Aims of Anaesthesia

Question 1

What is the triad for anaesthesia

Answer 1

Anaesthesia (unconsciousness)
Analgaesia
Akinesia

Question 2

What is meant by analgaesia in the unconscious patient

Answer 2

Noxious stimuli can still evoke physiological responses in the anaesthetized patient. Drugs that reduce these physiological responses are considered to be providing analgaesia

Question 3

Compare the effects of volatile agents with IV induction agents with regard to the triad of anaesthesia

Answer 3

Anaesthesia (unconsciousness): BOTH

Akinesia: Volatiles only (inhibition spinal reflexes)

Analgaesia: Volatiles only and ketamine

Question 4

What are the effects of benzodiazepines on the anaesthetic triad

Answer 4

Anaesthesia: contribute (amnesia)
Akinesia: contribute
Analgesia: none

Question 5

What are the effects of muscle relaxants on the anaesthetic triad

Answer 5

Anaesthesia: none
Akinesia: Pronounced
Analgesia: none

Question 6

What is the clinically relevant effect of simple analgaesics (paracetamol and NSAIDs)

Answer 6

Reduction of postoperative opiate requirements

Question 7

What are the effects of opiates on the anaesthetic triad

Answer 7

Anaesthesia: MAC sparing - reduce requirements for anaesthetic agents

Akinesia: No muscle relaxation but by blunting perception of pain reduce movement to pain during surgery

Analgaesia: Central role during and after surgery

Question 8

What are the effects of regional anaesthesia on the anaesthetic triad

Answer 8

Anaesthesia: NA

Akinesia: muscle relaxation in the distribution of the block

Analgaesia: within the distribution of the block

Question 9

What is balanced or multimodal anaesthesia? What is the purpose of this?

Answer 9

Combinations of agents and techniques –> can reduce amounts of each drug required while still being clinically effective and reducing unwanted side effects..

Question 10

What are non-pharmacological techniques which can reduce PONV

Answer 10

Hydration
Temperature management

Minimize airway instrumentation
Care with BVM to avoid gastric distension

Choice of anaesthesia (TIVA in patients with high risk)
Choice to use N2O (Increases PONV)
Choice and doses of opioids

Question 11

Describe the neurohumoral response to significant tissue injury (surgery)

Answer 11

Increased Catecholamines
Increased O2 consumption
Increased CO2 production

ACTH
Vasopressin (ADH)
Vasopressin
Prolactin
Growth Hormone
Insulin resistance

Question 12

What are some important unwanted effects of the Surgical Stress Response

Answer 12

Unwanted CVS changes (tachycardia/hypertension)
Fluid retention (SNS/ADH/RAAS)
Electrolyte disturbances
Catabolism + hyperglycaemia
SIRS
Hypercoagulability

Question 13

What is the benefit of the pain ladder

Answer 13

Additive/synergistic effects of combining drugs may enable lower doses of the individual components to achieve adequate pain relief (reducing side effects to individual components)

Question 14

What are the three elements of conscious sedation

Answer 14

Anxiolysis
Sedation
Analgaesia

Question 15

Describe the ASA definitions of sedation and analgaesia

Answer 15

Minimal sedation (anxiolysis)

• Conscious
• No ABC intervention required

Moderate sedation/analgaesia

• Purposeful response to verbal or tactile stimulation
• No ABC intervention required

Deep sedation/analgaesia

• Purposeful response after repeated or painful stimulation
• Interventions for AB may be required. C usually maintained

General anaesthesia

• Unrousable
• ABC interventions often required

Question 16

Which patients require anxiolytic medication

Answer 16

1. Patients who remain extremely anxious despite a thorough preoperative visit
2. Pre-existing anxiety disorders
3. Patients with learning difficulties
4. Undergoing major surgery -> anxiolytic premed will be beneficial to help blunt detrimental physiological effects of anxiety

Question 17

What are the doses of commonly used anxiolytics:
Lormetazepam
Lorazepam
Temazepam

Answer 17

Lormetazempam: 0.5 - 1.5 mg

Lorazepam: 1 - 3 mg

Temazepam: 10 -30 mg

Question 18

Define analgaesia

Answer 18

Reduction or removal of pain from a normally painful stimulus

Question 19

Describe the three techniques for local (as apposed to general anaesthesia)

Answer 19

Local - infiltration of the local tissue
Regional - nerve/plexus block
Neuraxial - Spinal/epidural block

Question 20

What is the induction dose versus the sedation dose of propofol

Answer 20

Induction: 1.5 - 2.5 mg/kg

Sedation: 10mg boluses titrated to effect
(other options include a Computer controlled infusion which estimates the administration profile required for a target plasma concentration of 0.5 - 1.5 ug/ml)

Question 21

How long does propofol take to work and how long until its peak effect

Answer 21

30 seconds to for observed clinical effect

2 minutes until peak effect

Question 22

What is the dose of midazolam used for sedation, how long until its peak effect and what is its prominent effect

Answer 22

Anterograde Amnesia is its prominent effect

Dose: 1 - 2 mg titrated to effect

Time to peak effect: 4 minutes

(Take it slower in the elderly: 0.5 mg boluses)

Question 23

Describe the name and important properties of the benzodiazepine antidote

Answer 23

Flumazenil - benzodiazepine antagonist

Short acting (repeat boluses may be required)
Can precipitate arrhythmias or seizures

Question 24

Describe ketamines prominent effect and compare ketamine induction dose with dose for sedation

Answer 24

Dissociative state and profound analgesia with superficial sleep.

IV Induction dose: 1 - 2 mg/kg

Sedation: 10mg bolus titrated to effect.

Question 25

How can ketamines unpleasant hallucinations be reduced

Answer 25

Pre-med with benzodiazepine