Haemodilution Techniques in Canine Extracorporeal Circulation Using Bubble and Disc Oxygenators

Experimental extracorporeal circulation in dogs using bubble or disc oxygenators and priming with pure blood, Rheomacrodex or Ringer lactate revealed the following: From a haemodynamic point of view, priming with Rheomacrodex in both oxygenator systems is preferable to Ringer lactate or blood. After an initial fall, the blood pressure remains stable during the perfusion period, the central venous pressure is kept within normal limits, a constant flow rate at 100 ml/kg/min is easily achieved and no loss of oxygenator volume into the dogs is observed. Haemolysis is less pronounced when haemodilution is used in both oxygenator systems. The most favourable results are obtained using Rheomacrodex as priming agent. An initial fall in circulating leucocytes is observed in all experiments and is more pronounced when pure blood is used as priming agent. Using haemodilution, this fall is followed by an increase in the number of circulating leucocytes to levels even higher than the initial values. At the same time, there is a decrease in the number of agranulocytes and an increase in that of granulocytes. These results are independent of the oxygenator system used. Platelets do not receive any protective effect from haemodilution and the same decrease in the number of circulating platelets is observed in both oxygenator systems. Plasma protein electrophoresis before and after 90 min bypass reveal only minor insignificant changes.