Neuromuscular blockers Flashcards
Discuss the two assessments that should be addressed prior to administration of a neuromuscular blocking agent (NMBA).
- Assess endotracheal tube (ET) placement**
- Patient must have adequate sedation AND analgesia prior to initiation of a Neuromuscular Blocking Agent (NMBA)***
—>Continuous Intravenous (IV) sedative*
Must have amnestic properties and a deeper level of sedation
—>Continuous IV analgesic*
Morphine, Fentanyl
Succinylcholine (one dose hyperkalemia)
ADR
Hyperkalemia***
Aminosteroidal vs. Benzylisoquinolinium
Aminosteroidal not recommended with dose corticosteroids (i.e. ≥1 gram methylprednisolone
Pancuronium
(~90% of patients) vagolytic effect (transient) Increase: HR, BP, CO
Patient with cardiovascular disease will not tolerate
Vecuronium
Metabolism and eliminated: Renally and hepatically eliminated – Never use with renal or hepatic insufficiency
Cisatracurium
Preferred in critically ill patients with organ dysfunction
Bolus does – do not worry about renal inssuficnecy
Rocuronium
Onset: 3 minutes
Duration of blockade mildly affected by renal or hepatic impairment
Factors altering effects of NMBA: Potentiating Block
Antibiotics
Aminoglycosides, clindamycin, amphotericin B
Cardiovascular agents
Calcium channel blockers, furosemide, β-blockers, lidocaine, procainamide, quinidine
Corticosteroids –IV and PO only
Myasthenia gravis
The interactions are NOT contraindicated when using a NMBA but should be considered when initiating/ adjusting therapy
Factors altering effects of NMBA: Antagonize Block
Phenytoin
Pregnancy
Burns
The interactions are NOT contraindicated when using a NMBA but should be considered when initiating/ adjusting therapy
Recovery from paralysis
occurs in the reverse order—when you see the patients blinking, the patient has drug out of the system
Paralysis occurs sequentially
Smaller, fast twitch muscles
i.e. eyes and larynx
Limbs
Neck
Trunk
Upper airway
Intercostals and diaphragm
Until respirations
Monitoring of NMBA: Clinical exam
Visual, tactile assessment of patients’ muscle tone
Observation of skeletal muscle and respiratory efforts
Monitoring allows for lowest effective NMBA dose
Minimizes adverse effects or prolonged muscle weakness
Signs and symptoms suggesting inadequate sedation and analgesia (increased–> HR, BP, sweating
Monitoring of NMBA: TOF
Two small conductive pads are applied at the wrist to deliver a series of four mild electric stimuli
Monitor q4hours to avoid muscle weakness
Mark anatomic sites: Facial nerve and Ulnar nerve
Responses: Out of 4 Twitches Responses Percentage of block 4 0-75% 3 75-80% 2 80-90% 1 90% 0 100%
1/4 to 2/4 – Requires no change with infusion rate Response
Troubleshooting: Weak batteries Unsecured lead wire attachments Peripheral or periorbital edema Diaphoresis Incorrect positioning Directly stimulating orbicularis oculi
Reversal of Neuromuscular Blockade
Neostigmine
After surgery
Dose: 0.5- 2.5 mg IV
–>Give with atropine or glycopyrolate to prevent adverse effects
Neostigmine-IV only
Mechanism of action: anti-acetylcholinesterase agent
AE
Adverse effects Bradycardia* Salivation Bronchoconstriction Confusion
Adverse Effects of NMBAs
Slowed gastric motility – on phentyl or morphine drip
increase risk of VTE May mask seizure activity may mask proper sedation/analgesia skin break down corneal abrasiaon
Continuous Infusion NMBA Interventions
Airway/breathing
Proper endotracheal tube (ET) placement
Ventilator alarms set
Sedation and analgesia
- Continuous administration of sedation and analgesia
- -Sedative with amnestic properties
- —>Benzodiazepine (lorazepam, midazolam), propofol
Assess for pain
Neuro-exam (per unit practice)
Immobility Skin breakdown prevention -Eye care --->Ocular lubricants -Specialty bed consult -Turn/positions
DVT prophylaxis
- Enoxaparin
- Heparin
- Mechanical prophylaxis
Stress Ulcer prophylaxis
- H2 blockers
- PPI
Foot drop boots/ Multi-podus boots
Wrist splints
Physical Therapy
Family education
Nutrition
+/- Laxatives/ Stimulants
Discuss the appropriate indications for neuromuscular blocking agents.
Short-term Indications
Facilitate short-term procedures
Endotracheal intubations
Long-term Indications
Improve ventilator synchrony to enhance oxygenation
Prevent interference with surgical repair
Increased intracranial pressure
Therapeutic hypothermia after cardiac arrest
Prevent shivering
When all other means have been tried without success
-Used for intubated patients with persistent hypoxia despite ADEQUATE sedation and analgesia
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Depolarizing agents
Succinylcholine
IV bolus only
Onset of action and duration: onset within 60 seconds and lasts 3-6 minutes –FASTEST***
Metabolized in the blood; Not metabolized renally or hepatically
Adverse effects: Hyperkalemia***, bradycardia, increase intracranial pressure, malignant hyperthermia
Depolarizing agents
Succinylcholine
IV bolus only
MOA
Competitively inhibits the ACh receptor on the motor endplate
The drug binding to the receptor prevents the change in the receptor so the endplate potential is not generated
The nerve impulse stops
An action potential in the muscle cell fails to occur and the muscle fibers cannot contract
Aminosteroidal vs. Benzylisoquinolinium
Aminosteroidal not recommended with increase dose corticosteroids (i.e. ≥1 gram methylprednisolone)
Pancuronium
IV bolus only
Onset: 3 – 5 minutes
Duration: Long-acting 90-100 minutes
Active metabolite: 3-hydroxypancuronium
Active metabolite: 3-hydroxypancuronium
Adverse effects:
(~90% of patients) vagolytic effect (transient HR) BP, cardiac output
–Patient with cardiovascular disease will not tolerate
Skeletal muscle weakness, polyneuropathy, myopathy
—Can occur with all continuous infusion neuromuscular blockers
Vecuronium
IV bolus and Continous infusion
Active metabolite: 3-desacetylvecuronium
Adverse effects:
Minimal cardiovascular effects
Skeletal muscle weakness, polyneuropathy, myopathy
Prolonged paralysis in renal and liver impairment
Whats the Onset, Duration of action, Motablism
Onset: 1- 2 minutes (2nd Fastest)
Duration: Intermediate acting 35- 40 minutes
Metabolism and eliminated: Renally and hepatically eliminated – Never use with renal or hepatic insufficiency.
Cisatracurium
IV bolus and continuous infusion
Onset: 3- 5 minutes
Duration: 45- 60 minutes
How is this metabolized?
Metabolized by ester hydrolysis and Hofmann elimination
Adverse effects:
Duration of blockade not affected by renal or hepatic impairment - NOT Renally ELIMATED
Preferred in critically ill patients with organ dysfunction
Bolus does – do not worry about renal inssuficnecy.
Rocuronium IV bolus and continous infusion Onset: 3 minutes Duration: 30- 60 minutes Mildly hepatically metabolized
Adverse effects:
Duration of blockade mildly affected by renal or hepatic impairment
Skeletal muscle weakness, polyneuropathy, myopathy
