The ideal muscle relaxant used for a neonate undergoing porto-enterostomy for biliary atresia is:

Ans. is 'a' i.e. Atracurium In this case a muscle relaxant is required whose metabolism has nothing to do with liver (because liver is damaged in biliary' atresia)So Atracurium is the muscle relaxant of choice as it is inactivated in plasma by spontaneous non enzymatic degradation. (Hoffman elimination) so its duration of action will not be affected in patients with hepatic insufficiency.All other muscle relaxants given in the question undergo biliary excretion so they should be avoided in a case of biliary atresia.