Train of Four

MuscleRelaxants

Used During Train of Four

Neuromuscular blocking agents may be used during surgery, patients who have these administered should be monitored for neuromuscular function during the surgery. It is important to understand which relaxants are used, to better evaluate the patients during the surgery.

NON-Depolarizers

Depolarizers

NDMRs can be short, medium or fact acting. They are competitive antagonists that blocks conduction by acting on alpha subunit. - They decrease twitch response to a single stimulus - NDMR produces x (unstained response) to continuous stimulus - TOF ratio is less than 0.7 (T4 is less than 70% amplitude of T1) - Causes post-tetanic facilitation - Potentiation by other non-depolarizers, antagonism byanticholinesterase drugs.

Succinylcholine is used, and is two Ach molecules which act at the post-synaptic receptor. When they bind to the receptor they cause depolarisation and the muscle cannot be stimulated. PHASE I BLOCK: - Decreases single twitch amplitude - No fade to continuous stimulus - TOF ratio greater than 0.7 - Potentiation on Antichlinesterase - Cause fasciculation PHASE II BLOCK - Resembles non-depolariser blockage

Examples:- Curare - Pancuronium - Vecuronium - Rocuronium - Atracurium - Cis-Atracurium -Mivacurium

Examples:- Succinylcholine