Neuromuscular Junction Blocking Agents

1.

According to the sliding filament theory, what is the initial action in a muscle contraction?
A)
Troponin is freed and prevents actin and myosin from reacting with each other.
B)
Calcium binds to troponin, which causes the release of actin and myosin binding sites.
C)
Actin and myosin molecules react with each other sliding along the filament and making it shorter.
D)
Muscle filament relaxes or slides back to the resting position.
Ans:
C

Feedback:

Actin and myosin molecules react with each other again and again, sliding along the filament and making it shorter. This is a contraction of the muscle fiber according to the sliding filament theory. As the calcium is removed from the cell during repolarization of the muscle membrane, the troponin is freed and once again prevents the actin and myosin from reacting with each other. The muscle filament then relaxes or slides back to the resting position. Muscle tone results from a dynamic balance between excitatory and inhibitory impulses to the muscle.

2.

When causing depolarization of the muscle membranes, what neurotransmitter interacts with the nicotinic cholinergic receptors leading to the release of calcium ions?
A)
Acetylcholine
B)
Serotonin
C)
D-gluconamidoethyl methacrylate (GAMA)
D)
Epinephrine
Ans:
A

Feedback:

At the acetylcholine receptor site on the effector’s side of the synapse, the acetylcholine interacts with the nicotinic cholinergic receptors causing the depolarization. Serotonin, GAMA, and epinephrine are not part of muscle contraction and relaxation.

3.

The nurse, working in the preoperative holding area, is caring for a 70-year-old patient who is scheduled to receive succinylcholine as part of general anesthesia. When collecting the nursing history, what condition would require the nurse to notify the anesthesiologist of the need for caution?
A)
Bone fracture
B)
Malnutrition
C)
Fluid volume overload
D)
Narrow-angle glaucoma
E)
Pregnancy
Ans:
A, B, D

Feedback:

Succinylcholine should be used with caution in patients with fractures because the muscle contractions it causes might lead to additional trauma; in patients with narrow-angle glaucoma or penetrating eye injuries because intraocular pressure increases. Extreme caution is necessary in the presence of genetic or disease-related conditions causing low plasma cholinesterase levels (e.g., cirrhosis, metabolic disorders, carcinoma, burns, dehydration, malnutrition, hyperpyrexia, thyroid toxicosis, collagen diseases, exposure to neurotoxic insecticides).

4.

The nurse is caring for a patient who received succinylcholine during surgery. The nurse would expect the patient to spend more time in the postanesthesia care unit due to prolonged paralysis and inability to breathe if the patient was from what ethnic group?
A)
American Japanese
B)
Alaskan Eskimos
C)
Native Americans
D)
Hawaiian natives
Ans:
B

Feedback:

Alaskan Eskimos belong to a genetic group that is predisposed to low plasma cholinesterase levels, making them susceptible to prolonged paralysis after succinylcholine use. The other ethnic groups do not have this genetic predisposition.

5.

A patient scheduled for surgery is to have a nondepolarizing neuromuscular junction (NMJ) blocker as adjunctive anesthesia. The nurse will have cause for concern about prolonged paralysis if the patient has been taking what medication?
A)
An aminoglycoside
B)
Aminophylline
C)
A barbiturate anesthetic
D)
A cephalosporin
Ans:
A

Feedback:

Combining nondepolarizing NMJ blockers with aminoglycosides can result in prolonged paralysis, and this combination should be avoided. This interaction does not occur with barbiturate anesthetics, cephalosporins, or aminophylline.

6.

A patient is having outpatient surgery that should last only 45 minutes. The patient is planning to go home immediately after the surgery is complete. What nondepolarizing neuromuscular junction blocker will most likely be used as an adjunct therapy to general anesthesia for this patient?
A)
Atracurium (Tracrium)
B)
Cisatracurium (Nimbex)
C)
Pancuronium (Pavulon)
D)
Rocuronium (Zemuron)
Ans:
D

Feedback:

Rocuronium has a rapid onset of action and a short duration, making it a drug of choice for outpatient surgical procedures when the patient will be leaving to go home and will need to be awake, alert, and mobile. Atracurium, cisatracurium, and pancuronium are associated with longer paralysis and recovery.

7.

A patient is taking aminophylline for their chronic obstructive pulmonary disease. The patient is about to undergo emergency surgery and will receive an neuromuscular junction (NMJ) blocker as part of the procedure. It is important for the nurse to take what action?
A)
Make sure the patient receives the aminophylline on a regular schedule to maintain therapeutic levels.
B)
Monitor the patient very closely for signs of early arousal and return of muscle function.
C)
Carefully explain all that is going on because the patient will be unable to talk.
D)
Switch the patient to theophyllines before the procedure begins.
Ans:
B

Feedback:

Aminophylline can cause a decreased effectiveness of NMJ blockers, leading to reduced paralysis and early return of movement. If a patient has emergency surgery and has been taking aminophylline, the patient should be carefully monitored for early arousal and return of movement. The patient will not be awake during surgery using an NMJ blocker and will be intubated to ensure respirations. Aminophylline and other xanthine derivatives like the theophyllines will have the same effect.

8.

The nurse is caring for a patient who is being maintained on mechanical ventilation. Atracurium is administered to limit the resistance to mechanical ventilation. What is the nurse’s priority assessment?
A)
Hypotension
B)
Tachycardia
C)
Bradycardia
D)
Increased secretions
Ans:
C

Feedback:

Bradycardia is a common adverse effect associated with atracurium. The nurse should monitor the patient regularly to avoid serious adverse effects. Increased secretions and hypotension are common with tubocurarine. Option B is a distracter.

9.

The nurse is preparing a patient for surgery who will receive a neuromuscular junction blocker during the procedure. It is important for the nurse to review the patient’s medication history for concurrent use of what?
A)
Angiotensin-converting enzyme (ACE) inhibitors
B)
Beta blockers
C)
Calcium channel blockers
D)
Montelukast
Ans:
C

Feedback:

When calcium channel blockers are used concurrently with neuromuscular junction blockers, the patient is at increased risk of prolonged paralysis. The dose of the neuromuscular junction blocker should be lowered if this combination cannot be avoided and the patient should be monitored closely. There is no anticipated drug–drug interaction with ACE inhibitors, beta blockers, or montelukast.

10.

An elderly patient has received a neuromuscular junction blocker during surgery. What would be an appropriate nursing diagnosis for this patient?
A)
Excess fluid volume
B)
Risk for impaired skin integrity
C)
Deficient fluid volume
D)
Chronic confusion
Ans:
B

Feedback:

An elderly or frail patient will need extra nursing care to prevent skin breakdown during the period of paralysis because skin tends to be thinner and more susceptible to breakdown. Therefore, risk of impaired skin integrity would be an appropriate nursing diagnosis. Fluid excess or deficit should not be a concern and the patient may be acutely confused when awakening, but there is no reason to think he or she would remain chronically confused if he was not before surgery.

11.

What are the primary uses of neuromuscular junction blockers (NMJ) blockers? (Select all that apply.)
A)
To facilitate endotracheal intubation
B)
To sedate patient for general anesthesia
C)
To prevent injury during electroconvulsive therapy
D)
To provide greater ease in extubating patient
E)
To facilitate mechanical ventilation
Ans:
A, C, E

Feedback:

NMJ blockers are primarily used as adjuncts to general anesthesia, to facilitate endotracheal intubation, to facilitate mechanical ventilation, and to prevent injury during electroconvulsive therapy. NMJ blockers do not sedate the patient who will be paralyzed after administration but will remain alert unless another medication is given. These medications would not be given before extubation because respiratory muscles would be paralyzed, resulting in the inability to breathe.

12.

The pharmacology instructor is discussing nondepolarizing neuromuscular junction blockers (NMJ) blockers with the nursing class. How would the instructor explain the action of nondepolarizing NMJ blockers?
A)
Blocks acetylcholine (ACh) from acting
B)
Acts like ACh then prevents repolarization
C)
Takes the place of ACh in the depolarizing/repolarizing process
D)
Stops depolarization in the axion
Ans:
B

Feedback:

Depolarizing NMJ blockers cause muscle paralysis by acting like ACh. They excite (depolarize) the muscle and prevent repolarization and further stimulation. Options A, C, and D are incorrect.

13.

A patient is to have surgery and it is planned that atracurium (Tracrium) is to be used as an adjunct to general anesthesia. How will the atracurium work?
A)
Act as agonist to acetylcholine
B)
Stops depolarization in the axion
C)
Act as antagonist to acetylcholine
D)
Stops repolarization in the axion
Ans:
C

Feedback:

Nondepolarizing neuromuscular junction blockers compete with acetylcholine (ACh) for the ACh receptor site and after they occupy the site, stimulation cannot occur. This results in paralysis because the muscle cannot respond. Other options are incorrect.

14.

The nurse is caring for a patient who is receiving pancuronium (Pavulon) to facilitate mechanical ventilation. The patient is also receiving a barbiturate. How will the nurse administer these two medications?
A)
They can be mixed and given in the same syringe.
B)
Administer IM quickly after mixing the two drugs.
C)
Shake vigorously when mixed in one syringe.
D)
If given together, a precipitate may form.
Ans:
D

Feedback:

Do not mix this drug with any alkaline solutions such as barbiturates because a precipitate may form, making it inappropriate for use. Pancuronium is only given IV. Shaking does not prevent precipitation.

15.

The nurse is caring for a patient who is scheduled for abdominal surgery in the morning and is scheduled to receive rocuronium (Zemuron). The patient asks the nurse to describe the adverse effects of rocuronium. What would the nurse describe for the patient?
A)
“This drug is associated with pulmonary hypertension.”
B)
“This drug contains benzyl alcohol.”
C)
“This drug is associated with bradycardia.”
D)
“This drug is associated with an increased heart rate.”
Ans:
A

Feedback:

Rocuronium may be associated with pulmonary hypertension. Cisatracurium (Nimbex) contains benzyl alcohol; Atracurium (Tracrium) is associated with bradycardia; and Pancuronium (Pavulon) is associated with an increased heart rate.

16.

The postanesthesia care unit (PACU) nurse is caring for a patient that had succinylcholine (Anectine) as an adjunct to anesthesia. What is the nurse’s priority assessment while caring for this patient?
A)
Movement
B)
Temperature
C)
Mental status
D)
Heart rate
Ans:
B

Feedback:

Succinylcholine is more likely to cause malignant hyperthermia than other drugs so it is very important that the nurse carefully monitor the patient’s temperature while in the PACU. Movement, mental status, and heart rate monitoring are all routine components of PACU care, but after receiving this medication, temperature monitoring becomes the priority.

17.

The nurse is caring for a patient scheduled for abdominal surgery in the morning. The patient confides that he or she watched a movie last week about someone who had surgery and the anesthetic did not work, but no one knew because that patient could not move. What nursing diagnosis will the nurse include in this patient’s plan of care?
A)
Alteration in fluid volume
B)
Deficient knowledge regarding drug therapy
C)
Fear related to paralysis
D)
Risk for skin impairment
Ans:
C

Feedback:

Nursing diagnoses related to drug therapy may include Fear related to paralysis. This care plan would not include alteration in fluid volume; deficient knowledge regarding drug therapy; or risk for skin impairment.

18.

The nurse is caring for a patient in the intensive care unit who has been receiving neuromuscular junction (NMJ) blockers, sedatives, and analgesics for the past 2 weeks. The NMJ blocker therapy has been discontinued and the other medications are being reduced gradually. The patient is now alert and awake, communicating with his or her family by using paper and pencil. The family asks why the patient cannot sustain normal respirations. What is the nurse’s best response? (Select all that apply.)
A)
“His or her muscles need to get their strength back again.”
B)
“This is a common occurrence in situations like this.”
C)
“He or she is likely to breathe better each day.”
D)
“The drugs created temporary muscle damage.”
E)
“He or she will not be taken off the mechanical ventilator until he is ready.”
Ans:
A, B, C, E

Feedback:

After 2 weeks of muscle paralysis, the muscles are weak and will take time to strengthen as the patient begins using them again. Profound and prolonged muscle paralysis is always possible; patients must be supported until they are able to resume voluntary and involuntary muscle movement. When the respiratory muscles are paralyzed, depressed respiration, bronchospasm, and apnea are anticipated adverse effects so the patient will remain ventilated until he or she can demonstrate adequate respiratory effort. The drugs did not damage the muscle, but lack of use has weakened them.

19.

The nurse is caring for a very anxious 33-year-old female patient scheduled for abdominal surgery today. The patient says the anesthesiologist said she would receive succinylcholine (Anectine) during surgery and asks the nurse how long it will take before the medicine starts to work. What is the nurse’s best response?
A)
1 to 2 minutes
B)
30 to 60 seconds
C)
5 to 10 minutes
D)
30 minutes
Ans:
B

Feedback:

Succinylcholine has an onset of action of 30 to 60 seconds. The other options are incorrect.

20.

The patient returns from surgery complaining about muscle pain after receiving succinylcholine during the procedure. After reviewing the postoperative orders, which of these ordered analgesics will the nurse administer to treat this pain?
A)
Aspirin
B)
Acetaminophen (Tylenol)
C)
Ketorolac (Toradol)
D)
Morphine
Ans:
A

Feedback:

Succinylcholine is associated with muscle pain, related to the initial muscle contraction reaction. A nondepolarizing neuromuscular junction blocker may be given first to prevent some of these contractions and the associated discomfort. Aspirin also alleviates much of this pain after the procedure. Tylenol is not an antiinflammatory medication and would not be appropriate. Toradol and morphine provide stronger pain relief than what is indicated for this discomfort.

21.

A student asks the pharmacology instructor how succinylcholine differs from acetylcholine (ACh). What should the instructor respond?
A)
“Succinylcholine is not broken down instantly.”
B)
“It results in a prolonged contraction of the muscle.”
C)
“The muscle becomes hyper stimulated by succinylcholine.”
D)
Succinylcholine’s duration of action is about 2 hours.”
Ans:
A

Feedback:

Unlike endogenous ACh, succinylcholine is not broken down instantly. Succinylcholine, a depolarizing NMJ blocker, attaches to the ACh-receptor site on the muscle cell, causing a prolonged depolarization of the muscle. This depolarization causes stimulation of the muscle and muscle contraction (seen as twitching) and then as flaccid paralysis, so the contraction of the muscle is not prolonged and the muscle is incapable of being stimulated. The duration of effects of succinylcholine is 4 to 6 minutes and not 2 hours.

22.

The certified registered nurse anesthetist documents the anesthesia plan as using a depolarizing neuromuscular junction (NMJ) blocker as adjunct to other anesthetics on the patient when they go to surgery. The nurse would understand from this note that the patient will receive what drug?
A)
Rocuronium (Zemuron)
B)
Pancuronium (Pavulon)
C)
Succinylcholine (Anectine, Quelicin)
D)
Cisatracurium (Nimbex)
Ans:
C

Feedback:

Currently the only agent classified as a depolarizing NMJ blocker is succinylcholine. rocuronium, pancuronium, and cisatracurium are all nondepolarizing NMJ blockers.

23.

The nurse administers pancuronium to the mechanically ventilated patient in the pediatric intensive care unit. What assessment finding would the nurse suspect is an adverse effect resulting from the drug?
A)
Bradycardia
B)
Bronchospasm
C)
Should not be used in neonates
D)
Associated with pulmonary hypertension
Ans:
B

Feedback:

Adverse effects of pancuronium include respiratory depression, apnea, bronchospasm, and cardiac arrhythmias. Rocuronium is associated with pulmonary hypertension, cisatracurium should not be used in neonates, and atracurium is associated with bradycardia.

24.

The nursing student asks the mental health nurse why pancuronium was administered to the patient before electroconvulsive therapy was performed. What is the mental health nurse’s best response?
A)
To prevent aspiration of vomitus
B)
To reduce the pain of the procedure
C)
To put the patient to sleep
D)
To reduce the intensity of muscle contractions
Ans:
D

Feedback:

Pancuronium is used, in this case, to induce skeletal muscle relaxation and to reduce the intensity of muscle contractions in electroconvulsive therapy. Pancuronium has no analgesic or amnesic effects. It would not reduce the risk of aspiration unless an endotracheal tube was placed with the cuff inflated and then it would not be the drug that was preventing aspiration.

25.

When a nondepolarizing neuromuscular junction blocker is used as an adjunct to surgery, what classification of medications could reverse the neuromuscular blockage leading to early arousal and return of muscle function?
A)
Xanthines
B)
Barbiturates
C)
Opiates
D)
Antihypertensives
Ans:
A

Feedback:

Administering xanthines (e.g., theophylline, aminophylline) could result in reversal of the neuromuscular blockage. Patients receiving this combination of drugs should be monitored very closely during the procedure for the potential of early arousal and return of muscle function. Barbiturates, opiates, and antihypertensives do not reverse neuromuscular blockage.

26.

The nursing instructor asks the student nurse what causes the respiratory obstruction that can occur with many of the depolarizing neuromuscular junction (NMJ) blockers. What is the student’s most accurate response?
A)
Acetylcholine (ACh)
B)
Histamine release
C)
Serotonin
D)
Hyperkalemia
Ans:
B

Feedback:

The histamine release associated with many of the depolarizing NMJ blockers can cause respiratory obstruction with wheezing and bronchospasm. Hyperkalemia is an adverse effect of the depolarizing NMJ blockers, ACh is what is acted on by the NMJ blockers, and serotonin is a distracter for this question.

27.

The nurse is assisting the nurse practitioner who is preparing to intubate the patient. The nurse practitioner has ordered atracurium and midazolam (Versed), a short acting benzodiazepine used to sedate the patient. In what order will the nurse administer these medications?
A)
It does not matter; they can be given in any order.
B)
Give the midazolam first and then atracurium a few moments later.
C)
Give atracurium and then give midazolam a few moments later.
D)
Benzodiazepines are contraindicated with atracurium.
Ans:
B

Feedback:

Atracurium induces muscular paralysis resulting in the inability to breath due to paralysis of respiratory muscles but it has no impact on perception of consciousness. Receiving this drug before being sedated would be frightening and extremely anxiety provoking for the patient, so the sedative should be given first to reduce perception and consciousness before administering atracurium. There is no contraindication of benzodiazepines and the order they are given does matter.

28.

When a normal muscle functions, several actions take place. In what order do these actions occur?
1. Acetylcholine (ACh) is broken down by acetylcholinesterase.
2. ACh interacts with the nicotinic cholinergic receptors.
3. ACh is released by the motor nerve.
4. ACh crosses the synaptic cleft.
5. The muscle membrane is depolarized.
6. The muscle membrane is repolarized.
Put these actions in the correct order.
A)
1, 3, 5, 2, 4, 6
B)
2, 4, 6, 5, 3, 1
C)
6, 5, 4, 1, 2, 3
D)
3, 4, 2, 5, 1, 6
Ans:
D

Feedback:

Normal muscle function involves the arrival of a nerve impulse at the motor nerve terminal, followed by the release of the neurotransmitter, ACh into the synaptic cleft. At the acetylcholine receptor site on the effector side of the synapse, ACh interacts with the nicotinic cholinergic receptors, causing depolarization of the muscle membrane. ACh is then broken down by acetylcholinesterase (an enzyme), freeing the receptor for further stimulation.

29.

The patient has been mechanically ventilated for the past week and is receiving a neuromuscular junction (NMJ) blocker, an analgesic, and a sedative. The goal is to extubate the patient. What medication will the nurse stop administering first?
A)
NMJ blocker
B)
Sedative
C)
Analgesic
D)
All three medications will be stopped at the same time.
Ans:
A

Feedback:

NMJ blockers have no effect on pain perception or consciousness and should not be used without sedation so the NMJ blocker should be removed first. Because the patient has been receiving analgesics for a week, he or she will have to be weaned off them to overcome dependence. Sedatives can be removed more quickly after the NMJ blocker’s effects are gone.

30.

The student asks the physiology instructor where the motor neuron communicates with a skeletal muscle fiber. What would the instructor respond?
A)
Synapse
B)
Neuromuscular junction
C)
Synaptic cleft
D)
Afferent junction
Ans:
B

Feedback:

The neuromuscular junction (NMJ) simply is the point at which a motor neuron communicates with a skeletal muscle fiber. The synapse and synaptic cleft are part of the NMJ. The afferent junction is a distracter for this question.

31.

What drug will the nurse administer to reverse the actions of neuromuscular junction (NMJ) blocker?
A)
Cholinesterase inhibitor
B)
Xanthine
C)
Halothane
D)
Aminoglycoside
Ans:
A

Feedback:

Ensure that a cholinesterase inhibitor is readily available to overcome excessive neuromuscular blockade caused by nondepolarizing NMJ blockers. Although xanthines reverse NMJ blocking effects, they would not be administered for that purpose because their effects are not predictable. Halothane and aminoglycosides enhance paralytic effects of NMJ blockers.

32.

How can the nurse assess the degree of neuromuscular blockage the patient is experiencing?
A)
Peripheral nerve stimulator
B)
Measure vital signs
C)
Assess response to painful stimuli
D)
Test reflexes
Ans:
A

Feedback:

Have a peripheral nerve stimulator on standby to assess the degree of neuromuscular blockade, if appropriate. Vital signs can indicate degree of sedation and assess pain sensation, but they are not an indicator of the degree of neuromuscular blockade. Response to painful stimuli would be more of an indication of effects of sedation and/or analgesic than degree of muscular blockade. Any neuromuscular junction blockage would reduce or eliminate reflexes so it would not be a means of assessing degree of blockage.

33.

Why will the nurse administer a small dose of nondepolarizing neuromuscular junction (NMJ) blocker before administering succinylcholine?
A)
To reduce discomfort of depolarization of muscles
B)
To reduce the risk of malignant hyperthermia
C)
To reduce negative effects of dantrolene
D)
To increase the duration of effect for succinylcholine
Ans:
A

Feedback:

Succinylcholine is associated with muscle pain related to the initial muscle contraction reaction. A nondepolarizing NMJ blocker may be given first to prevent some of these contractions and the associated discomfort. Administering a small dose of nondepolarizing NMJ blocker will not reduce the risk of malignant hyperthermia or increase the duration of effects. Dantrolene is a drug given to treat malignant hyperthermia.

34.

The nurse administers a sedative followed by a neuromuscular junction (NMJ) blocker after which the neonatologist attempts to intubate the patient without success. While waiting for the anesthesiologist to come to the unit to establish an artificial airway, what is the nurse’s priority of care?
A)
Reposition the patient frequently.
B)
Monitor oxygen saturation.
C)
Monitor respirations and pulse rate.
D)
Use a bag-valve-mask to ventilate the patient.
Ans:
D

Feedback:

Following administration of an NMJ blocker, the patient will be unable to breathe independently so maintaining an airway and breathing for the patient using a bag-valve mask is the nurse’s number-one priority. The patient will not be repositioned until after the artificial airway is placed (endotracheal tube or tracheostomy). Monitoring oxygen saturation and pulse will be second in priority after providing breathing for the patient. The patient will have no independent respirations until the NMJ is metabolized.

35.

The nurse is caring for the intensive care unit patient who is mechanically ventilated and receiving a neuromuscular junction (NMJ) blocker, a sedative, and an analgesic. What are priorities of nursing care for this patient? (Select all that apply.)
A)
Reposition patient frequently.
B)
Ensure care of the patient’s eyes.
C)
Monitor temperature.
D)
Provide a means for patient communication.
E)
Increase ventilator breaths per minute as needed.
Ans:
A, B, C

Feedback:

Frequent repositioning is important because the patient is unable to move and protect skin integrity independently. The loss of blink reflex due to muscle paralysis from NMJ blockers can result in conjunctival damage so eye care is very important. Monitor patient temperature for prompt detection and treatment of malignant hyperthermia. The patient cannot communicate while receiving NMJ blocker. Ventilator changes are made by physician order in most facilities and are usually based on arterial blood gas results.