6- Neuromuscular Blocking Agents Flashcards by A H

Where do NA+ ion bind when an action potential is undergoing?

The presynaptic neuron axon terminal membrane

How well did you know this?

Not at all

Perfectly

What ion voltage gates are open after NA+ channels are open?

Ca2+

How well did you know this?

Not at all

Perfectly

What does Ca2+ do?

triggers the fusion of acetylcholine vesicles with the presynaptic membrane

How well did you know this?

Not at all

Perfectly

The binding of acetylcholine to the postsynaptic membrane chemically opens what gates?

Na+ gate channels that depolarize the postsynaptic membrane

How well did you know this?

Not at all

Perfectly

What happens to acetylcholine in the synaptic cleft after the action potential?

Broken down by acetylcholinesterase into Acetyl CoA + choline

How well did you know this?

Not at all

Perfectly

What happens to the acetylcholine in the presynaptic cell after an action potential?

Synaptic transmission (acetylcholine and vesicles are recycled

How well did you know this?

Not at all

Perfectly

What happens to acetylcholine once they enter the synaptic cleft?

Bind to receptors on the postsynaptic membrane

How well did you know this?

Not at all

Perfectly

The action potential travels along what tubule

T-tubules

How well did you know this?

Not at all

Perfectly

What happens after the action potential travels along the T-tubules?

It induces the Sarcoplasmic reticulum

How well did you know this?

Not at all

Perfectly

What is released once the action potential induces the Sarcoplasmic reticulum?

More Calcium

How well did you know this?

Not at all

Perfectly

What does Ca2+ bind to?

Troponin

How well did you know this?

Not at all

Perfectly

What does Troponin relieve?

It relieves tropomyosin from the myosin binding site

How well did you know this?

Not at all

Perfectly

How does myosin bind to actin?

Via ATP

How well did you know this?

Not at all

Perfectly

What happens when ATP is hydrolyzed?

a power stroke occurs

How well did you know this?

Not at all

Perfectly

During a power stroke, what is brought together?

Z lines

How well did you know this?

Not at all

Perfectly

When Z lines are brought together what does it lead to?

Muscle contraction

How well did you know this?

Not at all

Perfectly

During a normal action potential what neurotransmitter binds to the Nicotinic ACh-receptor?

ACh

How well did you know this?

Not at all

Perfectly

During a (depolarizing muscle relaxant) action potential what neurotransmitter binds to the Nicotinic ACh-receptor?

Depolarizing muscle relaxant

How well did you know this?

Not at all

Perfectly

What breaks down the depolarizing muscle relaxant and where is it returned?

broken down by pseudocholinesterase and returned to the BLOOD

How well did you know this?

Not at all

Perfectly

What type of drug is Succinylcholine?

Depolarizing NMBA

How well did you know this?

Not at all

Perfectly

What is the onset of IV Succinylcholine?

30 - 60 seconds

How well did you know this?

Not at all

Perfectly

What are the routes of administration of Succinylcholine and what dose?

IV 1 mg/kg

IM 4 mg/kg

How well did you know this?

Not at all

Perfectly

To what receptors does Succinylcholine bind?

Nicotinic postsynaptic receptors

How well did you know this?

Not at all

Perfectly

What signs are seen upon the binding of Succinylcholine to the Nicotinic receptors?

1- Depolarization

2- Fasciculation

3- Flaccid paralysis

How well did you know this?

Not at all

Perfectly

True or False: Fasciculation ceases when all nicotinic receptors are bound to nicotinic receptors?

True

What age group is at increased risk of muscle pain with muscular builds after SCh?

Adolescents

What is the duration of Succinylcholine?

3-5 minutes

What are the clinical effects of Succinylcholine paralysis?

1- Adductor pollicis (10 minutes) 2- Diaphragm (5 min)

What is the first dose consideration seen with Succinylcholine?

Bradycardia

What is the second dose consideration seen with Succinylcholine?

Asystole

How do you attenuate to Succinylcholine induced Bradycardia and asystole? And what signs are sometimes seen?

Administer Atropine or glycopyrrolate Increase in catecholamine release and tachycardia

What type of trigger is Succinylcholine?

Malignant hyperthermia

How does Succinylcholine lead to MH?

Increase in serum potassium by 0.5-1 mEq/L Hyperkalemia

What type of patients needs extra care with Succinylcholine?

Pts that aren't normokalemic rental faliure patients

What is a phase II block?

1- continuous activation of ACh receptors which leads to ongoing shifts of NA+ into the cell and K+ out of the cell 2- Receptors do not respond appropriately to ACh, neuromuscular blockade is prolonged

True or False: Succinylcholine is incriminated as the trigger of allergic reactions more often than any other drug used in anesthesia?

True approcimately 1:5,000 - 1:10,000

Abnormality of pseudocholinesterase activity leads to prolonged paralysis in two abnormal ways?

1- Hetrozygous -> 15 min more delay in paralysis 2- Homozygous -> 1-2 hours of delay - Homozygous population is 1:3,000 - 1:10,000

How is pseudocholinesterase abnormality tested?

Dibucaine number (genetic testing) Normal 80 Hetro 50 Homo 20

True or False: Non-depolarizing and Depolarizing Neuromuscular blockers bind differently to the nicotinic receptors?

False The only difference: Depolarizing such as Succinylcholine is returned into the BLOOD Non depolarizing such as Rocuronium is returned to the LYMPH

Non-depolarizing agents are classed based on chemical structure into?

1- Aminosteriods (Rocuronium, Vecuronium pancuronium) 2-Benzylisoquinolinium (mivacurium, atracurium, cisatracurium)

For pancuronium, what is the bolus dose, and where is metabolized?

0.05-0.1 mg/kg (Nondepolarizing Aminosteriods) renal

For vecuronium, what is the bolus dose, and where is metabolized?

0.08- 0.1 mg/kg (Nondepolarizing Aminosteriods) Hepatic

For Rocuronium, what is the bolus dose, and where is metabolized?

0.6 - 1 mg/kg (Nondepolarizing Aminosteriods) Hepatic

For Atracurim, what is the bolus dose, and where is metabolized?

0.4- 0.5 mg/kg (Nondepolarizing Benzylisoquinolinium ) Hoffmann reaction

For Cisatracurium, what is the bolus dose, and where is metabolized?

0.1-0.2 mg/kg (Nondepolarizing Benzylisoquinolinium ) Hoffmann reaction

For Succinylcholine, what is the bolus dose, and where is metabolized?

1 mg/kg (depolarizing) Plasma cholinesterase

How many stimuli are delivered and at what time/frequency for the Train of Four Monitoring?

4 stimuli 2HZ over 1.5 seconds

What is the percent of blocked receptors for the Train of Four Count?

TOFC of 1= >95% of receptors blocked TOFC of 2= 85-90% of receptors blocked TOFC of 3= 80-85% of receptors blocked TOF of 4= 70-75% of receptors blocked

How is the estimated degree of the block calculated?

ratio of T4/T1

Majority of Surgeries require what percent of block?

80% TOFC of 3

What are the clinical signs of the level of paralysis?

1- Sustained head lift = 50% blockade 2- Hand grasp= 50% blockade 3- TV > 5 ml/kg = 80% blockade or less

What areas precede the adductor pollicis by 1-2 min following an NMBD?

Larynx and orbicularis oculi

True or False: Muscles with relatively high blood flows have faster onset and recovery?

TRUE such as diaphragm, masseter, and laryngeal muscles

True or False: the effectiveness of reversal agents depends directly of the degree of recovery present and should be given on when 4 twitches are visible " preferably measured at the adductor pollicis"?

TRUE

Why isn't the presence of spontaneous ventilation considered a sign of adequate neuromuscular recovery?

Because the diaphragm recovers earlier than the much more sensitive upper airway muscles EX: Geniohyoid recovers on average at the same time as the adductor pollicis

Reversal agents are divided into two types?

Anticholinesterases Sugammadex

What is the MOA of Anticholinesterases?

Impairs the breakdown and rate of ACh which in return allows the excess ACh to displace the non-depolarizing NMBA

What is the dose of Neostigmine?

0.05 mg/kg max 5mg

When Neostigmine is given, Glycopyrrolate is given?

0.2 mg of Glyco for every 1 mg of neo max 1mg

Preceding NEO, Atrpine/ Edrophonium given, what crisis could result?

Acute cholinergic crisis

How does Sugammadex work?

it encapsulates nondepolarizing steroidal NMBAs in a 1:1 ratio

What should you tell your female patients after giving Sugammadex?

Decreased effectiveness of hormonal birth control

what is the dose of Sugammadex?

Based on the depth of NMBA TOF> 2 2mg/kg TOF=1 4mg/kg TOF=0 16mg/kg (in this case Roc can not be used for 24 hrs)

what is the emergency dose of Sugammadex?

16mg/ kg