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Y4 Acute and Critical Care > Anaesthetics > Flashcards

Anaesthetics Flashcards

1
Q

What are the components of ‘balanced’ general anaesthesia?

A

Amnesia (lack of response and recall to noxious stimuli; unconsciousness)

Analgesia - pain relief

Akinesis - immobilisation, paralysis

*Not harmful to the patient

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2
Q

What monitoring is required as a minimum prior to giving any anaesthetic agent?

A

Established monitoring prior to giving an anaesthetic agent:

  • ECG
  • SpO2
  • NIBP (non-invasive BP)
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3
Q

What monitoring is required after the patient is anaesthetised?

(ECG, SpO2 and NIBP were established prior to anaesthetisation)

A
  • Airway gasses: O2, CO2, vapour
  • Airway pressure
  • Nerve stimulator (if muscle relaxant used)
  • Temperature monitor
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4
Q

Why is IV required during anaesthetisation?

A

To give the anaesthetic agents, to administer fluids.

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5
Q

Why are fluids required as part of anaesthetisation?

A

Patients have been fasting for 6 hours

To minimise surgical loss

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6
Q

After establishing IV access, and prior to induction what is an important step in the anaesthetisation process?

A

Preoxygenation

You need to ensure the patient is well perfused

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7
Q

Which type of anaesthetic agent is used to establish amnesia?

A

Induction agents establish amnesia

Maintenance agents maintain amnesia

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8
Q

How quickly to induction agents work?

A

10-20 seconds

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9
Q

What are the four most commonly used induction agents?

A

Propofol

Thiopentone

Ketamine

Etomidate

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10
Q

Propofol is the commonly used induction agent. What is the correct dose of propofol?

A

1.5-2.5 mg/kg

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11
Q

What is the main benefit of propofol?

A

It has an excellent ability to suppress airway reflexes and decreases the incidence of post-operative nausea and vomiting.

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12
Q

What are the main unwanted effects of propofol?

A

Marked drop in HR and BP

Pain on injection

Involuntary movements

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13
Q

Which of the main anaesthetic inducers is a barbiturate?

A

Thiopentone

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14
Q

Thiopentone is a barbiturate. What is the correct dose of thiopentone?

A

4-5 mg/kg

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15
Q

True or false: Propofol is the most rapid inducing agent.

A

False. Thiopentone works faster than propofol.

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16
Q

Which induction agent is used for RSI?

A

Thiopentone

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17
Q

True or false: Thiopentone is an antiepileptic and protects the brain.

A

True. Thiopentone has antiepileptic properties and protects the brain.

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18
Q

What are the unwanted effects of thiopentone?

A

Drops BP, raises HR

Rash, bronchospasm

Intra-arterial injection: thrombosis and gangrene

Contraindicated in porphyria

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19
Q

What is the correct dose of ketamine as an induction agent?

A

1-1.5mg/kg

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20
Q

When is ketamine usually used?

A

Anaesthetic for short procedures

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21
Q

How does ketamine affect BP and HR?

A

Ketamine raises HR and BP

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22
Q

What are the unwanted effects of ketamine?

A

Nausea and vomiting

Emergence phenomenon

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23
Q

Which is the slowest of the induction agents?

A

Ketamine ~90 seconds

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24
Q

True or false: Etomidate is a good choice because is maintains haemodynamic stability.

A

True

However, it is not used often because it suppresses the adrenocortical system, which is essential for postoperative recovery.

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25
Q

What are the unwanted effects of etomidate?

A

Pain on injection

Spontaneous movements

Adrenocortical suppression

High incidence of postoperative nausea and vomiting

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26
Q

What is the best induction agent for a patient requiring a burn dressing change on a ward?

A

Ketamine

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27
Q

What is the best induction agent for a patient undergoing arm operation under GA with an LMA?

A

Propofol

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28
Q

What is the best induction agent for a patient with a history of heart failure but requires a GA?

A

Etomidate

Doesn’t cause haemodynamic instability

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29
Q

What is the best induction agent for a patient with an intestinal obstruction who requires an emergency laparotomy (RSI)?

A

Thiopentone

Used for RSI

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30
Q

What is the best induction agent for a patient with porphyria who comes in for an inguinal hernia repair?

A

Propofol

Cannot use thiopentone (contraindicated in porphyria)

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31
Q

What are the broad options for maintaining anaesthesia?

A

Total IV anaesthesia

Inhalational anaesthesia

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32
Q

What are the four main inhalation agents used in anaesthesia?

A

Isoflurane

Sevoflurane

Desflurane

Enflurane

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33
Q

What is 1 (one) MAC?

*Minimum alveolar concentration

A

Concentration of the vapour that prevents the reaction to a standard surgical stimulus in 50% of subjects, while 100% of patients have amnesia.

*standard surgical stimulus is traditionally a set depth and width of skin incision.

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34
Q

What is one MAC of the following vapours?

1) Nitrous oxide
2) Sevoflurane
3) Isoflurane
4) Desflurane
5) Enflurane

A

1) Nitrous oxide = 104% (extrapolated data)
2) Sevoflurane = 2%
3) Isoflurane = 1.15%
4) Desflurane = 6%
5) Enflurane = 1.6%

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35
Q

True or false: The target of inhaled anaesthetic agents is to achieve one MAC of the agent in the expired air.

A

True. The target is to achieve one MAC of the inhaled agent in the expired air.

One MAC:
Sevoflurane = 2%
Isoflurane = 1.15%
Desflurane = 6%
Enflurane = 1.6%
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36
Q

What are the beneficial properties of sevoflurane?

A

Sevoflurane is sweet smelling, can be used as an inhalational induction agent where IV access is not practical.

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37
Q

What are the beneficial properties of desflurane?

A

Desflurane has a low lipid solubility - does not store in the fat easily, therefore rapid onset and offset. Can be good for long operations.

Other vapours that are more lipid soluble remain in the fat, so after a long operation the patient can take much longer to wake up.

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38
Q

What are the beneficial properties of isoflurane?

A

It has the least effect on visceral blood flow, therefore it is an excellent option for organ donation.

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39
Q

Which inhalation agent would be the most appropriate in the following situations?

1) A long (8 hour) finger replantation
2) Child with a high BMI with no IV access
3) Organ retrieval from a donor

A

1) A long (8 hour) finger replantation

Desflurane: Low lipid solubility, will accumulate less in the adipose tissues and allow for a quicker wake up.

2) Child with a high BMI with no IV access

Sevoflurane: Sweet-smelling, can be used as an ihaled induction agent.

3) Organ retrieval from a donor

Isoflurane = less impact on visceral blood flow makes it the best agent to use for organ donation.

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40
Q

Why is analgesia required as part of anaesthesia?

A

Insertion of airway (LMA/intubation) is painful

Intraoperative pain - reduce stress on body

Postoperative pain

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41
Q

Which of the following is the faster acting analgesic?

A) Alfentanil
B) Fentanyl
C) Morphine
C) Remifentanil

A

C) Remifentanil

Remifentanil > Alfentanil > Fentanyl

Morphine is a long acting opioid

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42
Q

Which is the most commonly used short-acting opioid for analgesia in anaesthetic?

A

Fentanyl

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43
Q

Which is given first: amnesic agent or analgesic agent?

A

Analgesic agent is given first as it take up to 5 minutes to take effect. A couple of minutes later the amnesic agent is given (usually only takes 10-30 seconds to work).

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44
Q

What are the commonly used non-strong opioid analgesic drugs in anaesthesia? Which of these can be given IV?

A

Paracetamol*

NSAIDs: Diclofenac, parecoxib, ketorolac

Weak opioids: Tramadol, dihydrocodeine*

*can be given IV

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45
Q

True or false: You cannot use tramadol and morphine together.

A

False. Tramadol and morphine can be used together.

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46
Q

True or false: Tramadols main adverse effects include nausea, vomiting and confusion.

A

True.

Tramadols main adverse effects include nausea, vomiting and confusion.

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47
Q

What is the most commonly used analgesic?

A

Paracetamol

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48
Q

What is the most commonly used oral opioid in adults?

A

Codeine

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49
Q

Name the commonly used NSAIDs that can be given intravenously

A

Parecoxib

Ketorolac

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50
Q

Which opioid can be used with morphine?

A

Tramadol

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51
Q

How do muscle relaxants work?

A

Muscle contraction caused when action potential arrives at neuromuscular junction, releasing acetylcholine into the synapse. Acetylcholine causes depolarisation of the nicotinic receptors, leading to muscle contraction.

Depolarising muscle relaxants: Molecules similar to acetylcholine that are not easily hydrolysed by acetylcholinesterase. They bind to the acetylcholine receptor sites and cause depolarisation, but continue to act the site, causing fatigue and preventing repolarisation.

Non-depolarising muscle relaxants: block the nicotinic receptors, therefore maintain relaxation.

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52
Q

Which is the main depolarising muscle relaxant?

A

Suxamethonium

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53
Q

What is the correct dose of suxamethonium?

A

1-1.5 mg/kg

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54
Q

What is suxamethonium generally used for?

A

Rapid sequence induction (rapid onset, rapid offset)

Gets to work in 30-45 seconds, works for 4-10 minutes

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55
Q

What are the adverse effects of suxamethonium?

A

Muscle pains (prolonged contraction leads to damage of some fibres, pain can last several days to weeks and feel like flu-like symptoms)

Fasciculations

Hyperkalaemia (potassium can be released from the contracted muscle fibres)

Malignant hyperthermia

Rice in ICP, IOP, gastric pressure

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56
Q

How long do each of the main non-depolarising agents work for?

A

Short acting: Mivacurium - 15 minutes

Intermediate acting: Vecuronium, rocuronium, atacurium - 30-60 minutes

Long-acting: Pancuronium - 60-90 minutes

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57
Q

Which agents are used to reverse non-depolarising muscle relaxants?

A

Neostigmine & glycopyrronium

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58
Q

Which vaso-active drugs are commonly used to treat intraoperative hypotension? How do they work?

A

Ephedrine
(acts on alpha- and beta- receptors, increasing heart rate and contractility to raise BP. Therefore used when BP and HR are low)

Phenylephrine
(acts directly on alpha receptors to cause vasoconstriction; drops HR. Therefore, used in situations such a hypovolaemia where the HR is high but BP is low)

Metaraminol
(acts predominantly on alpha receptors to cause vasoconstriction, acts longer than phenylephrine. Therefore, used in situations such a hypovolaemia where the HR is high but BP is low)

The following are only used for severe hypotension or in ICU settings:

  • Noradrenaline
  • Adrenaline
  • Dobutamine
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59
Q

What would be your intraoperative vasoactive agent of choice in the following circumstances?

1) Low BP, low HR
2) Low BP, high HR
3) Intensive care, severe sepsis

A

1) Low BP, low HR = Ephedrine
2) Low BP, high HR = Phenylephrine/Metaraminol
3) Intensive care, severe sepsis = Noradrenaline/Adrenaline

60
Q

Why are antiemetics given as part of anaesthesia?

A

Roughly 25% of patients are sick after general anaesthesia if no antiemetic is given: postoperative nausea and vomiting.

61
Q

What are the commonly used perioperative antiemetics?

A 
Ondansetron (5HT3 blocker)
Dexamethasone (steroid)
Cyclizine (antihistamine)
Prochlorperazine (phenothiazine)
Metoclopramide (antidopaminergic)
62
Q

What are the important steps for waking up an anaesthetised patient?

A

Stop anaesthetic vapours

Give O2

Perform throat suction

Reverse muscle relaxation (neostigmine & glycopyrrolate)

63
Q

How do you reverse non-depolarising muscle relaxants?

A

Either [neostigmine + glycopyrrolate] or [sugammadex]

Give neostigmine (cholinesterase inhibitor) to prevent the breakdown of acetylcholine in the synapse (therefore, more acetylcholine available)

To counteract profound antimuscarinic effects (such as severe bradycardia) give neostigmine in combination with glycopyrrolate (antimuscarinic agent).

OR

Give sugammadex (directly reduces the concentration of the non-depolarising muscle relaxant by forming a water soluble complex with it). However, sugammadex is very expensive!

64
Q

What are the side effects of neostigmine & glycopyrrolate?

A

Nausea and vomiting

65
Q

What are some potential problems of using neostigmine & glycopyrrolate?

A

May not be able to reverse a profound block (which is why nerve stimulator is used to monitor level of akinesia, ensure the patient is not profoundly blocked)

Slow onset to peak (7-11 minutes)

66
Q

Put these anaesthetic steps in the right order:

  • Give opioid (e.g. fentanyl)
  • Bag valve mask ventilation
  • Muscle relaxant
  • Oxygenation
  • Turn on volatile agent (e.g. sevoflurane)
  • ET intubation
  • Induction agent (e.g. propofol)
A
  1. Oxygenation
  2. Opioid
  3. Induction
  4. Volatile agent
  5. BVM ventilation
  6. Muscle relaxant
  7. ET intubation
67
Q

What are the important components of a preoperative assessment?

A

Systems history:

CVS: Chest pain, hypertension, paroxysmal nocturnal dyspnoea, orthopnoea, exercise tolerance.

RS: Asthma, evidence of chest infection, smoking history.

Airway: Teeth/dentures, neck and mouth movement

Previous anaesthetic history: any problems, PONV, pain relief, family history of problems.

GI: GORD, last meal time

PMH: Diabetes, epilepsy, renal disease, thyroid disease, TIA/stroke or other.

Medications (inc. allergies)

Examination of systems.

Assess Mallampatti score.

68
Q

What is the Mallampatti score? What is visible in each class?

A

Airway assessment for ease of intubation.

Class I: Uvula, fauces, soft palate, pillars

Class II: Uvula, soft palate, fauces

Class III: Base of uvula, soft palate

Class IV: Only hard palate visible

69
Q

What is ASA grading?

A

ASA grading is a classification system for assessing physical fitness for surgery. Patient can be graded 1 (healthy)-6 (brain dead).

70
Q

Go through each of the ASA grades.

A

ASA grade…

1: A healthy patient with no systemic disease
2: Mild systemic disease, no substantive functional limitations
3: Severe systemic disease with substantive functional limitations
4: Severe systemic disease which is a constant threat to life
5: Moribund patient not expected to survive with or without the operation
6: Brainstem-dead patient whose organs are being removed for donor purposes
* emergency cases have the suffix ‘E’

71
Q

What is the ASA grade?

1) Normally fit, healthy patient
2) Obese patient (BMI 30-40)
3) 70 year old patient, on ICU with non-survivable brain injury for insertion of an ICP monitor

A

1) 1
A healthy patient with no systemic disease

2) 2
Mild systemic disease, no substantive functional limitations

3) 5
Moribund patient not expected to survive with or without the operation

72
Q

What is the ASA grade?

1) Social alcohol drinker
2) Well controlled asthma or hypertension
3) BMI > 40

A

1) 2
Mild systemic disease, no substantive functional limitations

2) 2
Mild systemic disease, no substantive functional limitations

3) 3
Severe systemic disease with substantive functional limitations

73
Q

What is the ASA grade?

1) Moderately obese diabetic patient on insulin
2) Recent MI < 3 months
3) 20 year old patient with severe head injury from road traffic accident
4) End stage renal disease on hemodialysis

A

1) 3
Severe systemic disease with substantive functional limitations

2) 4
Severe systemic disease which is a constant threat to life

3) 4
Severe systemic disease which is a constant threat to life

4) 4
Severe systemic disease which is a constant threat to life

74
Q

What is the grade of surgery?

1) Emergency laparotomy
2) Ingrowing toenail
3) Knee arthroscopy
4) Fractured neck of femur fixation

A

1) Major
2) Minor
3) Intermediate
4) Major

75
Q

What types of operation constitute minor, intermediate and major surgery?

A

Minor:
Excision skin lesion, cystoscopy, drainage of an abscess

Intermediate:
Inguinal hernia, tonsillectomy

Major or Complex: Hysterectomy, thyroidectomy, joint replacement, thoracic operations, total hip replacement, radical neck dissection

76
Q

When is FBC required as part of a preoperative assessment?

A

Major/complex surgery

Over 80yo

Severe renal disease

77
Q

When is U&E required as part of preoperative assessment?

A

Major/complex surgery

Over 80yo

At risk of AKI

Known renal/CVS disease

78
Q

When is ECG required as part of preoperative assessment?

A

Major/complex surgery + over 65

Renal/CVS disease

79
Q

When might you need to carry out a preoperative sickle cell test?

A

Patients of Africa/Afro-Caribbean descent or if they have a positive family history

80
Q

Is a pregnancy test required as part of a preoperative assessment?

A

Only for women who may be pregnant

81
Q

When is it appropriate to carry out a CXR as part of the preoperative assessment?

A

Intensive care admission

Respiratory disease in ASA 3 or 4

82
Q

According to the NCEPOD classification of surgery, immediate or emergency surgery must be completed within _____?

A

minutes

Examples of immediate or emergency surgery include:

  • Repair of ruptured aortic aneurysm
  • Fasciotomy
  • Hemicolectomy for life-threatening GI bleed
83
Q

According to the NCEPOD classification of surgery, urgent surgery must be completed within _____?

A

hours

Examples of urgent surgery include:

  • Debridement plus fixation of fracture
  • Hemicolectomy for perforated large bowel
84
Q

According to the NCEPOD classification of surgery, expedited/scheduled surgery must be completed within _____?

A

days

Examples of expedited/scheduled surgery include:

  • Repair of tendon and nerve injuries
  • Excision of tumour with potential to bleed or constrict
  • Hemicolectomy for developing large bowel obstruction
85
Q

According to the NCEPOD classification of surgery, elective surgery must be completed within _____?

A

No time frame given: timing to suit patient, hospital and staff.

Examples include:

  • Elective AAA repair
  • Laparoscopic cholecystectomy
  • Hemicolectomy for non-obstructing carcinoma
86
Q

A twenty year old boy is scheduled for elective tonsillectomy. He had a slice of white toast with tea 4 hours ago. Is he fit for surgery?

A

No

His surgery is elective, and he needs to ideally fast from solid food for minimum of 6 hours prior to surgery. His tea four hours prior would be fine if it was black tea, as the fasting period for clear liquids is two hours. If it contained milk, then 6 hours.

87
Q

What is the recommended preoperative fasting period for solid food or milk-containing drinks?

A

6 hours. This should be adequate to completely empty the stomach.

88
Q

What is the recommended preoperative fasting time for breast-fed infants?

A

4 hours (human milk contains less fat)

89
Q

What is the recommended preoperative fasting period for clear fluids?

*water, black tea/coffee, juice with no pulp

A

2 hours

90
Q

If a patient needs to take oral medication within the two hour period before their surgery, what is the maximum amount of fluid they can use to wash the tablets down?

A

A minimal sip: i.e. <30mL allowed

91
Q

What is the recommended preoperative fasting period for alcohol?

A

24 hours

Alcohol delays gastric emptying, increasing the risk of aspiration.

92
Q

True or false: Non-ingested boiled sweets and chewing gum will mean surgery has to be postponed.

A

False.

While surgery may go ahead, they should be avoided. Non-ingested boiled sweets and chewing gum lead to increased gastric volume and acidity.

93
Q

Thirty year old man who had his tea at 6:00 pm yesterday and had 50 mL of water with medicines 30 minutes before surgery.

Fit or Unfit?

A

Unfit.

Should only take tablets with minimal water i.e. ~30mL

94
Q

Thirty year old man who had his dinner at 6:00 pm yesterday and is listed for the afternoon list. You get to see him in the morning at 7:00 am.

Fit or Unfit?

A

He is fit, but to avoid adverse effects from prolonged fasting he could have a light breakfast (as long as he can still fast for 6 hours) or consider IV fluids on the ward.

95
Q

Forty year old who had full meal an hour ago was involved in road traffic accident and has an open fracture of femur.

Fit or Unfit?

A

Fit

This is an emergency surgery that will require Rapid Sequence Induction.

96
Q

What is the indication for RSI?

A

Full stomach for any reason (i.e. high risk of aspiration)

97
Q

What is the aim of preoxygenation in rapid sequence induction?

A

Replace the nitrogen in the Functional Residual Volume (FRC) with oxygen, achieving an end-tidal O2 of >90%.

Done by using a tight-fitting face mask for three minutes or 5 full vital capacity breaths.

98
Q

What is the process of RSI?

A
  1. Preoxygenation
    - Tight-fitting mask for 3 mins or 5 full vital capacity breaths, EtO2 > 90.
  2. Give one induction agent and one muscle relaxant
    - Induction: Thiopentone (4-5 mg/kg) or propofol (1.5-2.5 mg/kg)
    - Muscle relaxant: Suxamethonium (1-1.5 mg/kg) or rocuronium (0.9-1 mg/kg)
  3. No Ventilation
  4. Cricoid pressure, place ET tube and confirm placement (EtCO2, direct visualisation, moisture in expired air, chest expansion, chest auscultation)
99
Q

60 year old man with chest pain for a month, 3-6 times a day.

Elective cholecystectomy

FBC, ECG and clotting screen was done 2 months ago

Is the patient fit or unfit and what is the ASA grade? What do you need to do?

A

Unfit.

ASA grade 3. Severe systemic disease with substantive functional limitations.

Surgery is intermediate if laparoscopic, major if open.

Need to take history and investigate chest pain.

FBC, U&E, ECG and ECHO will be useful.

This is elective surgery and delaying the surgery allows the necessary investigations to be carried out in order to optimise the patient.

ASA grade may change to 2 after investigations, treatment.

100
Q

What are three methods of assessing pain?

A

Verbal rating scale (mild-moderate, severe; rate 0-10)

Visual analogue scale (0-10 on a visual scale)

Faces pain scale

101
Q

The first relay in the nociceptive pathway is located in the ____?

A

dorsal horn

102
Q

The second relay in the nociceptive pathway is located in the ____?

A

thalamus

103
Q

How do local anaesthetics work?

A

Local anaesthetics transiently block the transmission of the nerve impulse by inhibiting sodium channels.

104
Q

What are the two chemical types of anaesthetics? How do they differ in structure?

A

Esters and amides

Both composed of a lipid-soluble hydrophobic aromatic ring + a charged, hydrophilic amide group. These two groups are joined by either an ester link (COO-) or an amide link (NH-).

105
Q

Both ester and amide local anaesthetics contain which two chemical groups?

A

1) Lipid-soluble hydrophobic aromatic ring

2) Charged hydrophilic amide group

106
Q

Which of the following is not an ester?

A) Amethocaine
B) Benzocaine
C) Bupivacaine
D) Cocaine

A

C) Bupivacaine

Bupivacaine is an amide.

The ester local anaesthetics include:

  • Benzocaine
  • Chloroprocaine
  • Cocaine
  • Procaine
  • Proparacaine
  • Tetracaine
107
Q

Which of the following is not an amide?

A) Levobupivacaine
B) Prilocaine
C)Ropivacaine
D)Tetracaine

A

D) Tetracaine

Tetracaine is an ester.

The amide local anaesthetics include:

  • Bupivacaine
  • Levobupivacaine
  • Lignocaine
  • Mepivacaine
  • Prilocaine
  • Ropivacaine

(-vacaines all seem to be amides)

108
Q

What is the maximum dosage of lignocaine?

A

3 mg/kg

109
Q

What is the maximum dosage of bupivacaine?

A

2 mg/kg

This is the same for levobupivacaine, too.

110
Q

What is the maximum dosage of prilocaine?

A

6 mg/kg

111
Q

Which local anaesthetic has a longer duration of action that other LA’s?

A

Bupivacaine and levobupivacaine have a longer duration of action. However, they also have a slower onset; taking up to 30 minutes for full effect.

The does for both of these is 2 mg/kg.

112
Q

You are in theatre anaesthetising a 60 kg woman for a laparotomy.

At wound closure, the surgeon asks you how much local anaesthetic he is able to give to safely infiltrate the wound to help reduce post-op pain.

You decide to use bupivacaine because is is the longest acting LA available to you.

Bupivacaine comes in 0.25% and 0.5% concentrations. How much bupivacaine is contained in 1 ml of each of these solutions?

A
  1. 25% solution = 2.5 mg/ml
  2. 5% solution = 5 mg/ml

Multiply % by 10 and you get the content of the local anaesthetic in mg/ml.

113
Q

You are in theatre anaesthetising a 60 kg woman for a laparotomy.

At wound closure, the surgeon asks you how much local anaesthetic he is able to give to safely infiltrate the wound to help reduce post-op pain.

You decide to use bupivacaine because is is the longest acting LA available to you.

What is the maximum safe dose for this patient?

A

120 mg total.

The maximum dose for bupivacaine (and levobupivacaine) is 2 mg/kg. As the patient is 60kg:

60 x 2 = 120 mg

114
Q

You are in theatre anaesthetising a 60 kg woman for a laparotomy.

At wound closure, the surgeon asks you how much local anaesthetic he is able to give to safely infiltrate the wound to help reduce post-op pain.

You decide to use bupivacaine because is is the longest acting LA available to you.

How much of 0.25% bupivacaine can be administered?

A

48 ml maximum

Max. dose = 2mg/kg
Patient weight is 60kg, therefore 60 x 2 = 120 mg max.

0.25% = 2.5 mg/ml
120/2.5 = 48 ml
115
Q

You are in theatre anaesthetising a 60 kg woman for a laparotomy.

At wound closure, the surgeon asks you how much local anaesthetic he is able to give to safely infiltrate the wound to help reduce post-op pain.

You decide to use bupivacaine because is is the longest acting LA available to you.

How much of 0.5% bupivacaine can be administered?

A

24 ml maximum

Max. dose = 2mg/kg
Patient weight is 60kg, therefore 60 x 2 = 120 mg max.

0.5% = 5 mg/ml
120/5 = 24 ml
116
Q

You are anaesthetising a 90 kg young man for a tendon repair of his left forearm following a work accident.

He is keen to avoid general anaesthetic so you decide to use 2% lignocaine (quicker acting, shorter duration than bupivacaine) to inject around his brachial plexus in the supraclavicular area.

You use 30 ml of the solution. Is this safe?

A

No

The max dose of lignocaine = 3 mg/kg.

This patient weighs 90kg, therefore max dose = 270 mg of lignocaine.

2% solution = 20 mg/ml.

270/20 = 13.5 ml maximum.

30 ml of 2% lignocaine solution would administer 600 mg of lignocaine - way above this patient’s maximum dose of 270 mg.

117
Q

What is the maximum dose per kg of lignocaine mixed with adrenaline?

A

7 mg/kg

3 mg/kg without adrenaline

118
Q

After administering 30ml of lignocaine the block works well. However, as the surgeon is about to start, the patient complains of a tingling sensation around his mouth and ringing in his ears. He says “I don’t feel well, doctor” before having a tonic-clonic seizure. What do you do?

A

This is likely local anaesthetic toxicity.

  • Stop the surgery.
  • Call for help and request crash trolley and intralipid.
  • Give 100% oxygen.
  • Start IV fluids.
  • ABC approach
119
Q

What is the role of Intralipid in local anaesthetic toxicity?

A

Intralipid reduces the concentration of free LA by absorbing it up from the blood.

120
Q

What are the three layers surrounding the spinal cord?

A

Dura mater

Arachnoid mater

Pia mater

121
Q

Where is CSF found?

A

Between the pia and arachnoid mater (i.e. subarachnoid space)

122
Q

Into which space would you inject a spinal block?

A

The subarachnoid space (into the CSF)

123
Q

Into which space would you inject an epidural injection?

A

The epidural space - the area outside the dura mater (between the dura mater and the vertebral canal)

124
Q

Where does the spinal cord end in adults?

A

Lower border of L1

125
Q

Where does the spinal subarachnoid space end in adults?

A

S1 level

126
Q

At which level can you administer a spinal block?

A

L4/L5, L3/L4 or L2/L3.

Spinal blocks are administered into the subarachnoid space, which continues down to S1 level. However, you want to avoid the spinal cord (ends at L1/L2) and L5 is usually fused to the sacral bone.

Always choose the lowest suitable level to minimise the risk of damage to the spinal cord.

127
Q

At which level does the epidural space end?

A

Sacrococcygeal hiatus

128
Q

At what level can an epidural block be administered?

A

Epidural block can be administered at any level, but there is a risk of damage to the cord if it is done above the level of L1.

Labour analgesia is done at the same level as a spinal block (lowest suitable out of L2/3, L3/4, L4/5).

However, for a laparotomy the block is done at the thoracic level.

129
Q

Through which structures does the needle pass when administering an epidural or spinal injection?

A

Both pass:

  • Skin
  • Subcutaneous fat
  • Supraspinous ligament
  • Interspinous ligament
  • Ligamentum flavum

Spinal block also passes these structures to reach the subarachnoid space:

  • Dura mater
  • Arachnoid mater
130
Q

Which of the following is not a component of general anaesthesia?

A) Akinesia
B) Amnesia
C) Analgesia
D) Autonomic hyperreflexia
E) Unconsciousness
A

D) Autonomic hyperreflexia

131
Q

Which of the following induction agents causes dissociative anaesthesia?

A) Etomidate
B) Ketamine
C) Propofol
D) Sevoflurane
E) Thiopentone
A

B) Ketamine

132
Q

What is the recommended fasting time for breastfeeding?

A) 1 hour
B) 2 hours
C) 4 hours
D) 6 hours
E) 8 hours
A

C) 4 hours

133
Q

A 34-year-old woman (ASA grade 1) is undergoing a dental extraction under local anaesthesia. Within a few minutes of administration she starts to complain of palpitations, tremor and becomes panicky. On examination her blood pressure is 190/110 and her heart rate is 120 / minute. What is the most likely cause of these symptoms?

A) Adrenaline
B) Hypertensive crisis
C) Inadequate block
D) Lidocaine toxicity
E) Vasovagal reaction
A

A) Adrenaline

134
Q

Which of the following muscle relaxant is recommended for use in rapid sequence induction?

A) Adrenaline
B) Atracurium
C) Mivacurium
D) Succinylcholine
E) Vecuronium
A

D) Succinylcholine

Also known as suxamethonium

135
Q

A patient needs to take his regular medications on the morning of surgery. How much water is permitted to take tablets?

A) None - wait until after sugery
B) 20 ml
C) 30 ml
D) 40 ml
E) 50 ml
A

C) 30 ml

136
Q

A 78 year old male has been admitted to ED with a bleeding AAA. His observations are:

BP 70/40; HR 140; Hb 75.

What will you do?

A) Give 4 units of O-neg and then take to theatre
B) Resuscitate with blood, stabilise and then take to theatre
C) Stabilise with fluids and blood, wait six hours and take him to theatre if he survives.
D) Take sample, inform blood bank, activate AAA protocol, call cell saver team, get help, no delay to theatre.
E) Take to theatre straight away

A

D) Take sample, inform blood bank, activate AAA protocol, call cell saver team, get help, no delay to theatre.

137
Q

NCEPOD classification of a AAA repair is:

A) Elective
B) Emergency
C) Expedited
D) Urgent
E) Any of the above - dependent on circumstances
A

E) Any of the above - dependent on circumstances

138
Q

Which of the following is not a muscle relaxant?

A) Atracurium
B) Curare
C) Dobutamine
D) Mivacurium
E) Succinylcholine
A

C) Dobutamine

139
Q

Which of the following investigations is least indicated in an 81 year old patient with fractured neck of femur?

A) Chest XR
B) Clotting screen
C) ECG
D) FBC
E) U&Es
A

A) Chest XR

140
Q

Which of the following is true regarding epidural block?

A) Dripping of CSF indicates correct position of needle
B) Epidural space ends are the sacrococcygeal hiatus
C) Epidural space is deeper than spinal subarachnoid space
D) The space comes after two pops or giveways
E) Works quicker than a spinal block

A

B) Epidural space ends are the sacrococcygeal hiatus

141
Q

Which of the following is NOT an antiemetic?

A) Cyclizine
B) Dexamethasone
C) Ondansetron
D) Prochlorperazine
E) Tramadol
A

E) Tramadol

142
Q

Which of the following is not used routinely to treat pain?

A) Co-codamol
B) Gabapentin
C) Oxycodone
D) Parecoxib
E) Tramadol
A

B) Gabapentin

143
Q

Which of the following is NOT true of PCA with morphine?

A) Can be safely self-administered by patients
B) It provides better pain relief that intermittent morphine injections
C) Lock out interval is 5 minutes
D) Regular dihydrocodeine is safe to use alongside
E) Usually 1mg bolus is administered

A

D) Regular dihydrocodeine is safe to use alongside

144
Q

Which of the following is NOT correct with respect to safe doses of local anaesthesia?

A) Bupivacaine 2 mg/kg
B) Levobupivacaine 4 mg/kg 
C) Lignocaine 3 mg/kg
D) Prilocaine 6 mg/kg
E) All are correct
A

B) Levobupivacaine 4 mg/kg

The correct dose is 2 mg/kg (same a bupivacaine)

145
Q

Which of the following has no role in management of acute local anaesthetic toxicity?

A) ABC assessment and maintenance
B) Adrenaline for cardiac arrest
C) Intralipid
D) Phenytoin
E) Propofol in small doses
A

D) Phenytoin

Seizures can be controlled with a benzodiazepine, thiopental or propofol in small
incremental doses.

Y4 Acute and Critical Care (27 decks)

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