Anaesthesia Flashcards
what is anesthesia?
- It is the reversible loss of noxious stimuli
what are the different types of anaesthesia and how does each type work?
- Local - numbs small area of the body
- IV - causes mild sedation and relaxes you
- Regional - causes numbeness is one part of the body e.g epdiural
- General - associated with loss of consciuouness
what is the mechanism of local anaesthetics?
- They block transmission of signals generated by nociceptors
- Block na+ channels which prevents depolarisation and hence action potential formation
give examples of local anaethtics drugs and their durtaion of actions?
- Lidocaine - short acting fast onset
- Mepivacaine is long cating fast onset
The addition of vasoconstrictors e.g epinephrine can lead to extention of duration of action of local anaesthetics. true or false?
true
How can local anaesthtics be administered?
- Topically
- infilitration - injection of intradermal and subcutaneous
- Regional block- injection to connective tissue
- Epidural
Epidurals can cause motor deficits at higher doses. true ro false?
treu
what do general anaethesia cause?
- Loss of consciouness
- Analgesia
- Amnesia
- Muscle relaxant
For general anaesthetics what are the premedication given?
- Sedatives (anxiollytics)
- Analgesia (NSAIDS)
intravenous anaesthetics is for induction and short procedures. true ro false?
true
inhalation anaesthetics is for maitainance. true ro false?
true
Provide examples of drugs for Inhalation anaethetics, IV, pain killers, Relaxants and adiuvants?
- Inhalation anaethetics : (N2O)
- IV - (propofol)
- pain killers (NSAIDS, pacetamol)
- Relaxants - depolarising (succinilcholine), non depolarising (atracurium)
- adiuvants - diazepam
what are the advantages of inhalation anaesthesia?
- Controls the depth of anaesthesia
- Metabolism is minimal
- Excreted via exhalation
what are the two divisions of inhalation anesthetics?
- Volatile liquids
- gases
what are the three theories of how inhalation anaesthtics work?
- Cause generalised depression of CNS
- lipid solubility theory
- direct membrane receptor (interaction with ion channel)
what is the anaethetic depth determined by?
- The partial pressure in the brain
how do the anaethtic molecules reach the brain?
- Inspired air - alveoli - blood - brain
The minimum alveolar anaesthetic conc (MAC) is the % of the inspired air at which 50% of patients do not respond to the stimuli. true ro false?
true
MAC value is a measure of what?
- Inhalation anethetic potency
what does a high MAC value equal?
- Low potency
what MAC value are used during surgery?
1.1 to 1.2
Ether is flammable. TRUE OR FALSE?
TREU
What is the blood gas partition co-effeicient?
- It is a measure of solubility in the blood
what does the blood gas partition co-efficient determine?
- The rate of induction an drecovery of inhalation anasthetics
what does the oil partition co-efficient measure?
- It measurs solubiltiy
The higher the oil partition coeffecient the lower the MAC.TRUE OR FALEE?
TRUE
the higher the lipid solubility the higher the pontency of the anaesthtic. true or false?
true
Ether has highest Blood/gas PC
Halothane has the highest Oil/gals PC. true or flase?
for inhalation anasethtics
true
Isoflurane is a less soluble isomer of enflurane, and is widely used. true or false?
true
Isoflurane potentiates the action of neuromuscular blockers. true or false?
true
why is isoflurane an agent of choice for neurosuregry?
- because cerebral blood flow is little affected by isoflurane
Uterine tone is maintaine with isoflurane compared to halothane or enflurane. true ro false?
true
isoflurane is used to reduce post-patrum hermorrhage. true or false?
true
halothane is non-flammable volatile aneathtic. true ro false?
true
what are the issues with halothane?
- Increase myocardial excytability
- BP drops due to CNS depression
- Cerebral blood flow is increased so contraindicated in head injury patient s
- Not a good analgesic
- can produce massive hepatic necrosis
- Cuases malignant hyperthermia
Nitrous oxide is used during child birth, used as na adjunct, weak, risks of bone marrow depression with prolonged use. true ro false?
true
what are IV induction agents used for?
- Inductio of anaesthesia
Recovery of IV induction agents is by redistribution. true or false?
true
hwo does propofol work?
They modulate GABAergic neuronal transmission
propofol is
Anti-emetic in action
Non-irritant to airways. true or false?
true
Sodium thiopental is Rapid-onset ultra-short acting barbiturate, it binds to GABAAreceptor, increases the duration of time for which the Cl-ionoporeis open. True ro false?
true
what is the short duration of action of sodium thiopental due to?
due to its redistribution away from central circulation towards muscle and fat
what are the adverse reactions of sodium thiopental?
- Hypotension
- airway obstruction
Ketamine is a general dissociative anaesthetic
Ketamine is classified as an NMDA Receptor Antagonist. true or false?
true
Heart rate and BP are elevated due to sympathetic stimulation with ketamines. true or false?
true
Respiration is not depressed and reflexes are not abolished with ketamine. true or false?
true
General anaesthetics:
Sample gases: Nitrous oxide and Xenon
Halogenated hydrocarbons: Isoflurane
Barbiturates: Thiopental. TRUE OR FALSSE?
TRUE
Local anaesthetics:
Ester: Cocaine, Procaine, Tetracaine
Amide: Lidocaine, Bupivacaine. TRUE OR FALSE?
TRUE
All local anaesthetics drugs work by inhibition of Na+ channel. true ro false?
true
