. . "However, when a syringe or other device is used to create a decrease in fluid pressure inside the central lumen 34, the tubular member 38 partially collapses to open the inlet ports 40 and allows fluid to flow from the body and into the lumen 34 as generally illustrated in FIG. 3A. FIGS. 4A,B respectively illustrate the tubular member 38 in its normal state and when it is partially collapsed due t" . .