Humoral Rheology I. Viscosity Studies and Anomalous Flow Properties of Human Blood Systems with Heparin and Other Anticoagitlants by Alfred L. Copley, Ludwig C. Krchma, and Mary E. Whitney

The effect of anticoagulants on the flow properties of blood, plasma, and serum has been subjected to investigation with various results. Trevan (1) studied the viscosity of blood with various anticoagulants. He found that hirudin has no appreciable influence on the viscosity, whereas oxalate, citrate, and fluoride in the solid state were inadmissable because they altered the volume of the corpuscles by osmotic changes. Oberst (2) has recently stated that heparin produces an increase in the consistency of plasma and serum whereas potassium oxalate produces no change. Eckstein, Book, and Gregg (3) reported that heparin, in vitro or in vivo, has not been observed to alter the blood viscosity significantly. Our purpose was to discover whether various units of purified heparin, added to blood and serum, would alter their viscosities. In the course of these studies it became apparent that anomalous flow properties of the blood contributed to the complexity of the problem. These anomalies have been referred to in the literature. Dow and Hamilton (4) occluded the aorta of dogs and studied the curve of declining pressure, measured peripherally to the point of occlusion. At a pressure of about 20 mm. of mercury the flow of blood stopped. They attributed this phenomenon to the anomalies of the apparent viscosity of blood, thus agreeing with the findings of Whittaker and Winton (5) who studied the apparent viscosity of blood suspensions. The latter found this phenomenon in glass viscometers as well as in the biological viscometer which they developed in the isolated hind limb of the dog. This same phenomenon was also found following arterial occlusion by employing a piezographic sphygmomanometer by Lahy (6) who estimated that a minimum pressure between 5.7 and 8.2 mm. of mercury will maintain circulation. The similarity of these phenomena to those studied and analyzed in other fields of theology, where relationships have been developed, justified an attempt to apply these relationships to the blood-anticoagulant systems.