[Hypothermal perfusion: protection or damage?]

Ninety six patients were examined during operations on the open heart and great vessels: 25 perfusions were performed at a temperature of 30-32 degrees C; 41 perfusions at 26-29 degrees C; 10 at 23-26 degrees C; 20 at 12-14 degrees C. It was found that with superficial hypothermia and moderate PaO2, blood myoglobin (MG) release was minimal and the count and activity of platelets were optimal. The degree of myoglobinemia increased as PaO2 rose. As the body's temperature lowered, the blood concentrations of MG, its differences smoothed in the subgroups with different PaO2 values. Critical myoglobinemia (over 30 times higher than the baseline values) was noted in a group with superdeep cooling to a temperature of 14 degrees C. By taking into account the fact that the myocardium contains large quantities of MG, loss of this heme-containing protein involves myocardial blood supply disorders and hence decreased myocardial contractility. A considerable platelet loss entails higher postoperative hemorrhagic diathesis and requires efforts in correcting coagulopathies.