Effects of Changes in Viscosity by Means of Defibrination (Arvin) and Changes in Hematocrit (High and Low Ht) Using a Shock Model with Intact Animals

Summary

Changes in viscosity were produced in intact dogs by means of defibrination (Arvin) and/or changes in hematocrit (a high Ht of ca. 60–65 and a low Ht of ca. 30). Shock provocation was carried out by stepwise withdrawal of blood (5 ml/kg body weight per 5 minutes). After a period of one hour at a PAo of 35 mmHg, the shed blood was reinfused.

After reinfusion of the original volume of blood and stabilization for 30, 60, and 90 minutes, the control series C was compared with the following series:

• 1. series H (hemodilution with dextran 40, 5%);

• 2. series HA (hemodilution plus Arvin);

• 3. series DC (high hematocrit);

• 4. series DA (high hematocrit plus Arvin).

In view of the results obtained, a classification of the circulation as “normal”, “compromised”, “inadequate” or “enhanced” was proposed on the basis of low-shear viscosity (ηLS) and pulmonary capillary wedge pressure (PCWP).

Assuming that the heart ventricular function is normal, it could be concluded that a high viscosity plus a low wedge pressure gives inadequate results after shock and that the circulation is compromised when one of the two is unfavorable, i.e. the viscosity high or the wedge pressure low.

When both are normal, the peripheral circulation is normal and when one of the two parameters is favorable and the other is normal, or both are favorable, the results in the face of shock are enhanced.

In this light one could say that the circulation is normal in series C, enhanced in series H, and compromised in series HA and DC, while in series DA it is inadequate.

The series from a former investigation are also easy to classify in this way: a compromised circulation in series A (normal Ht plus Arvin) and an enhanced circulation in series B (hemodilution plus extra volume with NaCl 0.9%).

In the series with Arvin (HA, DA and A) there was a definite decrease in viscosity but also a decrease in wedge pressure, which makes treatment with Arvin without extra volume controversial.

The results can be clinically important, because both parameters are readily measurable and can provide a prognostically valuable impression as to the quality of the peripheral circulation in the face of shock and trauma.