PPT neuromuscular blocking and reversal Flashcards
First successful administration of NMB?
Curare in 1912 by Arthur Lawen a German Surgeon.
What type of antagonist is a nondepolorizing NMB?
competative antagonist.
Tell me how Succ works?
Succ. produces a prolonged depolarization of the endplate region that results in desensitization of nicotinic acetylcholine receptors; inactivation of voltage gated sodium channels at the neuromuscular junction and increase in potassium permeability in the surrounding membrane. Thus producing the failure of the action potential generation due to membrane hyperpolarization and a block ensues
what is responsible for the rapid hydorlysis of released acetylcholine to acetic acid and choline?
acetylcholinesterase (true cholinesterase)
what hydrolysis succ, and where does it occur?
plasma cholinesterase or pseudocholinesterase and it occurs mainly in the plasma.
what are all neuromuscular blockers structurally related to?
acetylcholine
what is the one NMB that is not a synthetic alkaloid?
tubocurarine which is extracted from the Amazonian vine (cheaper this way)
Nondepolorizing NMB what twho classes are their?
Steroidal
Benzylisoquinoinium
example of a Benzylisoquinolinium?
South American Indian’s arrow poisons. Tubocurarine is the most important curare alkaloid.
Atracurium
cisatracurium (nimbex)
what type of patients should you not use tubocurarine with?
not suitable for renal or liver failure patients.
intubating dose of tubocurarine?
.5-.6mg/kg
Atracurium (what is important about it’s metabolism?)
can undergo ester hydrolysis
what does laudanoisine depend on?
depends on the liver for clearance with ~70% excreted in bile with remainder in the urine
what is laudanoisine?
a metabolite of the neuromuscular-blocking drugs atracurium and cisatracurium with potentially toxic systemic effects. It crosses the blood-brain barrier easily and may cause excitement and seizure activity
what patients would laudanoisine be a problem with?
not good for liver patients, liver cirrhosis (according to class notes from Hammon talking)
cisatracurium tell me about it?
what does it come from, what elimination does it use, histamine? What patients would you use it with?
Isomer of atracurium
hoffman elimination to laudanosine and monoquatenary alcohol metabolie.
Hoffman is 77% of clearance
does not cause histamine release like atracturium if given in clinical dose range.
Good for patients with renal issues.
where does hoffman elimination occur?
in the plasma?
list steroidal NMB?
Pancuronium
Vecuronium
Rocuronium
Pancuronium remains stable for how long at room temp?
6 months
Vecuronium, if you have what kind of issues this med will last longer on you?
liver issues (principal elimination is liver)
which will you have to re-dose more often Vec or Roc?
Vecuronium
Rocuronium, onset time and potency?
fast onset (1-3 min depending on dose) 6 times less potent than vecuronium.
Roc is stable at room temp for how long?
60 days
in relation to NMB ED50 and ED95 would mean?
ED50 is 50% reduction in twitch height, and ED95 is 95% reduction in twitch height.
inhalation anesthetics potentiate the NMBlocking effects of NMB, list from most to least to potentiate.
DES>SEVO>ISO>HALO>Nitrous Oxide>barbiturate>propofol
Can Des affect your Rocuronium?
YES! Potentiates it.
Can antibiotics potentiate NMB? If so then how?
Yes, All inhibit the prejunctional release of acetylcholine and also depress postjunctional nicotinic acetylcholine receptor sensitivity to acetylcholine
Whats the relationship between clindamycin, penicillin and Ancef?
Clindamycin was given to people with allergy to penicillin at one time, so that is why you will see it, otherwise they take ancef.
Link thought between penicillin and ancef, but has now been found false.
what antibiotics potentiate NMB?
aminoglycosides polymyxins lincomycine clindamycin and tetracycline (exhibits post junctional activity only)
name some other conditions or drugs that potentiate blockade of NMBD?
hypothermia
magnesium sulfate
High magnesium concentrations inhibit calcium channels at the presynaptic nerve terminals that trigger the release of acetylcholine
quinidine an antidyshythmic
What drugs or conditions will decrease the potency of NMBD?
Chronic use of anticonvulsant therapy
hyperparathyroidism, hypercalcemia is associated with decreased sensitivity to atracurium and thus a short duration of neuromuscular blockade.
what will eat up your drugs quicker?
anticonvulsant therapy and street drug usage.
link between potency and onset of action of NMBD?
Onset of action is inversely proportional to potency of NMBD
Low potency = rapid onset
High potency = slow onset
What NMBD is the exception to the potency and drug onset time inverse rule?
atracurium
what is potency expressed in and why?
moles per kilogram
ultimately, we have a variable number of molecules chasing a fixed number of nicotinic receptors. The fewer molecules it takes (per kilogram of body weight) to achieve a given degree of receptor occupancy, the greater the affinity the drug has for the receptor. This is best expressed in micromoles per kilogram rather than in milligrams per kilogram.
what is buffered diffusion and what drugs does it occur with?
The process in which diffusion of a drug is impeded because it binds to extremely high-density receptors within a restricted space
Can be seen with high potency but not low potency drugs
Buffered diffusion causes repetitive binding to and unbinding from receptors keeping potent drugs such as tubocurarine in the neighborhood of effector sites and potentially lengthening the duration of effect
Explain the autonomic effects of NMBD?
NMBD interacts with nicotinic and muscarinic cholinergic receptors within the SNS and PNS and at the nicotinic receptors of the neuromuscular junction.
Adverse effects of tubocurarine?
marked ganglion blockade resulting in hypotension;
histamine manifestations (hypotensin, reflex tachy,bronchospasm) in susceptible patients.
adverse effects of pancuronium?
direct vagolytic effect. Can block muscarinic receptors on sympathetic postganglionic nerve terminals resulting in inhibition of a negative feedback mechanism whereby excessive catecholamine release is modulated or prevented Can also stimulate catecholamine release from adrenergic nerve terminals.
Benzylisoquinoliniums release histamine what can occur bc of this and which NMBD that falls under this category does not release histamine?
How can you help prevent histamine release?
the exception is cisatracurium.
release histamine can cause increase airway resistance and bronchospasm in patients with hyperactive airway disease
also, skin flushing, hypotension, decreased SVR, increased pulse rate.
slow administration over 60 sec.
prophylactic use of combined histamine H1 and H2 receptor antagonists.
In typical doses are steroidal NMBD associated with histamine release?
NO
which type of reaction is mediated through immune responses involving immunoglobulin E antibodies fixed to mast cells?
anaphylactic
not immune mediated and represent exaggerated pharmacologic responses in very sensitive individuals who represent a very small portion of the population
anaphylactoid reaction
Treatment of analyphylaxis?
Turn the gas off and 100% 02
IV epi 10-20 micrograms/kg (subq if no IV)
TELL THE SURGEON bc he needs to close and you are going to wake up the patient.
If IV blows before succ is given then you gas em and get an IV.
consider intubation if angioedema develops
If you give them a pressor and it stops working (push) then give fluids they may need the circulation (give norepinephrine or a phenylephrine)
treat dysrhythmias