Ch. 22: Neuromuscular Blocking Agents Flashcards
1
Q
NMBA Physiology
A
- Cholinergic nicotonic receptor postsynaptic
- ACH in presynaptic cell
- AcetylCholinesterase and reuptake clear the synapse.
- Succinylcholine is a depolarizer.
- Rocuronium & Vecuronium are non-depolarizing and compete with ACh for the receptor.
- Neostigmine, edrophonium and pyridostigmine inhibit ACHE
- Sugammadex is a Rocuronium reversal agent.
2
Q
Succinylcholine
A
1.5 mg/kg 45 second onset 6-10 min duration.
- SCh is 2 ACH connected by Ester
- Stimulates all Nicotinic and muscarinic cholinergic receptors. Parasympathetic and sympathetic.
- Broken down by PseudoCholinesterase in plasma and liver. Thus bigger doses given for RSI.
- Repeat doses can cause bradycardia, esp kids
3
Q
Succinylcholine Contraindications
A
- Personal or FH of malignant hyperthermia
4
Q
SuccinylCholine Dose
A
- 1.5mg/kg normally.
- If poor circulation 2mg/kg
- IM 4mg/kg but will be slower incomplete onset requiring BVM.
- If just estimating the weight it’s safer to go higher than lower.
- Age less than 10 2mg/kg. Less than 1 year often give atropine along with.
5
Q
SuccinylCholine Adverse Effects
A
- Fasciculations: May cause increased ICP!
- Hyperkalemia: In upregulated immature ACH receptors.
- BURNS after 3 to 5 days.
- Denervation after 3 days: SCI, stroke, GBS, ALS and MS
- Crush injury 3 days to 6 months.
- Sepsis: After 3 days.
- Myopathy: Esp kids w unknown heriditary myopathy.
- Hyperkalemia: Only ESRD, AKI w arrhythmia.
- Bradycardia: Multiple doses
- Prolonged NMB.
- Acquired PCHE deficiency liver disease, cocaine use, pregnancy, burns, BCP, Reglan, bambuerol or esmolol.
6
Q
Malignant Hyperthermia
Succinylcholine
A
TREATMENT:
- Dantrolene 2.5 mg/kg IV q 5 min. Max 10mg/kg till muscle regidity improved.
- Monitor K, ABG
Signs:
- Muscle Rigidity
- Autonomic instability
- Hypoxia
- Hypotension
- Lactic acidosis
- Hyperkalemia
- Myoglobinemia
- DIC
- Hyperthermia LATE!!
7
Q
Trismus/Masseter Muscle Spasm
SuccinylCholine
A
- Treat with Nondepolarizing NMBA
- Consider underlying Malignant Hyperthermia
8
Q
Competitive Neuromuscular Blocking Agents
Rocuronium & Vecuronium
A
Rocuronium
- 1-1.2 mg/kg
- 60 sec onset
- 40-60 min duration
Vecuronium
- 0.01 mg/kg prime 3 min 0.15 mg/kg GO
- 75-90 sec onset
- 60-75 sec duration
9
Q
Competitive Neuromuscular Blocking Agents
Pharmacology
A
- Block one or both alpha subunits of receptor
- ACHE inhibitors cause reacumulation of ACH
- Neostigmine 0.06 to 0.08 mg/kg
- Atropine 0.01mg/kg to prevent the excessive salivation and nausea of neostigmine.
- Sugammadex i Rocuronium reversal.
10
Q
Competitive NMBAs
Indications & ContraIndications
A
- Myasthenia patients may have longer paralysis
11
Q
Competitive NMBA
Dosage
A
- Rocuronium 1 to 1.2 mg/KG
- Onset 60 seconds
- Vecuronium Priming 0.01 mg/kg
- 3 min later 0.15mg/kg.
- For ongoing paralysis
- Vecuronium 0.1mg/kg
- Pancuronium 0.1mg/kg
12
Q
Competitive NMBA
Adverse Effects
A
- Pancuronium tachycardia.
- Competitive are slower and longer than SCh