In vitro model of intravenous fluid administration: analysis of vein resistance to rapid fluid delivery

Rapid fluid administration is the cornerstone of successful trauma resuscit ation of patients in a state of shock. Intravenous (IV) fluid delivery is a physical intrusion into a vein which results in a complex interaction betw een the rigid catheter and the compliant vein. We present an experimental m odel of IV infusion into a vein-like compliant tube that (a) demonstrated t he interdependence between fluid administration and blood flow in a complia nt tube and (b) allowed investigation of the contribution of the central ve nous system (between the infusion site and the heart) to the total resistan ce to infusion flow rate. The results show that in cases with very high res istance in the central venous system a significant increase of infusion flo w rate cannot be achieved just by increasing the infusion pressure. Similar ly, in cases of small veins when only small catheters can be used, infusate flow rate may be increased only by using two independent infusion ports. I n cases with increased tissue pressure due to edema, gravity-driven infusio n may not produce sufficient perfusion of the vascular compartments. It was also shown that the vein valves do not always close, and that peripheral b lood flow may continue together with the infusate fluid (e.g., when there i s a small downstream resistance and infusion with a small catheter). (C) 20 00 IPEM. Published by Elsevier Science Ltd. All rights reserved.