Anaesthetics Flashcards
types of Anesthesia used
arrow represents we can use a mixture of these
what is Conscious sedation? when do we use it?
use of small amounts of anaesthetic or benzodiazepines to produce a ‘sleepy-like’ state. (Maintain verbal contact but feel comfortable)
Guedel’s signs?
what 4 things is anaesthesia is a combination of?
the range of effects on the CNS produced during general anaesthesia
(alaa hates depressed moods)
when a patient is fully anesthetized we say they r?…..
insensible and immobile
what is potency?
concentrational dose range of which a drug produces its effect
what is MAC?
MAC>>Minimum Alveolar Concentration
what is the anatomical substrate for determining MAC?
spinal cord
- if we sectioned spinal cord right at the top, & the brain is no longer connected, the MAC doesn’t change!*
- so we use spinal cord to determine MAC*
- and the subsrtate for falling to sleep is the brains job*
factors affecting induction and recovery of a volatile? (2)
Partition coefficients (solubility)
• Blood:Gas partition (solubility of volatile in the blood)
so ur breathing in by lungs> alveoli> then it has to partition into the blood> tranported to brain> then u get the effects which u see>> (loss of conciousness etc.)
– A Low value of “Blood:Gas partition” means fast induction & recovery
ex: DESFLURANE
• Oil:Gas partition (solubility of volatile in the in fat)
– Determines potency and slow accumulation due to partition into fat (e.g, halothane)
the greater ur ability to partition into fat (plasma membrane) >> then potency increases. BUT…. if it ends up in fat, it partitions and accumalates, & when in accumalates (in an obese person) u end up w/ like a “human vaporizer” , that once in equilibream, the anesthetic partitions into fat, & when u turn of the anesthetic, it takes them FOREVER to wake up?
What Affects MAC ?
(increases and decreases)
What should u do to the vaporiser if ur gunna give more than 1 anesthetic or an opiod? Why?
If uve got more than 1 anaesthetic or opiod agent on>> ur MAC will reduce>> so u need to turn the vaporiser down
If u keep the vaporiser up & u give them smthing else, they can go into a very DEEP state of anaesthesia which is unnecessary > put patient in harm
Why do we add NO to certain anesthetics?
when we added NO to those volatile agents>> their MAC DECREASED
by doing this (mixing and matching), u can reduce the side effects for those agents that have a slightly worse side effect profile
ex: side effects of NO, side effect of sevo r worse>>put em togezer > u have a perfect mix & match !
anesthetic is partitioning into fat, but fat itself doesnt do very much, its the PROTEIN embedded w/ in it that t r important!
ok
role of the GABA receptors in anaesthesia
W/ the exception of Xe, NO and ketamine
ALL anaesthetics potentiate (increase effect) GABAA recepter activity!
sooooo……
Cl- goes in> cell is hyperpolarized> hard to become active now> so it shuts things down= (depress CNS activity)
then what is the target recepter for Xe, NO and ketamine
NMDA glutamate recepter
(exitatory recepetor)
During anesthesisa, in the brain, consciousness is a balance between excitation & inhibition.
explain this concept
excitation > Glutamate> wake up
inhibition > GABA > sleep
balance of GABA & Glutamate determine whether ur awake or asleep
what produces anesthesia in context of “Systems Target: Brain Circuitry” (2)
- Reticular formation (hindbrain, midbrain and thalamus) depressed.
- Connectivity lost (bits of brain not speaking to each other, or not speaking in an approporiate way)
Reticular system often called “activating system” due to ability to increase arousal.
which area of the brain is VERY sensitive to Volatiles? what happens to it
name areas of brain effected during anesthesia and their effects
- Hippocampus >> depressed>> no memory
- Brainstem >> depressed>> respiratory & some CVS collapse.
- Spinal cord-depress dorsal horn>> analgesia & motor neuronal activity (MAC).
names of intravenous anaesthetics
The Mightly King, Proposes to oprah
How do we describe Intravenous Anaesthetic Potency ?
measure it as the plasma concentration, so the plasma concentration to achieve a specific end point (loss of eyelash reflex or a BIS value)
give patient a bag of saline to hold >give em the IV> if they drop bag, the concentration is the concentration that puts them to sleep…?
TIVA> u program an infusion device based on weight, size, pharamkokinetics, pop patient to sleep, pre-ceeded by a bolus & then let the infusion system keep patient sleeping
Bispectral index (BIS)>is one of several technologies used to monitor depth of anesthesia.
indications for local and regional anaesthesia
O** **D**ear give him **CPR
Obstetrics
Dentistry
Chronic pain management (PHN)
Post-op (wound pain)
Regional surgery (patient awake)
mechanism of action for wound analgesia
prefer we use amides or esters ? why?
put some local anes. on the wound, local is NOT charged, can pass easily through PM, once it gets to the plasma membrane, depending on it PKA, it then becomes charged, & in a water based environment, it gets sucked into the inner core of the volt-gated Na+ channel!
& if u block a voltage-gated Na+ channel, you block an AP! (no pain)
the faster the rate of firing of that AP (ex: heavy pain), the rate in which the anesth. gets sucked into the channel is INCREASED>> “diffused dependent block!”
how can we increase the duration of action of a local?
by adding Adrenaline !
produce local vasoconstriction and stops the peripheral circulation taking the anesthetic away from the target sight!
what is diffused dependent block?
the faster the rate of firing of that AP (ex: heavy pain), the rate in which the anesth. gets sucked into the channel is INCREASED
what r Local Anaesthetics?
indications, mechanism of action, side effects, drugs
Local anesthetic structure
what r the charecteristics of the drug which r important?
an aromatic ring & amine>> w/ a linker in btw
linker can be either ester ur amide link
what r the main local Anaesthetics?
bupi the cocaine boy!
bupi bought a Pro rope from lidl
Lidocaine, Bupivacaine, Ropivacaine and Procaine.
what r the short acting anesthetics? long acting?
how can we differentiate btw them?
short acting are ESTERS
long acting are AMIDES
nc we have esterases in the plasma which break down the esters!> making it short acting
local anesthetic drug name
Delhi to bombai, Love Priyanka Chopra
Lidocaine, Bupivacaine, Ropivacaine and Procaine.
which is more potent w/ a longer duration of action?
Procaine or Bupivacaine?
Compared to Procaine, Bupivacaine is more potent with a longer duration of action.
Procaine is esterase metabolised and has a slower onset time but not much in it.
Regional Anaesthesia.
alaa ask doha for panapto!
main anaesthetic ADRs / Side effects
General anaesthesia
– PONV (opioids)
– CVS – hypotension
– POCD (increases with increasing age) – Chest infection
Local and regional
– Depends on the agent used and usually result from systemic spread (Locals are Na+ channel blockers so cardiovascular toxicity)
Increased general concern re: allergic reactions/anaphylaxis
