Question 1

Clinical factors that potentiate neuromuscular blockade include
1)acidosis.
2)hyponatremia.
3)hypocalcemia.
4)hypokalemia.
5)hypothermia.

Accepted Answer

11ea589b_08a5_090c_91e5_f356b2258b88_TB3777_00

Question 2

A nondepolarizing agent has a(n)_____________duration of action to a depolarizing agent.

Accepted Answer

Nondepolarizing agents have a longer duration of action than the depolarizing agent succinylcholine.

Question 3

Factors that should be considered when choosing a neuromuscular blocking agent include
1)duration of procedure.
2)onset of action.
3)hemodynamic stability.
4)histamine release.
5)cost.

Accepted Answer

Selection of an appropriate neuromuscular blocking agent depends on the situation.Several factors must be taken into account when choosing an agent: duration of procedure (consider duration of action),the need for quick endotracheal intubation (consider onset of action),adverse-effect profile (hemodynamic stability,histamine release),route of elimination (especially in patients with renal or hepatic insufficiency),concurrent medications and drug interactions,and cost.

Question 4

Succinylcholine is metabolized by

Accepted Answer

Succinylcholine is metabolized by plasma cholinesterase,which is also called pseudocholinesterase.

Question 5

Succinylcholine is metabolized to

Accepted Answer

Succinylcholine has a very short duration of action,mostly owing to its rapid hydrolysis by plasma cholinesterase in blood.Succinylcholine is metabolized to succinylmonocholine,which provides weak nondepolarizing activity.Laudanosine is a breakdown product of Hofmann degradation.Laudanosine,which is eliminated primarily by the kidneys and is slowly metabolized by the liver,has a long half-life and can cross the blood-brain barrier.

Question 6

Your patient has been given neostigmine for reversal of the nondepolarizing blockade agent he received during surgery.On examination,you observe severe bradycardia and increased salivation.What is a possible explanation?

Accepted Answer

Because the reversing agents increase the levels of acetylcholine (ACh),they also increase the effects of ACh at parasympathetic ganglia,producing cholinergic autonomic side effects.Major side effects of these agents include severe bradycardia and salivation.To reduce such adverse effects,agents such as atropine or glycopyrrolate are given with the cholinesterase inhibitors.As vagolytic and anticholinergic agents,atropine and glycopyrrolate prevent the bradycardia,increased salivation,and hyperperistalsis associated with excessive ACh.

Question 7

Clinical factors that inhibit neuromuscular blockade include
1)alkalosis.
2)hypernatremia.
3)hypercalcemia.
4)thrombocytopenia.
5)hypothermia.

Accepted Answer

11ea589b_08a5_301d_91e5_61c15a688c11_TB3777_00

Question 8

A technique used for monitoring blockade that evaluates the conduction of an impulse across the neuromuscular junction using supramaximal stimulus at a frequency of 2 Hz over 2 seconds is referred to as

Accepted Answer

The most commonly used technique for monitoring blockade is the train-of-four (TOF)evaluation.In TOF,a supramaximal stimulus at a frequency of 2 Hz is applied to the nerve over 2 seconds.The nonpainful stimuli are delivered as four pulses,one every 0.5 second.The number of twitches that occur,ranging from 0 (100% blockade)to 4 (<75% blockade),are measured.Objective assessments include measurement of vital capacity,negative inspiratory force,and spontaneous respiratory rate.

Question 9

Nondepolarizing agents

Accepted Answer

Neuromuscular blocking agents (NMBAs)are divided into two types: depolarizing and nondepolarizing.Depolarizing agents bind to acetylcholine receptors and cause a sustained postsynaptic membrane depolarization.By preventing repolarization of the nerve ending,the postsynaptic ending becomes refractory and unexcitable,resulting in flaccid muscles.At the present time,succinylcholine is the only available agent in this class.Nondepolarizing agents produce paralysis and muscle weakness by competing with acetylcholine for binding at the acetylcholine receptors.By preventing the binding of acetylcholine,nondepolarizing agents block the depolarizing effects of acetylcholine,preventing muscle contraction.

Question 10

You are taking care of an intubated trauma patient who must remain immobile.The patient has a medical history of end-stage renal failure and atrial fibrillation.What is the most appropriate neuromuscular blocking agent?

Accepted Answer

Because of the lack of liver and kidney elimination,atracurium and cisatracurium provide optimal choices for patients with hepatic or renal failure.

Quiz 18: Skeletal Muscle Relaxants Neuromuscular Blocking Agents

Clinical factors that potentiate neuromuscular blockade include 1) acidosis. 2) hyponatremia. 3) hypocalcemia. 4) hypokalemia. 5) hypothermia.

A nondepolarizing agent has a(n) _____________duration of action to a depolarizing agent.

Factors that should be considered when choosing a neuromuscular blocking agent include 1) duration of procedure. 2) onset of action. 3) hemodynamic stability. 4) histamine release. 5) cost.