Anaesthetics - conduct of anaesthesia

Question 1

• Describe the basic phases of general anaesthesia (eg, induction, maintenance and recovery).
• Discuss the priorities involved in and the skills required for the care of the unconscious patient.

Answer 1

.

Question 2

What are the basic phases of general anaesthesia (7)

Answer 2

Pre-operative Assessment
Preparation
Induction 
Maintenance
Emergence
Recovery
Post-operative Care and Pain Management

Question 3

What are the 4 factors to consider in the induction phase of anaesthesia

Answer 3

Quietness
Gas or IV Agent
Careful monitoring of conscious level
Airway maintenance

Question 4

For quietness, where is GA usually induced

Answer 4

Mostly in theatre now, may still do it in separate anaesthetic room

Question 5

GA is administered either by … or … agent

Answer 5

Gas or IV

Question 6

Examples of IV GA agents

Answer 6

Propofol - COMMONEST

Thiopentone

Question 7

How long do IV GA agents usually take to have an effect

Answer 7

Rapid - one ‘arm-brain’ circulation time (~20s)

Question 8

What resp condition is common when you’re under IV GA

Answer 8

Apnoea

Question 9

Example of gas GA agent

Answer 9

Sevoflurane

Question 10

How long do gas GA agents usually take to have an effect compared to IV agents

Answer 10

Slower

Question 11

Gas GA agents are more used in what group of people

Answer 11

Children

Question 12

Gas agents have more obvious ‘planes’ of anaesthesia than IV agents - what does this mean

Answer 12

Means that there’s more identifiable stages the patient is progressing through

Question 13

What are the planes of anaesthesia

Answer 13

Analgesia/sedation
Excitation
Anaesthesia - light –> deep
Overdose

Question 14

What happens to reflexes as anaesthesia progresses from light –> deep

Answer 14

Heightened during light stage then supressed

Question 15

During the induction phase, conscious level also has to be monitored - what ways can this be done?

Answer 15

Loss of verbal contact

Any movement

Respiratory pattern

EEG

What “plane” of anaesthesia they’re in

Question 16

Airway has to be maintained during the induction of GA - what are the ways this can be done?

Answer 16

Triple airway manœuvre - head tilt + chin lift + jaw thrust
+

Simple apparatus
-face mask
-oropharyngeal airway - common
-nasopharyngeal airway - less common
OR
Advanced apparatus
-laryngeal mask airway
-(endotracheal) intubation

Question 17

Oropharyngeal airways can only be tolerated when

Answer 17

unconscious

Question 18

A laryngeal mask airway (supraglottic airway) is a more advanced airway management option where a cuffed tube with a ‘mask’ sits over the glottis (vocal cords)

Although it maintains the airway (i.e. lets air in), it doesn’t do what?

Answer 18

protect the airway (i.e. making sure gastric contents aren’t aspirated into resp tract)

Question 19

What is the ‘i-gel’ + when is it the airway of choice?

Answer 19

A newer generation of the laryngeal mask airway (LMA)

In emergency situations like MI

Question 20

A complication of the airway is OBSTRUCTION - what can cause this (3)

Answer 20

Ineffective triply airway manoeuvre

Malpositioning of airway device

Laryngospasm

Question 21

A complication of the airway is ASPIRATION - what can cause this (2)

Answer 21

GA - protective airway reflexes lost, e.g. gag, swallow, cough

Foreign body in lower airway, e.g. gastric contents, blood

Question 22

Difference between maintaining and protecting the airway + what are the only 2 ways of protecting an airway

Answer 22

Maintaining means keeping it open and unobstructed but protecting refers to the prevention of things being aspirated into the airway

If conscious or anaesthetised with a cuffed tube below the vocal cords

Question 23

What does endotracheal intubation involve

Answer 23

Placing cuffed tube in the trachea

Question 24

Reasons for intubation (5)

Answer 24

Protect airway from gastric contents

If muscle relaxants are used

Shared airway, i.e. if the surgery is performed in the same space as the airway

When blood gases need to be tightly controlled

When there’s restricted access to airway, e.g. maxillofacial surgery

Question 25

Risks faced by unconscious patients (5)

Answer 25

Airway obstruction

Loss of other protective reflexes, e.g. corneal

VTE risk

Consent + identifying the right patient

Pressure area damage

Question 26

How is anaesthesia maintained when the induction agents wear off

Answer 26

Further IV/gas agent or both

Question 27

What ways are the patient monitored throughout the surgery?

Answer 27

Basic minimum monitoring - PO2, ECG, FiO2 etc

Resp function

Monitoring effect of anaesthetic agent

Temp, urine output

Invasive venous/arterial monitoring

EEG

Make sure ventilator doesn’t disconnect

Question 28

Risk factors of still having a degree of awareness whilst on GA (4)

Answer 28

Previous episode of awareness

Chronic CNS depressant use

Major trauma

Cardiac surgery

Question 29

What should happen and be done in the emergence (awakening) phase

Answer 29

Muscle relaxation wears off
Anaesthetic agents are turned off
Spontaneous respiration resumes
Airway reflexes return

Extubate the patient

Question 30

What should happen and be done in the recovery phase of anaesthesia (in a dedicated unit)

Answer 30

Monitor ABCs

Continue monitoring airway

Control any pain

Treat any post-op nausea/vomiting

Set criteria for discharging back to ward