A child operated for bladder extrophy with renal failure. Anaesthesia of choice is? (AIIMS Nov 2009)
Always in renal or hepatic failure muscle relaxant of choice is atracurium.
Available as Atracurium Besylate
Dose - 0.5 mg / kg, Duration - 15 -20 min., t 1/2 - 20 min
Metabolism: metabolized by Hoffman degradation (95%) in plasma & ester hydrolysis (5%)
Metabolism produces laudanosine which crosses blood brain barrier& can produce convulsions & ↑in MAC of halothane.
Effect: Releases histamine but in significant amount at clinical doses
- Allergic reactions ranging from pruritic rash to angioneurotic edema can occur
It is relaxant of choice in
a. Renal failure
b. Hepatic failure
c. Patients with atypical pseudocholinesterase
d. Myasthenia gravis (1 / 10th of normal dose)
e. small children
a. Fastest and shortest acting non depolarizing blocker- succinylcholine
b. Fastest onset of action among non depolarizing group – Rapacuronium (1 min)
c. Second Fastest of action- Rocuronium (90 seconds)
d. Shortest duration of action – Mivacurium/ Rapacuronium
e. D.O.C. in renal dysfunction – Atracurium, Mivacurium, or Vecuronium (Low dose)
f. D.O.C. in liver dysfunction – Atracurium, Mivacurium
g. Hydrolysis in plasma – Atracurium (Hoffmann degradation; Non enzymatic self hydrolysis of muscle relaxant in the plasma), Mivacurium (By Pseudocholinesterase)
h. Ganglion blocker – DTC > Metocurine
i. Vagal blocker – Gallamine Pancuronium and Rocuronium – increased H.R.
j. Histamine release – DTC > Metoc > Atrac > Miva. (Avoided in asthmatics)
k. Doxacurium is devoid of side effects.
l. Ropacuronium cause severe bronchospasm
m. Laudanosine – Toxic metabolite of Atracurium cause CNS excitation.
n. Liver metabolism – Pancuronium, Rocuronium, Rapa and Vecuronium
o. Renal excretion – Gallamine, DTC and Metocurine.