Fig. 3:

Line pressure measurements during prescribed infusions over time. 3A) In vitro step-ramp reference infusion: near prototypical infusion line pressure (in-line non-membrane pressure transducer, Harvard PHD 2000 infusion pump, previously reported). A rapid, near vertical pressure reduction is noted. 3B) In vitro step-ramp Alaris® System infusion: Curved tracing represents measured line pressure with the infusion protocol utilized in 3A. At 25 minutes and a total of 75 microliters planned infusion, the pump is inactivated leading to tapered reduction in line pressure. The stepped lines represent steady state infusion pressures at 1.0, 2.0, 3.0 (interpolated), 4.0 (interpolated), and 5.0 microliters per minute. 3C) Ex vivo occlusion demonstration: Curved tracing indicates measured line pressure increasing after 25 minutes until reaching a maximum line pressure above 500 mmHg. The desired 100 microliter infusion volume was retained internal to the infusion system as the fixed cadaveric specimen served as a complete catheter infusion at the distal catheter tip.