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Intravenous Induction Agents Flashcards

1
Q

Name 4 rapidly acting true Induction agents.

A

Etomidate
Propofol
Ketamine
Thiopental

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2
Q

Name two neuroleptic that can be used as IV induction agents

A

Haloperidol plus opioids
Droperidol plus opioids

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3
Q

Are benzodiazepines true induction agents?

A

Nope they are sedators

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4
Q

State twoe benzodiazepines that can be used for sedation in Anaesthesia.

A

Midozolam
Diazepam

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5
Q

Name five opioids that can be used as induction agents.

A

Morphine
Fentanyl
Remifentanil
Alfentanil
Sufentanil

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6
Q

What is the one arm brain circulation time of rapidly acting IV induction agents?

A

Approx 30 seconds

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7
Q

State 4 advantages of intravenous induction

A
  1. Rapid onset of action
  2. Smooth induction with rapid transfer through stage II (stage of excitement)
  3. More pleasant for the patient
  4. Pollution free
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8
Q

State four disadvantages of intravenous induction

A
  1. Venepuncture required
  2. Overdose easy
  3. No removal of drug via the lungs (as with inhalational agents). Once it’s in, it’s in; there is
    no going back (cf. the inhalational agents that can be switched off to reverse the effect).
  4. Sudden loss of normal protective mechanisms and often apnoea
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9
Q

State how recovery is achieved after administration of intravenous induction.

A

Recovery requires redistribution, metabolism and excretion

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10
Q

Which receptor does Ketamine target?

A

N methyl D aspartate receptor

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11
Q

Name a receptor target by most anaesthetic induction drugs.

A

GABA a

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12
Q

State how termination of the action of the IV induction agents is achieved

A

Redistribution of drug from the brain to less well-perfused tissues

Note: Drug is mobilised from the tissues where it is initially deposited because of their rich blood supply, to tissues of poorer blood supply

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13
Q

Is Rapid awakening due to metabolism or excretion of the drug

A

Nope rather REDISTRIBUTION

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14
Q

State three things that a patient should avoid for at least 24 hours after recovering from intravenous general anaesthesia

A

sedatives, analgesics and alcohol.

Note: Even any legally binding decisions

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15
Q

The importance of metabolism and excretion terminating the drug effect
increases with high plasma concentrations due to multiple doses or continuous IV infusion.

A

Didn’t know how to card YOU

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16
Q

Name an agent commonly used for total intravenous anaesthesia

A

Propofol

Note: Ketamine is for occasional usage

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17
Q
A
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18
Q

Explain what total intravenous Anaesthesia is

A

refers to an anaesthetic technique in which no inhalational agents are used during induction or maintenance of general anaesthesia

Note: The patient would still require a mixture of air / nitrous oxide and oxygen to be delivered via the breathing circuit of the anaesthetic machine.

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19
Q

State the best way to reliably administer the intravenous agent at a steady, set rate and avoid either over-dosage or awareness
under anaesthesia

A

Syringe pump is the WAY TO GO

Note: Continuous monitoring of the syringe pump
and the dedicated intravenous line to which it is attached is vital to prevent unwanted patient
awakening and awareness.

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20
Q

Name two ways of delivering TIVA.

A

Syringe pump
Alternative
Target Controlled Infusion”

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21
Q
A
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22
Q

What is TCI?

A

a microprocessor-controlled syringe pump automatically and variably controls the rate of infusion of a drug to attain the anaesthetist-defined target level (μg ml-1 or рg ml-1) in the plasma or an “effect site”, i.e. where the drug takes effect, which is the patient’s CNS.

Note: age, gender, weight and height of the patient are required

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23
Q

Who described two methods of giving propofol TIVA via TCI.

A

Marsh and Schnider

Stupid card 😤

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24
Q

State an advantage of target controlled infusion

A

This technique greatly simplifies maintenance of a steady blood or brain level, in spite of the fact
that it can only provide an estimate of the actual drug concentration.

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25
What is the most commonly used intravenous agent?
Propofol Why: CHEAP is the WAY TO GO
26
Outline the current preparation of propofol.
Current preparation 1 % w / v (10 mg ml-1) aqueous emulsion containing 10 % soybean or, 1,2 % egg phosphatide and 2,25 % glycerol (essentially Intralipid Note: Newer preparations may substitute soy for coconut oil.
27
Is propofol water soluble?
Nope
28
How many hours can propofol be used after preparation?
within 6 hours of opening.
29
What are the commonly used ampoules of propofol?
Ampoule sizes: 20 ml, 50 ml, 100 ml (each containing 10 mg ml-1 of propofol) Note: It is also available as a 2 % solution (20 mg ml-1) for infusions
30
What is the commonest side effects of propofol during injection?
Pain occurs in 30-40% of patients receiving it.
31
Do patients with egg allergy usually react to propofol?
Nope
32
Three uses of propofol
1. Induction of anaesthesia 2. Maintenance of anaesthesia 3. Sedation – ICU sedation, regional anaesthesia, cardioversion
33
List three instances where propofol can be used a sedative.
ICU sedation, regional anaesthesia, cardioversion
34
State properties result in a rapid decrease in propofol concentration following continuous infusions, regardless of infusion duration
Propofol's clearance exceeds hepatic blood flow; it is also highly fat-soluble and sequesters in fat following long infusions Note: The nett effect is that propofol can be infused for long periods of time, while still resulting in rapid emergence on termination of the infusion.
35
State the induction doses for propofol.
Adults: 1.5-2.5 mg/kg Elderly: 1-1.5 mg/kg Young children: 2.5-3 mg/kg
36
State the dose of propofol used for TIVA.
6-12 mg/kg/hour
37
When should propofol doses be reduced when offering maintenance of anaesthesia?
Reduce in combination with N20 and/or opioids
38
What are the plasma concentration of propofol when using TCI?
Induction 4–8 μg/ml and maintenance 3–6 μg/ml
39
What is the dose of propofol used for sedation?
1,5 –3 mg/kg/hr and Cp 0,1–2,5/μg/ml.
40
What is an indication of the rapidity of onset of an intravenous agent’s effects
Time to peak effect
41
What is the time to peak effect of propofol
In children the TTPE ~ 2.5 min with adults ~ 3 min and longer in the elderly
42
Why is loss of consciousness usually seen before time to peak effect in healthy individuals?
regular induction doses in healthy patients often overshoot that required for loss of consciousness and result in profound suppression of CNS activity Note: Patients with poor physiological reserve should receive carefully titrated induction doses and it is recommended to wait for the TTPE before administering additional drug.
43
How long does a patient take to recover from propofol effects
4-6 minutes
44
List 4 CNS effects of propofol
Sedation and drowsiness at low doses Impairment of psychomotor function is minimal with complete recovery in about 3 hours Hangover effect Excitatory phenomena
45
State two common adverse effects of propofol
Hypotension and apnoea
46
State why laryngospasm is less when propofol is used.
It depressed laryngeal reflexes this is the reason why OPA are also well tolerated in light anaesthesia
47
Does propofol lead to release of histamine?
Nope
48
Name a very useful GIT effect of propofol.
Anti emetic
49
List 4 clinical, features of propofol infusion syndrome
lipaemia, metabolic acidosis, cardiomyopathy and cardiac failure, skeletal myopathy and death Note: Doses exceeding 5 mg kg-1 hr-1 for > 48 hours are implicated in this. Children appear to be at a greater risk
50
State how the burning when infusing propofol is avoided.
Adding lignocaine (2 %) 1 - 2 ml; using a new IV line, and larger size cannula Now there is a New formulation (Lipuro ) reduces burning
51
State a good method of injecting lignocaine for prevention of burning when giving propofol
Mini Biers block: Apply a venous tourniquet above the IV cannula and inject 1 –2 ml of lignocaine while maintaining the venous tourniquet for about 1 – 2 min, prior to propofol administration
52
Is propofol anti itching?
Yep
53
State an advantage and disadvantage of the synergetic relationship between propofol and opioids
Advantage: Reduction in propofol required to achieve a specific pharmacodynamic endpoint (such as immobility during surgery) Disadvantage: increases side effects especially in elderly patients.
54
What is the induction agents of choice in porphyria
Propofol
55
What is the best induction agent for asthmatics?
Propofol
56
State three absolute contraindications of propofol
heart failure, hypovolaemia, fixed cardiac output Used with caution in the elderly
57
State two absolute contraindications of sodium thiopental
Porphyria and allergy( occurs in 1 in 20000)
58
State two relative contraindications of thiopental
Asthma and cardiovascular systems disorders
59
State the doses of sodium thiopental for induction.
Adults: 3-5 mg/kg Children: 5-6 mg/kg
60
Why is sodium thiopental not used for maintenance of anaesthesia?
long elimination half-life with accumulation
61
What is the time to peak effect of thiopental
2 minutes
62
When was thiopentone introduced?
1934
63
What is the storage form of thiopentone?
Yellow amorphous powder Usually dissolved in water for usage
64
State why thiopentone should not be mixed with glucose solutions.
When mixed with water is extremely alkaline with a pH of 10,5 so when mixed with glucose containing solutions which typically have a low pH, precipitation of free barbiturate occurs Note: It also precipitates when mixed with muscle relaxants; they have a higher pH as they are weak bases.
65
What is the preferred strength of thiopental.
2,5 % (mix 500 mg amp with 20 ml = 25 mg ml-1) Note: Do not use a higher concentration due to local irritant effects. Solution is stable for 24 - 48 hours.
66
State four common adverse effects of thuopentone
Hypotension Potent respiratory depressor: patient will often take a few deep breaths followed by a transient period of apnoea. Cause histamine release and active respiratory reflexes Irritation locally Increases sensitivity to pain in small doses Anticonvulsant and CNS protective
67
What is the time it takes to recover from thiopental infusion?
5-10 minutes
68
State why propofol is contraindicated in asthma.
Causes Histamine release and active respiratory reflexes
69
List CVS contraindications of thiopental.
heart failure, hypovolaemia, fixed cardiac output (stenotic valve lesions, cardiac tamponade, and constrictive pericarditis).
70
State why early instrumental may trigger laryngospasm when using thiopental
Laryngeal reflexes are not depressed until deeply anaesthetised
71
What is the commonest local effect of thiopental.
Venous thrombosis: When using 5% solutions Note: With extra-vascular injection, sequelae vary from slight pain to extensive tissue sloughing and necrosis.
72
What is a serious complication of thiopental
Intra arterial injection Why: The pH of blood (7,4) causes precipitation of solid crystals of thiopentone blocking arterioles and capillaries of narrow diameters
73
State early signs of intra arterial injection of thiopental
White hand with cyanosed fingers, skin discoloration, and slow onset of anaesthesia.
74
State late signs of intra arterial injection of thiopental
Ulcers, blisters, oedema of the arm, and gangrene
75
State the treatment of intra arterial injection of thiopental
3. Treat spasm – Leave the cannula in the artery and inject one of the following: a) Papaverine 40 - 80 mg in 10 - 20 ml saline b) Procaine 10 - 20 ml of 0,5 % solution (not available in South Africa) or c) Phenoxybenzamine 0,5 mg (not available in South Africa) 4.Brachial plexus or stellate ganglion block: Sympathetic block for vasodilatation 5.Treat thrombosis with anticoagulation (heparin bolus of 5 000 IU) 6. Analgesia
76
8 indications of ketamine
• Paediatric surgery • Debridement, painful dressings and skin-grafts in patients suffering from burns • Short procedures – Diagnostic or surgical • Analgesia • Anaesthesia in sub-optimal conditions, e.g. trauma, "field work" • Has been used for the treatment of status asthmaticus • Used in psychiatry in low dose infusions as an alternative to electroconvulsive therapy for resistant depression • High risk surgical patients
77
List 6 contraindications of ketamine
• CVS disorders – Hypertension, ischaemic heart disease, aortic aneurysms, severe heart failure • No longer considered contraindicated with raised intracranial or intraocular pressure • Epileptics • Thyrotoxicosis • Does not protect the patient from regurgitation or aspiration. An ET tube is mandatory if the patient is at risk of aspiration. Relatively intact reflexes can lead to cough or laryngospasm, so that ketamine is unsuitable for oral cavity or airway surgery • Early pregnancy • Patients on tricyclic antidepressants – The drug interaction causes hypertension and cardiac dysrhythmias
78
Describe the physical properties of ketamine.
Non irritant Stable in solution for long shelf time It is acidic thus suitable for IV, IM and oral Administration Note: Available as a 1 % (10 mg ml-1) and 10 % (100 mg ml-1) solution.
79
How much of ketamine remains after the anaesthesia is terminated?
50-60% in an active form
80
What is the main metabolite of ketamine
Norketamine Note: Causes protracted emergence
81
What is the onset of action and duration of action of ketamine depending on dose: a. 1-2 mg/kg IV b. 5-10 mg/kg IM
IV: Onset=30-50 seconds and duration=5-15 minutes IM: Onset=3-8 minutes and duration=10-30 minutes
82
What is the maintenance dose of Ketamine
0,5 mg kg-1 IV as incremental boluses or 1 - 4 mg kg-1 hr-1 by infusion
83
What is the dose of Ketamine when used as an analgesia
0,2 - 0,4 mg kg-1 IV or 2 - 4 mg kg-1 IM, followed by infusion of 0,2 - 0,3 mg kg-1 hr-1
84
Why is ketamine unique?
Causes complete amnesia and analgesia It is a potent bronchodilator
85
Does Ketamine increase intracranial and intraocular pressure?
Nope
86
What is special K?
Fun Ketamine for joy( I mean abuse)
87
List CVS effects of ketamine
rise in blood pressure, pulse rate, peripheral resistance and cardiac output. Dyrrhythmia uncommon
88
Why should Ketamine be avoided in severe shock?
it is a direct myocardial depressant that may be unmasked if the catecholamine stores are depleted
89
Name an induction agent which is a potent analgesia.
Ketamine Note: It also exerts its analgesic activity at 25% of the dose required for surgical anaesthesia.
90
Name an induction agent that have an induction onset>one arm brain circulation.
Ketamine up to 90 seconds for onset
91
List instances where the incidence of psychic reaction of ketamine is less during the recovery peiod
lower in children, elderly, males, long procedures, repeated administration
92
When are the psychic side effects of ketamine common during the recovery period? State the antidote
Higher incidence if patient is stimulated during awakening Antidote: place patients in a quiet darkened area to recover peacefully.
93
Name an induction agent which is a 2nd line treatment of status asthmaticus
Ketamine: Potent bronchodilator
94
Name two agents given to patients taking Ketamine to reduce its salivation effect.
Glycopyrrolate or atropine
95
96
Name the commonest side effects of ketamine post-op.
Nausea and vomitjng
97
Does Ketamine increase uterine contractions?
Yes during the first trimester
98
Where is ketamine commonly used?
In veterinary practice
99

Anaesthesia 2.0 (9 decks)

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