Blood viscosity determination device

Diagnostic apparatus for determining in vivo the whole blood viscosity of blood in the vein of a subject animal while the venous blood pressure in at least a portion of said vein is maintained substantially constant, said diagnostic apparatus comprising:

• a hollow needle having a pointed end for in vivo connection with said whole blood through puncture of said portion of said vein;
• blood withdrawing means including means for collecting the blood withdrawn from said vein through said hollow needle and for quantitatively measuring the volume of such withdrawn and collected blood, said blood withdrawing means connected to said hollow needle at an end distal from said pointed end and adapted to establish a negative pressure thereat with respect to said venous pressure thereby withdrawing said in vivo blood through the hollow needle;
• a negative pressure measuring means connected to said distal end of the hollow needle for indicating the negative pressure in the region thereof as the blood is being withdrawn through said hollow needle;
• said blood withdrawing means also including means for controlling said negative pressure in accordance with said negative pressure measuring means so as to establish a predetermined, substantially constant negative pressure drop across the hollow needle;
• timing means for measuring elapsed time from a starting time signal;
• automatic actuation means connected to automatically provide said starting time signal to said timing means when said predetermined negative pressure is established;
• said timing means providing an output signal after measuring a predetermined preset elapsed time;
• wherein the in vivo blood viscosity is directly proportional to the time required to withdraw a predetermined quantity of blood and inversely proportional to the volume of blood withdrawn during a predetermined time interval.