Anaesthetics

Question 1

What are the three types of anaesthesia?

Answer 1

• general
• local
• regional

Question 2

What does a general anaesthetic do?

Answer 2

Produces insensibility to the whole body, usually causing unconsciousness

Question 3

What does a regional anaesthetic do?

Answer 3

Produces insensibility in an area or region of the body

- applied to nerves supplying relevant area

Question 4

What does a local anaesthetic do?

Answer 4

Produces insensibility in only the relevant part of the body

- applied directly to the tissues

Question 5

What is a necessary component of any general anaesthetic?

Answer 5

Hypnosis

Question 6

What is relaxation?

Answer 6

Refers to skeletal muscle relaxation
- necessary to provide immobility for certain procedures, allow access to body cavities and permit artificial ventilation

Question 7

Name an example of balanced anesthesia

Answer 7

Using less GA to provide hypnosis if muscle relaxant is used for access and immobility
Could use less of both if a regional/local anesthetic is used

Question 8

What are two types of general anesthetic agents?

Answer 8

• inhaled

- iv

Question 9

How do GA agents act on a molecular level?

Answer 9

Hyperpolarization of neurons, making them less likely to fire

• inhaled: dissolve in membranes
• iv: GABA receptors - open chloride ion channels

Question 10

How does GA affect the body?

Answer 10

• Cerebral function lost from “top to bottom”
• Most complex functions lost first then most primitive functions lost later
• Reflexes relatively spared (spinal)

Question 11

What are 2 main characteristics of IV anesthetics?

Answer 11

• Rapid onset of unconsciousness (1 arm brain circulation time)
• Rapid recovery (due to disappearance of drug from circulation)

Question 12

Rank the body tissue from highest to lowest concentration of drug

Answer 12

• Blood
• Viscera
• Muscle
• Fat

Question 13

What device is used for IV administration of drugs?

Answer 13

TCI (Target Controlled Infusion) pump system

Question 14

What are inhalational anaesthetics composed of?

Answer 14

Halogenated hydrocarbons

Question 15

How are inhalational anaesthetics taken up and excreted?

Answer 15

By lungs

Question 16

What is MAC?

Answer 16

Minimum alveolar concentration
Concept of concentration of drug required in alveoli which is required to produce anesthesia
Low MAC - agent is potent

Question 17

Give two examples of inhalational anaesthetics

Answer 17

• Halothane

- Desflurane

Question 18

What are characteristics of inhalational anesthetics?

Answer 18

• slow induction

- extension and continuation of anaesthesia (maintenance)

Question 19

How does GA impact the CVS?

Answer 19

1- reduce sympathetics outflow
2- direct negative chronotopic and inotropic effect on heart (Smooth muscle and myocardium)
3- ventilation (reduce CO)
4-arterial vasodilation (reduce TPR)

Question 20

How does GA impact the respiratory system?

Answer 20

depresses it:
reduce hypoxic and hypercarbic drive
decrease tidal volume
increase rate

Question 21

What are indications of muscle relaxants?

Answer 21

• ventilation and intubation
• immobilization
• body cavity surgery

Question 22

What are problems that can arise from muscle relaxants?

Answer 22

• awareness: due to separation of unconsciousness
• incomplete reversal of relaxant with some residual effect in post op period (can lead to airway obstruction and ventilatory insufficiency)
• apnea

Question 23

If patient cannot feel unpleasant stimulus due to their anaesthetic, is there a need for unconsciousness?

Answer 23

No

Question 24

Why do we use intraoperative analgesia?

Answer 24

• prevention of arousal
• opiates produce hypnotic effect of GA
• suppression of reflex response to painful stimuli (i.e. tachycardia, hypertension=

Question 25

What are characteristics of local/regional anesthetics?

Answer 25

• Retain awareness/conciousness
• Derangement of CVS physiology - proportional to size of anesthetized area
• Relative sparing of respiratory function

Question 26

What is the process of anesthesia?

Answer 26

• Pre-operative assessment
• Preparation
• Induction
• Maintenance
• Emergence
• Recovery
• Post-operative care and management

Question 27

What are the preparative measures for anaesthesia?

Answer 27

• Planning
• Right patient, right operation
• Right or left side
• Pre-medication
• Right equipment/right personnel
• Drugs drawn up
• IV access
• Monitoring

Question 28

What are the induction measures for GA?

Answer 28

• Quietness (separate, dedicated anesthetic room)
• Gas/IV agent
• Careful monitoring of conscious patient
• Airway maintenance

Question 29

How do we monitor a patient’s consciousness level?

Answer 29

• Loss of verbal contact
• Movement
• respiratory pattern
• EEG
• “Stages” or “planes” of anaestheisa

Question 30

What is the triple airway manoeuvre?

Answer 30

Head tilt
Chin lift
Jaw thrust

Question 31

What is the apparatus used for airway maintenance?

Answer 31

Simple apparatus:

• face mask
• oropharyngeal (guedel) airway
• nasopharyngeal airway

Question 32

When is the airway maintained?

Answer 32

When it is open and unobstructed

Question 33

How is the airway protected?

Answer 33

When a cuffed tube in the trachea prevents contamination - endotracheal intubation

Question 34

Why do we perform an endotracheal intubation?

Answer 34

• Protect airway from gastric contents
• Need for muscle relaxation
• Risk of blood contamination
• Need for tight control of blood gases

Question 35

What are the risks faced by unconscious patients before surgery even begins?

Answer 35

• airway
• temperature
• loss of protective reflexes (corneal, joint position)
• DVT
• Consent and identification
• pressure areas

Question 36

How do we monitor an unconscious patient?

Answer 36

• SpO2, ECG, WTCO2, NIBP, FiO2
• Respiratory parameters
• Temperature
• Urine output
• Invasive venous/arterial monitoring
• EEG
• Agent monitoring