cilary body nerves
What sedatives do we use for cattle ?
xylazine
detomidine
What GA do we use fro cattle
ketamine
What opiods do we use for cattle ?
butorphanol
TRUE/FALSE ACP is licensed in horses
true
When to avoid using ACP in horses ?
neonates , pregnant , hypotensive , breeding stallions ( effects retractor penis muscle )
TRUE/FALSE Brachy at risk of airway obstruction in recovery
true
What are some common causes of upper airway obstruction ?
-loss of pharyngeal muscle tone
-regurgitation or vomiting
-laryngospasm or laryngeal oedema ( especially cats - don’t extubate too late
-traumatic intubation
-brachy
Signs of upper airway obstruction
-increased resp noise and effort
-abdominal effort
-nares flare
-“air hunger “ - head and neck extended
-cyanosis ( late sign )
-restless
-agonal breathing ( terminal sign )
why high mortality rate in horse anaesthesia ?
-fractures in recovery
-post anaesthetic myopathy
-neuropathies and spinal cord malacia
-intraoperative cardiac arrest
-resp obstruction
What risk factors increase mortality rates in horses ?
-increase ASA grade
-increase age and foals
-surgery type and position - dorsal
-duration - pressure on parts of body
-time of day - in OOH vet tired , less staff
-agents - premed TIVA
-recovery quality
What fresh gas flow rate to use for a large animal circle ?
-start 6-8l/min
-after 15 min reduce to 3-4l/min
TRUE/FALSE: ACP as a pre med for horses reduces mortality rates
true
Common induction agents in equine
-ketamine
-benzodiazepine
TRUE/FALSE biggest problem with maintenance of anaesthesia in horses is hypotension
true
How long does triple drip last ?
45 min
What top-up bolus injections can you give to a horse to maintain anaesthesia ?
ketamine 0.5mg/kg every 10 min - can only do for 20 minutes
What PIVA can you use for horse and what will this do ?
-ketamine infusion
-lidocaien CRI
-Alpha 2 agonist infusion
-reduce MAC and amount of inhalation agent required
State some complications that occur during equine anaesthesia .
-hypotension
-hypoxaemia
-hypercapnia
-bradycardia
-tachycardia
-neuropathy
-eye problems
How would you improve hypotension in horse under anaesthesia ?
-positive inotrope - dobutamine
-reduce iso
-use PIVA
-increase fluid
How would you improve hypoxaemia in horse under anaesthesia ?
-check not just machine
-switch down iso
-IPPV
-IVFT
-tilt head
-give beta agonist - salbutamol
How would you improve hypercapnia in horse under anaesthesia ?
- can tolerate up to 70 CO2
-reduce iso
-IPPV
How would you improve bradycardia in horse under anaesthesia ?
-cause - volatile agent? opiod?
-if still low give hyoscine N butylbromide
How would you improve tachycardia in horse under anaesthesia ?
-cause ? - sympathetic stim ? , CO2 ?
-increase depth with ket bolus iv
-more analgesia
TRUE/FALSE must protect lowermost eye with padding and lubricate when a horse is anesthetised or they’ll get corneal ulcers
true
What are the optimal timings for a horses movement in recovery ?
-lateral - 30 min
-sternal - 10-15 min
-standing - 15 min
TRUE/FALSE give a low dose sedative while in recovery so horses don’t hurt themselves as the anaesthesia wears off
true
Name some causes of bradycardia when under GA
-drug
-toxaemia
-vagus stimulation (e.g if touching eye , gut)
-heart problem
-hypoxia
-hypothermia
How to approach bradycardia in anaesthetised patient ?
-look ABP and SPO2 -see if affected
-check depth , vagal tone , hypoxia , toxaemia
-if drug induced give reversal or give anticholinergics ( e.g atropine )
What might cause tachycardia in an anaesthetised patient?
-sympathetic stimulation - too light
-abnormalities in ph , CO2 ,O2
-low ABP
-drugs
How would approach tachycardia in anaesthetised patient ?
-check ABP and O2
-depth of anaesthesia ,CO2
-IV opiod ( fentanyl , methadone) /lidocaine
*can increase volatile agent with increase in opioid
What might cause a ventricular ectopic beat in the anaesthetised patient ?
-circulating catecholamines ( stress)
-hypoxia/hypercapnia
-hypovolaemia or hypotension
-drugs
-myocardial inflammation or stimulation
-trauma
How would you approach a ventricular ectopic beat in patient under GA ?
-check ABP,O2
-is there risk fibrillation
-check depth , CO2
-IV opiod /lidocaine
*vaporiser setting increased with opiod
What are the common causes of hypotension in GA ?
-anaesthetic drugs
-hypovolaemia and haemorrhage
-cardiac insufficiency
How would you approach hypotension ?
-try determine cause
-reduce volatile agent
-increase IVFT
-re-check ABP
-inotrope ( dobutamine ) - make heart pump harder
-or vasopressor ( noepinephrine ) -
Why would hypercapnia occur in GA ?
-depth
-hypoventilation - panty
-pyrexia
-rebreathing
-fresh gas too low
Reasons why hypocapnia might occur under GA
-disconnection
-mis -intubation
-obstruction
-hyperventilation
-cardiac arrest
TRUE/FALSE cats have a higher ET CO2 reading on non-breathing systems
false -its lower
TRUE/FALSE = cardiogenic oscillations are an emergency
false - nothing to worry about
How would you approach hypoxaemia ?
-replace pulse oximeter probe to check right
-check not disconnected
-reduce volatile agent
-improve perfusion - IVFT, inotropes
-ventilate , tilt table if obese
-investigate other causes ( haemorrhage , pneumothorax )
State some signs of cardiopulmonary arrest
-loss of consciousness
-apnoea /agonal gasp
-no corneal reflex or palpebral
Name reversals / antagonists of alpha 2 , opiod , opiods, benzodiazepine
-alpha 2 - atipam ( atipamezole)
-opiod - naloxone
-benzodiazepine - flumazenil
What is Asystole and PEA and what would you do to correct these ?
-asystole - flat line
-PEA - pulseless electrical activity * can look normal
-adrenaline - shunts blood from preiphery to heart
-vasopressin - peripheral vasoconstriciton
-atropine - reduce vagal tone
How would you prepare for operation of sick animal ?
-preop bloods
-IVFT resuscitation
-anti anxiety
What pre med would you give to a sick patient ?
-opiod
-fentanyl and midazolam
-ketamine and midazolam - cats
-alfaxalone with opiod
*avoid alpha 2 agonists
How would you induce a sick patient
-palpate pulse during induction
-mucous membranes
How is maintenance and monitoring of GA different in sick animal ?
-avoid too much depth
-PIVA and TIVA can reduce reliance on volatile agent
-IVFT
-analgesia , local blocks
-emergency drugs ready and calculated
-efficiency
-warm
What does APL stand for and what does it allow ?
-adjustable pressure limiting valve
- allows exhaled waste gas and fresh gas to leave the breathing system when pressure within the system exceeds the valves opening pressure
TRUE/FALSE don’t need to starve rabbits before surgery
true
How would you ventilate rabbit?
v-gel
TRUE/FALSE you want to keep a rabbit in sternal for as long as you can when undergoing surgery
true
( want to keep thorax higher than abdomen if have to lie on back - so organs don’t effect resp rate as much )
What would you use to monitor rabbit ?
-capnograph - very important
-doppler
-temp
*SPO2- bv too small
ECG - too fast hard to read , hair
How would you increase rabbits bp ?
-warm up
-drugs - vasopressins
-fluids - 10ml/kg for 10-15 min - can do at least 3-4 times
-increase heart rate with atropine
TRUE/FALSE = red blood cells in bird are nucleated
true
*messes up SPO2 reading
Where would you administer fluids to bird ?
-iv in wing vein or medialmetitarsal vein
-interoseous - easy in birds
TRUE/FALSE tortoises will stop metabolising the drugs you’ve given if the surrounding area is around 30 C
true
Why is it important to ventilate tortoises in recovery ?
their breathing isn’t stimulated by co2 in blood is triggered by oxygen
What are the top 5 anesthetic complications ?
-hypotension
-hypothermia
-abnormal heart rate
-hypoventilation
-difficult recovery
