BAC - Chapter 5: Anaesthetic Drugs Flashcards

1
Q

Advantages of IV induction agents:

A
  1. Rapid onset
  2. Smooth induction
  3. More pleasant for patient
  4. Less theatre pollution
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2
Q

Disadvantages of IV induction agents:

A
  1. Venipuncture needed
  2. Easily overloaded
  3. No elimination by lungs - needs metabolism and excretion
  4. Sudden loss of normal protective mechanisms & apnoea
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3
Q

Sodium Thiopentone - indications:

A
  1. Induction
  2. Maintenance
  3. Rx of status epilepticus
  4. Reduce ICP
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4
Q

Sodium Thiopentone - CIs:

A
  1. Allergy
  2. Porphyria
  3. CVS disorders - CCF, fixed CO, hypovolaemia
  4. Asthma - relative
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5
Q

Special precaution in Sodium Thiopentone:

A
  1. Intra-arterial injection
  2. Causes arterial spasm & thrombosis
  3. Prevention: don’t used veins next to arteries/ use 2.5% solution
  4. Rx: Inject papaverine 80 mg in 20 ml N/S.
  5. Anticoagulation
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6
Q

Propofol - precautions:

A
  1. Good culture medium
  2. CVS depression so beware in:
    Hypovolemia
    HPT
    Fixed CO
    Elderly
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7
Q

Propofol - Indications:

A
  1. Favoured IV induction agent - rapid return of consciousness
  2. Most suitable for TIVA - minimal accumulation
  3. Sedation for regional anaesthesia
  4. Sedation in ICU
  5. Agent for porphyria
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8
Q

PRIS - risky dose?

A
  1. > 5mg/kg/hr for > 48 hrs
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9
Q

PRIS - features:

A
  1. Lipaemia
  2. Metabolic acidosis
  3. Cardiomyopathy
  4. Cardiac failure
  5. Skeletal myopathy
  6. Death
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10
Q

Etomidate - Indications:

A
  1. Induction with CVS compromise
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11
Q

Etomidate - precautions:

A
  1. Suppress cortisol synthesis

2. Long infusion - Reduce immunological competence

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12
Q

Ketamine - features of induction:

A
  1. Dissociative anaesthesia:
    Catatonia
    Amnesia
    Analgesia
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13
Q

Ketamine - precautions:

A
  1. Distressing emergence phenomena
  2. Increased secretions - pre-med with anticholinergic
  3. Avoid in IHD/ HPT
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14
Q

Ketamine - Indications:

A
  1. Shocked pts
  2. Severe asthmatics - potent bronchodilator
  3. Paeds
  4. Difficult locations - accident scene
  5. Short procedures
  6. Analgesia + sedation - wound dressings
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15
Q

Ketamine - CIs:

A
  1. CVS disorders - HPT, IHD, AA
  2. Raised ICP
  3. Open eye injuries - raised IOP
  4. Psych pts.
  5. Pts. on TAD
  6. Thyrotoxicosis
  7. Early pregnancy
  8. Epileptics
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16
Q

Thiopentone - dose:

A
  1. Induction: 3-5 mg/kg

2. Infusion: 4mg/kg/hr

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17
Q

Thiopentone - preparation:

A

500 mg amp in 20 ml = 25mg/ml

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18
Q

Thiopentone - CVS affects:

A
  1. Decreases myocardial contractility
  2. Decreases CO by 10-20% d/t peripheral vasodilation
  3. Reflex tachycardia
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19
Q

Thiopentone - Resp affects:

A
  1. Central depression
  2. Potent apnoea
  3. A/W reflexes not abolished - risk of L/G or bronchospasm
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20
Q

Thiopentone - CNS affects:

A
  1. Decreased ICP
  2. Anticonvulsant
  3. Cerebral protection in focal ischemia
  4. Commonly used in neuroanaesthesia
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21
Q

Propofol - dose:

A
  1. Induction: 2-3 mg/kg

2. Infusion: 6-8 mg/kg/hr

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22
Q

Propofol - how to reduce pain when giving IV:

A
  1. Mixing with 10 mg lignocaine in syringe
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23
Q

Propofol - effect on emesis:

A
  1. Thought to be anti-emetic
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24
Q

Propofol - CVS affects:

A
  1. Up to 40% decrease in BP d/t:
    Myocardial depression
    Decreased PVR
  2. Tachycardia
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25
Q

Propofol - Resp affects:

A
  1. Apnoea common with induction
  2. Decreased TV w/ infusion
  3. Increased RR w/ infusion
  4. Laryngeal reflexes suppressed - reduced risk of laryngospasm
  5. Drug of choice for LMA
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26
Q

Propofol - CNS affects:

A
  1. Anticonvulsant

2. Reduces ICP

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27
Q

Etomidate - dose:

A
  1. Induction: 0.2 - 0.3 mg/kg

2. Maintenance: 10-20 ug/kg/min (generally not used for infusion d/t adrenal suppression)

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28
Q

Etomidate - effect on emesis:

A
  1. 30% increased risk - “vomidate”
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29
Q

Etomidate - CVS affects:

A
  1. Minimal CVS depression
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30
Q

Etomidate - Resp affects:

A
  1. Ventilation affected less
  2. No apnoea with induction
  3. No histamine release
  4. Good for asthmatics
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31
Q

Etomidate - CNS affects:

A
  1. Reduces ICP
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32
Q

Ketamine - dose:

A
  1. Induction: 2 mg/kg IVI
  2. Infusion: 4-6 mg/kg/hr
  3. Analgesia: 0.5 mg/kg
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33
Q

Ketamine - analgesic affect:

A
  1. Intense visceral & somatic analgesia
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34
Q

Ketamine - emergence phenomena:

A
  1. Delirium
  2. Agitation
  3. Nightmares
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35
Q

Ketamine - CVS effects:

A
  1. Increases arterial BP by 25%
  2. Increases HR by 20%
  3. Increases myocardial O2 consumption
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36
Q

Ketamine - Resp effects:

A
  1. Upper A/W reflexes remain largely intact
  2. No histamine release
  3. Potent Bronchodilator
  4. Increases secretions
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37
Q

Ketamine - CNS effects:

A
  1. Increases ICP

2. Dissociative amnesia

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38
Q

Midazolam - dose:

A
  1. Induction: 0.2 mg/kg
  2. Sedation: 2.5 - 7.5 mg
  3. Pre-med: 5mg IMI
  4. ICU:
  5. 1 Initial bolus of 5mg/kg
  6. 2 Then infusion of 1-20 mg/hr titrated to response
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39
Q

Midazolam - affect on emesis:

A
  1. Incidence of PONV
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40
Q

Midazolam - CVS affects:

A
  1. Slight decrease in BP

2. Slight increase in PR

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41
Q

Midazolam - Resp affects:

A
  1. Risk of resp depression/ apnoea
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42
Q

Ways to create faster gas induction:

A
  1. Increase concentration of gas
  2. Increase flow rate
  3. Use non-rebreathing circuit
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43
Q

Ways to increase elimination of volatile:

A
  1. Increase minute ventilation

2. Give high inspiratory O2 concentration

44
Q

MAC - definition:

A
  1. The alveolar concentration of a volatile
  2. That prevents movement
  3. In 50% of patients
  4. In response to a surgical stimulus
45
Q

N20 - MAC/ colour/ BG co-eff:

A

MAC: 105%

Colour: Blue

BG co-eff: 0.47

46
Q

Halothane - MAC/ colour/ BG co-eff:

A

MAC: 0.75%

Colour: Red

BG co-eff: 2.4

47
Q

Enflurane - MAC/ colour/ BG co-eff:

A

MAC: 1.7%

Colour: Orange

BG co-eff: 1.9

48
Q

Isoflurane - MAC/ colour/ BG co-eff:

A

MAC: 1.15%

Colour: Purple

BG co-eff: 1.4

49
Q

Desflurane - MAC/ colour/ BG co-eff:

A

MAC: 6%

Colour: Blue

BG co-eff: 0.42

50
Q

Sevoflurane - MAC/ colour/ BG co-eff:

A

MAC: 2%

Colour: Yellow

BG co-eff: 0.65

51
Q

Nitrous - CVS affects:

A
  1. Stable
52
Q

Nitrous - Resp affects:

A
  1. Impairment of hypoxic drive
53
Q

Nitrous - CNS affects:

A
  1. Increases ICP
54
Q

Nitrous - Renal affects:

A
  1. Decreases RBF
55
Q

Nitrous - CIs:

A
  1. Diffuses rapidly into body cavities

2. CI in: pneumocephalus, pneumothoracies, air emboli

56
Q

Halothane - CVS affects:

A
  1. Myocardial depression
57
Q

Halothane - Resp affects:

A
  1. Resp depression
  2. Decreases hypoxic drive
  3. Increases apnoeic threshold
  4. Potent bronchodilator
58
Q

Halothane - CNS affects:

A
  1. Increases ICP
59
Q

Isoflurane - CVS affects:

A
  1. Decreases BP & SVR
  2. Minimal cardiac depression
  3. Not sensitise heart to catecholamines
  4. Coronary artery dilation - coronary steal syndrome
60
Q

Isoflurane - Resp affects:

A
  1. Good bronchodilator
61
Q

Isoflurane - CNS affects:

A
  1. Good for neuroanaesthesia
62
Q

What makes sevoflurane a smooth and rapid inhalational induction agent?

A
  1. Decreased solubility

2. Increased potency

63
Q

Sevoflurane - Renal affects:

A
  1. Potential for nephrotoxicity
64
Q

Desflurane - Resp affects:

A
  1. Increased salivation

2. Laryngospasm

65
Q

What changes to make when increasing or decreasing volatile concentration?

A
  1. Increase fresh gas flow rate to make change occur more rapidly
  2. Then turn down to low flow anaesthesia later
66
Q

Which volatiles are implicated in MH?

A
  1. All except N2O
67
Q

Indications for mm. relaxation:

A
  1. Facilitation of intubation
  2. Improvement of surgical access
  3. Prevent movement in delicate surgery
  4. Manipulation of #s
  5. Used in ECT & ICU
68
Q

Types of mm. relaxants agents?

A
  1. Depolarising agents

2. Non-depolarising agents

69
Q

Example of depolarising mm. relaxant?

A
  1. Only suxamethonium
70
Q

MOA of Sux:

A
  1. Act as ACh-receptor agonist
  2. Generates mm. action potential
  3. Causes fasciculation
  4. Then paralysis
  5. Metabolised by pseudo-cholinesterase
  6. Motor end plate remains depolarised
  7. No further action potential can take place
71
Q

Sux - dose:

A
  1. 1 - 1.5 mg/kg
72
Q

Sux - onset of action:

A
  1. 30 sec
73
Q

Sux - duration of action:

A
  1. < 10 min
74
Q

Sux - indication:

A
  1. RSI

2. Short acting mm. relaxation

75
Q

Sux - S/E:

A
  1. Bradycardia
  2. HyperK - increases K by 0.5
  3. Anaphylaxis
  4. MH
  5. Scoline apnoea
  6. Massester spasm
  7. Mm. pain
76
Q

MOA of NDMR:

A
  1. Bind to ACh-receptor
  2. Doesn’t generate action potential
  3. Blocks ACh from binding
  4. Competitive antagonist
77
Q

Types of NDMR:

A
  1. Benzylisoquinolones: Atracurium, Cisatracurium

2. Aminosteroids: Vecuronium, Rocuronium

78
Q

Atracurium - dose/ side effects:

A
  1. Dose: 0.5 mg/kg

2. S/E: Hypotension, tachycardia, bronchospasm

79
Q

Cisatracurium - dose:

A
  1. Dose: 0.15 mg/kg
80
Q

Rocuronium - dose:

A
  1. 0.6 - 1.2 mg/kg
81
Q

Rocuronium - onset:

A
  1. 45 sec - 3 min
82
Q

Rocuronium - duration:

A
  1. 30 - 40 min
83
Q

Drug + dose to reverse NDMR:

A
  1. Neostigmine

2. Dose: 0.04 mg/kg

84
Q

MOA of neostigmine:

A
  1. Inhibits ACh-esterase
  2. Increases concentration of ACh in NMJ
  3. Displaces NDMR off nicotinic ACh-receptor
85
Q

S/E of reversal with neostigmine:

A
  1. Bradycardia
  2. Bronchospasm
  3. Secretions
86
Q

How to Rx S/E of reversal with neostigmine:

A
  1. Glycopyrrolate - 0.01 mg/kg

2. Atropine - 0.02 mg/kg

87
Q

Site of measurement of nerve stimulator?

A
  1. Adductor pollicis
88
Q

TOF pattern with DMR:

A
  1. Constant decrease in twitch height
89
Q

TOF pattern with NDMR:

A
  1. Results in fade - each twitch is smaller than the preceding twitch
90
Q

What is the TOF ratio?

A
  1. Compares the ratio between the first twitch (T1) & fourth twitch (T4)
91
Q

When to give neostigmine for reversal?

A
  1. When there are 3 or more twitches on the TOF count
92
Q

What is regarded as adequate reversal?

A
  1. TOF ratio > 0.9
93
Q

Def - local anaesthetic drug:

A
  1. Drug which causes reversible interruption of conduction

2. In autonomic, motor and sensory nerves

94
Q

MOA of LA:

A
  1. Inhibit Na-influx
  2. By blocking Na channels
  3. Block generation & propagation of electrical impulses
95
Q

Types of LA drugs:

A
  1. Esters - procaine, cocaine

2. Amides - lignocaine, bupivacaine

96
Q

Lignocaine - dose:

A
  1. 3 mg/kg without ADR

2. 7 mg/kg with ADR

97
Q

Lignocaine - duration:

A
  1. Around 1 hr
98
Q

Bupivacaine - dose:

A
  1. 2 mg/kg regardless of ADR
99
Q

Bupivacaine - duration:

A
  1. 4-6 hrs
100
Q

LA toxicity - how does presentation differ between lignocaine vs bupivacaine in terms of toxicity?

A
  1. Lignocaine: CNS Sx first, CVS collapse second

2. Bupivacaine: CVS collapse first, CNS Sx second

101
Q

CNS Sx in LA toxicity:

A
  1. Dizziness
  2. Perioral paresthesia
  3. Slurred speech
  4. Tinnitus
  5. Metallic taste
  6. Seizures
102
Q

CVS Sx in LA toxicity:

A
  1. Tachycardia
  2. HPT
  3. Decreased CO
  4. Sinus bradycardia/arrhythmias
103
Q

Prevention of LA toxicity:

A
  1. IV access before giving local
  2. Choose least toxic drug
  3. Consider max dose for patient
  4. Aspiration before administration
  5. Observe pt
  6. Stop injection immediately when noticing Sx
104
Q

Mx of LAST:

A
  1. Stop injection of LA
  2. Call for Help
  3. ABCD
  4. Maintain airway - head tilt, chin lift
  5. 100% O2
  6. Ventilate if needed
  7. IVF
  8. Vasopressors - ephedrine, phenylephrine, ADR
  9. Correct electrolytes
  10. Convulsions - Rx w/ BZDs, no effect - thiopentone
  11. Arrhythmias - amiodarone, Intralipid 20%
105
Q

Intralipid administration dosage:

A
  1. 100 ml stat
  2. Run rest of bag over 15 mins
  3. 2 more 100 ml boluses if needed