A 70 kg athlete is taken for surgery, due to unavailability of vecuronium, succinylcholine is given repeatedly (>640mg). He now is unable to take breath and his lower limbs are paralyzed. What will be cause?
Phase II block
Succinylcholine causes muscle paralysis due to fasciculation
Hidden muscle dystrophy
Pseudo cholinesterase deficiency
Prolonged apnea due to repeated dosing with succinylcholine is due to it entering phase 2 block. Phase I depolarizing block is preceded by muscle fasciculation. During paial neuromuscular block, phase I depolarizing block is characterised by: No fade during repetitive stimulation (tetanic or TOF) No post tetanic facilitation (potentiation) Rapid hydrolysis by butyrylcholinesterase (plasma cholinesterase) terminates phase I depolarizing blockade of succinylcholine. Phase II block resembles non depolarizing block, is characterised by: Fade during repetitive stimulation (tetanic or TOF) Post tetanic facilitation (potentiation) Phase II block can be antagonized by administering a cholinesterase inhibitor like neostigmine.
Neuromuscular Blocker