Pharmacology - General Principles Flashcards
what are the three subtypes of anaesthesia
general
regional
local
describe general anaesthesia
loss of consciousness
complete lack of awareness
centrally acting drugs
describe regional anaesthesia
nerve and plexus blocks
effects distal site of nerve
describe local anaesthetic
injected directly into tissues
has effect at site of injection
what are functions of a modern anaesthetic machine
regulates fresh gases delivers precise concentrations of gas CO2 removal mechanical ventilation using microcompressor monitors patient
what makes up the ‘triad of anaesthesia’
hypnosis
analgesia
muscle relaxation
what is hypnosis
unconsciousness
what IV agents are used for hypnosis
propofol
ketamine
thiopental sodium
etomidate
what inhaled agents are used for hypnosis
sevoflurane
desflurane
isoflurane
nitrous oxide
what drugs are used for analgesia
fentanyl
alfentanil
remifentanil
morphine
what is the function of analgesics in operations
pain relief
suppress reactions/reflex response to noxious stimuli like tachycardia and movement
prevents arousal
can contribute to hypnotic effect
what drugs are used as muscle relaxants
benzodiazepines like midazolam
what are general anaesthetic agents
drugs providing unconsciousness, muscle relaxation, pain relief, suppress neuronal activity
what are common IV general anaesthetic agents
thiopentone
Propofol
what are features of IV anaesthetic agents
lipophilic
fast acting
leave circulation quickly
enter muscle and then fat
what drugs are used as inhaled anaesthetic agents
halogenated hydrocarbons
what does a lower MAC value of a drug mean
lower value = higher potency
what does a TCI pump system do
device that gives a real time ‘guestimate’ of concentration of IV agents
how do general anaesthetics work
depress CNS (except ketamine)
what are physiological effects of general anaesthetics
reduces synpathetic outflow inotropic effect on heart vasodilation reduced venous return and CO reduce hypoxic drive decrease tidal volume increase resp rate
what are common local anaesthetics
lingocaine
bupivacaine
ropivacaine
how do local anaesthetics work
block Na channels
what nerves are harder for local anaesthetic to penetrate
motor nerves
pain nerves are easier
what is the major risk of using local anaesthetics
incorrect administration - very toxic
what are symptoms of local anaesthetic toxicity
circumoral and lingual numbness and tingling lightheaded tinnitus visual disturbances muscular twitching drowsiness muscular twitching drowsiness CVS depression Convulsions Comma Cardiopulmonary arrest
what are symptoms of local anaesthetic toxicity
circumoral and lingual numbness and tingling lightheaded tinnitus visual disturbances muscular twitching drowsiness muscular twitching drowsiness CVS depression Convulsions Comma Cardiopulmonary arrest
What is the anaesthetic triad?
- hypnosis - unconsciousness
- analgesia - pain relief
- muscle relaxant - relaxes skeletal muscle.
- local anaesthetic = pain relief (+ muscle relaxant)
- general anaesthesia = hypnotic (+ muscle relaxant and pain relief)
- opiates = pain relief (+ hypnotic)
- muscle relaxant = relaxes muscles only
You can give analgesia on its own, you can give hypnotic on its own but NOT muscle relaxant.
