Blood volume and hemodynamic changes in relation to extensive vascular operations.

In 37 patients without cardiopulmonary insufficiency, postoperative changes in blood volume have been correlated to changes in the systemic and the central circulation. Postoperatively, the blood volume had decreased an average of 8 per cent, and diastolic blood pressure, 7 per cent, while cardiac index had increased 14 per cent and heart rate, 16 per cent. No significant changes could be demonstrated in pulmonary artery pressures, central venous pressure or invascular resistance. A highly significant correlation between the blood volume and pulmonary artery pressures and a significant correlation between the blood volume and central venous pressure were noted. Hematocrit was negatively correlated to vascular resistance. It is concluded that an unchanged blood volume during the first postoperative hours results in increased pulmonary artery pressures and central venous pressure. Therefore, in patients suspected of having increased pulmonary artery pressures, complete restoration of blood volume should take place over some hours postoperatively. An increase in hematocrit over normal values should be avoided.