Flashcards in Inhalational Anaesthetics Deck (42)
How are inhaled anaesthetics transported?
in carrier gasses
Name 3 types of inhaled anaesthetics
- Isoflurane (MUST KNOW)
- Sevoflurane (MUST KNOW)
What are these inhaled anaesthestics known as
Volatile anaesthetic agents
How is the level of agent determined
by dial up vaporiser
What do all inhaled anaesthetics cause some degree of
- respiratory depression
- cardiovascular depression
Do inhaled anaesthetics provide analgesia?
What are the two most commonly used inhaled anaesthetics
Isoflurane and Sevoflurane
Name the two carrier gasses?
Oxygen, Nitrous oxide, Carbon dioxide
What cylinder is oxygen kept in?
Black cylinders with white shoulders
What are 3 uses of oxygen
- 100% given to animals with anaemia, pulmonary pathology, hypoventilation, animals recovering from N2O anaesthesia/ supplied during recovery if needed
- Used operatively routinely
- Used pre-operatively if you think intubation will be difficult e.g. brachycephalics
- Post operatively
Name a benefit of oxygen?
- Does not depress ventilation
- Does not cause toxic nervous changes
- Does not cause toxic pulmonary changes
- Can be combined with nitrous oxide
How is nitrous oxide delivered?
from compressed air tanks
What is nitrous oxide combined with
What % of concentration will provide analgesic effects?
What % is nitrous oxide usually delivered at?
66% (33% oxygen)
What is the ratio of nitrous oxide to oxygen in non-rebreathing circuits?
What is the ratio of nitrous oxide to oxygen in rebreathing circuits?
Why can the use of nitrous oxide cause the anaesthetic sparing effect
if delivered at 66% then lowers need for high volatile agent levels
With what inhaled anaesthetic does nitrous oxide have a second gas effect?
What cylinders do N2O come in?
What must you do once N20 is switched off?
Name 3 negatives with nitrous oxide?
- not to use more than 80% (will lower oxygen below normal levels and patient will go hypoxic)
- N20 diffuses into gas-filled spaces and accumulates
- Do not use in bowel obstruction
- Do not use in middle ear disease
- Delivering nitrous oxide with pneumothorax can double the size of the pneumothorax in 10 minutes
When might hypoxia occur? And how do you avoid it
if animal is breathing room air - as room air contains high levels of nitrogen
Avoid it by giving al patients 5-10 minutes of pure oxygen once N2O is switched off
What piece of equipment should you use if concerned about hypoxia?
What cylinder is carbon dioxide in?
When is co2 used?
if patient is hypo-capnic
At what level is co2 used?
Name 3 advantages of inhalational anaesthetics over injectable anaesthetics?
- depth of anaesthesia readily altered
- Concentration of anaesthetic in blood or brain may be altered rapidly by changing vaporiser setting
- Elimination of inhaled agents occurs mainly via the lungs therefore advantage of liver/kidney patient
- Allows constant delivery of oxygen alongside agent
- Most patients are intubated therefore IPPV may be performed and anaesthetic is 'safe'
- Delivered to the lungs and then goes very quickly across the blood brain barrier to the brain and into the CNS
Name 3 disadvantages of using inhaled anaesthesia over injectable anaesthesia?
- need for anaesthetic machine and range of equipment (costly)
- Hazards, personnel risk, explosion risk
- Knowledge required of circuits and machine
- Induction and recover possibly delyaed due to lung pathology (not great induction agents)
- Only alternative is IV total anaesthesia