Short cannulas can be inserted in emergency using ultrasound guidance, either in the veins of the forearm (basilica and cephalic) or in the veins of the elbow (cephalic, antecubital, basilica); the deep veins of the arm (basilica, brachialis) are rarely used.
Both teflon or polyurethane cannulas are used (the former, more rigid, will be easier to place); in emergency caliber between 20G and 16G are appropriate. The use of smaller cannulas (22G-24G) is associated with greater difficulty in infusion; the use of 14G cannules is associated with a greater risk of vein damage (rupture during the maneuver; late venous thrombosis caused by excessive caliber of the cannula). Considering that these agocannulas are inserted for urgent needs (for example for volume repletion, transfusion, etc.) it is advisable to prefer 18G and 16G.
In all cases, ultrasound guided short cannulas have short duration: the limited length of the cannula (typically 30-50 mm) will imply a high risk of dislocation within the first 24-48 hours, considering that part of the length of the cannula will remain extravascular.