w/c 10-Feb-14 Flashcards
(87 cards)
Definition of MAC
Minimum Alvelolar concentration of inhalation agent requried to prevent movement in 50% of individuals in response to painful stimuli
MAC of a) Isoflurane
b) Sevoflurane
a) Isoflurant: 1.3%
b) Sevoflurane: 2.3%
Potency inversely proprotional to MAC
Which factors reduce MAC?
Reduce amount of drug required i.e. MAC.
-Hypothermia, old age or VERY YOUNG, intercurrent disease, pregnancy, use of opiods, hypoxia
Isoflurane and Sevoflurane cause more ____ than halothane
Isoflurane and Sevoflurane cause more vasodilation and respiratory depression than halothane. BUT Halothane more myocardial depression (CO) and sensitises to catechoamines = arrthymias
CHECK RESP DEPRESSION
What do Neutromuscular blocking drugs do?
Inhibit acetylcholine preventing propagation of action potential therefore muscle contraction. ALL SKELETAL MUSCLES.
What are important considerations when using NMB drugs
ensure adequacy of anaesthetic as animals won’t be able to move in response to painful stimuli
ANIMAL WON’T BE ABLE TO BREATHE! VENTILATOR
Reverse using acetylcholinesterase e.g. neostigmine/
What drug should be administered alone with NEOSTIGMINE?
Neostigmine is a acetylcholinesterase. Should administer anticholinergic e.g. atropine to prevent bradycardia following reversal of the NMB drug
Pulse oximetry measures the
Patients arterial oxygen saturation i.e. SaO2 NOT NOT PaO2
What does capnography measure? What is the normal range?
Capnography measures end tidal CO2 which approximates to arterial CO2.
Normally 35-45mmHg
How to detemine sufficient depth of anaesthesia?
Eyes rotate ventrally, minimal, sluggish palpebral reflex, loose jaw tone, no swallowing reflex.
Must visualise the laryngeal opening to make sure epiglottis is not pulled dorsally!!
How do you measure the length of endotracheal tube required? Why is this important?
Measure to point of shoulder; too long and it may enter the bronchi leading to unilateral perfusion
Important consideration when using ‘Intubeaze’?
Don’t spray more than once, easy to overdose; CAVE - Local anaesthetic overdose
5 Injectable GA agents
Propofol, Alfaxalone, Ketamine, Thiopental, Etomidate
Which 2 of the injectable GA agents can be used in food producing animals?
Ketamine and Thiopental.
ALSO ISOFLURANE ON INHALATIONAL LIST
When using ketamine as an injectable agent for maintenance, what only class of drug has to be given?
Muscle relaxant.
Ketamine is the only injectable agent that provides some analgesia
Soluble injectable agents will have a _____ partial pressure in lungs, therefore a ____ partial pressure in brain
More soluble= lower pp in lungs and brain. Will be SLOWER induction and recovery agents
But the following in order depending on their relative solubilities and therefore speed of induction
Sevoflurane, Isoflurane, Halothane, N20
LIST FROM SOLUBLE –> NOT SOLUBLE
LIST FROM SLOW –> QUICKER
Halothane –> Isoflurane–> Sevoflurant –> N2O
Why can Nitrous oxide not be used as an induction agent?
MAC in animals is 200% therefore cannot be used on its own.
Had mild analgesic properties.
Very insoluble therefore very fast onset.
‘Second gas effect’
DIFFUSION EFFECT AT END OF ANAESTHETIC - TURN OFF 5 MINUTES BEFORE AS DISPLACES OTHER GASES .
Check if staff are PREGNANT
Which ions are ‘thoretically’ released from the metabolism of sevoflurane?
Theoretically free fluride ions are released which are toxic to kidney. No problems reported clinically.
Compound A formation during reaction with hot/dry CO2 absorber - newer absorbers prevent this
Which induction agent tends to keep the eye more central (rather than turning ventrally as most)
Ketamine tends to keep the eye more central (esp in horses)
Which group of premeds can cause poor mucous membrane colour?
A2 agonists e.g. Romifidine, Detmoidine, Xylazine
Electrocardiogram is useful to measure….
Electrical activity of heart, diagnosis of arrthymias NOT NOT NOT CARDIAC OUTPUT
Normal systolic and mean MAP of dog and cat
Dog: Systolic: 140. Mean: 100
Cat: Systolic: 180. Mean 135
Which animals is dopler flow detection best in (for measurement of ABP)
Better in small animals than horses.
Add on 15mmHg in cats.
Useful in HYPOTENSIVE patients