anaesthesia 1 - intro

Question 0

what is the normal pathway of a sensation signal to the brain? (t, t, m, p)

Answer 0

1. stimulation of peripheral nerves (transduction)
2. transmitted through afferent nerves to the spine/brainstem
3. modulation (amplified or depressed)
4. to the brain - thalamus - cerebral - perception. (anaesthesia can interfere any where along this pathway. )

Question 1

what is the definition anaesthesia? which senses? which is the most important?

Answer 1

elimination of sensation by the controlled, reversible depression of the CNS cavity using drugs (anaesthetics) most importantly the sensation of pain. + heat and cold + pressure/touch +5 senses.

Question 2

3 classes of anaesthetics - depends where in the pathway they act?

Answer 2

1. conduction blockade - peripheral nerves (local)
2. neuraxial blockade - spinal cord. eg. extradural local. (no loss of conciousness)
3. general aneasthetic. affects brain. - lose conciousness.

Question 3

what is a general anaesthetic? but? need what aswell?

Answer 3

a state of drug induced insensibility and unconciousness which allows surgery to be performed safely and with comfort but - will still have some reflexes - so need something else!!!!!!!

Question 4

for a successful anaesthetic you need what? (3)

Answer 4

1. unconcoiusness
2. muscle relaxation
3. analgesia

Question 5

what is the difference between pain and nociception?

Answer 5

pain is a concious feeling

nociception is when you still feel it but not percieved as pain = unconconcious.

Question 6

what is the massive down side of anaesthesia? all come with side affects like what?

Answer 6

also supresses BP, plasma o2 levels, temperature, ventilation,
can also supress or eliminate cranial nerve reflexes. eg. coughing (may lead to inhalation pneumonia.
can use reflexes to assess level of anaesthesia eg. eye position, jaw tone, ocular reflex, gagging.

Question 7

how can you stop these bad side effects? what does the animal need to be to tolerate it well?

Answer 7

need to have a balance. give high doses but must manage the side effects!! is all tolerated well by a HEALTHY ANIMAL!

Question 8

there are 3 ways to achieve conditions for anaesthesia?

Answer 8

1. deep general
2. deep supoorted general
3. balanced anaesthesia

Question 9

explain deep general anaesthesia?

Answer 9

high doses of drugs eg. inject/inhale. depresses normal functions - for a short time and only effective on young healthy animals.

Question 10

explain deep supported general anaesthesia? give examples of how we manage things?

Answer 10

have extrinsic support!!
adverse effects are monitored and compensated for.
-airway - food and water deprived
plus intubation (endotracheal)
-hypoventilation - O2 enriched breath and assisted ventilation
-hypotension - fluid therapy and vasoconstritors
- hypothermia - topical heat , brief surgery, hot water bottles, hot water into stomach
-eye drops as cant blink

Question 11

explain balanced anaesthesia?3 drug classes used at once. what does this ensure?

Answer 11

three drug classes can be used?
-unconcious - anaesthetics/hypnotics
-analgesia - analgesics
- muscle relaxation - neuromuscular blocking agent
all these ensure that vital centre activity is maintained with minimum dosages - very useful for an old/ill patient.

Question 12

give an example of an anaesthetic?

Answer 12

sevoflurane plus n20.

Question 13

give an example of an analgesia?

Answer 13

retrotubular blockade and local opioids. eg. morphine

Question 14

muscle relaxation drugs?

Answer 14

atracurium - stop movement and ocular movement.

Question 15

what is arreflexia?

Answer 15

it is the abolition of all responses to surgery eg. prolactin release

Question 16

what is the DO2?

Answer 16

maiantainence of O2 to all vital tissues.

Question 17

give some exapmples of ways to achieve anaesthsia?

Answer 17

general alone
sedative plus analgesia
low dose general and high doe analgesia.

Question 18

what do you need to consider about the pateint?

Answer 18

species
ethological (stress)
anatomical (venous access, tubing cattle)
physiological (regurgtate pigs, epam in horses)
pharmalogical (MH sensitive pigs - cook themselves)

Question 19

what d you need to consider about the individual animal?

Answer 19

size, temperament, age, medication, repro, function (athlete is worse), health status, breed

Question 20

what do you need to consider about the surgical procedure?

Answer 20

duration, invasivesness, location, help, safety.

Question 21

what else may you need to consider about the anaesthetic?

Answer 21

cost, convenience, legality, licensing, experience, assitance factor