Anaesthesia Flashcards
1
Q
Define pain
A
Unpleasant sensory and emotional experience associated with or resembling that associated with actual or potential tissue damage
2
Q
Define nociception
A
Neural process of encoding noxious stimuli
3
Q
What is the difference between pain and nocicpetion
A
Pain is the interpretation of nociception, dependent on the individual, nociception can be present without pain
4
Q
What is the purpose of pain and why does it need to be treated?
A
Protection
Can affect function and well-being of individuals
5
Q
Define nociceptive pain
A
Pain from actual damage to non-neural tissues, activation of nociceptors
6
Q
Define neuropathic pain
A
Pain from a lesion or disease to somatosensory system
7
Q
Explain the difference between nociceptive and neuropathic pain
A
Nociceptive is in a normally functioning somatosensory system, neuropathic pain is in a damaged somatosensory system due to lesion or disease, harder type of pain to treat
8
Q
Define hyperalgesia
A
Increased level of pain in response to a normally painful stimuli
9
Q
Define allodynia
A
Pain from a normally non-painful stimuli
10
Q
What is the differences between acute and chronic pain?
A
Acute- short term, acts as protection, can lead to chronic pain if untreated
Chronic- long term, generally not protective, causes suffering
11
Q
What are physiological signs of pain?
A
Tachycardia Hypertension High body temperature Altered RR and pattern Release of stress hormones (adrenaline, cortisol etc.)
12
Q
What factors affect how animals present signs of pain?
A
Species
Individual
Condition
Prey or predator
13
Q
What are signs of pain common to dogs and cats?
A
Hunched over Pain face Lack of grooming Inappetence Condition specific signs
14
Q
What are signs of pain in dogs?
A
Positive signs rather than reducing normal behaviour
Attention seeking
Submission
Vocalisation
15
Q
What are signs of pain in cats?
A
Absence of normal behaviour Hiding Tense Fear-aggression Unwilling to have human contact
16
Q
What are signs of pain in rabbits?
A
Tend to mask signs of disease Immobility Depression Closed eyes Not grooming Isolation Bruxism Hunched over Change in temperment
17
Q
What are signs of pain in horses?
A
Fight or flight response Low head Vocalisation Grooming Agitation Restless Lameness Pain face Bruxism
18
Q
Why is it important to be able to quantify pain?
A
Determine the course of treatment and assess if its effective and if the animal has a good quality of life
19
Q
Name and briefly describe different methods of quantifying pain
A
Numerical rating scale- number pain 1-10
Visual analogue scale- marking pain on a line
Simple descriptive scale- provide description of pain to assign
20
Q
What is the preferred method of assessing pain and how is it used?
A
Composite pain scale
Tailored to dogs and cats, has specific parameters that are assessed to determine pain
Analgesia provided for cats above 5/20 and dogs above 5/20 or 6/24
21
Q
What are challenges of pain assessments?
A
Animal themselves can’t tell you what or where the pain is
Needs to rely on owner or vets judgement which is subjective
Some patients will have different reactions to pain, some hide it etc so hard to be definite
22
Q
What are some methods used for chronic pain assessments and how do they work?
A
LOAD questionnaire- mobility questions scored 0-4
CSOM- 5 normal behaviours determined and assessed over time whether they engage with these and how they change with treatments
Videos- track changes in normal environment
Tend to look at patterns not one point in time
23
Q
Why are chronic pain assessments important?
A
Aid decision on treatment, keeps it consistent or need for euthanasia
24
Q
Define preventative analgesia
A
Administering effective analgesia before, during and after procedure
25
Why is preventative analgesia important?
Prevents upregulation of nervous system in noxious stimuli so lowers intensity and length of acute pain, should also reduce chronic pain
26
What is multi-modal analgesia?
Using different classes of analgesic agents and techniques
27
Why is multi-modal analgesia used?
No single analgesic will block all nociceptive pathways
| Leads to more effective analgesia and lowers doses so reduces side effects
28
What are the legal requirements for opioids?
Controlled drugs so need CD cabinet, records of drugs
Full agonists- schedule 2, special prescription, storage, destruction and record keeping requirements
Partial agonists- schedule 3, special prescription requirements, buprenorphine needs to be locked in cabinet
29
How do opioids produce analgesia?
Act at endogenous opioid receptors in brain and spinal cord
| Mu agonists are most effective at providing analgesia
30
Name examples of opioids of full and partial agonists and antagonists
Full agonists- methadone, fentanyl
Partial agonists- buprenorphine, butorphanol
Antagonist- naxolone
31
State the type of opioid, licencing, species used in, use and duration of action of fentanyl
Type of opioid- Full mu agonist
Licencing- cats and dogs
Species used in- cats, dogs, rabbits, horses
Use- intraoperative, short term infusions
Duration of action- minutes
32
State the type of opioid, licencing, species used in, use and duration of action of morphine
```
Type of opioid- full mu agonist
Licencing- non
Species used in- dogs, cats, horses
Use- general acute pre-, peri- and post-op pain
Duration of action- 2-4 hours
```
33
State the type of opioid, licencing, species used in, use and duration of action of methadone
```
Type of opioid- full mu agonist
Licencing- cats and dogs
Species used in- cats and dogs
Use- general acute pre-, peri- and post-op pain
Duration of action- 2-4 hours
```
34
State the type of opioid, licencing, species used in, use and duration of action of pethidine
```
Type of opioid- full mu agonist
Licencing- dogs, cats, horses
Species used in- mainly horses
Use- general acute pre-, peri- and post-op pain
Duration of action- minutes
```
35
State the type of opioid, licencing, species used in, use and duration of action of buprenorphine
```
Type of opioid- partial mu agonist
Licencing- dogs, cats, horses
Species used in- dogs, cats, rabbits
Use- general acute pre-, peri- and post-op pain
Duration of action- 6 hours
```
36
State the type of opioid, licencing, species used in, use and duration of action of butorphanol
```
Type of opioid- K agonist/mu receptor
Licencing- dogs, cats, horses
Species used in- dogs, cats, rabbits
Use- general acute pre-, peri- and post-op pain
Duration of action- 2 hours
```
37
How are opioids administered?
Usually IV, cant for pethidine
| Well absorbed orally, SC, IM but oral has significant first pass metabolism
38
What are side effects seen when using opioids?
Respiratory depression- dose dependent, mainly when under anaesthesia
Sedation- more in dogs, dose dependent
Excitement- high doses, usually in pre-med
Bradycardia
Nausea- more in pre-med
Low GI motility- issue if using chronically
Urinary effects- when give epidurally
39
How do NSAIDs work to provide analgesia?
Inhibit prostaglandin production which are inflammatory mediators by inhibiting COX (cyclooxygenase) or LOX (lipoxygenase)
40
What are cautions that should be taken when using NSAIDs?
Metabolised by liver so care when patient has hepatic compromise
Care when patient is dehydrated or hypotensive
Can only use one in multi-modal analgesia
41
What NSAIDS and by what administration are licenced for dogs?
```
Meloxicam- injection, oral
Carprofen- injection, oral
Robenacoxib- injection, oral
Ketaprofen- injection, oral
Firocoxib- oral
Phenylbutazone- oral
Grapiprant- oral
```
42
What NSAIDS and by what administration are licenced for cats?
Meloxicam- injection, oral
Carprofen- injection
Robenacoxib- injection, oral
Ketaprofen- injection, oral
43
What NSAIDS are used in rabbits?
Meloxicam- most common
| Carprofen- sometimes used
44
What NSAIDS and by what administration are licenced for horses?
```
Meloxicam- injection, oral
Firocoxib- injection, oral
Flunixin- injection, oral
Phenylbutazone- injection, oral
Ketaprofen- injection
```
45
What are common side effects of using NSAIDs?
GI ulceration- particularly if history, or has reduced drug clearance ability
Renal ischemia
Hepatopathy/liver disease- rare idiosyncratic reaction in dogs
CNS- unknown cause, dullness and lethargy in cats
46
When should dog and cat owners seek medical attention when using NSAIDs?
Vomiting, diarrhoea
| General illness
47
When should horse owners seek medical attention when using NSAIDs?
Colic, diarrhoea, dehydration, weight loss
| General illness
48
When should rabbit owners seek medical attention when using NSAIDs?
Anorexia, bruxism, depression, vomiting
49
Explain how local anaesthetics work as analgesics
```
Enter nerve fibres and block voltage-operated Na+ channels, stabilising membrane so blocks nerve conduction
Blocks nociception (perception) before blocking proprioception (body position) and mechanoreception (stimuli detection)
```
50
What are the characteristics of local anaesthetics?
Weak bases
Only can cross lipid membranes and enter nerve cells when uncharged
When in higher pKa or lower pH more of drug is ionised so has slower and less effect
51
What are the two types of local anaesthetics and their properties?
Amide- i in name before caine, stable, broken down by cytochrome P450 liver enzymes, longer plasma half life
Ester- no i in name before caine, relatively unstable, rapidly broken down by cholinesterase so short plasma half life, PABA formed in hydrolysis which can be allergen
52
What are local anaesthetics used for?
Balanced anaesthesia
Desensitisation
Post-op pain relief
Lameness investigations
53
What is the licencing, species used in, length of action and other information about procaine?
Licencing- dogs, cats, horses
Species used in- dogs cats, horses, rabbits
Length of action- 50 minutes
Other- licenced versions contain adrenaline to vasoconstrict and keep in local area, least potent
54
What is the licencing, species used in, length of action and other information about lidocaine?
Licencing- dogs, cats, horses
Species used in- dogs, cats, horses, rabbits
Length of action- 20-40 minutes
Other- 2-5 minute onset, lower cardiotoxicity than bupivacaine, low potency
55
What is the licencing, species used in, length of action and other information about bupivacaine?
Licencing- none
Species used in- dogs, cats, rabbits
Length of action- 6 hours
Other- longer onset than lidocaine, most potent
56
What is the licencing, species used in, length of action and other information about mepivacaine?
Licencing- horses
Species used in- horses
Length of action- 2 hours
Other- used mainly for digit nerve blocks, more potent and toxic than lidocaine
57
What is the licencing, species used in, length of action and other information about ropivacaine?
Licencing- none
Species used in- small animals
Length of action- 6 hours
Other- lower CVS and CNS toxicity than bupivacaine, high potency
58
What is the licencing, species used in, length of action and other information about EMLA/eutectic mix of local anaesthetic/lidocaine and procaine?
Licencing- none
Species used in- rabbits
Length of action- 30-45 minutes
Other- topical, IV catheter placement
59
What is the licencing, species used in, length of action and other information about proparacaine and tetracaine?
Licencing- none
Species used in- cats, dogs
Length of action- 15 minutes in cats, 45 minutes in dogs
Other- opthalamogical preparations to desensitise cornea
60
Explain toxicity pharmacology for local anaesthetics
Increases as potency and dose increases
Causes neurotoxicity and CV toxicity
Prevented by not exceeding maximum dose, if need larger volumes dilute, aspirate to make sure isnt in vessels
61
How are local anaesthetics formulated?
Made into salt solution as otherwise poorly water soluble, does lower pH causing stinging on injection
62
What is meant by baricity?
Weight of one substance compared to another
63
How does baricity affect use of local anaesthetics in epidurals?
If moves into higher space could compromise respiratory muscles, need to add glucose to make solution heavier
64
What factors affect duration of action of local anaesthetics?
Lipid solubility
Strength of binding to channel
Speed of removal and metabolism
65
Why do vasoconstrictors get added to local anaesthetics?
Reduce speed of systemic absorption, prolongs duration of action, reduces toxicity and reduced bleeding at injection site
66
How does protein binding affect local anaesthetics?
Those that bind more readily have longer duration of action and lower toxicity risk as are only active when unbound
67
Side effects of local anaesthetics
Increased risk at increased doses
CNS- seen at lower doses, minor behavioural changes, muscle twitching, tremors, CNS depression, death
CV system- hypotension, dysrhythmias
Treat symptomatically as cant reverse local anaesthetics
68
What is paracetamol licenced for and when is it used?
Dogs, orally
| Alternative to NSAIDs when contraindicated, useful to add to horse analgesia when in extreme pain. Toxic to cats
69
What is tramadol licenced for and when is it used?
Dogs, injection and oral
Also used in cats and rabbits, may cause GI motility decrease in horses
Alternative for opioids use at home, second analgesia in chronic pain
70
How does tramadol provide analgesia?
Acts centrally on mu opioid, noradrenergic and serotonergic systems
Wide therapeutic index but questions about efficacy
Should be used as co-analgesic
71
What analgesics have no licencing in animals and are used as second line anaesthesia to treat chronic pain?
Gabapentin
Pregabalin
Amantadine
Amitriptyline
72
How does gabapentin cause analgesia and what are side effects?
Binds to voltage gated calcium channels
| Sedation, more when combined with tramadol, potentially toxic in liquid solutions with xylitol
73
What does pregabalin have a similar structure to and how does it differ?
Gabapentin
| Better oral bioavailability and half life
74
What are features of amantadine?
NMDA receptor agonist
Antihyperalgesic, used along side other analgesics
Short duration of action
Renal excretion
75
How do you calculate fresh gas flow ml?
body weight (kg) x tidal volume (ml/kg) x respiratory rate x circuit factor
or
minute volume x circuit factor
76
How do you calculate drug volume (ml)?
(body weight (kg) x drug dose (mg/kg))/drug strength (mg/ml)
77
How do you convert mcg/kg to mg/kg?
mcg/kg / 1000
78
How to convert drug strength in % to mg/ml
% x 10
79
Define anaesthesia
Reversible state of production of state of unconsciousness
80
Define general anaesthesia
State of unconsciousness with absence of pain across whole body
81
Define local anaesthesia
Lack of sensation in localised part of the body
82
Define analgesia
Reduced pain
83
Define sedation
Alloying of excitement or irritability
84
Define premedication
Combination of drugs prior to inducing general anaesthesia
85
What is the purpose of anaesthesia?
Prevent pain and cause immobility to allow surgery and diagnostic testing
86
Define anxyolysis
Reduced anxiety
87
Define narcosis
Sleep like state
88
What is the risk of mortality due to anaesthesia in cats, dogs, horses and rabbits?
Cats- 0.24%
Dogs- 0.17%
Horses- 2.2%, 11.7% if colic
Rabbits- 1.39%
89
What increases risk of anaesthesia death?
If already sick
Extremes of patient size- unsuitable equipment
Aggressive patient- hard to examine pre-op, remove IV and ETT early
Drug sensitivities in certain breeds
Obesity- hard to inject IM, easily overdose as liver not bigger with higher body mass, more thoracic pressure so harder to breathe
Brachycephalic- harder to intubate, prone to gastroesophageal reflux, prone to dry eyes
90
What are the different classes of drugs in the schedule and examples?
```
1- no veterinary use, amphetamines
2- full mu agonists, morphine, fentanyl
3- barbiturates, tramadol, gabapentin
4- benzodiazepines, steroids
5- codeine, morphine in small doses
```
91
What is meant by anaesthetic triad?
Narcosis
Analgesia
Muscle relaxation
92
Define balanced anaesthesia
Anaesthesia produced by smaller doss of multiple drugs
93
Why is balanced anaesthesia used?
Anaesthetic triad cant be provided by a single agent
| By using smaller doses of multiple drugs it lowers risk of side effects
94
What needs to be included in owner conversation and consent pre-op?
```
Explain procedure, risks, costs etc.
Get full history
Confirm fasting times
Gain informed consent, sign documents
Tell when they will hear from practice
```
95
Why is pre-op fasting recommended in dogs and cats?
Reduce risk of gastroesophageal reflux, regurgitation, aspiration
Help ventilation as less pressure on diaphragm
96
When should you not fast patients pre-operatively?
Not in rabbits as cause gut stasis
| If too long excess stomach acid produced causing increased risk of reflux
97
What is checked in pre-op vet exam?
Full clinical exam, particularly MM for petechia, CRT, heart, pulses, respiration, temperature and any owner concerns
ASA classification
Drugs planned to use
Any diagnostic testing such as bloods or urine
98
What are the different ASA classifications?
I- normal healthy animal
II- mild systemic disease
III- controlled systemic disease
IV- severe uncompensated systemic disease
V- unlikely to survive 24 hours without intervention
99
Why are surgical checklists used?
Reduce rate of death and surgical complications
100
What preparation is taken before inducing an animal under anaesthesia?
Set up machines and equipment
Prepare medications, drugs and fluids
Place IV catheter
Premed patient
101
What is the purpose of premedication?
Calm patient
Lower risk of injury
Aid restraint
Decreases stress as stress hormones reduce response to anaesthesia
Pre-emptive pain relief
Reduce induction and maintenance drugs needed
Smooth induction and recovery
102
What are the routes of admin of premed?
IV
IM
SC
OTM
103
What are advantages and disadvantages of IV admin of premed?
Advantages- rapid onset, predictable effect
| Disadvantages- need restraint and IV access
104
What are advantages and disadvantages of IM admin of premed?
Advantages- fairly rapid onset, predictable effect
| Disadvantages- painful
105
What are advantages and disadvantages of SC admin of premed?
Advantages- easy administration
| Disadvantages- not suitable for all drugs, slow onset, can be unpredictable
106
What are disadvantages of OTM admin of premed?
Not suitable for all drugs
Slow onset
Can be unpredictable
107
How does ASA grading affect premed protocols?
I and II- standard protocols and routine monitoring
III- stabilise prior, IV catheter and fluids in place
IV and V- same as III, also brief owners on risk, calculate and draw up first CPCR medication doses
108
What premedication protocols are typically used for cats and dogs with ASA I or II?
ACP + opioid
| Alpha 2 agonist + opioid
109
What premedication protocols are typically used for dogs with ASA III?
ACP + opioid
| Benzodiazepine + opioid
110
What premedication protocols are typically used for cats, dogs and rabbits with ASA VI or V?
Benzodiazepine + opioid
Benzodiazepine + ketamine
Opioid alone
111
What premedication protocols are typically used for cats with ASA III?
Benzodiazepine (midazolam) + ketamine
112
What premedication protocols are typically used for rabbits with ASA I or II?
ACP + opioid
Alpha 2 agonist + opioid
Fluanisone alone or with benzodiazepine
113
What premedication protocols are typically used for rabbits with ASA III?
Benzodiazepine + opioid
114
Name the classes of drugs used for premedication
```
Phenothiazines
Alpha 2 agonists
Benzodiazepines
Butyrophenones
Opioids
```
115
How do phenothiazines act in the body and what effects do they produce?
Dopamine receptor antagonist in CNS
| Sedation
116
How do alpha 2 agonists act in the body and what effects do they produce?
Alpha 2 adrenergic receptor in CNS
| Sedation, analgesia, muscle relaxation
117
How do benzodiazepines act in the body and what effects do they produce?
Enhance GABA at GABA alpha receptor
| Sedation, minor tranquiliser, muscle relaxation, anticonvulsant
118
How do butyrophenones act in the body and what effects do they produce?
Dopamine receptor antagonist in CNS, interferes with GABA, norepinephrine, serotonin mediated activity
Sedation
119
How do opioids act in the body and what effects do they produce?
Endogenous opioid receptors in CNS
| Sedation, analgesia
120
Which drug is a phenothiazine, what is its licencing and what is it used for?`
Acepromazine
| Cats and dogs for pre-med and sedation often in combination with opioids
121
How is acepromazine administered and how does each method effect time to peak effect?
SC
IM- 30-40 minutes
IV- 10-15 minutes
122
How long is duration of action of acepromazine and how is it eliminated?
4-6 hours
| Liver metabolises
123
Why can't acepromazine be given orally?
Poor oral bioavailability
124
What are side effects of acepromazine?
Peripheral vasodilatation causing lowered body temperature, and blood pressure
125
What are examples of alpha 2 agonists and what are they licenced for?
```
Dexmedetomidine
Medetomidine
Romifidine
Xylazine
Cats, dogs and rabbits
```
126
How is dose of alpha 2 agonists calculated and why is it done this way?
Very potent so done by body surface area
127
How are alpha 2 agonists administered and how does this effect time to effect?
IV- rapid effect after 5 minutes
| IM- effect after 15 minutes
128
What agent can be used to reverse alpha 2 agonists?
Atipamezole
129
If not reversed what is the duration of action of alpha 2 agonists and how are they metabolised?
2-3 hours
| Liver metabolism
130
What are side effects of alpha 2 agonists?
```
Bradycardia
Reduced CO
Second degree AV block
Hypertension initially then hypotension
Respiratory depression
GI stasis
Hyperglycaemia
Increased urine production
Uterine contractions
```
131
What are examples of benzodiazepines and what are they licenced for?
Diazepam in cats and dogs
| Midazolam in horses
132
How are benzodiazepines administered?
IV by slow infusion as rapidly crosses blood brain barrier
133
How are benzodiazepines metabolised?
Liver
134
How does duration of effects of diazepam and midazolam differ?
Diazepam has shorter half life but longer length of action as its metabolites are active
135
What is the reversal for benzodiazepines and why is it rarely used?
Flumazenil
| Very expensive
136
What are side effects of benzodiazepines?
Mild dose dependent respiratory depression
| Minimal CVS effects
137
What is an example of butyrophenones and what is it licenced for?
Fluanisone, only in combination with fentanyl
| Small furries
138
How is sedation as a result of benzodiazepines improved?
Combining with opioid, ketamine or alpha 2 agonist
139
What is the duration of action of fluanisone?
30-60 minutes
140
What is the result of combining benzodiazepine with fluanisone?
20-40 minutes of muscle relaxation
141
What are side effects of fluanisone?
Respiratory depression
142
How are opioids metabolised?
Liver
143
How should you care for premedicated or sedated patients?
Keep in quiet environment
| Regular but preferably continuous monitoring of ABC, TPR, CRT, MM
144
What are common issues when patients have been premedicated?
```
Excitement
Excess sedation
Airway obstruction
CVS up to and including cardiac arrest
Decompensation of existing conditions
```
145
Why is sedation used?
Allow procedures that would be impossible in fully conscious animals
Handling anxious, dangerous or feral animals
Keeping still for radiography
Minor procedures such as wound dressing
146
What drugs and protocols and used for sedation?
Same as premedication but higher doses
147
State the main method of admin of premed
IM
148
What is mean by induction phase?
Taking patient from conscious to unconscious state
149
Why should you pre-oxygenate patients before induction?
Give more time to place ETT before decompensation
150
What are the different methods of admin of injectable induction?
IV- titrate to effect, 2-10 minute onset, reliable, little stress to animal, does need IV access
IM- 10-20 minute onset, reliable, painful
SC- easy, less painful, 30-45 minute onset, lower efficacy, less reliable
151
What are different methods of inhalational induction?
Face mask- held tightly over face, cheap, easy, can give oxygen and VA quickly, lacks air way protection, not always tolerated, increased deadspace, harder to monitor, cant IPPV
Chamber- good when cant get IV, easy, cheap, stressful for animal, hard to observe
152
Why is injectable induction prefered?
Prevents risk of exposure to staff of inhalant VA
153
What needs to be considered when restraining for induction?
Minimal as possible physical restraint but ready for more
Dont compromise ventilation
Chemical restraint as needed
154
What are risks involved to the patient with restraining for induction?
Stress
Respiratory compromise
Cardiac arrhythmia
Raised ICP and IOP
155
Why do you need to restrain for induction?
Aid tube and catheter placement
| Keep patient and staff safe
156
How does a laryngeal mask airway work and why are they uncommonly used?
Sits over larynx
| Not designed for veterinary species
157
How do v-gels work and what are advantages and disadvantages?
Sits in pharynx forming secure seal over trachea
Advantages- can be reused, structure mirrors anatomical structure, useful in rabbits
Disadvantages- species and weight specific so need range, need to be trained to use
158
What is the gold standard for airway management and why?
Endotracheal tube
| Prevent atmospheric exposure, protects airway and allows accurate provision of gases
159
What is the benefits of a cuffed ETT?
Prevents gas leakage and aspiration
160
What are the different types of cuffs on ETT?
Low volume high pressure- pressure produced on small area of trachea
High volume low pressure- pressure evenly distributed on larger area
161
What are safety features present on ETT?
Murpheys eye- hole in side of tube to allow ventilation if end of tube is blocked
Armoured- only some tubes, inner wire to prevent kink if in awkward position
162
List equipment needed for intubation
```
Laryngoscope
ETT- length reaches from incisors to shoulder tip
Local anaesthetic- cats to prevent laryngeal spasm
Tie
Cuff syringe
Swab
Suction
Mask to pre-oxygenate
```
163
How do you check ETT is in correct place?
```
Leak test
Capnograph trace (gold standard)
Visualise tube between vocal folds
Condensation in clear tubes
Feel air movement
```
164
What are common complications during induction?
```
Injury to patient and staff
Lack of airway patency
Aspiration and regurgitation
Hypothermia
CV and respiratory effects from anaesthetic agents
Post induction apnoea
```
165
What are common complications involving the ETT during maintanance?
Twisted
Disconnected
Extubation
Wrong tube size placed
166
What factors determine technique used for anaesthetic maintenance?
```
Species
Behaviour
Access to IV
Procedure
Facilities
Expertise
```
167
What is the purpose of anaesthetic machines?
Delivery of oxygen and volatile gases to the patient
168
How should oxygen cylinders be stored?
Under cover, clean and dry
Indoors in well ventilated fireproof room
Not exposed to extreme heat, cold, flammable or combustible materials
Empty and full seperate
F, G, J stored vertically
C, D, E stored horizontally
169
How should you handle oxygen cylinders?
Hold correctly or move with trolley
170
What are the pressures inside oxygen and nitrous oxide cylinders?
Oxygen- 13700kPa
| Nitrous- 4400kPa
171
How much do E, F and J oxygen cylinders hold?
E- 680 litres
F- 1360 litres
J- 6800 litres
172
What is a cylinder yolk on anaesthetic machine and what is its function and key features?
Area that holds cylinders in place, specific to each type of gas
Provides tight bodok seal to keep unidirectional flow
Has pin index safety system to make sure correct cylinder attaches
173
What do the different coloured pipelines supply?
White- oxygen
Nitrous- blue
Black- medical air
174
How are pipelines prevented from misconnection?
Connect to anaesthetic machine Schrader socket with their Schrader probe (unique diameter index collar to correspond to socket)
175
What are NISTs on pipeline and what is their purpose?
Non-interchangeable screw thread
| Unique for each gas and has valve for one way flow
176
What is the function of pressure gauges on anaesthetic machines?
Indicate gas cylinder and pipelines pressure so shows when cylinder needs changing
177
What is the purpose of pressure regulators on anaesthetic machines?
Reduces pressure of gas from the cylinder to prevent damage
Compensate pressure as it decreases when cylinder empties
Smooth pressure fluctuations
178
How does an oxygen failure alarm work?
Alarm when oxygen supply falls below 200kPa
| Should also cut off nitrous delivery
179
What is the purpose of hypoxic guard?
Prevent hypoxic mixture being delivered as nitrous is cut off when oxygen falls below 130-70kPa
Linked valves means minimum 1:1 ratio is maintained
Oxygen always on if nitrous is
180
How does a non-return pressure relief safety valve work?
One way valve preventing backflow to gas machine, opens when back bar pressure is more than 35kPa
181
What is a flow meter?
Measures flow of each gas passing through
182
What are the components of a flow meter?
Flow control valve- fine adjustment of gas flow, reduces pressure from 420kPa to 100 kPa
Tapered transparent tube- visual scale of gas flow
Bobbin or ball- rotates in tube as gas passes around
183
How do you read the bobbin and ball in flowmeter?
Bobbin- top
| Ball- centre
184
What is the function of a vaporiser?
Contains volatile liquid anaesthetic agent picked up by gas from flow meter to deliver to patient
185
How do calibrated vaporisers work?
Gas entering from flowmeter goes down bypass channel or into chamber above liquid anaesthetic to pick up anaesthetic
Control valve adjusts how much gas goes to vapour chamber determining concentration of anaesthetic agent picked up
186
What is the effect of temperature cooling on vaporisers and how is it minimised?
Bi-metallic strip bends to resistance is reduced and more gas passes through VA chamber so more anaesthetic is delivered to the patient
Housed in brass and has TEC/temperature compensating mechanism
187
What is the purpose of wicks and baffles in vaporisers?
Wicks- increases surface area for anaesthetic agent to evaporate
Baffles- direct incoming gas to surface of liquid
188
What is the function of the back bar on anaesthetic machines?
Connects vaporiser by selectatec and interlock systems
189
What is the common gas outlet on anaesthetic machines?
Attaches breathing systems to deliver gases to patient
190
What is the purpose of oxygen flush and how does it work?
Remove gas from system in an emergency
| Supplies oxygen at 400kPa and 35-75l/minute, bypassing flowmeter and vaporiser
191
When should you never use the oxygen flush?
When connected to the patient
192
What is meant by scavenging?
Removal of environmental contaminants as waste VA and gases are subject to COSHH and HASAWA
193
Describe active scavenging
Waste anaesthetic agents drawn outside of building by fan and vent system, with air break to prevent negative pressure on patients breathing effort
194
Describe passive scavenging
Gas pushed by patients expiratory effort to outside building with increases resistance or into activated charcoal canister
195
How do oxygen concentrators work?
Take in and purifies air using molecular sieve to remove nitrogen from air
196
How is liquid oxygen stored?
In cold specific container, liquifies at -183 degrees, with vacuum installed evaporator
Outside
197
How is liquid oxygen used?
Oxygen drawn off as needed, passed through vaporiser and turned to gas to enter pipes, flow regulated by control pannel
198
Name safety features present on anaesthetic machines
```
Pin index system
NIST on pipelines
Colour coding
Touch coded oxygen flowmeter (easier to turn than others)
Ratio regulators
Nitrous cut off and alarms
Air intake valve
Reserve oxygen cylinders
```
199
How are staff kept safe when using anaesthetic machines?
Well ventilated rooms, 15-20 air changes per hour
IV induction when possible
Cuffed ETT
Connect breathing system before turning on VA
Low flow techniques
Leak check
Oxygen flush before disconnecting
Fill vaporiser with key and at end of day
Monitor exposure
200
Define dead space
Volume of gas that doesn't eliminate carbon dioxide
201
Define tidal volume
Volume of gas entering lungs on each inspiration
202
Define minute volume
Volume of gas entering lungs per minute
203
Define metabolic oxygen requirements
Oxygen required each minute for metabolic processes
204
Define rebreathing
Inspired gases reaching alveoli contain more carbon dioxide than can be accounted by just inhalation from patients dead space
205
List functions of anaesthetic breathing systems
Provides oxygen and anaesthetic agents via common gas outlet to airway management device
Allow IPPV or spontaneous ventilation
Allow scavenging of expired gases
206
List components of breathing systems
Reservoir bag
APL/adjustable pressure limiting valve
Tubing
Soda lime in circles
207
What is the rough estimate for the size of reservoir bag to use?
3-6x tidal volume
208
What is the effect of leaving the APL valve closed?
```
Reservoir bag extends
System becomes high pressure
Thoracic movement reduces
Tachycardia, hypoxia
Pneumothorax, pneumomediastinum
Death
```
209
How is resistance of tubing effected?
2x length = 2x resistance
| 2x radius = 16x less resistance
210
What are the two arrangements of tubing in breathing systems?
Parallel- tubing lies next to each other
| Coaxial- one tube inside the other
211
What is the purpose of soda lime in circles?
Absorbs carbon dioxide in exothermic reaction
212
What factors affect the choice of breathing system used?
```
Size of patient
Valve position
IPPV requirement
Ease of scavenging
Cleaning and sterilisation
Heat and moisture retention
```
213
What is the impact of increased resistance in breathing systems?
Low RR, altered pattern and increased effort
Decreased tidal volume
Hypoventilation, hypoxia, hypercapnia
Light plane anaesthesia due to reduced alveolar ventilation
214
What causes increased dead space in breathing systems?
Long ETT
| Part of system used
215
What is the effect of increased dead space?
Increased PaCO2
| Increased work of breathing to increase minute volume
216
What are the two types of breathing systems?
Non-rebreathing
| Rebreathing
217
How do non-rebreathing systems work?
Fresh gas flow removes expired carbon dioxide
218
What are advantages and disadvantages of non-rebreathing systems?
Advantages- inspired agent same as shown on vaporiser, low resistance, light weight, cheap
Disadvantages- more expensive, heat and moisture lost, increased risk of pollution
219
State patient weight requirement, circuit factor, resistance, dead space and drag, ability to scavenge and location of bag for T-piece
Weight- less than 10kg
Circuit factor- 2-3
Resistance, dead space and drag- low resistance and dead space, reasonable drag
Ability to scavenge- hard unless APL valve present
Location of bag- expiratory limb
220
State patient weight requirement, circuit factor, resistance, dead space and drag, ability to scavenge and location of bag for bain
```
Weight- over 8-10kg and under 15-20kg
Circuit factor- 2-3
Resistance, dead space and drag- low drag and dead space
Ability to scavenge- easy
Location of bag- expiratory limb
```
221
State patient weight requirement, circuit factor, resistance, dead space and drag, ability to scavenge and location of bag for lack
Weight- over 10kg less than 25-30kg, mini for over 1kg
Circuit factor- 1
Resistance, dead space and drag- moderate
Ability to scavenge- good
Location of bag- inspiratory limb
222
Which breathing systems can be used for IPPV?
T-piece
Bain
Circle
223
How do rebreathing systems work?
Soda lime removes expired carbon dioxide
224
What are advantages and disadvantages of circle?
Advantages- lower FGF so lower pollution, less expensive to run, heat and moisture retained
Disadvantages- Slow changes in inspired anaesthetic agent concentration, higher resistance
225
How is FGF calculated in circles?
Metabolic oxygen requirement
| 5ml/kg for large animals, 10ml/kg for small animals
226
What is the weight requirement and resistance of circles?
Weight- over 10-15kg
| Resistance- high due to unidirectional valves and soda lime canister
227
What are the features of an ideal injectable anaesthetic agent?
```
Rapid onset
Non-irritant allowing IM or IV admin
Minimal cardiopulmonary effects
Rapid metabolism and elimination
Non-cumulative to allow top ups
Good analgesia and muscle relaxation
```
228
What are injectable anaesthetic agents commonly used for?
Induction of anaesthesia
Along side inhalational anaesthesia for balanced technique
Triple for short term anaesthesia- alpha 2 agonist, opioid, ketamine IM
TIVA
Euthanasia
229
What factors affect the effect of injectable anaesthetics?
```
Blood flow to brain- need to cross BBB
Amount of non-ionised drugs- brain protected from ionised drugs
Lipid solubility- BBB is lipid
Molecular size
Concentration gradient
Protein binding- only unbound cross BBB
Distribution and metabolism
Excretion
```
230
Why is TIVA used?
Reduce exposure to inhalational anaesthetics
Allow anaesthesia without access to machines
Maintain stable plane of anaesthesia as no bolus
231
What are the disadvantages of TIVA?
Can have longer recovery
| Complicated calculations need to be done for dosing
232
What are ideal properties of injectable anaesthetic agents that make it suitable for TIVA?
Rapid metabolism and elimination
Fast onset
High therapeutic index
Pharmacokinetics available to allow CRI dose calculations
233
List the injectable anaesthetic agents available for use in animals
```
Propofol
Alfaxalone
Ketamine
(mainly used^)
Tiletamine
Zolazepam
Thiopental
```
234
What is licencing for propofol and how is it typically administered?
Cats and dogs
| IV as irritant otherwise
235
What is the drug class and mode of action of propofol?
Drug class- substituted phenol
| Mode of action- GABA agonist (enhances inhibitory GABA in CNS)
236
State the speed of onset and length of effect for propofol
Rapid onset
| 5-10 minutes effect
237
What are features of propofol (protien binding, solubility, metabolism and elimination, cumulation)?
Highly protein bound
Lipid soluble
Rapid liver metabolism and elimination
Cumulative in cats (lack glucorinidation pathway) not in dogs
238
What physiological effects can be seen after propofol admin?
Post induction apnoea
| Hypotension from myocardial depression and peripheral vasodilation
239
What components of the anaesthetic triad are provided by propofol?
Muscle relaxation
| No analgesia
240
What is the difference between propofol with and without preservatives?
```
Non-preservative containing- discard whats not used in dose, used for TIVA
Preservative containing (benzyl alcohol)- can store 28 days once opened
```
241
What is licencing and administration method of alfaxalone?
Cats, dogs and rabbits
| IV, maybe irritant if IM
242
What is alfaxalones drug class and mode of action in the body?
```
Neuroactive steroid
GABA agonist (enhances inhibitory GABA in CNS)
```
243
What is the formulation of alfaxolone?
Clear solution containing cyclodextrin ring as alfaxalone isnt water soluble without
244
State features of alfaxalone (protein binding, speed of onset, metabolism, length of effect, cumulation)
```
20-50% protein bound
Rapid onset
Rapid liver metabolism and elimination
15-30 minute effect
Non-cumulative
```
245
What are potential physiological effects seen after alfaxalone admin?
Respiratory depression
Post induction apnoea
Tachycardia as response to hypotension
246
What is licencing and method of admin for ketamine as injectable anaesthetic?
Cats, dogs and horses
| IV and IM
247
What is ketamines drug class and mode of action?
Drug class- phencyclidine derivative
| Mode of action- NMDA antagonist (dissociative anaesthetic)
248
Why is ketamine not used as a sole anaesthetic agent?
Muscle relaxation is poor and reflexes are maintained
249
State features of ketamine when used as anaesthetic agent (speed of onset, length of effect, cumulation and metabolism, excretion, protein binding)
```
Slow onset so need calm environment
20-40 minute effect
Non-cumulative through active metabolite by liver nor-ketamine
Renal excretion
50% protein bound
```
250
What can be physiological effects seen after administering ketamine?
Increased IOP and ICP
251
What components of the anaesthetic triad does ketamine provide?
Analgesia (and antihyperalgesia)
252
When is ketamine most commonly used as an anaesthetic agent?
Horses for maintenance by TIVA
| Cats IM as sedative or IV for induction
253
What is tiletamine licencing and how is it administered?
Dogs and cats
| IV or IM
254
What is the mode of action of tiletamine?
NMDA antagonist
255
What is licencing and mode of action of zolazepam?
Dogs and cats
| GABA agonist
256
What are the features of thiopental (mode of action, formulation, pH, speed of onset, protein binding, metabolism, cumulation)?
```
Barbituate acting at GABA receptor
Powder, 2.5% or 5%
Alkaline
Rapid onset
Highly protein bound
Metabolised after redistributing
Does accumulate
```
257
What can be physiological effects seen after admin of thipental?
Perivascular tissue necrosis
Cardiorespiratory depression
Short term ventricular bigeminy (alternating normal sinus and premature ventricular complexes)
258
Define volatile anaesthetic
Liquid at room temperature changes to vapour and inhaled to produce general anaesthesia
259
What are the main uses of inhalational anaesthesia?
Maintenance of anaesthesia
| Induction
260
What are the advantages and disadvantages of inhalational anaesthesia?
Advantages- easy to administer and calculate doses, can be used for most patients
Disadvantages- higher risk of death, exposure to staff
261
List ideal properties of inhalational anaesthetic agents
```
Non-irritant to MM
Minimal cardiopulmonary effects
Rapid uptake and elimination
Non-toxic
Non-flammable and chemically stable
Easily vaporised
Provide good analgesia and muscle relaxation
```
262
Define MAC and state what it stands for
Concentration required to prevent purposeful movement in response to supramaximal noxious stimuli in 50% of patients
Minimum alveolar concentration
263
Define MAC sparing
Reducing MAC by use of other drugs
264
What increases and decreases MAC?
Increases- hyperthermia, young animals, hyperthyroidism
| Decreases- drugs, hypothermia, pregnancy
265
How does MAC affect potency?
Higher MAC the less potent a drug
266
What factors affect uptake of inhalational anaesthetic agents?
Concentration in inspired air- higher has quicker uptake
Alveolar ventilation- higher increases uptake
Blood gas solubility- lower increases onset and recovery as moves to target organ faster
CO- lower increases onset and recovery as rapidly increases alveolar concentration so picked up in blood
Blood tissue solubility- affects distribution
267
How are inhalational anaesthetics eliminated?
Metabolism
Biotransformation
Exhalation
268
What needs to happen for animals to recovery from anaesthetic in terms of levels of agent?
Needs to be low enough in CNS
269
What are side effects to animals when using inhalational anaesthetics?
Cerebral
CV
Respiratory
270
What are effects to humans when exposed to inhalational anaesthesia?
Mutagenic
Tetragenic- cause congenital disorders
Reduced fertility
Renal and hepatic disease
271
How are inhalational anaesthetics used safely?
```
Avoid staff exposure
Avoid gaseous induction
Inflate cuff before turning on vaporiser
Keep patient on breathing system for few minutes to allow VA scavenging
Recover in well ventilated area
Training to deal with spillages
```
272
Which inhalational anaesthetic agents are licenced for cats and dogs?
Isoflurane
| Sevoflurane
273
State features of isoflurane (whether irritant, toxicity, stability, ease of vaporising, MAC)
```
Irritant to airways and MM
Toxic
Stable and non-flammable
Easily vaporised
MAC- 1.4-1.6
```
274
State features of sevoflurane (whether irritant, toxicity, stability, ease of vaporising, MAC)
```
Non-irritant to airways and MM
Toxic
Stable in presence of soda lime, flammable in oxygen or nitrous
Easily vaporised
MAC- 2.1-2.6
```
275
What elements of the anaesthetic triad are achieved by isoflurane?
Muscle relaxation
| No analgesia
276
What elements of the anaesthetic triad are achieved by sevoflurane?
No analgesia or muscle relaxation
277
State physiological effects associated with isoflurane use
```
Vasodilation
Hypotension
Respiratory depression, hypoventilation, hypercapnia
Bronchodilation
Reduced renal and hepatic perfusion
```
278
State physiological effects associated with sevoflurane use
Cerebral vasodilation, increase intercranial blood volume
Hypotension
Respiratory depression, hypoventilation, hypercapnia, less than isoflurane
Bronchodilation
Reduced renal and hepatic perfusion
279
How does uptake and elimination differ between isoflurane and sevoflurane?
Iso- slower, blood gas solubility 1.4, 1% metabolic elimination
Sevo- faster, blood gas solubility 0.69, 3% metabolic elimination
280
Which inhalational anaesthetics no longer have licencing?
Halothane
| Desflurane
281
What is nitrous used for in anaesthesia?
Analgesic
282
What is meant by nitrous second gas effect?
Inhaled gas higher in alveoli than blood so nitrous diffuses into blood and isoflurane in alveoli is in much higher concentration
283
What is meant by diffusion hypoxia of nitrous?
Equal nitrous and oxygen delivered and in blood, nitrous stopping causes it to rapidly diffuse to alveoli diluting alveolar oxygen
284
State features of nitrous as anaesthetic gas (uptake and elimination, MAC, ratio given with oxygen)
Rapid uptake and elimination due to being insoluble
MAC over 100%
1:2 with oxygen in non-rebreathing systems
1:1 with oxygen in rebreathing systems
285
Why should 100% oxygen be provided for 5-10 minutes after turning off nitrous?
Compensate hypoxia
286
Why is it important to position patients correctly under anaesthesia?
Support joints to prevent muscle or nerve damage
Prevent pain post-op
Optimise ventilation
Aware of nasal congestion
287
Why do you need to use GA records and how often are they updated?
Legal requirement
| Every 5 minutes, sometimes continuous if needed
288
What should be recorded on anaesthetic records?
```
HR
RR
Temperature
BP
Pulse oximetry
Drug doses, oxygen, anaesthetic gas
Start time, date, finish time, critical event
```
289
What parameters are monitored under anaesthesia?
```
Depth of anaesthesia
CV system
Respiratory system
Drug administration
Temperature
Urine output
Blood parameters
Neuromuscular function
Pulses
Eye position
MM
CRT
```
290
In what ways can heat be lost when anaesthetised?
Convection- loss of heat to cool air
Conduction- loss of heat to surfaces in contact
Radiation- loss of heat to structures not in contact
Evaporation- loss of heat from moisture evaporation
291
What factors of patients will increase heat loss?
```
High surface area: body weight
Low fat
Thin hair
Exposed internal tissues
Extreme age
```
292
Why does anaesthesia cause hypothermia?
Increase blood flow from core to periphery so more heat lost
| Reduced metabolic rate reducing heat produced
293
What are the effects of hypothermia?
```
CNS depression
Hypotension
Bradycardia
Hypoventilation
Low metabolic rate
Low urine output
```
294
How do you minimise the risk of hypothermia?
```
Minimal anaesthetic time
Minimal wetting of patient when scrubbing
High ambient temperature
Appropriate breathing system
Warmed fluids
Use insulating materials or heat sources
```
295
What information does a capnograph give you?
Inspired carbon dioxide
Expired carbon dioxide
RR
Capnograph trace
296
What are the normal ranges for end tidal carbon dioxide in cats and dogs?
Cats- 28-35
| Dogs- 35-45
297
What causes high and low end tidal carbon dioxide?
High- hypoventilation due to reduced RR and tidal volume
Low- hyperventilation, low CO, low metabolic rate, hypothermia, pulmonary embolism, leak in sample line or breathing system
298
What causes high inspiratory carbon dioxide in non-rebreathing and rebreathing systems?
Non-rebreathing- too low FGF or too much dead space
| Rebreathing- exhausted soda lime, faulty valves
299
What are the two types of capnography machines and how do they work?
Side stream- takes small sample of air through sample line to machine for analysis
Mainstream- gas analysed in breathing system using infrared detectors of absorption by carbon dioxide
300
State advantages and disadvantages of side stream capnography
Advantages- cheaper, less likely to break, easy to replace
| Disadvantages- delay in readings, when low FGF can take large proportion, easily damaged sample line
301
State advantages and disadvantages of mainstream capnography
Advantages- real time, doesnt effect FGF
| Disadvantages- expensive, easily damaged, adds drag
302
What are some advantages of capnogrpahy?
Non-invasive
Easy to set up and use
Effective monitoring of ventilation
Informs about CO (low carbon dioxide implies low CO)
303
What are some disadvantages of capnography?
Increased dead space
Need ETT
Takes time to learn normal or abnormal
304
What information is shown on ECG and how is this used?
ECG trace and HR
| Non-diagnostic, look for normal and report abnormal
305
What is meant by electromechanical dissociation?
Pulseless electrical activity of the heart few minutes post death
306
What are common abnormalities that can be interpreted from ECG trace?
Electrolyte imbalance
Myocardial hypoxia
Arrhythmias
307
What are indications for use of ECG?
```
Arrhythmias on auscultation
Investigating syncope/fainting
Investigating CV disease
Monitoring arrhythmia
General monitoring
```
308
How is ECG attached to paitents?
Clips or adhesive pads in good contact with skin, improved with ultrasound gel or surgical spirit
309
What ECG leads are used in small animals?
Red- right fore
Yellow- left fore
Green- left hind
310
What ECG leads are used in large animals?
Red- neck
Yellow- sternum
Green- lateral thorax
311
What are potential reasons for abnormal ECG traces?
Poor contact
Leads fallen off
Electrical or movement interference
312
What do the different waves on the ECG represent?
P- atrial depolarisation
QRS- ventricular depolarisation
T- ventricular repolarisation
313
What is different about equine ECG compared to normal ECG?
Upside down QRS complex as leads are base apex not limbs
314
What do some ECG abnormalities mean (tall p wave, wide p wave, tall r wave, wide r wave, deep s wave, wide s wave, abnormal t wave)?
Tall p wave- right atrial enlargement
Wide p wave- left atrial enlargement
Tall r wave- hypertrophy
Wide r wave- left bundle branch block
Deep s wave- right ventricular hypertrophy
Wide s wave- right bundle branch block
Abnormal t wave- myocardial ischemia, electrolyte imbalance
315
What is commonly seen on ECG traces under anaesthesia?
```
Tachycardia
Bradycardia
Heart block
Premature ventricular contraction
Arrhythmia/fibrillation
```
316
What is a 1st degree block and how is it shown on ECG?
Signal held up in first part of cycle
| Long PR distance
317
What are the two types of 2nd degree block?
Wenckebach- lenghtening of PR until beats lost and impulse blocked
Mobitz- sudden beat loss
318
What are 3rd degree blocks?
Complete block to signal at AV node, fatal
319
What are the causes of ventricular premature comples?
High sympathetic tone
| Electrolyte acid base imbalance
320
What information does pulse oximetry give?
Haemoglobin oxygen saturation
HR
Pulse rate
321
How does pulse oximetry work?
Probes emit and detect light which changes dependent on oxyhaemoglobin (absorbs more infrared) and deoxyhaemoglobin (absorbs more red light)
Only works on arterial blood
322
Where should pulse oximeter be placed?
```
Hairless and non-pigmented area
Tongue
Interdigital
Ear
Prepuce
Vulva
Skin webbing
```
323
What do different haemoglobin saturations mean?
100%- best case
95-100%- good
90-95%- start to worry
Less than 90%- very concerned
324
Define plethysmography
Trace mimicking arterial blood pressure on pulse oximeter
325
What is a diachronic notch seen on plethysmograph caused by?
Aortic valve closing and distending aorta contracts causing brief arterial pressure change
326
What are advantages of pulse oximetry?
Non-invasive
Widely available
Easy to set up and use
Can be used when conscious or unconscious
327
What are disadvantages of pulse oximetry?
Can give false readings
Easily damaged
Not good if anaemic as shows good saturation even if have very low numbers of RBC
Large probes can compress small animal tissues
Ineffective if poorly perfused
False elevation with carboxyhaemoglobin
328
What should you do if there are problems with pulse oximeter?
Reposition probe
Wet area
Test on own finger
Check actual patient status
329
Define blood pressure
Measurement of pressure exerted by blood on walls of blood vessels
330
Why does anaesthesia effect BP?
Drugs are vasodilatory
331
What are advantages and disadvantages of direct BP measurements?
Advantages- accurate, reliable, beat to beat information
Disadvantages- invasive, need experience, risk of infection and bleeding, risk of patient removing, pressure bandage needed on removal
332
What are the two methods of direct BP monitoring and how do they work?
Arterial line, gold standard- catheter in dorsal pedal or femoral artery
Haemodynamic monitoring- electronic using fluid filled tubing with catheter detecting pressure waves in arteries, transducer detects movement and converts to electrical signal
333
What are advantages and disadvantages of indirect BP measurement?
Advantages- non-invasive, easier to run
| Disadvantages- unreliable sometimes, less accurate, slower
334
What are advantages and disadvantages of doppler for BP measurement?
Advantages- inexpensive, efficient, can detect pulses in low flow states, fast results
Disadvantages- only provides systolic information
335
How does oscillometric BP monitoring work?
Artery wall oscillates as blood flows through as cuff inflates and deflates
Rapid increase in oscillation amplitude is systolic and rapid decrease is diastolic
336
What are advantages and disadvantages of oscillometric BP monitoiring?
Advantages- provides systolic, diastolic and mean information, automated process
Disadvantages- less reliable as affected by movement, cant pick up trends well in small animals, more expensive
337
What is the impact of incorrect cuff size when taking BP measurements?
Too big- artificially low result
| Too small- artificially high result
338
How should you manage hypotension?
```
Find underlying cause and treat
Reduce VA as vasodilatory
Increase analgesia and local blocks
Manage bradycardia
Give fluids
Ensure adequate ventilation
```
339
What is meant by SpO2?
Measurement of how much oxygen the blood is carrying as percent of maximum able to be carried
340
What checks should be made if SpO2 has fallen?
Check pulse oximeter is correctly working
Is patient intubated?
Is anaesthetic machines pressure gauges okay?
Is flow rate adequate?
Is breathing system correctly attached?
Are there any leaks in the breathing system or ETT?
Is the patient spontaneously breathing/are ventilator settings correct?
Does thorax expand if bag is squeezed or is there pressure or airway blockage?
Can lungs contract?
341
What are causes of lungs being unable to contract when SpO2 has fallen under GA?
```
Expiratory pathway blockage
Twisted bag
Closed APL valve
Kink in tubing
Blocked tube
```
342
If SpO2 is fallen but all checks are normal what is causing the problem?
Poor tissue perfusion
343
What are causes of abnormal breathing under GA?
Panting- inadequate anaesthesia
| Paradoxical breathing- respiratory tract obstruction
344
What are some causes of no breathing when under GA?
Post induction apnoea
Too deep anaesthesia reducing respiratory drive
Too light anaesthesia causing breath holding
345
How do you identify tachycardia and bradycardia?
Monitoring pulses
| Cardiac auscultation
346
What are common causes of tachycardia when anaesthetised?
```
Inadequate depth
Hypercapnia
Hypovolaemia
Drug action
Electrolyte abnormalities
```
347
What causes of tachycardia under GA in ASA 1 and 2 pateints?
Inadequate depth
| Hypercapnia
348
How do you respond to tachycardia in response to inadequate depth of anaesthesia and what are signs this is the cause?
Increase depth of anaesthesia
| Reaction to noxious and non-noxious stimuli, increased muscle tone, increased RR, increased BP, movement
349
How do you respond to tachycardia in response to hypercapnia and what are signs this is the cause?
Follow steps for when SpO2 falls
| Poor respiration
350
How do you respond to tachycardia in response to hypovolaemia and what are signs this is the cause?
Stabilise before anaesthetic and manage fluid deficit
| Patient is hypovolaemic or dehydrated
351
What should you do if suspect drug action is the cause of tachycardia under GA?
Rule out other causes
352
How do you respond to patients with electrolyte imbalances to prevent tachycardia under GA?
Identify on pre-assessment and stabilise
353
What is stage one of anaesthesia and what can be observed in this stage?
From induction to unconsciousness
| Increased pulse rate and RR, may have breath holding and dilated pupils
354
What is stage 2 of anaesthesia and what can be observed in this stage?
Onset of unconsciousness until rhythmic breathing is present
| All cranial nerve reflexes present, eyes wide and open with dilated pupils
355
What is plane 1 of stage 3 of anaesthesia suitable for and what can be observed in this stage?
Minor procedures
Regular and deep respiration, brisk pedal reflex (pinching paw), slowing and disappearing nystagmus (involuntary rhythmic eye movement), eyes pointing ventromedially
356
What is plane 2 of stage 3 of anaesthesia suitable for and what can be observed in this stage?
Most surgical procedures
Eyes ventromedial with partially separated eyelids, sluggish palpebral reflex (touching periocular skin), present corneal reflexes, relaxed muscles, lower pedal reflex, lower tidal volume, lower HR, lower BP
357
What is plane 3 of stage 3 of anaesthesia suitable for and what can be observed in this stage?
All procedures
Eyes face centrally and eyelids start to open, increased pupillary diameter, no pedal reflex, relaxed abdominal muscles, low HR, low BP
358
What is stage 4 of anaesthesia and what can be observed in this stage?
Overdose
| Respiratory failure, rapid or slow pulses, eyes central, no palpebral reflex
359
What are caused of bradycardia under anaesthetic?
```
Too deep anaesthesia
Drug action
High vagal tone
Hypoxia
Hypothermia
Hyperkalaemia
```
360
What are signs too deep anaesthesia is the cause of bradycardia and how do you respond?
Low RR, hypotension, low muscle tone, lack of reflexes
| Adjust depth of anaesthesia
361
How do you respond when drugs are the cause of bradycardia during GA?
Treat with atropine if worried about hypotension or arrhythmia
362
What causes high vagal tone leading to bradycardia in GA and how is it treated?
Occulocardiac reflex- eye compression decreases pulse rate
| Anticholinergics
363
How should you treat patient to prevent bradycardia under GA when pre-assessment picks up hyperkalaemia?
Stabilise before anaesthesia and treat underlying cause
364
What are causes of hypotension when under anaesthetic?
Reduced inflow to the heart, reduced pumping, vascular resistance due to drugs, hypovolaemia, shock, arrhythmia etc.
365
What are some causes of respiratory failure under anaesthesia?
Depression of brains respiratory centre
Impaired movement of thorax
Impaired lung movement
Airway obstruction
366
What is meant by cardiac arrest?
Cessation of effective circulation
367
What are possible causes of cardiac arrest?
```
Pre-existing CV disease
Anaesthetic overdose
Arrhythmia
Hypovolaemia
Electrolyte abnormalities
Respiratory arrest
```
368
What are causes of hypertension under GA?
Nociception
Hypercapnia
Hypoxia
Drugs
369
How can you prevent vomiting in patients under anaesthesia?
Fast before anaesthetic
Elevate head until ETT cuff inflated
Consider omeprazole in patients with high risk
370
How do you respond to patients who vomit under anaesthesia?
Keep head down
| Suction pharynx
371
What are risks of oesophageal reflux when under anaesthesia?
Excess or inadequate fasting
Drugs
Abdominal pressure
Abdominal surgery
372
What are causes of emergencies and accidents during anaesthesia?
Sick patients- stabilise before anaesthesia, prepare equipment and drugs
Human error, poor communication, not doing checklists, leaving APL valve open, drug admin errors, poor airway management, poor positioning, inadequate eye protection
Equipment failure
Poor preparation
Poor monitoring
373
Name drugs used for euthanasia and what species they are used for
Pentobarbital- lots of species
| Secobarbital sodium plus cincocaine hydrochloride- dogs, cats, horses, cattle
374
What mode of action do euthanasia drugs act by?
Barbiturate enhances action of GABA at GABA receptor
| Local anaesthetic blocks sodium channels in heart interrupting action potentials
375
Explain the general stages of recovery from anaesthesia
End of procedure so need to regain consciousness
Stop anaesthetic agent and antagonise injectable drugs either just before or after procedure ends
Give 100% oxygen if nitrous was used
Maintain analgesia
Remove airway device as appropriate
Place in suitable recovery area
376
What makes a suitable area to recover from anaesthetic?
```
Safe
Secure
Well ventilated
Warm
Easy to observe
Good access to supplies
```
377
What should be observed in patients from extubation to full recovery?
Lift head
Sternal recumbency
Standing
No signs of sedation
378
How should you prepare for extubation?
Untie ties
| Deflate cuff when close
379
When should you extubate dogs and rabbits?
Signs of laryngeal reflexes and spontaneous movement
380
When should you extubate cats?
Early reflexes, before laryngeal reflex
381
What happens if you extubate too early or late?
Early- unsupported airway
| Late- distress, damage to airway, laryngospasm in cats
382
What factors need considering when recovering animals?
Drug factors and doses
Species, breed, age
Co-morbidities
CV function- delivery and distribution to kidneys
Hepatic and renal function- metabolism and excretion
Temperature- hypothermia causes slower metabolism and renal plasma flow
383
What parameters need monitoring when recovering animals?
```
TPR
MM
CRT
Quality of recovery
Pain
Excretions
Comfort
Catheters
Surgical site
Food and water
```
384
What causes hypothermia in recovery?
Vasodilation from drugs
Lack of movement
Cold environment
385
What are the effects on recovery of hypothermia?
```
Bradycardia
Cardiac arrhythmia
Atrial fibrillation - 30 degrees
Ventricular fibrillation- 24-38 degrees
Impaired coagulation and wound healing
Longer drug action so slower recovery
Low oxygen delivery
Slower metabolism
```
386
What causes hyperthermia in recovery?
Decreased heat loss
Warm environment
Increased metabolic heat production
387
What are the effects of hyperthermia in recovery?
```
Higher metabolic rate
Higher oxygen requirement
Cell damage
Irreversible brain damage- 41 degrees
Death- 43 degrees
```
388
What needs monitoring for respiration in patient recovery?
Patent airway
RR
Breathing pattern
389
What measures should you put in place to protect respiration in recovery?
If worried of aspiration or vomiting, keep head down
Remove water bowl to prevent drowning
Supplement oxygen where needed
390
How do you maintain a good quality of recovery?
Keep calm and stress free
Re-sedate if too excited
Be aware of causing injury
391
What are signs of pain in recovery?
```
Inappetence
Immobility
Vocalisation
Agression
Sleeping
Increased HR
Increased RR
Increased temperature
Increased BP
```
392
What does CPCR stand for?
Cardiopulmonary cerebral resuscitation
393
What are the mortality rates for patients who experience CPA?
Under anaesthesia- 53%
| In general- 90%
394
What does RECOVER stand for and what is its purpose?
Reassessment campaign on veterinary resuscitation
| Use evidence based guidelines to treating CPA and identifies areas that need more development
395
How should you prepare for a CPA?
Everyone involved knows what to do, what protocols are and where equipment, drugs etc. are kept
396
When should you initiate CPCR?
Unresponsive apnoeic patient with no pulses
397
What is classed as basic life support in CPCR?
Recognising CPA
Compressions- 100/minute 1/3 to 1/2 chest in lateral recumbency, compressing main part of heart and allowing full recoil
Ventilation- securing airway while compressions take place, 10 breaths/minute providing oxygen, can check effectiveness with capnography as hypoxia and hypercapnia reduce chance of circulation returning
398
What are roles in a CPCR team?
```
Lead
Cardiac compressor
Ventilator
Note keeper
Runner
```
399
What is classed as advanced life support?
Drugs- IV where possible
Correcting cause of arrest
Monitoring- ECG, capnography, pulse oximeter
Fluids, eye lubrication, temperature regulation, IV catheter placement
400
What is involved in post CPA care?
IVFT
Oxygen therapy
Referral where needed
Make sure CPCR process was correctly recorded
401
Why is it important to debrief after CPCR?
Emotions high
Discuss what happened
Clear the air of any problems
Restock equipment and drugs
402
How is CPA managed in already anaesthetised pateint?
```
Note time and inform surgeon
Start compressions
Manually ventilate
Stop anaesthetic drugs and consider adrenaline
Manage same as other crashes
```
403
What is a main contributor to pollution in veterinary practices and how does it contribute to global warming?
Anaesthetic gases
| Greenhouse gases or plug atmospheric window (used to cool earth as low absorption of natural greenhouse gases)
404
Why is nitrous bad for the atmosphere?
Although less global warming effect has lower potency so more needs using, is also ozone depleting
405
How can practices improve carbon footprint?
```
Dont use nitrous
Avoid unneeded anaesthesia
Use TIVA where possible
Sevoflurane is better than isoflurane
Dont waste resources
Low flow anaesthetic techniques
```
406
How does low flow anaesthetic work with circle and lack and what are negatives?
Circle- over 5kg, has reduced FGF. Can dilute anaesthetic, slower onset and hypoxic mixture if using for long time
Lack- under 5kg, uses capnography to find lowest FGF that prevents rebreathing
407
How should waste be disposed of in practice and what is the negative to reusing?
Correctly separated
Dont use unnecessary resources
Re-use and recycle where possible
Re-using has higher risk of infection and failure of equipment
408
What should be checked before sedation or anaesthetising horses?
Check passport (food producing so drug regulations)
Assess temperament to decide drugs
Assess CV and respiratory systems
Assess facilities, procedure and pain levels likely
Dont withhold food
Get owner consent, inform that best for vet to be present whole time
409
Describe the ideal environment for equine sedation
```
Quiet
Calm
Lots of time
Safe
Equipment and drugs prepared
```
410
How is equine sedation administered?
IV to jugular- ideal as fastest onset and most control of drug
IM- remote when cant gain IV access, need higher doses
411
What sedative are licenced in horses?
```
Acepromazine
Xylazine
Romifidine
Butorphanol
Buprenorphine
Pethidine
```
412
What is the most common sedation combination used in horses?
Alpha 2 agonist and opioid
413
When is acepromazine used in equine sedation?
Alone or in combination to provide mild sedation
414
What is the onset time, length of effect, metabolism and any other effects of acepromazine in horses?
30 minute onset
4-6 hour duration
Metabolised by liver
Vasodilatory
415
What effects does alpha 2 agonists have in horses?
Sedation
Muscle relaxation
Analgesia
416
What side effects can alpha 2 agonists have in horses?
Bradycardia, second degree AV block so initially causes hypertension and vasoconstriction, then hypotension
Hypoinsulinemia
Decreased GI motility
417
What are the alpha 2 agonists used in horses for sedation?
Xylazine- shorter lasting, faster onset
| Romifidine
418
Which opioids are used in horses for sedation?
Butorphanol- provides less analgesia
Buprenorphine- needs large volume
Pethidine- need to give IM, relieves colic
419
What effects do opioids have when given to horses for sedation in combination with alpha 2 agonist?
Synergistic effect on analgesia, increases sedation and ataxia (un coordination)
420
How should catheters be cared for in recovery?
Covered and suitably padded
| Pressure placed on removal to prevent haemotoma
421
What are common causes of death in equine anaesthesia?
Fractures
Myopathy
Cardiac arrest
422
What are risk factors for equine anaesthesia?
```
Drugs
Age
Duration of procedure
Type of procedure
Environment (field or hospital)
```
423
What determines if horses are anaesthetised in field or hospital?
```
Temperament
Can you get to hospital
Type of procedure
Length
Facilities available
```
424
How should horses be prepared for general anaesthesia?
Full exam
Gained consent
Groom and remove shoes
Weigh
Antibiotics 30 minutes before anaesthesia if using to lower BP
Rinse mouth to prevent debris pushed into airway
IV catheter placed in left jugular
425
What equipment is needed for equine anaesthesia?
```
Padded head collar and lead rope
Towel for eyes and eye lubrication
Drawn up and labelled drugs
ETT and gag prepared
Table, monitors and machines prepared
```
426
How are horses induced for anaesthesia?
Once fully sedated
Ketamine/diazepam and thiopental in fast IV bolus
May use GGE/guaiphenesin, a muscle relaxant
Field- free fall guiding head
Practice- tilt tables and gates
427
What technique is used for equine intubation?
Blind technique, extend head and neck
| Oral but can be nasotracheal
428
What maintainace is used for horses in field and theatre?
Field- TIVA for max 2 hours
| Theatre- TIVA, sevoflurane, isoflurane
429
What are side effects of inhalational anaesthetics used in equine anaesthesia?
Respiratory depression
Hypotension
Rapid recovery
430
What analgesics are used for equine surgery?
```
NSAIDs- before anaesthetising
Opioids
Alpha 2 agonist
Ketamine
Local blocks
```
431
What should be monitored in equine anaesthesia?
RR and pattern- easily compromised leading to hypoxaemia, hypoventilation, hypercapnia as not designed to lay down for long times
Eye position, nystagmus- depth of anaesthesia
Palpebral reflex
Muscle tone
Movement- may be sudden
BP- CO decreased in anaesthesia, commonly get hypotension
ECG- common to initially get 2nd degree AV block
432
How should you recover horses from anaesthesia?
Quiet environment
Cover eyes to reduce stimulation and fear
Supplement oxygen
Remove ETT when respiratory effort increases (weak laryngeal reflexes)
Alpha 2 agonist to keep calm
Analgesia
Catheterise bladder to remove stimulation to stand
433
What are causes and prevention of equine post anaesthetic myopathy?
Causes- damage during anaesthesia
Prevention- careful positioning, let down (take out of training) fit horses few days pre-op, minimise anaesthetic time, lighter anaesthesia, avoid hypoxia
434
What are signs of equine post anaesthetic myopathy?
```
Lameness
Cant stand
Distress
Hard swollen muscles
Myoglobinuria
High creatinine kinase muscle enzyme
```
435
What is treatment for equine post anaesthetic myopathy?
```
Analgesia
Sedation
Fluids
Nursing care
May need euthanasia
```
436
What are common neuropathies/nerve compression in horses after anaesthesia and what are the prognoses?
Radial, facial and femoral, brachial plexus
| Depends on degree of damage
437
What is spinal cord malacia?
Softening of spinal cord
438
What are causes, signs and result of spinal cord malacia?
Cause- unknown
Sign- complete hind limb paralysis
Result- fatal
439
What are common causes of fractures in equine anaesthesia?
Trauma in induction, recovery
Pre-existing injury
Myopathy increases risk
440
When is equine castration carried out typically?
6 months to 2 years
| Testicles fully descended
441
Where can equine castration be carried out and how?
In hospital or field by vet
| Standing or under GA
442
Why are horses castrated?
Behaviour modification- reduced agression, easier to handle geldings
Management- turn out with mares
Control breeding
Medical reasons- neoplasia etc
443
What determines if a castration is done standing or under GA?
Size of horse for visualisation
Temperament
Cost
444
What is an open castration?
Vaginal tunic incised and left open
445
When are open castrations carried out?
Young unbred horses when being castrated standing in field
446
How is an open castration performed?
Incision through skin and vaginal tunic to expose testes
| Emasculators used on vas deferens and testicular vessels to crush and transect
447
What is semi-closed castration?
Vaginal tunic incised then sutured closed
448
What environment is semi-closed and closed castration carried out in?
Hospital under GA
449
What is closed castration?
Vaginal tunic sutured proximally to testes before incision
450
How is closed castration performed?
Incision through skin only with blunt dissection of vaginal tunic containing testes
Ligatures placed before emasculation
451
What are options for the scrotum following castration?
Primary closure- sutured
Secondary closure- left open, used in field
May need ablation
452
What are advantages and disadvantages of standing castration?
Advantages- quick, effective, cheap in well handled young horses
Disadvantages- poor asepsis, commonly get minor complications, risk to surgeon
453
List equipment needed for standing castrations?
```
Sedation
Local anaesthetic
Analgesia
Antimicrobials
Gloves
Scrub
Swabs
Needles and stitch kit
Scalpel
Emasculators
Ketamine and IV prepared if GA is needed
```
454
What is the general process for preparing for standing castrations?
```
Sedate
Check 2 testicles present
Scrub
Inject local anaesthetic into subcutis and testicle
Rescrub
```
455
How should horses be positioned for GA castration in hospital or field?
Hospital- dorsal or lateral recumbency
| Field- lateral recumbancy
456
What are some common post-castration complications in horses?
Swelling
Bleeding
Infection- scirrhous cord/infection of spermatic cord remnant, staphylococcal infection
Tetanus
Evisceration- prolapse of omentum or intestine through inguinal ring, intestine is emergency
457
What needs to be monitored post-castration in horses?
Bleeding- drips normal for 12 hours
Swelling- shouldn't be more than original size
Surgical site- check for protrusions
Sedation- may cause colic, monitor appetite etc
458
How do you manage horses after castration?
```
Box rest for 24-48 hours
Walk 2-3 times daily after 2 days to reduce swelling and encourage drainage
Turn out after 7-10 days
NSAIDs
Fertile for 2 months
```
459
What is cryptorchidism and how is it detected?
Failure of testicular descent
| Inguinal palpation, ultrasound, blood tests, surgical exploration
460
How is cryptorchidism treated?
Laparoscopic cryptochidectomy
461
What are potential causes of higher mortality rates in exotics under anaesthesia?
May lack history
Pre-existing diseases may be unrecognised
Small to hard to weigh accurately, examine, place IV
Completely different anatomies
Handling causes high stress
Equipment not suitable
462
What parts of the patient to be considered in exotic anaesthesia?
Eyes- protuberant risks damage, corneal dissection
Pharyngeal pouch- needs emptying before intubation
Mouth- hard to intubate if large incisors, narrow jaw, obstructive pharyngeal tissue
Physiology- metabolic rate, rate of glucose and oxygen consumption
Temperature- high SA:V ratio
Respiratory system- hard to auscultate
GI system- diet, rabbits cant be starved
Species specific- drug concerns, diseases, husbandry
463
What factors need considering for birds when anaesthetising?
Wide range of species
Hide illness
Handling causes stress, if too tight stops breathing as sternum cant move
Prone to hypothermia and hypoglycaemia
Hard to intubate as small and cant cuff as complete tracheal rings
Muscle relaxants majorly affect completely active respiration
Low HR
High metabolic rate
464
What factors need considering for reptiles when anaesthetising?
```
Can carry zoonotic disease on surface
Ectothermic
Free moving organs
Breath hold
Only open larynx in active respiration
1 heart ventricle
Long soft palette making intubation hard
Lower oxygen consumption
Snakes have single functional right lung
Cant cuff as complete tracheal rings
No muscular diaphragm so other muscles needed to respire such as tortoises limbs
Cant regurgitate
```
465
What are recommended pre-op starvation for exotics?
```
Rabbits/rodents- none
Guinea pigs- up to 4 hours, empty pharyngeal pouches
Ferrets- 6 hours
Reptiles- none, avoid live insects
Birds- species dependent
```
466
What anaesthetic breathing equipment may be needed for exotic anaesthesia?
```
T-piece
Gas chamber
Mask
ETT
V-gel
```
467
List routes of admin of drugs to exotics
IV- basilic, medial tarsal, right jugular
IM- pectoral
IP
SC
IO- cranial tibiotarsus, ulna (high risk of pain and infection)
Inhalation
Oral
468
What are signs of acute and chronic pain in exotics?
Acute- escape attempts, avoidance, agression, restlessness, increased respiration
Chronic- immobility, agression
469
What parameters are monitored for exotics under anaesthesia to assess depth?
Rightwing reflex- ability to correct orientation of body by vestibular system, only when light
Withdrawal reflex
Jaw tone
Pulses
470
What equipment can be used to monitor exotics under anaesthesia and how can it be adapted to be better suited?
Pulse oximeter- foot or tail base instead of tongue
Capnograph- mainstream to prevent reducing FGF
ECG- cut down pads, use needle electrodes
Doppler
Temperature- rectal, small probe
