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Conditions + definitions > Anaesthetics > Flashcards

Anaesthetics Flashcards

1
Q

What is general anaesthesia?

A

Produces insensibility in the whole body, usually unconsciousness
Centrally acting drugs

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2
Q

What is regional anaesthesia?

A

Produces insensibility in an area or region

Local anaesthetics applied to nerves supplying area

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3
Q

What is local anaesthesia?

A

Produces insensibility in only relevant part of body

Applied directly to tissues

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4
Q

What is the triad of anaesthesia?

A

Analgesia
Hypnosis
Relaxation

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5
Q

What drugs tend to be used to cause analagesia in surgery?

A

Opiates

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6
Q

What agents are used to cause hypnosis in surgery?

A

General anaesthetic agents

Lectures…

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7
Q

What agents are used to cause relaxation in surgery?

A

Muscle relaxants

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8
Q

What is balanced anaesthesia?

A

Using different drugs to do different jobs
Titrating each drug separately
Avoids overdose
Gives flexibility

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9
Q

What are the problems with muscle relaxants?

A

They create the need for:
Artificial ventilation
A means of airway control

Awarness
Incomplete reversal = airway obstruction

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10
Q

How do general anaesthetic agents work?

A

They interfere in neuronal ion channels

Hyperpolarise neurone cells making it less likely to send impulses

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11
Q

How do inhalational agents work?

A

They dissolve in membranes

Gives a direct physical effect

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12
Q

How do IV agents give their effect?

A 
Through allosteric (enzyme) binding
GABA receptors open choloride channels
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13
Q

What function is lost in general anesthesia? What is retained?

A

Cerebral function “from top down” lost
Most complex first
More primative lost later

Reflexes relatively spared
As primitive with small number of synapses

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14
Q

What are the downsides of general anaesthesia?

A 
Long drawn out resus
Mandates airway management
Impact on resp function + control of breathing
CVS impact
Care of unconcious patient
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15
Q

What are the benefits of IV anaesthesia?

A

Rapid onset of unconciousness
>arm-brain circulation time
Rapid recovery
>however drug not necessarily out of system, just distributed

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16
Q

What are the inhalational agents?

A

Halogenated hydrocarbons

Main one sevoflurane (halothane)

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17
Q

What is MAC?

A

Minimum alveolar concentration
Measure of potency
Low number=high potency

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18
Q

What are the benefits/downsides to inhaled anaesthetics?

A

Slow induction
However, very flexible duration
And quick to come back round

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19
Q

What is the generic way of adminstering anaesthesia in surger?

A

Induction with IV

Maintain with inhalation

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20
Q

What is general anaesthesia’s effect on the cardiovascular system?

A

Depresses central cardiovascular centre
>Reduces sympathetic outflow
>Negative iontropic effect on heart
>reduced vasoconstriction -> vasodilation

Causes decreased peripheral resistance
Causes venodilation (Decreased venous return = decreased Cardiac Output)
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21
Q

What is the effect of general anaesthesia on the respiratory system?

A 
Respiratory depressant
Reduce hypoxic drive
Decreased tidal volume, increases rate
Paralyse cilia
Causes VQ mismatch, which may be prolonged
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22
Q

What are the indications of muscle relaxants?

A

Ventillation + incubation
When immobility essential
Body caivty surgery

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23
Q

Why is analgesia used intraoperatively?

A

To prevent arousal
Opiates contribute to hypnotic effect of GA
Supression of reflexes to painful stimuli (tachycardia, hypertension)

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24
Q

What are the benefits of local/regional analgesia?

A

The patient retains awareness/consciouness (pregnancy)
Lack of global effects
Derangement of CVS proportional to affected area
Relative sparing of resp function

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25
Q

What are the limitations of local anaesthetics?

A

Toxicity
High plasma concentration due to IV
Absorption faster than metabolism

They vasoconstrict

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26
Q

Why do local anaesthetics cause a differential cascade?

A

Due to different penetration of nerve types
Motor fibres are thicker + myelinated so are relatively spared
Whereas pain fibres as thinner and so affected first
Allows for no paralysis but analgesia

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27
Q

What are the main IV anaesthetic drugs?

A

Propofol

Thiopentone (used less, but still in maternity hospital)

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28
Q

What are the downsides to IV induction?

A

Easy to overdose
Apnoea very common
Generally rapid loss of airway reflexes

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29
Q

When would you normally use gas induction?

A

In young children

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30
Q

What are the planes of anaesthesia?

A

Analgesia/sedation
Excitation
Anaesthesia (light-> deep)
Overdose

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31
Q

What is the light/deep “sleep” of inhaled anaesthesia dependant on?

A

Responsivness to stimuli

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32
Q

How is conciousness monitored when a patient is under anaesthesia?

A 
Loss of verbal contact
Movement
Respiratory pattern
Processed EEG
Stages/planes of anaesthesia
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33
Q

What is the triple airway manoeuvre?

A

Head tilt
Chin lift
Jaw thrust

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34
Q

What simple apparatus are used for airway maintenance in anaesthesia?

A 
Face mask
Oroopharyngeal aiway (guedal)
Nasopharyngeal airway (less used)
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35
Q

Why should you wait for a patient to be in deep anaesthesia before using a oropharyngeal/ guedal airway?

A

As insertion in light patient may cause vomitting or laryngospasm
Only tolerated by unconcious patient

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36
Q

What is the laryngeal mask airway?

A

A cuffed tube with a mask sitting over glottis

Maintains but does not protect airway (aspiration)

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37
Q

What is a laryngospasm?

A

Forced reflex adduction of vocal cords
May result in complete airway obstruction
Caused by airway simulation in light planes of anaesthesia
Often not relieved by simple manoeuvres

38
Q

What can cause obstruction?

A

Innefective triple airway manoeuvre
Airway device malposition/kink
Laryngospasm

39
Q

What are the possible complications with the airway

A

Obstruction

Aspiration

40
Q

What is endotrachieal intubation?

A

Placement of cuffed tube in trachea
Laryngeal reflexes must be abolished
>Possible in awake patient using local anaesthetic + fibre optic scope

41
Q

Why are people intubated?

A

To protect airway from gastric contents
Need for artificial ventilation after muscle relxants
Shared airway with risk of blood contamination
Need for tight control of blood gases
If restricted access to airway

42
Q

What are the risks to an unconcious patient?

A 
Airway
Temperature
Loss of other protective reflexes - conreal, joint position
VTE risk
Concsent/identification
Pressure areas
43
Q

What is the process to emergence

A 
Muscle relaxation reversed
Turn off anaesthetic agents
Resumption of spontaneous respiration
Return of airway reflexes/control
Extubation

Can be quick or slow

44
Q

What are the signs in someone who is euvolaemic (has the right amount of fluid in body)

A 
Not thirsty
Veins well filled
Warm extermities
Mild sweat
Normal BP/HR
Normal urine
45
Q

What are the signs of someone who is hypovolaemic?

A 
Feels nauseous/thirsty
Flat veins
Cool peripheries
No sweat
Low/postural BP
High HR
Concentrated urine
Response to SLR
46
Q

What are the needs of someone who is hypovolaemic?

A

Resuscitation fluids (If low BP)
Rehydration fluids
Find the cause and stop it

47
Q

What are the signs of hypervolaemia?

A 
Breathless, not thirsty
Distended veins
Warm /oedematous extermities
Sweaty
High BP/HR
Dilute urine
48
Q

How do you manage someone who is hypervolaemic?

A

Stop any fluids
Possibly diuretics
Haemofiltration if anuric

49
Q

What is resuscitation fluid?

A

IV fluids to restore circulation with hypovolaemia
>Reassess after! (BP)
In shock!

50
Q

What is routine maintenance fluid?

A

IV fluids if cannot take orally ot enterally to meet patient maintenance requirements
If cannot eat
>Limited as if cannot eat not getting any nutrients
Reassess after (fluid balance every day)

51
Q

What are the 5 Rs of fluid?

A 
Resus
Routine maintenance
Replacement
Redistribution
reassessment
52
Q

What is replacement resuscitation?

A 
Don't need urgent IV resuscitation but do need additional IV to maintenance to correct existing deficit or ongoing abnormal external losses
Reassess after (bloods - did it work?)
53
Q

What is redistribution resuscitation?

A

Patients with abnormal internal fluid redistribution/abnormal fluid handling
Particularly with sepsis/major illness, cardiac, liver or renal disease etc

54
Q

When is dextrose useful?

A

Chronic dehydration

Hypernatreamia

55
Q

When is dextrose not useful?

A

Resuscitation

Or low albumin

56
Q

What are the properties of dextrose fluid?

A

Moves through all compartments
>Not useful for blood volume expansion
No sodium so depletes sodium, isotonic

57
Q

When are crystalloids useful?

A

acute dehydration
AKI
Resuscitation

58
Q

When is crystalloids not useful?

A

Long term maintainence

Hypernatraemic patient

59
Q

When are plasma expanders useful?

A

Liver patients

Select intraopertative

60
Q

How do you work out how much fluid they need?

A

Work out fluid balance (input/output charts)

61
Q

What are the properties of crystalloids?

A

Remain in ECF
High sodium load, which can cause problems over time
Lots of different types

62
Q

What are colloid expanders?

A

Colloids

>Examples such as Blood and TPN, Albumin

63
Q

What are teh ASA grades?

A 
ASA1: healthy patient
ASA2: Mild-moderate systemic disturbance
ASA3: severe systemic disturbance
ASA4: Life threatening disease
ASA5: Moribund patient
ASA6: organ retrieval
64
Q

What are some potenital anaesthetic problems?

A

Airway
Spine
Reflux
Obesity

65
Q

What are METs?

A

A measure of exercise tolerance

66
Q

What are the classifications of pain?

A 
Duration
>Acute/chronic/ Acute on chronic
Cause
>Cancer/non cancer
Mechanism
>Nociceptive
>Neuropathic
67
Q

What is chronic pain?

A

Pain lasting more than 3 months
Pain lasting after normal healing
Often no identifiable cause

68
Q

What is cancer pain?

A

Progressive pain

Mix of acute and chronic

69
Q

What is nociceptive pain?

A

Obvious tissue injury/illness
“Physiological”/”inflammatory” pain
Protective function

Sharp +/- dull pain
>Often well localised

70
Q

What is neuropathic pain?

A

Nervous system damage/abnormality
Injury may not be obvious
No protective function

Burning, shooting +/- numbness/parasthesia
>Not well localised

71
Q

What fibres carry nerve pain?

A

A delta

C nerve fibres

72
Q

What pathway carries nerve pain?

A

Spinothalamic tract
>Dorsal root synapse
>Thalamus synapse
>Cortex destination

73
Q

What are the pathological mechanisms causing neuropathic pain?

A

Increased receptor numbers
Abnormal sensations of nerves
Chemical changes in dorsal horn
Loss of normal inhibitory modulation

74
Q

What are the advantages for paracetamol?

A

Cheap and safe
Oral, rectal or IV administrations
Good for mild pain by itself, and moderate-severe pain with others

75
Q

What are the advantages of NSAIDs?

A

Cheap and gernally safe (GI/renal side effects)

Good for nociceptive pain

76
Q

What are teh advantages/disadvantages of codein?

A

Cheap/safe
Good for mild-moderate acute nociceptive pain

However, constipation and not good in chronic pain

77
Q

What does tramadol do?

A

Weak opoid effect + inhibition of serotonin/noradrenaline uptake

78
Q

What are the advantages/disadvantages of tramadol?

A

Less respiratory depression than with other opoids
Can be used with opoids/other analgesics
Not a controlled drug

However, can cause nasuea/vomitting

79
Q

What are teh advantages of morphine?

A 
Cheap + generally safe
Oral, IV, IM + Subcut administration
Effective if regular
Good for mod-severe acute nociceptive pain
Chronic cancer pain
80
Q

What are the disadvantages of morphine?

A

Constipation
Respiratory depression in high dose
Misunderstandings about addiction
Controlled drug

Oral dose 2-3 x IV/IM/SC

81
Q

What is amitriptyline?

A

Trycyclic antidepressant

Increases descending inhibitory signals

82
Q

What are the advantages of Amitriptyline?

A

Cheap, safe in low dose
Good for neuropathic pain
Also treats depression, poor sleep

However, anticholinergic side effects

83
Q

What are some examples of anticonvulsant drugs?

A

Carbamazepine (Tegretol)
Sodium valproate (Epilim)
Gabapentin (Neurontin)

84
Q

What are the delivery routes for local anaesthetics?

A 
Epidural (+/- Opiates)
Intrathecal (+/- Opiates)
Wound Catheters 
Nerve Plexus Catheters
Local Infiltration of wounds
85
Q

What scoring systems can be used to rate pain?

A 
Verbal Rating Score
Numerical Rating Score
Visual Analogue Scale
Smiling faces
Abbey Pain Scale (for confused patients)
86
Q

What non-pharmaceutical treatments can be used for pain?

A

RICE
Surgery
Acupuncture, massage, physio

Psychological meassures - explanation, reassurance, counselling

87
Q

What is the pain ladder?

A

Step 1:
>Non-opoids (Aspirin, NSAIDS, paracetamol)
Step 2
>Mild opoids (codeine) w/ or w/o non-opoids
Step 3
>Strong opoinds (morphine) w/ or w/o non-opoids

88
Q

Where do you start/stop someone on the pain ladder?

A

Mild Pain: Start at Bottom of Pain Ladder
Moderate Pain: Bottom of Pain Ladder plus Middle Rung
Severe: Bottom of Pain Ladder plus Top of Ladder. Miss out the middle

To stop, move down one rung at a time

89
Q

What is the RAT approach?

A

Recognise
>Do they have pain (ask/look)
Assess
Treat

90
Q

How do you assess in RAT?

A

What is pain score (rest/movement)
How does pain affect patient (can they move, cough work?)
Type
>Look for neuropathic features
>Burning/shooting pain, phantom limb, parasthesia
Other factors
>Physical/psychological (other illness, anger, anxiety etc)

91
Q

How do you treat neuropathic pain?

A 
Traditional drugs may not be useful
Use other drugs early
>Amitriptylline
>Gabapentin 
>Duloxetine
Don’t forget non-drug treatments

Conditions + definitions (68 decks)

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