Mainly length and the duration of the catheter dwell (length of time the catheter can typically stay in the vein). A Midline is a catheter that is from 3 to 8 inches in length. Upon insertion of a Midline catheter into a vein of the upper extremity; the tip of the Midline lies in the upper arm at or below the axillary vein level distal to the shoulder (see Infusion Nurses Society (INS) 2006 standard #42.3). A PICC line extends from the antecubital area or upper arm with the tip in the superior vena cava. Dwell time of a PICC is longer than the dwell time of the Midline.