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Anes. Pharm I Test 1
Succinylcholine
| Question | Answer |
|---|---|
| What is the ED 95 of Succinylcholine (Anectine)? | 0.3 mg/kg |
| What is the intubating dose of Succinylcholine (Anectine)? | 1 - 1.5 mg/kg IV and 4 - 5 mg/kg IM |
| What is Succinylcholine's (Anectine) onset? | 45 - 90 seconds (whether given IV or IM) |
| What is Succinylcholine's (Anectine) duration? | 5 - 10 minutes (8 minutes) |
| How is Succinylcholine (Anectine) metabolized? | hydrolyzed by plasma cholinesterase |
| What is Succinylcholine's method of action? | Binds to both alpha subunits of the postsynaptic nicotinic receptors & mimics acetylcholine by causing the cell to depolarize. |
| What action allows the cells at the NMJ to repolarize after succinylcholine has been given? | the hydrolization of succinylcholine by plasma cholinesterase |
| What is the chemical structure of Succinylcholine (Anectine)? | 2 acetylecholine molecules linked by acetate methyl groups |
| True or False: Succinylcholine (Anectine) can also affect Acetylcholine receptors elsewhere in the body besides the NMJ.... | True |
| Why will you most certainly see bradycardia with any re-dosing of Succinylcholine (Anectine)? | because succinyl monocholine (a metabolite of SCh) also has affinity for muscarinic receptors in the SA node |
| If Succinylcholine (Anectine) binds with muscarinic receptors in the SA node or affects parasympathetic receptors what side effect will you see? | bradycardia |
| If Succinylcholine (Anectine) affects sympathetic ganglia what possible side effects of the drug will you see? | tachycardia and hypertension |
| What are the indications for use of Succinylcholine (Anectine)? | aspiration risk (short onset), difficult airways (short duration) |
| What occurs in a phase I block with Succinylcholine (Anectine)? | Depolarization with initial contractions, and then paralysis because cell can't repolarize. |
| In a phase I block will anticholinesterase (reversal agent) reverse the block or enhance it? | enhance it |
| What is a phase II block? | a NMB caused by the depolarizer Succinylcholine that mimics a non depolarizing blockade |
| What kinds of situations predispose a phase II block? | NMJ is repeatedly exposed through subsequent doses or a continuous drip of Succinylcholine, causing tachyphylaxis |
| What drug will reverse a phase II block? | an anticholinesterase drug, like edrophonium |
| What drug and dosage would you give to determine if a patient has gone into a phase II block? | edrophonium 0.1 - 0.2 mg/kg IV |
| If you give edrophonium to a patient who was on a drip of Succinylcholine and the block is attenuated (lessened), what would you assume? | Assume the patient has moved into a phase II block and give the remainder of the full dose of edrophonium to antagonize the block |
| If you give edrophonium to a patient who received multiple doses of Succinylcholine and the block is accentuated, what would you assume? | Assume the patient is in a phase I block and do not give any more anticholinesterase drugs. |
| Why do you use edrophonium with a phase II block? | Because edrophonium has no effect on plasma cholinesterase, and plasma cholinesterase is what breaks down succinylcholine |
| What controls the amount of succinylcholine that makes it to the receptor? | plasma cholinesterase |
| Recovery of neuromuscular function after the administration of Succinylcholine is prolonged by decreased concentration of what? | plasma cholinesterase |
| What are some causes of plasma cholinesterase deficiency? | severe liver disease (<20% function), pregnancy, malignancies, hypothermia, malnutrition, collagen vascular disease, hypothyroidism, genetic predisposition |
| What does the dibucaine number test for? | the genetic component of plasma cholinesterase, does not speak to the quantity, only the quality |
| What is a normal dibucaine number? | 80 |
| What dibucaine number would a person with heterozygous atypical plasma cholinesterase have? How long would SCh last in these people? | dibucaine number 40 - 60; SCh would last 30 minutes |
| What dibucaine number would a person with homozygous atypical plasma cholinesterase have? How long would SCh last in these people? | dibucaine number 20; SCh would last 3+ hours |
| What is the fluoride resistant gene? | a rare gene that causes inability to metabolize SCh |
| Any inhibition of plasma cholinesterase, no matter what is causing it, will lead to what? | prolonged duration of Sch |
| Can you give atropine as a pretreatment to prevent the bradycardic effect that Succinylcholine (Anectine) can cause? | No. It will not prevent bradycardia, it can only be used to treat it after it occurs. |
| Succinylcholine (Anectine) is a triggering agent for what medical emergency? | Malignant Hyperthermia |
| A ________ ________ is a sign of Malignant Hyperthermia, but could also be a normal response to the onset of Succinylcholine (Anectine)? | masseter spasm |
| How much does a patient's serum potassium typically increase with the administration of Succinylcholine (Anectine)? | 0.5 - 1 mEq/L |
| What conditions could lead to a potentially fatal increase in potassium related to the use of Succinylcholine (Anectine)? | damaged & diseased muscle membranes, burns/massive tissue trauma, neurologic injuries/trauma, neuromuscular disorders (ALS, MS, etc...) |
| What timeframe after a burn injury is it still safe to administer Succinylcholine (Anectine)? | within 48 hour window after burn injury; after 48 hours, proliferation of extra junctional receptors, which can last 6 months - 2 years |
| Why would the administration of Succinylcholine (Anectine) to a patient who had recent eye surgery or who has an open eye injury be of concern? | Succinylcholine can cause increased intraocular pressure |
| What potential side effect of Succinylcholine (Anectine) would be important to consider for a patient undergoing a craniotomy? | Increased ICP |
| Although Succinylcholine is commonly used for aspiration risk patients, what potential side effect of the drug could actually contribute to aspiration? | Increased Intragastric Pressure. The findings are inconsistent, but could cause GE sphincter to spontaneously open. |
| Which side effect of Succinylcholine is a patient satisfaction issue and is of concern in younger patients, who are typically ambulatory after surgery? | Mylagia |
| What is the pretreatment for myalgia caused by Succinylcholine? | NSAIDs, de-fasiculating dose of non depolarizing NMB (10% of intubating dose), and Na channel blockers (lidocaine) |
| Which potential side effect of Succinylcholine occurs mostly in pediatric patients rather than adults? | Rhabdomyelosis (myoglobinuria) |
| Why do we pretreat with a small dose of a non depolarizing NMB before the administration of Succinylcholine? | to prevent the fasiculations that occur with the onset of SCh due to widespread depolarization |
| What is a risk of pretreatment with non depolarizing NMB? | Even this small dose (10% of intubating dose) could cause paralysis in a patient with undiagnosed myasthenia gravis |
| How does pretreatment with non depolarizing NMB affect the dose of Succinylcholine given? | pretreatment requires increased dose of SCh (1.5 mg/kg) |
| What side effects can potentially be prevented or lessened by pretreatment with a non depolarizing NMB? | cardiac dysrhthymias, myalgia, increased ICP, increased intragastric pressure, increased intraocular pressure |
| Pretreatment with non depolarizing NMB has NO effect on which potentially fatal side effect of Succinylcholine? | hyperkalemia |
| The de-fasiculating dose of a non depolarizing NMB given prior to the administration of Succinylcholine is usually _____ of the intubating dose | 1/10th of the intubating dose |
Created by:
Mary Beth
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