Anaesthetics General Flashcards
1
Q
Which anti-hypertensives must be stopped before surgery
A
Stop ACEi and diuretics on day of surgery as they have a risk of prolonged hypotension
Only exception is if the diuretic is being used for heart failure
2
Q
How do you manage someone’s antiplatelets before surgery
A
Should stop anti-platelets 7 days before surgery as this allows new platelets to come back into circulation
However, aspirin is a grey area. half life is 24 hours and risk of bleeding is relatively low so now usually continue until the day before then stop.
3
Q
What surgery MUST aspirin be stopped 7 days before
A
Intracranial surgery - neurosurgery
Orthopaedics
Bleeds would be very high risk
4
Q
How should warfarin be managed prior to surgery
A
Should be stopped 5 days before surgery and then restarted post-op
If on for low risk reason like AF then stop completely with no replacement is fine
If high risk like mechanical valve, recurrent PE they are high clot risk so give bridging therapy (stop warfarin for 5 days, give LMWH on day 4 and 5 then restart)
5
Q
How should DOACs be managed prior to surgery
A
These needs stopped 2 days before and can be restarted - easier to manage
6
Q
How long should someone fast before surgery
A
Should fast for at least 6 hours pre-op - this is the timing of gastric emptying
Stop drinking 2 hours - can sip till send (sip small amounts of water to reduce dehydration)
7
Q
How should you manage diabetics prior to surgery
A
They are at risk of both hyper (due to body stress) and hypos (due to fasting)
Make them 1st on list to minimise risk from fasting (hypo risk)
Monitor glucose regularly
Get them back into usual routine as fast as possible
IV insulin can be used in more complex case
8
Q
When is jaw thrust preferable to head tilt chin lift
A
If there suspicion of C-spine pathology
9
Q
What are the 2 types of airway adjunct
A
Oro-pharyngeal or Guedel airway
Naso-pharyngeal airway
10
Q
How do you size a oro-pharyngeal airway
A
Roughly the distance between the patient’s incisors and the angle of the jaw
Better to be slightly too big than too small
11
Q
How do you size a naso-pharyngeal airway
A
Length corresponds to the distance between the tip of the patient’s nose to the tragus/earlobe
If too long it might make them gag
12
Q
When should you remove an oro-pharyngeal airway
A
If the patient starts gagging
NP is better tolerated
13
Q
How much O2 can be delivered via nasal cannula
A
1-4L/min
14
Q
Which type of mask is needed for high flow (15L/min) O2 delivery
A
Non-rebreather
15
Q
How can reduced consciousness lead to airway obstruction
A
There is a decrease in muscle tone which results in posterior displacement of the tongue and soft palate which can block the airway
This may be as a result of drugs, neurological conditions, anaesthetics or patients in critical condition
16
Q
When are naso-pharyngeal airways used
A
If patient is not deeply unconscious
If they have a clenched jaw trismus or maxillofacial injuries
17
Q
What is the major contraindication to nasopharyngeal airway use
A
Base of skull fracture
18
Q
What are the signs of a clear airway on bag-mask ventilation
A
Misty, Chesty, Tracey
- mask misting
- smooth respiratory mechanics of the chest
- square wave capnography trace
19
Q
Where are supraglottic airways positioned
A
Inserted into the oropharynx
The cuff at the bottom forms a seal around the laryngeal opening - above the epiglottis
20
Q
What are the absolute contraindications to supraglottic airways
A
History of gastric reflux or hiatus hernia
Intra-abdominal pathology
Pregnancy
Recent major trauma or administration of opiates
Morbid obesity
Gastroparesis
This is due to aspiration risk
21
Q
What is the only total contraindication to endotracheal intubation
A
Total airway obstruction of the upper airway preventing laryngeal access and necessitating a front-of-neck-airway
22
Q
List some potential complications of endotracheal intubation
A
Dental damage
Damage to other structures such as trachea or larynx
ETT may go down the wrong hole into the oesophagus
ETT may go too far down into the bronchi
23
Q
When is a front-of-neck intubation needed
A
If the patient is not being oxygenated but cannot be intubated
24
Q
Where is a front-of neck airway placed
A
In the cricothyroid membrane into the trachea
Called a cricothyroidotomy
25
Describe the 'ladder' of critical care
Ward based
HDU - single organ failure
ICU - multi-organ failure and/or ventilation
26
What conditions may present post-ICU survival
PTSD, anxiety etc
Muscle weakness
Fatigue
Long term renal and respiratory support needed
27
When would you use CPAP vs BiPAP
CPAP - gives pressure on expiration. Used for type 1 resp failure and pulmonary oedema.
BiPAP - also gives inspiratory pressure so better for type 2 resp failure and hypercapnia as helps decrease CO2
28
Those with end stage lung disease may not be accepted for mechanical ventilation - true or false
True
They would be unlikely to be able to wean off it - will never recover their resp function
Often considered a terminal event and discussed in AD - support until end of life
29
What is ECMO
A way of oxygenating the blood outwith the body - bypasses heart and lungs
Used for severe respiratory failure
30
How are vasopressors a used
In vasodilatory, neurogenic or distributive shock
| e.g. in sepsis, anaphylaxis etc
31
How do vasopressors work
Primarily alpha-adrenergic Used in vasodilatory/distributive shock
Causes venoconstriction - increases venous return (and CO etc)
And arterial constriction - increases SVR
32
How do positive inotropes work
Primarily beta-adrenergic stimulation
Increase cardiac output by increased contractility
33
How are inotropes used
In states of low CO such as cardiogenic shock
| When hypotension is caused by poor contractility and has not responded to fluids
34
What are the first line fluids in the critically ill
Crystalloids such as Hartmann's
| Balanced solutions like this are better than saline alone
35
If drug treatment fails, how can you treat cardiogenic shock
Intra-aortic balloon pump
- inflate in diastole to increase pressure and improve coronary filling
- deflates in systole to reduce afterload and myocardial O2 demand
36
When would you need a central venous catheter
Monitoring of Central Venous Pressure
Venous Access for Haemodialysis
Venous Access for Cardiac Pacing
Administration of Inotropes, cytotoxic agents
37
List some immediate complications of central venous catheter insertion
```
Arterial puncture
Haemorrhage Pneumothorax / haemothorax
Air embolism
Cardiac arrhythmia
Damage to nearby structures - eg trachea, oesophagus, thoracic duct, nerves
```
38
List some late complications of central venous catheter insertion
thrombosis
infection
endocarditis
cardiac or valve rupture
39
Where should a central venous catheter sit
The tip should be at the entrance to the right atrium
40
What is a vasopressor
A substance which increases the systemic vascular resistance
41
What is an inotrope
A substance that affects the force of muscular contraction, either positively or negatively.
When discussing medication we mean positive ones - increase contraction
42
Inotropes must always be given by infusion through a central venous catheter - true or false
True
43
List examples of positive inotropes
Adrenaline
| Dobutamine
44
List examples of vasopressors
Nor-adrenaline
Metaraminol
Adrenaline
Ephedrine
45
What happens to pO2 as air moves through the body
It decreases
| Highest in atmospheric gas and gets lower as it moves through the steps of respiration - lowest in mitochondria
46
How does hypovolaemic shock cause hypotension
It decreases preload - the amount of blood getting back to the heart
47
How does cardiogenic shock cause hypotension
It decreases myocardial contractility
48
How does septic/neurogenic shock cause hypotension
It decreases afterload - the resistance the heart is beating against
decreased SVR
49
List signs of shock
Tachycardia, tachypnoea and vasoconstriction (waiting for BP drop is dangerous)
Decreased urine output
Decreased conscious level
Acid Base Abnormality - Metabolic Acidosis/Respiratory compensation
50
How is haemorrhagic shock classed
4 classes based on how much blood has been lost.
51
Where is the majority of body fluid stored
As the intracellular fluid - 2/3
| Rest is extracellular - interstitial and plasma
52
List examples of crystalloid fluids
Saline
Hartmann's
Dextrose
53
What are the benefits of crystalloid fluids
Easily available
| Cheap
54
What are the cons of crystalloid fluids
Variable volume of distribution (can end up in undesirable spaces) - easily diffuses through a semi-permeable membrane
55
What are the benefits of colloid fluids
Stays in intravascular space - does not diffuse through membranes due to large protein/carb particles
Expands plasma volume - draw in water from interstiital fluid
Relatively expensive
56
What are the cons of colloid fluids
Risk of anaphylaxis
| No proven benefit over saline in hypovolaemia
57
List examples of colloid fluids
Gelofusine
58
What are the benefits of using blood to resus
Well recognised
Good colloid - stays in intravascular space
Replaces ‘like with like’
Carries oxygen well
59
What are the drawbacks of using blood to resus
```
Expensive
Risk of transfusion reactions
Infection risk etc
Packed red cells does not contain platelets and
clotting factors
```
60
What type of pain is usually seen in acute scenarios
Nociceptive
Direct response to injury (physical, chemical), or
other pathology - proportionate
61
How can under-treated pain affect the cardiovascular system
```
Tachycardia
Hypertension
Increased peripheral vascular resistance
Increased myocardial oxygen consumption
Myocardial ischaemia
```
62
How can under-treated pain affect the respiratory system
```
Decreased lung volumes
Atelectasis
Decreased cough and sputum retention
Infection
Hypoxaemia
```
63
How can under-treated pain affect the GI system
Decreased gastric and
| bowel motility
64
How can under-treated pain affect the GU system
Urinary retention
65
How can under-treated pain affect the MSK system
Muscle spasm
| Immobility
66
How can under-treated pain affect the endocrine system
Increased catabolic hormones and decreased anabolic hormones
| Insulin resistance
67
How can under-treated pain affect the patient psychologically
Anxiety and fear
Depression
Sleeplessness
68
Is it better to use high doses of one drug or lower doses of multiple drugs to treat acute pain
Best done by using a combination of drugs
from different classes -so lower doses of
each drug can be used
69
If someone with an opiate problem needs analgesia what do you give them
If they are already prescribed Methadone then continue at same dose
If not already in progranne, do not start methadone! Give normal opioids plus extra to control pain but monitor closely
70
As required pain medication should be avoided in patients with substance abuse issues - true or flase
True
| Better to aim for a stable plasma opioid level- e.g. with long acting opioids
71
Which medications are typically used for chronic pain
Maintained on opioids - regular dose plus breakthrough
Regular paracetamol/NSAID as baseline
May need to consider other adjuvant analgesics
72
Which analgesic should be avoided in renal failure
NSAIDs
| Those with many active metabolites - may accumulate due to decreased renal function
73
How do you convert oral morphine to IV or IM
Divide by 2-3
| IV dose needs to be lower
74
How does paracetamol work
Inhibits prostaglandin synthesis in the CNS
75
What is the typical dose of paracetamol
```
1 gram (2x500mg tabs) 6 hourly - max 4x daily
Dose will need reduced if patient is below 50kg
```
76
How do NSAIDs work
These drugs inhibit the enzyme cyclo-oxygenase [cox]
| 1 and 2
77
What are the contraindications to NSAID use
```
GI bleeding - old or new
Active peptic ulcers
Coagulopathy
Renal impairment
Aspirin or NSAID allergy
```
78
When should NSAIDs be used with caution
```
Elderly
Dehydration
Asthmatics
Certain types of surgery, e.g. - plastic or eye
surgery, some orthopaedic surgery
Cardiac failure
Pregnancy
Concurrent medication e.g. anticoagulants
```
79
How do you reverse respiratory depression caused by opioids
Give oxygen
Adjust dose or stop delivery of opioid until
situation satisfactory
If necessary give naloxone and titrate to effect
80
Clinical opioids act on which receptor
μ (mu) opioid receptor.
81
How is morphine metabolised
Metabolised in the liver to M6G and M3G
M6G is responsible for the analgesic effect.
These have longer half-lives than morphine and are excreted via the kidney
82
How does tramadol work
Centrally acting synthetic analgesic
| Has mu opioid receptor activity and inhibits the uptake of noradrenaline and serotonin
83
Tramadol should be avoided in which patients
Epileptics
Not suitable as the sole analgesic in
morphine-dependent patient
84
What are the benefits of tramadol
Doesn't build tolerance
Lower abuse potential
Less respiratory depression
Less constipation
85
When is patient controlled analgesia used
Post-op pain
Severe non operative pain e.g. pancreatitis, fractured
ribs
86
What is used for patient controlled analgesia
The usual prescription is a 1 mg bolus of morphine with a 5 minute lockout-i.e. the patient can receive up to 12 mgs morphine per hour.
Bolus dose and lock-out period can both be varied
87
What are the contraindications to patient controlled analgesia
```
Patient inability to comprehend the
technique e.g. extremes of age
Patients inability to press the button e.g.
severe rheumatoid
Patient rejection
Ward staff must be trained appropriately
```
88
What are the complications of epidural anaesthesia
Spinal haematoma
Abscess
Cannot be used if patient is anti-coagulated
89
Cyclizine is which type of anti-emetic
Antihistamine - H1 antagonist
90
Ondasentron is which type of anti-emetic
5HT3 antagonists
91
Prochlorperazine and metoclopramide are which type of anti-emetic
Antidopaminergic
92
Hyoscine is which type of anti-emetic
Anticholinergic
| Good for motion sickness
93
What is the definition of chronic pain
Lasting > 3 months
| Typically after normal healing has occurred
94
List primary causes of circulatory/cardiac inadequacy
```
Ischaemia
Myocardial infarction
Hypertensive heart disease
Valve disease
Drugs
Electrolyte abnormalities
```
95
List secondary causes of circulatory/cardiac inadequacy
```
Asphyxia
Hypoxaemia
Blood loss
Septic shock
Any Shock
```
96
what is nociceptive pain and describe how it feels
Also called physiological or inflammatory pain
Pain occurring after obvious tissue injury or illness - protective
Typically sharp and well localised - may have associated ache
97
what is neuropathic pain and describe how it feels
Pain due to nervous system damage or abnormality
May not have obvious injury
Typically burning/shooting pain with numbness, pin and needles etc.
Not well localised
98
Chronic pain is typically a complex mix of nociceptive and neuropathic pain - true or false
True
99
What is nociception
How signals get from the site of injury to the brain
100
Describe the peripheral section of the nociceptive pathway
```
Get the initial tissue injury
Triggers release of chemicals
This stimulates the nociceptors - pain receptors
Signal travels in Aδ or
C nerve to spinal cord
```
101
Describe the spinal section of the nociceptive pathway
```
Dorsal horn is the
first relay station
Aδ or C nerve
synapses with second nerve here
Second nerve crosses and travels up opposite side of
spinal cord in the spinothalamic tract
```
102
Describe the brain section of the nociceptive pathway
The thalamus is the
second relay station - nerve connects here
This has connections to many other parts of the brain - cortex, stem etc
Pain perception
occurs in the cortex
103
Describe how the nociceptive pathway is modulated
```
Descending pathway
from brain to dorsal
horn
Usually decreases
pain signal
```
104
Give examples of pain caused by nervous system damage
Nerve trauma
| Diabetic pain/neuropathy
105
Give examples of pain caused by nervous system dysfunction
Fibromyalgia
| Chronic tension headache
106
List pathological mechanisms through which pain sensation can be increased
Increased receptor numbers
Abnormal sensitisation of nerves
Chemical changes in the dorsal horn
Loss of normal inhibitory modulation
107
Which treatments are good for peripheral pain
RICE
Anti-inflammatories
Local anaesthetic
108
Which treatments are good for pain arising from the spinal cord
Locals
Opioids
Ket
109
What are the main adverse effects of codeine
Constipation
| Also not great for chronic pain
110
In which type of pain is addiction most likely
Chronic, non-cancer pain
111
What is the main adverse effect of tramadol
Nausea and vomiting
112
Which drugs are good for neuropathic pain
Amitriptyline
| Anti-convulsants - gabapentin, sodium valproate and carbamazepine
113
What is the main adverse effect of amitriptyline
Anti-cholinergic side effects
| e.g. glaucoma, urinary retention
114
How does amitriptyline treat pain
Increases descending inhibitory signals
| Helps modulate pain
115
How do anti-convulsants treat pain
Reduce abnormal firing of nerves
| Also called membrane stabilisers
116
What are the treatable/reversible causes of cardiac arrest
```
4 H's 4 T's
Hypoxia
Hyovolaemia
Hyper/hypokalaemia
Hypothermia
Toxins
Tamponade - cardiac
Tension pneumothorax
Thrombosis - coronary or pulmonary
```
117
How often should adrenaline be administered during ALS
every 3-5 mins
118
How often should amiodarone be administered during ALS
After the 3rd shock
119
How do you treat a SVT
Vagal manoeuvres
If ineffective give adenosine
If that doesn't work give verapamil or a beta-blocker
120
How do you treat acute AF
Beta-blocker - rate control
Consider digoxin or amiodarone if evidence of heart failure
2nd line is DC shock
Anticoagulate if duration > 48hrs
121
How do you treat acute bradycardia
Atropine - 500mcg IV
If not enough repeat dose up to 3mg max and consider adrenaline, isoprenaline or TC pacing
122
What dose of glucose is given in acute hypoglycaemia
100mI of 10% Glucose
123
What should the HbA1c be before elective surgery is considered
<69mmol/mol (8.5%)
| Otherwise discuss with the diabetes team (especially if over 12%
124
What post-op complications can be caused by hyperglycaemia
Wound infection and cardiac problems
125
What post-op complications can be caused by hypoglycaemia
Hypoglycaemia can be masked by sedation or general anaesthesia. In extreme cases this may cause irreversible brain damage
126
Patient's become more prone to hypos post-op - why is this
They will have been fasted prior to their procedure
Paradoxically the surgical stress response may mean that patients become more prone to hyperglycaemia and insulin resistance after major surgery
127
There is an association between asthmatics with nasal polyps and sensitivity to NSAlDs - true or false
True
128
In general cardiac medication should be given over the peri-operative period - true or false
True - most are cardioprotective
| Exceptions - ACEi, diuretics, anti-coag and anti-plat
129
Typically you are aiming for an INR of 1.5 for surgery - true or false
True
| Exceptions- dental work or urological ops
130
Patients who have had a venous thrombo-embolic event 9 months ago are considered high risk of another thrombo-embolic event - true or false
False
| Once 3 months has passed, these patients are not considered high risk.
131
If there is no excessive bleeding post-operatively then warfarin should be restarted at the patient's usual dose on the day of the procedure - true or false
True
| Recheck INR 48 hours after restarting
132
Raised urea and creatinine can indicate dehydration - true or false
True
| Even pre-renal failure due to hypovolaemia
133
What is the minimal acceptable urine output
0.5ml/kg/hr
134
What is the risk of large, rapid NaCl infusion
Hypernatraemia and acidosis
| The influx of negative Cl- ions causes H+ to rise to balance it out
135
Which fluid department is depleted in pure dehydration
All
| Plasma, interstitial and ICF
136
Which fluid department is depleted in hypovolaemia
Just the plasma
137
Which fluid department is depleted in
The ECF
| Plasma + Interstitial fluid
138
Should PPIs be continued on day of surgery
Yes
139
How do benzodiazepines work
They bind to the GABA receptor in the CNS and increase the receptor affinity for GABA
Ion movement across the cell membrane is increased which hyperpolarises the cell membrane and reduces firing of neurons.
Leads to CNS depression
140
List anesthetic induction agents
```
Propofol
Thiopentone
Etomidate
Midazolam
Ket
```
141
Most anaesthetic agents work on which receptor
Majority are GABA mediated
142
Which drugs can be used for inhalational anaesthesia
Nitrous oxide and sevoflurane
| Used in kids or if difficult IV access
143
Which drugs can be used for maintained anaesthesia
Nitrous oxide
Sevoflurane
Desflurane
Isoflurane
144
How are neuromuscular blocking agents used in anaesthetics
Given to relax or paralyse muscles
Facilitate intubation
Improve surgical conditions (ie. relax abdominal wall)
145
List examples of neuromuscular blocking agents
Non-depolarising - atracurium and rocuronium
Depolarising - Suxamethonium
Patient will twitch for a short time with this one
146
How do local anaesthetics work
Reversible blockade of sodium channels, inhibiting transmission of action potentials in nerve cells.
147
What is the max dose of 1% lidocaine used
4mg/kg
148
Why is adrenaline sometimes given alongside local anaesthetci
It prolongs the duration of action by causing local vasoconstriction
therefore dont give to end artery regions!
149
Why should metoclopramide be avoided in women under 60
Can cause oliguric crisis
150
Which bloods can be used to help diagnose dehydration
Urea and Electrolytes
| Creatinine
151
What are the normal daily potassium requirements
1 mmol/kg
152
What are the normal daily sodium requirements
2mmol/kg
153
What are the normal daily water requirements
25-30ml/kg
| 2 litres for a 70kg man
154
How should naloxone be administered
40 microgram increments titrated to effect and reassess the patient
155
Poor control of blood glucose in the peri-operative period is associated with which complications
An increased risk of wound infection
Increased cardiovascular complications
Irreversible brain damage
156
What is the correct dose and route of adrenaline for administration during cardiac arrest
1mg IV
157
What is the correct dose and route of adrenaline for administration during anaphylactic shock
0.5mg IM
158
Delayed (up to 12 hours) respiratory depression can occur in patients with spinal or epidural opioid administration - true or false
True
159
What are the common side effects of using opioids in the epidural space
Itch
160
What are the common side effects of using local anaesthetic alone as a block in the epidural space
Hypotension
Partial block
Post dural puncture headache
Nausea
