vet anaesthesia Flashcards
first attempts at serious anaesthesia 1840s
nitrous oxide, ether, chloroform
3 reasons for anaesthesia
- asleep
- relaxed muscles,
- free of pain and fear
all anaesthetic drugs have
side effects
whats the death rate due to anaesthesia
- humans 1 in 200 000
- cats and dogs 1 in 2000
- horses 1 in 100
- lab animals 1 in 32
reasons death rate is so high in horses
- high centre of gravity and high body mass –> bad falls
- problems w ventilation of the lungs, sloping diaphragm
- cardiovascular system depression
- myositis (muscle inflammation)
- excitement when half awake leads to injury
what do we do for horse anaesthesia to help
- relax patient
- rapid induction
- small padded room
- assisted descent to floor
- monitor perfusion of blood and ventilation of the lungs and treat
- small dose of sedation as they wake up
- keep down time to a minimum
balanced anaesthesia
- low doses of multiple drugs each targeting specific components
analgesics
pain relief, often used before surgery
anaesthetic drugs
cause patient to lose consciousness
vets role in anaesthesia
- history from owner
- pre exam
- prep, operation and maintenance of anaesthesia equipment
- prep of drugs
- monitoring and reacting
- post monitoring too
history
- get as much info
- previous/ ongoing illnesses
- meds
- prophylaxis
- previous anaesthesia and surgery
- fasting
pre anaesthesia exam
- weight
- heart rate
- resp rate
- CRT
- mm colour and refill
- temp
plastic conduit tubes
which carry anaesthetic mixture (oxygen, nitrous oxide and vapour) to patient
oxygen flowmeter
source of oxygen flow
vapouriser
oxygen and nitrous oxide flow into the vaporizer to pick up anaesthetic vapour
nitrous oxide flowmeter
source of nitrous oxide flow
rebreathing bag
into which anesthetized patient breathes
anesthesia plan
- individualized for each patient
- responses to anticipated problems
- emergency drug and dosages prepped
anticipated problems
- hypothermia
- hypoventilation (inadequate ventilation of the lungs)
- bradycardia (slow heart rate)
- hypotension (low blood pressure)
- hypoxemia (low blood oxygen)
physiological considerations
- respiratory; provide oxygen; remove CO2
- cardiovascular; perfusion of tissues w blood
- hepatic; drug metabolism (removal)
- CNS (sleep, wake)
- renal; elimination of drugs
- GIT (fluid and electrolyte balance)
- endocrine (autoregulation)
monitor comes from the latin word
monere= to warn
why monitor
- patient must be unaware
- patient must have adequate analgesia
- patient must be still and in a stable physiological state
- anaesthesia must be reversible
monitoring devices do NOT
replace anaesthetists
philosophy 1 of monitoring
when measuring things biological, one measurement gives a window into a dynamic situation
repeated measurements give some idea of the dynamic pic
philosophy 2 of monitoring
all monitors have limited accuracy and reliability
trends can mean more than numerical values
philosophy 3 of monitoring
best equipment does not equal a good job of monitoring
check patient before checking the monitor
monitor the patient not the monitor
monitors should not/cannot replace a skilled anaesthetist
straight lines on a chart do not mean
you have done a good job
what kills more patients; surgery or anaesthesia
anaesthesia
