For years we have had as part of our work instruction to apply a warm k-pad to newly inserted PICC sites. The thought behind it is to facilitate vein dilation during initial contact with the PICC to decrease risk of thrombus. At a recent staff meeting we discussed whether or not this is best practice and most of all, where it came from. We have done this since before ultrasound use. Is there any evidence to support the practice and if so, does it apply today when we are using larger veins, visualizing their size on ultrasound, etc.? Was there ever any evidence to support it? The folks that initially instituted this are no longer on our team due to retirement, etc. Thank you for any input you may have in directing me to any studies or otherwise that may expedite our question.