Catheters and their uses for vascular access to a patient are described. The catheter comprises an arterial lumen and a venous lumen which run along the shaft of the catheter for most of the length. Near the catheter tip, the two lumens can twist around the longitudinal axis of the catheter. The catheter shaft has two openings, one where the arterial lumen begins the twist and another about 180 degrees into the twist. The catheter shaft also contains an opening for the venous lumen near the nose of the catheter shaft. The orientation of the arterial lumen opening on opposite sides of the shaft eliminates the possibility of side port occlusions since the catheter cant be pressed against a vessel wall that blocks both suction openings simultaneously. And using these openings at each point reduces the chance of occlusion due to blood clots and fibrin sheaths. Other embodiments are described.
