Term
| where do we get BARBs from? |
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Definition
Late 40's brought us barb acids urea malonic these acids by themselves have no sedation properties, have to have a side chain to be sedatives. Methohexitol Thiopent
barbituric acid which came from Melonic acid and urea |
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Term
| What drugs decrease CMRO2 and cerebral blood flow, do they all do it equally? |
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Definition
thiopental
methohexital
propofol
Above are "coupled"
Etomidate-"uncoupled"
Ketamine inc CMRO2 |
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Term
| Mechanism of action of Barbs |
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Definition
increased duration of ion channel open
decreased dissociation from receptor
Facilitate action of GABA
in high doses: can activate the receptor all by themselves.
Usually cases and usually clinical doses it facilitates GABA.
you have a 3 pronged complex, Receptor GABA and the BARB
test will say its a nueronal nicotinic antagonist- only happens at super clinical doses. like with inducing a coma in an injured patient.
Cl moves into the cell-> hyperpolarized cell--> inhibition of post synaptic membrane-->depression of the RAS
decreased transmission through SNS
-these arent great drugs to dampen the sympathetic nervous system. |
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Term
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Definition
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Term
Porphyria
What drugs need to be avoided in these patients |
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Definition
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Term
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Definition
Part of the RAS system
Excitatory in the brain (Thalamic to brain arousal)
inhibitory in the spinal cord (prevent people from moving in their sleep) |
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Term
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Definition
2 barbs for the same receptor site-additive
give benzo and 3 martinis-synergistic
bc benzo is not competing with alcohol it has its own place to bind. |
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Term
| What causes the perineum burning?? |
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Definition
phosphate in the barbs
this is not in thio or methohexitol |
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Term
Thiopental (generic) **know this name**
Na Thiopental
STP |
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Definition
comes in 2.5%--> 2.5 grams in a liter or multiply by 10. want to get mg/cc
know this!
its an acid (very few acidic drugs)
20cc syringe (makes the ph 10 or 11 to make it water soluble )
comes as a racemic mixture
protein binding is 85%
pt wakes up because med has been redistributed not because its gone.
change the dose in low protein states? no/no competing for binding sites
changes in liver blood flow--> no effect.
decreases blood flow and metabolic need in a coupled fashion |
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Term
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Definition
adult dose 3-5 mg/kg **4 mg/kg**
Clearance 3.4 ml/kg/min (low) (comes to zero order fairly rapidly)
E 1/2 life=11 hours |
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Term
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Definition
1 or 2% solution
usually 50 ml vial of 1%
may be prepared in 10ml stick
still an acid
oxybarb and racemic mixture
2 chiral carbons and 4 steroisomers
protein binding 85% |
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Term
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Definition
adult: 1.5 mg/kg
distribution: 5-6 minutes
clearance: 11 ml/kg/min
E 1/2 life: 4 hours
Produces much less of a hang over than his older brother thiopental |
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Term
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Definition
Epileptogenic
Myoclonus-muscle twitching looks similar to seizure, but not!
Hiccups
only drug now we are for sure causes seizures
Myoclonic movements are not associated with any energy requirements in the brain. no increase of lactic acid
Sooo..
Low doses- cause seizure
High doses-stop a seizure |
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Term
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Definition
depressants /free radical scavengers->decrease reprofusion injury.
sedation (still responsive to verbal commands as well as hypnosis (unconscious)
decrease CMRO2 CBF and ICP
depress nerve to nerve communication
Need goes down and so do blood flow
cerebral vaso constrictors
dec intraocular pressure
Depresses EEG
NO ANALGESIA PROPERTIES (anti analgesic??more sensitive to pain in the text)
whats actually going on is you depress inhibitory before excitatory. lose inhibition first.
*might see this with addicts that come to you clean, that person needs all their inhibitions to make them behave, if you sedate them and take away inhibitions that person goes nutzos
synergistic with opiods, benzo's gasses all attack same receptor but different sites on receptor.
Nueroprotective: dec re profusion injury and can dec. damage of focal ischemia during anesthesia
When is it nuero protective?focal ischemia (dec o2 requirement and stabilizes the membrane)no global hypoprofusion help ex MI. Cold is the only demonstarted benefit in nuero protection in global ischemia.
We decrease cells activity by full 60%.
40% left if what keeps cell alive. |
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Term
| cerebral blood down in 2 ways?? |
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Definition
need for it goes down
so delivery for that tissue goes down.
usually coupled-need coupled with the supply (unless you let map go below auto regulation) |
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Term
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Definition
dec blood flow 10-20mm Hg
dec sns outflow
histamine release and cause venous dilation
inc heart rate (helps preserve the CO when you have dec venous return)Barorecptors stay intact
dec CO
<-> SVR (arterial)
dec venous return
Who doesnt get this med? hypovolemic pt bc already have dec venous return
dont give to ischemic heart disease--> tachycardia will make them worse |
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Term
| All of our induction agents... |
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Definition
| ARE DIRECT MYOCARDIAL DEPRESSANTS |
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Term
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Definition
resp depression
medullary vent centers (what does this look like?)
talking to the pt and they breath fine..one deep breath and they stop!
the depressant effects on the hypercarbia and hypoxia outlast the anesthetic effect. IT HAS A TAIL
not good for COPD patients
watch using these in short cases bc of tail.
Rate TV dec
inc co2
dec 02
bronchial dilation
laryngeal reflexes-not enough to intubate one this solely
pentathol is histamine releaser: some say its not the drug of choice for asthmatic but it is not contraindicatedin asthma
light anesthesia vs histamine effect is what causes irritation to airway |
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Term
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Definition
Low hepatic clearance (zero order pentobar)
medium (methohexital)flow limited
enzyme induction (all)
constant amount of time of use enzyme activity can up regulate |
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Term
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Definition
genetic error of metabolism over production of porphyrins and their precursors
-heme containing molecule
worry about:
acute intermittent
variegate
heredity coproporphyria
*heme proteins
main precursor to hemoglobin
myoglobin
catalase
peroxidase
cytochrome p450
get purple color under the skin
vomiting abd pain
acute nueropathy, depression anxiety
seizure cardiac dysrythmia and DEATH! |
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Term
| What drugs to avoid with Porphyrias |
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Definition
methohexital
Thiopental
Etomidate
SCARY VAMPIRES LIKE TO BITE EVERY PERSON
Sulfonamides
valium
Lido
Tolbutamide
barbs
etomidate/ethanol
phenytoin |
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Term
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Definition
pregnancy: only one approved in pregnant pt Thiopental(might use propofol)
Elderly? decrease dosing by 30% very susceptible to most CNS depressants
Coumadin-interferes with the binding of methohexitol
how many are actually approved in pregnant people? not many
Drug mixing (cement in tubing)Stop the infusion to prevent venous thrombus,
intra arterial injection: arterial spasm, dec profusion to the tissue, do not put in A line (obvi)
Histamine release: (thiopental)
Allergic reaction: make sure and ask what happened when you took it? |
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Term
| If you put the barb in the A line..opps |
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Definition
Leave the iv site there
dilute the med
lidocain and heparin flush
papaverine phenoxybenzamine (dec alpha constriction)
sympathetic block
1 brachial plexus
2 stellate ganglion |
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Term
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Definition
induction of anesthesia
nuero anesthesia-thiopental
burst suppression- at high doses/max depression of EEG 60% dec because we are going to interupt arterial supply to the brain.
NEVER INTERRUPT ARTERIAL perfusion to the brain completely
ECT-seizures used to treat depression *most common use of it today (ECT) |
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Term
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Definition
Hypoxic pulmonary vasoconstriction
usually hypoxic tissue dilates dt byproducts of aneorobic metabolism
in the lungs hypoxia=constriction bc in the lungs use it as a shunting mechanism, arterial resistance and blood goes to alveoli that is being ventilated. puts all blood profusion to the good lung. Chronic sleep apnea..leads to pulm. htn because they are used to being hypoxic and whole lung constricts.
BARBS no effect on HPV |
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Term
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Definition
milk of amnesia
1% solution 10mg/cc
standard 20cc vial
weak acid
PKa11
NEVER WATER SOLUBLE
No REM sleep
not a chiral carbon
MOA: GABA system so will be synergistic with other drugs |
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Term
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Definition
2 mg/kg IV induction dose
unconscious in 30-60 sec
duration is 3-8 minutes
98% protein bound-altered protein states will mess with this drug**
25-100 mcg/kg/min for sedation
100-300 mcg/kg/min for TIVA
contact sens 1/2 time less than 40 min (up to 8 hours of infusion) |
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Term
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Definition
smooth
fast
responsive
no tail-no hang over when waking pt up.
not effective by liver disease
not effective by renal disaes
Augments GABA does not replace GABA
Has some inhibitory effect at the nueronal nicotinic Ach receptors and NMDA receptors (usually this is in higher doses and not the primary targets)
low doses for intractable nausea and vomiting
vasoconstrictor to treat migrain headaches
treat itchying |
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Term
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Definition
GABA agonist NMDA antagonist
inc cl channel opening
dec CMRO2 CBF ICP
Can be used as an antioxidant/neuroprotective agent-free radical scavenger, membrane stablilizer
dimishes the blood flow along with metabolic requiremetn with o2 provided you dont drop map below what the brain minimal needs
maintains autoreg to the brain and the CO2 response in the brain (low co2 vessels in brain constrict inc in co2 dilation of brain vessels)
depresses EEG-we want this
SSEP-can interfer with these so not great if monitoring brain activity. ok for cord activity monitoring
at low sedation doses-dreaming amorous behavior (just a little drug pt gets all lovey dovey)
occasional myoclonis very rare (opisthotonos)
anti emetic
anti prututic (takes away itch from opiods) |
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Term
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Definition
dec arterial smooth muscles
blunts baroreceptors
dec spb
negative inotrope effect
blunts sympathetic nervous system
Vagotonic? Deb doesnt like it, blunting of barorecptor response.
watch this in peds because they are VERY sensitive to BRADYCARDIA
dec IOP |
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Term
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Definition
depressant (expecting this)
profound blunting of laryngeal reflexes (much more than you would ever get with BARBS)
you do not have protective airway reflexes!
Dose dependent resp depression
dec RR dec TV
This is the drug you can do if you HAVE TO intubate with induction agent.
HPV attenuated until the studies come out and say different. As of right now the HPV is blunted with propofol. Still ok for one lung anesthesia |
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Term
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Definition
High hepatic clearance this is good. keeps it from having a tail and preventing accumulation.
Its high protein bounding keeps it from accumulation.
Extra hepatic metabolism 30% metabolized in the lungs and some metabolized in the kidneys
Phase 2 conjugation
*can be given to pts who have no hepatic phase of liver transplant without accumulation, extra hepatic metabolism |
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Term
| Problems--> Propofol infusion syndrome |
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Definition
bradycardia-->asystole
high doses or proloned infusions
Atropine resistance
Not OK for ninas and ninos under the age of 17.
Treat with isopril or Epi if atropine is a no go.
Criticall ill adults with head inj, long term and high dose infusions >58 hours 5mg/kg/hr
-lipidemia
-fatty infiltrates
-metobolic acidosis Lactic acidosis BE-10
-Rhabdomyolysis, Myoglobinuria
Could be triggered by peri operative infusion and first sign is tachycardia
*you should see slow heart rate not tachy! Unexplained Tachy-->shut off propofol. |
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Term
| Generic problems with propofol |
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Definition
sulfate preservative (allergic potential (asthma)
Egg allergy (rare)
contamination:
bc its a lipid it supports bact growth
admin within 6 hours of drawing up
NO MIXING
SING DOSE VIAL
Moms shouldnt get when nursing
decreased apgar score with baby when mom got it for C sections
IT hurts!
Highly addictive-feeling of well being :)
give some lido but it doesnt work instantly..put it in then turn off the iv..then open iv and give propofol.
Lido good at blunting sympathetic response to intubation! 2 birds one stone!
Still dont mix even with lidocain |
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Term
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Definition
pro drug
they wanted something that could be water soluble. and also make it not burn.
Metabolized to phosphate and formaldehyde
phosphate=burn
35 mg/ml
accurate data lacking
several different dosing ways.
slower onset bc has to be metabolized before it goes to work. |
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Term
| Propofol issues/side effects |
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Definition
myocardial depressant: dec Ca from the sarcolemma/drop in SVR
N/V: -dopamine, -glutamate, -aspartate and -seratonin 5Ht3
awareness potential even with higher doses
dec BP limits use for nueroprotection
awareness potential with high doses of propofol slightly higher than awareness with inhalation agents
Rarely used in Nuero anesthesia bc of drop of MAP and you wont profuse your brain.
Not good for burst suppression in aneurysm clipping. |
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