Induction of anaesthesia

Question 1

How can drugs be delivered?

Answer 1

• IM
• IV
• SC
• inhaled
• across the mm
• dart gun

Question 2

Induction agents

Answer 2

• propofol
• alfaxalone
• ketamine
• volatile agents e.g. iso, sevo

Question 3

Propofol licensing UK

Answer 3

• dogs & cats

Question 4

How to use propofol

Answer 4

• titrate to effect
• give slowly IV over 60 seconds

Question 5

Cons of propofol

Answer 5

• apnoea common, so quickly intubate and connect to breathing system
• repeat doses (each day for a week) can cause problems in cats
• twitching, myoclonus can occur
• poor oral bioavailability so only give IV
• not water soluble so has to be made as an emulsion for injection

Question 6

Effects of propofol on CO, HR, SVR, MAP, CVP

Answer 6

• stable cardiac output
• decreased heart rate
• decreased MAP, SVR, CVP

Question 7

Alfaxalone licensing UK

Answer 7

• dogs, cats & rabbits

Question 8

How to use propofol

Answer 8

• titrate to effect
• give slowly IV over 60s

Question 9

Cons of alfaxalone

Answer 9

• lack of premed can result in agitated recovery
• apnoea may be seen and IPPV may be necessary
• animals shouldn’t be disturbed during recovery as excitement can occur

Question 10

Benefits of alfaxalone

Answer 10

• apnoea much less common than propofol
• good bioavailability
• water soluble so can be used IV and IM
• good CV stability and produces good muscle relaxation

Question 11

Is propofol suitable for TIVA?

Answer 11

• yes (CRI or top ups)

Question 12

Is alfaxalone suitable for TIVA?

Answer 12

• yes (CRI or top ups)

Question 13

Effects of alfaxalone on CO, HR, SVR, MAP, CVP

Answer 13

• stable cardiac output
• stable hr
• stable MAP, SVR, CVP

Question 14

Ketamine licensing UK

Answer 14

• cats, cattle, dogs, goats, guinea pigs, hamsters, horses, mice, pigs, rabbits, rats, sheep, primates

Question 15

Cons of ketamine

Answer 15

• poor muscle relaxation so combine with other drugs
• schedule 2 drug
• studies have shown it can induce neurodegeneration in the developing brain, so use in neonates not recommended
• contraindicated in pts with coronary artery dz and poorly controlled hypertension

Question 16

Benefits of ketamine

Answer 16

• good bioavailability
• analgesic
• often used as an IV anaesthetic agent in pts with acute hypovolaemic shock
• minimal effects of ventilatory drive
• potent bronchodilator and preserves upper airway reflexes, but pts with increased risk of aspiration may require airway protection

Question 17

What is ketamine a component of for feline IM protocols?

Answer 17

• triple or quad

Question 18

Effects of ketamine on CO, HR, SVR, MAP, CVP

Answer 18

• stable cardiac output
• increased hr
• increased MAP, SVR, CVP

Question 19

Examples of volatile agents

Answer 19

• sevofluorane
• isofluorane

Question 20

Cons of volatile agents

Answer 20

• very depressive on cardiac and lung function

Question 21

Use of volatile agents

Answer 21

• mainly used to maintain anaesthesia but can be used to induce in some cases
• mask or chamber induction where possible
• IV/IM not possible
• birds, small furries, very compromised animals
• slowly increase %

Question 22

Effects of volatile agents on CO, HR, SVR, MAP, CVP

Answer 22

• reduced cardiac output
• reduced hr
• decreased MAP, SVR< CVP

Question 23

Speed of induction of anaesthesia when inducing with IV drugs vs mask or chamber

Answer 23

• IV drugs: proportional to the CO
• mask/chamber: inversely proportional to the CO
• e.g. if inducing via IV and the pt has low CO the speed of induction will be slow
• e.g. if inducing via mask and the pt has low CO the speed of induction with a volatile agent would be rapid