Abstract: A needle system which upon arterial entry provides a visual indication of pulsatile blood flow. The needle system includes an elongated needle with distal and proximal ends. There is a needle hub at the proximal end of the needle and a port position between the proximal needle end and proximal hub end. The visualization connector tube having two ends is provided. The tube is sufficiently clear to permit visualization of material held therein. The first end of the tube is in communication with the port. An elastomeric reservoir is provided. The reservoir is in free, direct, unrestricted two-way communication with a second tube end. The needle, needle hub, and tube all have predetermined volumes. The reservoir has an initial unexpanded state with a first pressure and a first volume and a second state expanded with a second pressure and a second volume. Air pressure in the needle system is increased upon arterial entry.