Anaesthetics

Question 1

What is general anaesthesia?

Answer 1

Centrally acting drugs causing loss of sensation to the whole body

Question 2

What is regional anaesthesia?

Answer 2

Local anaesthesia applied to nerves supplying area

Question 3

What drugs are used in anaesthetics?

Answer 3

Inhalation/IV anaesthetics
Muscle relaxants
Local
Analgesics

Question 4

What techniques/equipments are used in anaesthetics?

Answer 4

Tracheal intubation
Ventilation
Fluid therapy
Regional anaesthesia
Monitoring

Question 5

What is the Triad of anaesthesia?

Answer 5

Hypnosis
Analgesia
Relaxation

Question 6

What are the common problems of anaesthesia?

Answer 6

Polypharmacy
Muscle relaxation -> ventilation
Separation of relaxation & hypnosis

Question 7

General anaesthetics act on which part of the triad?

Answer 7

Relaxation

Hypnosis

Question 8

How do general anaesthetics act?

Answer 8

Interfere with neuronal ion channels
Hyperpolarise Cl- channels
Bind GABA receptors (IV)

Question 9

How is cerebral function affected by general anaesthesia?

Answer 9

Affected from top down
Complex first - hearing later
Reflexes spared

Question 10

What are the benefits of intravenous anaesthesia?

Answer 10

Rapid onset, recovery

Question 11

How is IV anaesthesia metabolised?

Answer 11

Hepatic metabolism

Renal excretion

Question 12

In what order do IV anaesthetics enter different compartments of the body?

Answer 12

Blood
Viscera
Muscle
Fat

Question 13

Where are inhaled anaesthetics excreted?

Answer 13

Lungs

Question 14

Arterial concentration of inhaled anaesthetics equates to what?

Answer 14

Alveolar partial pressure

Question 15

What is MAC?

Answer 15

Minimum alveolar concentration

Measure of potency (low number = high potency)

Question 16

How are patients awakened from inhaled anaesthetics?

Answer 16

Stop administration

Washout of conc. gradient

Question 17

What are the common forms of IV anaesthetic?

Answer 17

Propofol

Opiate

Question 18

What are the central effects of General Anaesthetic?

Answer 18

Depress CVS
Reduce sympathetic outflow
Negative inotrope
Reduced vasoconstrictor tone (vasodilation)

Question 19

What are the direct effects of General Anaesthetic?

Answer 19

Negative inotrope
Vasodilation
Venodilation

Question 20

What are the effects of venodilation?

Answer 20

Decreased venous return, decreased cardiac output

Question 21

What are the effects of vasodilation?

Answer 21

Decreased peripheral resistance

Question 22

What are the respiratory effects of GA?

Answer 22

Respiratory depressants
Paralyse cilia
Decrease FRC

Question 23

When are muscle relaxants indicated?

Answer 23

Ventilation and intubation

When immobility is essential

Question 24

In which surgeries is immobilisation essential?

Answer 24

Laparotomy
Neurosurgery
Body cavity surgery

Question 25

What problems are associated with muscle relaxants?

Answer 25

Awareness Incomplete reversal may require ventilation Apnoea

Question 26

Opiates affect which of the anaesthetic triad?

Answer 26

Hypnosis | Analgesia?

Question 27

Local anaesthetics affect which of the anaesthetic triad?

Answer 27

Analgesia | Relaxation

Question 28

Why is intraoperative analgesia used?

Answer 28

Prevention of arousal Opiates contribute to hypnotic effect Suppress reflex responses to painful stimuli

Question 29

What are the benefits of local anaesthesia?

Answer 29

Retain awareness Lack of global effects Spare respiratory function

Question 30

What are the negatives of local anaesthesia?

Answer 30

Derangement of CVS physiology | Toxicity

Question 31

Toxicity of local anaesthesia is associated with what?

Answer 31

``` Absorption > metabolism Dose used Rate of absorption Patient weight Drug used ```

Question 32

What are the signs of local anaesthesia toxicity?

Answer 32

``` Circumoral/lingual numbness Light headedness Tinnitus Visual disturbances Muscular twitching Drowsiness Cardiovascular depression Convulsions Coma Cardiorespiratory arrest ```

Question 33

Which fibres are affected by local anaesthesia?

Answer 33

Thick fibres spared (motor) | Pain blocked

Question 34

What are the effects of neuraxial block?

Answer 34

Inspiration spared Expiratory function impaired (loss of abdominal muscle function) Decreased FRC Increased V/Q mismatch

Question 35

What are the main types of local anaesthesia?

Answer 35

``` Local anaesthesia Field blocks Plexus blocks Limb blocks Neuraxial blocks ```