In one aspect, a medical device is provided which includes flexible tubing having a distal end and a proximal end and at least a first lumen extending from said distal end to said proximal end; a first needle cannula having proximal and distal ends, said first needle cannula being mounted at said distal end of said tubing and in fluid communication with said lumen; a second needle cannula mounted at said proximal end of said tubing and in fluid communication with said lumen; a shield disposed over said tubing, said shield extending substantially the entire length of said flexible tubing, and said shield being movable relative to said first needle cannula from an initial proximal position wherein said first needle cannula is exposed to a distal position wherein said distal end of said first needle cannula is covered by said shield; and an actuator for actuating the shield at a location spaced from the first needle cannula, preferably closer to the second needle cannula than to the first needle cannula.