In the case of a peripheral access for a period longer than 24-48 hours, in the presence of visible/palpable superficial veins of the upper limb, the most appropriate choice is a short cannula.
Though, considering the expected duration for several days, it is recommended to select an 'advanced' short peripheral cannula (i.e.: polyurethane, and equipped with a wide soft wing and a preassembled extension), preferably 24G or 22G. The use of 20G should be reserved for children with indication of blood transfusions or blood products.