anaesthetics Flashcards
1
Q
where does general anaesthetic provide sensensibility
A
whole body
implies loss of consciousness and global lack of awareness
2
Q
where does regional anaesthetic provide sensensibility
A
an area or region of the body
Nerve and plexus blocks
3
Q
where does local anaesthetic provide sensensibility
A
local relevant area - direct to tissue being anaesthetised
4
Q
what type of anaesthetics are spinal/ epidurals
A
regional
5
Q
what is the triad of anaesthetics
A
hypnosis
analgesiia
relaxation (skeletal muscle)
6
Q
what does hypnosis mean
A
unconscious
7
Q
what is the aim of pain relief
A
removal of perception of unpleasant stimulus
8
Q
what are some problems of balanced anaesthesia
A
¥ Polypharmacy - Inc chance of drug reactions / allergies
¥ Muscle relaxation - requirement for artificial ventilation, means of airway control
¥ Separation of muscle relaxation & hypnosis – awareness – patients awake from wrong dose yet paralysed so unable to communicate
9
Q
what are the principles of balanced anaesthesia
A
¥ Different drugs to do different jobs
¥ Titrate doses separately & therefore more accurately to requirements
¥ Avoid overdosage
Control over individual components of the triad
10
Q
how are general anaesthetics given
A
inhaled (maintenance) or IV (induction)
(Inhalational agents dissolve in lipid membranes Direct physical effect
Intravenous agents -allosteric binding e,g. GABA receptors also open chloride channels)
11
Q
what ion channel is sully targeted in GA and why
A
chlorine
Hyperpolarise neurones = Less likely to “fire” (suppress excitatory synaptic activity)
12
Q
after GA what functions are lost first
A
most complex then primitive lost later
13
Q
are reflexes spared in GA
A
yes
14
Q
what must be managed when the patient is under GA
A
airway and cardiovascular
15
Q
what is the name of the pump system that allows accurate infusion to achieve specific blood or brain concentrations of agents using complex pharmacokinetic algorithms
A
target controlled infusion (TCI)
16
Q
what is a problem with IV anaesthesia and how is this controlled
A
can’t measure drug concentration in real time
Use computers to calculate a guess
17
Q
are IV anaesthesia drugs fat or water soluble
A
fat - cross membrane quickly
18
Q
what is the rapid recovery form IV anaesthesia due to
A
drug leaving the circulation and moving to other parts of the body eg muscle and viscera organs
19
Q
list some anaesthetics that are given IV
A
thiopentone
propofol
20
Q
list some anaesthetics that are inhaled
A
halogenated hydrocarbons
21
Q
which organ does the uptake and excretion of inhaled anaesthestics
A
lung
(concentration gradient - lungs > blood > brain
cross alveolar BM easily
arterial concn equates closely to alveolar partial pressure)
22
Q
what is the MAC (mean alveolar concentration) a measure of (inhaled anaesthetic)
A
measure of potency
low number = high potency
(less concentration to produce the same affect)
23
Q
why are really high doses of inhaled anaesthesia given for induction
A
gas down the concentration gradient in to the patients blood and finally brain to achieve a high enough partial pressure there to produce unconsciousness
24
Q
what is the main role of inhalation agents
A
extension or continuation of anaesthesia
25
what are the central CVS effects of GA
depress cardiovascular centre
reduce sympathetic outflow
negative inotropic/chronotropic effect on heart
reduced vasoconstrictor tone → vasodilation
26
what do anaesthetics do to respiratory system
depress
Reduce hypoxic and hypercarbic drive
Decreased tidal volume & increase rate
paralyse cilia
27
what is the exception to all anaesthetics being CVS depressant
ketamine
28
why does CO fall under anaesthesia
vasodilation reduces venous return to the heart
29
what are the differences between anaesthetic and opiate respiratory depression
opiate - preserves tidal volume, low respiratory rate
| anaesthetic - reduced tidal volume, high respiratory rate
30
why do some post op patients need anaesthetics for several days
greatly reduced lung volume can interfere with ventilation/ perfusion matching
31
what are indications for muscle relaxants
ventilation & Intubation
when immobility is essential - microscopic surgery, neurosurgery
body cavity surgery (access)
32
list some problems with muscle relaxants
awareness
incomplete reversal → airway obstruction, ventilatory insufficiency in immediate post op period
apnoea = dependence on airway & ventilatory support
33
why is anaesthetic given intra-operatively
Prevention of arousal (pain)
Opiates contribute to hypnotic effect of GA
Suppression of reflex responses to painful stimuli (hypertension, tachycardia)
34
which system is relatively spared in regional anaesthetic compared to general
respiratory
35
what are the 7 steps in the process of anaesthesia
```
pre-opeartive assessment
preparation
induction
maintenace (monitoring)
emergence
recovery
post operative assessment
```
36
what is the time of onset for IV induction of anaesthetic
one arm brain circulation - 20s
37
do you remain conscious with local and regional anaesthetics
yes
| CVS derangement proportional to size of area
38
what is a limiting factor for use of local anaesthetic
toxicity
39
why is toxicity a risk factor in local anaesthetics
absorption > rate of metabolism = high plasma levels
40
what things does the toxicity of LA depend on
dose used
rate of absorption (site dependant - perfusion)
patient weight
drug ( bupivacaine > lignocaine > prilocaine )
41
list some signs and symptoms of local anaesthetic toxicity
```
Circumoral and lingual numbness and tingling
Light-headedness
Tinnitus, visual disturbances
Muscular twitching
Drowsiness
Cardiovascular depression
Convulsions
Coma
Cardiorespiratory arrest
```
42
why are some areas easier to block with LA than others (differential block)
different nerve fibre types - thickness and myelination
43
what makes pain fibres easier to block with LA than motor fibres
thinner and less myelinated
44
during anaesthesia what is a cough depednent on
abdominal muscles (expiratory function)
45
during anaesthesia which is more spared, inspiration or expiration
inspiration (instercostaals and accessory muscles higher root nerves)
46
list some considerations in the pre-operative preparation of GA
Planning - checklist - Right patient, right operation
Right (or left) side
Pre-medication (sedatives/ analgesia)
Right equipment, right personnel Drugs drawn up
IV access - Monitoring
47
what agents may be used for the IV induction of anaesthesia
Propofol - standard, less hangover, quick, less side effects
| thiopentone - barbiturate, maternity hospital
48
why do you need good airway control in GA
apnoea very common
49
what drug may be used for the gaseous induction of anaesthesia
sevoflurane
50
in what patients is gaseous induction of anaesthesia better than gaseous
younger children
| IV drug users
51
what is the triple airway manoeuvre in airway maintenance
head tilt, chin lift, jaw thrust
52
what manoeuvre can solve an airway obstruction but to loss on tone from the tongue
jaw thrust
53
what is the minimum monitoring in anaesthetics
SpO2, ECG, NIBP, FiO2, ETCO2
| temperature, urine output
54
what is a common post operative side effect of anaesthesia
nausea and vomitting
55
what are different planes of anaesthesia
analgesia
excitation
anaesthesia
overdose
56
list some different methods of airway management
```
Oropharyngeal airway (Guedel)
Laryngeal mask
endotracheal intubation
```
57
which patents can tolerate a Oropharyngeal airway (Guedel
unconscious
58
what is a laryngeal mask airway
Cuffed tube with ‘mask’ sitting over glottis
| Maintains, but does not protect the airway
59
what reflex must be abolished before endotracheal intubation
laryngeal
60
what is the most common airway complication
Ineffective Triple Airway Manoeuvre
61
list some complications of airway management
Ineffective Triple Airway Manoeuvre
Airway device malposition or kinking
laryngospasm
aspiration - gastric contents, blood, surgical debris
62
what is the only thing that protects the airway from contamination
cuffed tube in the trachea
63
list reasons for intubating
Protect airway from gastric contents
Need for muscle relaxation artificial ventilation
Shared airway with risk of blood contamination- e.g. tonsillectomy in ENT
Need for tight control of blood gases
Restricted access to airway - e.g. Maxillo-facial surgery
64
what are anaesthetic risks to an unconscious patient
```
“Airway, Airway, Airway”
Temperature
Loss of other protective reflexes - eg corneal, joint position (dislocate shoulder)
Venous thromboembolism risk
Consent & Identification
Pressure areas
```
65
what are the main complications of anaesthesia
airway, breathing, circulation
related to techniques. position
awareness
66
what are some of the anaesthetists roles pre-op
```
Assess patient as whole for procedure
Identify high risk - high morbidity and mortality
Optimise patients to minimise risk
Inform and support patients decisions
Consent from patient
```
67
should you continue a patients medications before an operation
mostly
especially Inhalers, Anti-anginals, Anti-epileptics,
Most cardio/ respiratory medications
68
what medications should be discontinued before an operation
anti-diabetic medication
| anticoagulants (if safe to stop)
69
what is the point in an anaesthetists pre-op assessment
Reduces;
Anxiety
Delays Cancellations (resources)
Complications Length of stay Mortality (well planned)
70
what things may be asked in the history for an anaesthetist's pre-op assessment
Known co-morbidities (Severity, Control)
Unknown co-morbidities - (Systemic enquiry, Clinical examination)
Ability of withstand stress - Exercise tolerance, Reason for limitation, Cardio-respiratory disease focus
Drugs and allergies - DDIs
Previous surgery and anaesthesia reaction
71
describe the ASA grading of surgical patients
ASA1 - Otherwise healthy patient
ASA2 -Mild to moderate systemic disturbance
ASA3 - Severe systemic disturbance
ASA4 - Life threatening disease
ASA5 - Moribund patient (ASA6 Organ retrieval)
72
list some risk assessment tools for pre-op anaesthesia
GUPTA perioperative cardiac risk
Surgical outcome risk tool American college of surgeons surgical risk calculator
STOP-BANG questionnaire P-POSSUM/ CR-POSSUM/ Q-POSSUM/ V-POSSUM
73
what things are considered in the cardiac risk index for anaesthesia pre op assessment
High risk surgery Ischaemic heart disease
Congestive heart failure Cerebrovascular disease
Diabetes Renal failure
74
what is the METS way of measuring exercise tolerance
Without getting breathless -
Walk around the house- 2 METS
Do light housework - 3 METS
Walk 100-200 metres on the flat- 4 METS
Climb a flight of stairs or walk up a hill - 5 METS
Walk on the flat at a brisk pace - 6 METS
Play golf, mountain walk dance, or any form of exercise - 7 METS
Run a short distance - 8 METS
Do either strenuous exercise or heavy physical work - 9 METS
(15% reduction in mortality risk per MET score point)
75
list some things a patient can do pre-op to improve their outcomes
Optimum medical control - Hypertension, Ischaemic heart disease, Heart failure,Asthma, COPD, Epilepsy, Diabetes
Lifestyle – smoking, alcohol, obesity,
exercise - improve fitness
76
what are the 0-3 levels of care
0 - primary care
1- Ward-based
2- High dependency unit – single organ support
3- ITU – multi-organ support
77
where is the only place invasive ventilation can be done
ITU
78
what is the main difference in the need for HDU and ITU
HDU -single organ support
| ITU - multiple organ support
79
what are the nice guidelines for Na+ fluid replacement
1 – 2mmol/kg/day
80
what are the nice guidelines for K+ fluid replacement
0.5 – 1mmol/kg/day
81
what are the nice guidelines for max fluid replacement
25-30ml/kg/day
82
what are the nice guidelines for glucose replacement
50-100g/day
83
how would you support GI failure
unblocking any blockages
stenting
TPN with a nasogastric tube.
84
how would you support renal failure
dialysis
85
how would you support pancreatic failure
support diabetes, digestive enzyme control
86
what are the outcomes of liver failure
self limiting
transplant
die
87
what GCU will be intubated below
8
88
how would you support brain failure
Ensure the brain is getting O2 and CO2 clearance by vasodilation/ vasopressin, drugs to stop vasospasm, manage raised ICP, sedate, moderate temperature for tissue recovery.
89
what are the fatality rates of ITU
25-30%
90
what are benefits of a tracheostomy over a endotracheal tube in ITU
inserted in neck so don't need sedation of gag reflex
91
what are the 2 jobs of the lungs
get O2 in
| get CO2 out
92
which respiratory failure is more common in ITU
```
type 1
(easier to treat - give O2)
```
93
what is the most sensitive marker of a deteriorating patient
increasing RR - tachypnoea
94
what 4 was can oxygen be given in critical care
```
High-flow nasal cannula. – max 4l a min
Facemask – 10L/min
CPAP.
Intubation and invasive ventilation.
ECMO.
```
95
what are peoples normal o2 sats
99% on 21% O2
96
why do people find high flow nasal cannulas uncomfortable
cold dry air blasted up nose
97
what is the best treatment of type 2 respiratory failure in critical care
invasive ventilation
98
what does positive pressure from ventilators do to the lungs
ventilators opens lung up so blood can be oxygenated
| also cause lung damage so shorten time
99
why is CO hard to measure
difficult to measure SV
100
what drugs speed up the heart
chronotropes
101
what drugs affect the contractility of the heart
inotropes (beta1 agonists)
102
what drugs affect the pre load or after load of the heart
pre - fluids
| after - vasopressors
103
what type of drugs are vasopressors
alpha-1 agonists - constrict blood vessels (mostly veins) - noradrenaline
104
give an example of a vasopressor drug
noradrenalien/ adrenaline
| alpha-1 agonist
105
where are central lines most commonly placed and why
R interval jugular vein - goes straight to SVC
106
what is a benefit of central lines over peripheral cannulas
can be left in for 7-10 days but a cannula only 3 days
107
what is lactate a marker of
tissue of hypo perfusion (produced in anaerobic metabolism)
| >2 abnormal, >4 really bad
108
what is pain
an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
109
what is the number 1 disease for years lost to disability worldwide
lower back pain
110
what are the physical benefits or treating pain
Improved sleep, Better appetite
| Better movement Fewer medical complication e.g. heart attack, pneumonia
111
what are the psychological/social benefits of treating pain
```
Reduced suffering
Less depression, anxiety
better family ember
able to keep working
lower health costs
contribute to community
```
112
what is the difference between acute and chronic
Acute:Pain of recent onset and probable limited duration
Chronic: Pain lasting for more than 3 months, lasting after normal healing, often with no identifiable cause
Can get acute on chronic (flare up )
113
what are the 3 most common classifications for pain
acute vs chronic
nociceptive vs neuropathic
cancer (progressive) vs non- cancer
114
how long does chronic pain last
> 3 months
115
what is the difference between nociceptive and neuropathic pain
nociceptive - damage to afferent nerves
| neuropathic - nervous system damage or abnormality
116
what type of pain has a physiological protective function
nociceptive
117
how is nociceptive pain commonly described
Sharp ± dull, Well localised (or visceral)
118
how is neuropathic pain commonly described
Burning, shooting ± numbness, pins and needles, Not well localised (all over)
119
give examples of neuropathic pain
```
nerve trauma
diabetic pain (neuropathy), fibromyalgia
chronic tension headache (dysfunction)
very common after thoracic surgery (intercostal nerves)
```
120
what are the pathological mechanisms involved in neuropathic pain
Increased receptor numbers – amplification
Abnormal sensitisation of nerves –Peripheral or Central – ie light touch
Chemical changes in the dorsal horn – neurotransmitters, neuromodulators, noradrenaline, serotonin, Ca
Loss of normal inhibitory modulation
121
what are the 4 steps of pain physiology
1 peripheral tissue injury
2 travels up spinal cord (spinothalamic)
3 brain - thalamus secondary relay station, pain perception in cortex
4 modulation - descending pathway from brain to dorsal horn to decrease signal
122
what chemicals do tissues release in response to pain
prostaglandin
| substance P
123
what are pain receptors called
nociceptors
124
what type of nerves do pain signals travel in
A(delta)
| C fibres
125
what treatments can be given to target the peripheral tissue injury (pain)
RICE (rest, ice, compression, elevation),
NSAIDs
LA (damp down response – C fibres, Aδ
126
what is the 1st and second relay station for pain
1st - dorsal horn
| 2nd - thalamus
127
where do pain fibres cross the spinal cord
at the level they enter
128
describe the route of the 1st and 2nd nerve in the physiology of pain
1st - tissue to dorsal horn
| 2nd - opposite side of spinal cord
129
what treatments can be used to target the spinal cord in pain management
acupuncture, massage, TENS
| Local anesthetics, opioids, ketamine
130
where does pain perception occur
cortex of brain
131
what is the gate theory of pain
Gate theory of pain - painful signal travels into dorsal horn interneuron can be switched off - this can be stimulated by Abeta nerve and stop pain firing
132
what treatments target the brain for pain management
paracetamol, opioids, amitriptyline, clonidine, psychological (cognitive behavior therapy)
133
what is the physiology of modulation of pain
Descending pathway from brain to dorsal horn
| Usually decreases pain signal
134
list 2 classes of simple analgesics
paracetamol
| NSAIDs
135
what are advantages of paracetamol
Cheap, safe, Can be given orally, rectally or intravenously
136
what are disadvantages of paracetamol
liver failure in overdose
137
what is the antidote to opiates
naloxone
138
give examples of mild opiods
codeine
| dyhydrocodeine
139
give examples of strong opiods
Morphine, Oxycodone, Fentanyl
140
what are advantages of mild opiates
Cheap, safe, Good for mild-moderate acute nociceptive pain,
| Best given regularly with paracetamol (synergism)
141
what are disadvantages of mild opiates
Constipation, Not good for chronic pain
142
what are advantages of strong opiates
```
Cheap
generally safe
Can be given orally, IV, IM, SC
Effective if given regularly
Got an antidote.
Good for Mod-severe acute nociceptive pain (e.g. post-op pain), Chronic cancer pain
```
143
what are disadvantages of strong opiates
```
Constipation
Respiratory depression in high dose
nausea,
addiction (Controlled drug,
not good for neuropathic
```
144
are opiates good for neuropathic pain
no
145
what is tramadol
(Mixed opiate and 5HT/NA reuptake inhibitor)
| plus inhibitor of serotonin and noradrenaline reuptake (modulation
146
what are advantages of tramadol
Less respiratory depression, can be used with opioids and simple analgesics, Now a controlled drug
147
what is amitriptyline
tricyclic antidepressant (TCA
148
what are advantages of amitriptyline
cheap, safe in low dose, good for neuropathic pain, also treats depression, poor sleep
149
what are disadvantages of amitriptyline
Anti-cholinergic side effects (e.g. glaucoma, urinary retention)
150
what anticonvuslantsa re used for pain manangemtn
gabapentin (Neurontin)
sodium valproate (epilim)
carbamazepine (tegretol)
membrane stabilisers – reduce abnormal firing of nerves (Good for neuropathic pain)
151
what is ketamine
NMDA Receptor antagonist
152
how may LA be administered
Epidural
Intrathecal
Wound Catheters Local Infiltration of wounds
Nerve Plexus Catheters (brachial/ femoral/ sciatic)
153
name a topical agent used to manage neuropathic pain
capsaicin
154
list ways to assess pain
Verbal rating score – no, mild, moderate, severe, excruciating
Numerical rating score – 0-10 – most people don’t like numbers, hard to interpret
Visual analogue scale – line with scale
Smiling faces – paediatric
Abbey pain scale - confused patients, looks at pain and patient behaviour
155
list some non-drug methods of managing pain
Physical - Rest, ice, compression, elevation
Surgery
Acupuncture, massage, physiotherapy
Psychological- Explanation – expected, Reassurance
Counselling – positive psychology
156
where on the WHO pain ladder do you start with mild pain
Start at Bottom of Pain Ladder
157
where on the WHO pain ladder do you start with moderate pain
Bottom of Pain Ladder plus Middle Rung
158
where on the WHO pain ladder do you start with severe pain
Bottom of Pain Ladder plus Top of Ladder.
| Miss out the middle
159
is it ok to start at the top of the WHO pain ladder
severe/ unbearable pain
160
would you stop NSAIDs or paracetamol first
NSAIDs as more adverse effects
161
what type of pain is the WHO ladder for
nociceptive NOT neuropathic
162
what is step 1 of the WHO pain ladder
aspirin, NSAIDs, paracetamol
163
what is step 2of the WHO pain ladder
mild opiods eg codeine
164
what is step 3 of the WHO pain ladder
strong opiods e.g. morpheine
165
what does the RAT assessment stand for
R - recognise
A- assess
T - treat
166
what drugs should be used for neuropathic pain
Amitriptylline, Gabapentin, Duloxetine
167
what is involved is the 'Recognise' of RAT assessment
Does the patient have pain? Ask, Look (frowning, moving easily, sweating)
Do other people know the patient has pain? Other health workers, Patient’s family
168
what is involved is the 'Assess' of RAT assessment
Severity - pain score at rest and with movement, how is pain affecting the patient? Can they move, cough, work
Type – acute, chronic, cancer, non-cancer, nociceptive, neuropathic (burning/ shooting, phantom limb, pins and needles, numbness)
Other factors – other illnesses (physical), lack of social support, home circumstances, work (social), anger, anxiety, depression (psychological)
169
how should you treat moderate nociceptive pain
Paracetamol (± NSAIDs)
170
how should you treat mild nociceptive pain
Paracetamol (± NSAIDs) + codeine/ alternative
171
how should you treat severe nociceptive pain
Paracetamol (± NSAIDs) + morphine
172
what should you always remember to do when treating your patient for pain
Reassess the patient: Is your treatment working?
| Are other treatments needed? Up or down pain ladder
