Blood donation unit
First Claim
Patent Images
1. A blood donor collection system wherein blood is withdrawn from a donor under negative pressure created by a pump means, said system comprising:
- a pump means, a phlebotomy needle, said needle having a length L (in centimeters) and an inner radius R (in centimeters), said needle also having a first end insertable into said donor and a second end coupled to junction means, said junction means joining said needle with both a first end of first conduit means and a first end of second conduit means, said first conduit means having a second end thereof connected to a whole blood collection bag and said second conduit means having a second end thereof connected to a bag at least partially containing anticoagulant, said pump means being disposed to achieve a flow rate Q of blood at least on the order of 70 ml per minute by maintaining an essentially constant negative pressure differential Δ
P of at least about 168 cm of water across the length L of the interior of said needle, said flow rate Q governed to a first order approximation in low Reynold'"'"'s number flow by the Hagen-Poiseulle Formula;
space="preserve" listing-type="equation">Q=Δ
Pπ
R.sup.4 /8 μ
L where μ
is the viscosity of blood (in gram/cm-sec).
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Abstract
A blood donation unit in which a reduced outside diameter phlebotomy needle is employed to minimize donor discomfort. The blood flow if, however, maintained at a flow level similar to that obtained with standard gauge phlebotomy needles by a roller pump which provides a predetermined pressure differential between the ends of the phlebotomy needle. The blood is mixed with a predetermined ratio of anticoagulant immediately after passing through the phlebotomy needle. The ratio of whole blood to anticoagulant is independent of the volume of whole blood collected.
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Citations
9 Claims
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1. A blood donor collection system wherein blood is withdrawn from a donor under negative pressure created by a pump means, said system comprising:
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a pump means, a phlebotomy needle, said needle having a length L (in centimeters) and an inner radius R (in centimeters), said needle also having a first end insertable into said donor and a second end coupled to junction means, said junction means joining said needle with both a first end of first conduit means and a first end of second conduit means, said first conduit means having a second end thereof connected to a whole blood collection bag and said second conduit means having a second end thereof connected to a bag at least partially containing anticoagulant, said pump means being disposed to achieve a flow rate Q of blood at least on the order of 70 ml per minute by maintaining an essentially constant negative pressure differential Δ
P of at least about 168 cm of water across the length L of the interior of said needle, said flow rate Q governed to a first order approximation in low Reynold'"'"'s number flow by the Hagen-Poiseulle Formula;
space="preserve" listing-type="equation">Q=Δ
Pπ
R.sup.4 /8 μ
Lwhere μ
is the viscosity of blood (in gram/cm-sec). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification