How does train of 4 Work?
How It Works: A battery-powered stimulator delivers a small electric current to a superficial nerve, usually the ulnar nerve. Activity stimulated by the four consecutive impulses is assessed by watching or feeling for associated muscle movement.
How does succinylcholine cause flaccid paralysis?
In less than a minute after IV administration a flaccid paralysis develops due to the development of a desensitized state where the membrane becomes repolarized, but insensitive to ACh (due to receptor desensitization).
How does succinylcholine cause hyperkalemia?
Systemic succinylcholine, in contrast to acetylcholine released locally, can depolarize all of the up-regulated AChRs leading to massive efflux of intracellular potassium into the circulation, resulting in hyperkalemia.
What is the mechanism for the muscle paralysis?
The resulting skeletal muscle paralysis occurs because the hydrolysis of succinylcholine is slow compared with Ach. This sustained depolarization renders the postjunctional membrane unable to respond to subsequent release of Ach because rapid fatigue of the muscle occurs.
What is the mechanism of action of pancuronium?
Mechanism of action Pancuronium is a typical non-depolarizing curare-mimetic muscle relaxant. It competitively inhibits the nicotinic acetylcholine receptor at the neuromuscular junction by blocking the binding of acetylcholine.
How is TOF ratio calculated?
The TOF ratio is calculated by comparing the magnitude of the fourth evoked response or twitch (T4) to that of the first response (T1). During partial nondepolarizing block, T4 decreases preferentially, such that there is fade (i.e., TOF ratio less than 1.0). In the illustration above, the TOF ratio = 0.40 (40%).
What is the purpose of train of four?
A peripheral nerve stimulator, also called the “train of four”, is used to assess nerve function in patients receiving neuromuscular blocking agents (AKA paralytic medications). It is commonly seen used in critical care units.
What is the mechanism of action of dantrolene?
Dantrolene depresses excitation-contraction coupling in skeletal muscle by binding to the ryanodine receptor 1, and decreasing intracellular calcium concentration. Ryanodine receptors mediate the release of calcium from the sarcoplasmic reticulum, an essential step in muscle contraction.
How is succinylcholine metabolized?
Succinylcholine is rapidly metabolized by plasma cholinesterase in the bloodstream to succinylmonocholine, which is then further hydrolyzed (albeit more slowly) to succinic acid and choline.
What receptor does succinylcholine work on?
Structurally, succinylcholine is 2 Ach molecules linked together by methyl groups. This binds and stimulates the Ach receptor on the postsynaptic neuromuscular endplate, causing ion channels to open and sodium influx to occur.
Are there any non depolarizing agents for succinylcholine?
A new non-depolarizing agent, gantacurium, is being investigated as a replacement for succinylcholine. It is degraded in the plasma non-enzymatically by endogenous l -cysteine.
What is the molecular structure of succinylcholine?
Molecular Structure. Of the depolarising agents, succinylcholine is a clinically used agent whose structure consists of two acetylcholine molecules linked back-to-back at the methyl ends. Non-depolarizing NMBDs are either aminosteroids (pancuronium, vecuronium, rocuronium) or benzyltetrahydroisoquinoliniums (atracurium, cisatracurium, mivacurium).
How is succinylcholine degraded by acetylcholinesterase?
Succinylcholine is not degraded by acetylcholinesterase, but rather by plasma cholinesterases. The pharmacokinetic profile of non-depolarizing NBMDs is affected by body temperature, volume status, and hepatic (rocuronium) or renal (pancuronium) disease.