PT  - JOURNAL ARTICLE
AU  - R. K. Roberts
AU  - B. M. Hillberry
AU  - J. A. Thornhill
AU  - W. E. Blevins
AU  - S. R. Ash
TI  - The Difficulties of Drawing Blood from Venous Catheters; A Hydraulic Model
DP  - 1987 Jan 01
TA  - PDA Journal of Pharmaceutical Science and Technology
PG  - 3--8
VI  - 41
IP  - 1
4099  - http://journal.pda.org/content/41/1/3.short
4100  - http://journal.pda.org/content/41/1/3.full
SO  - PDA J Pharm Sci Technol1987 Jan 01; 41
AB  - It is common knowledge that it is much easier to infuse fluid to a venous catheter than to withdraw blood from it. Venous catheters from which blood must be drawn quickly are usually of large size and have numerous side holes. The exact design is usually evolved through “trial and error,“ and the venous removal catheters still occasionally occlude during outflow. The purpose of this paper is to explain the genesis of outflow obstruction, and to quantitate the resistance and tendency of several catheters to occlude. Flow and pressure data are presented from experiments with jugular-vena cava catheters in dogs, and from an in vitro model with an artificial material simulating a vein. From this data, a mathematical model of the vein and catheter is developed. This type of study can be useful in design and testing of radically different approaches to vascular access.