Circulation, Ventilation and Fluid Balance in Patients During and Immediately After Heart-Valve Replacement

Eleven patients with aortic (9) and mitral (2) heart valve replacements with the Björk-Shiley disc valve were investigated at four periods during surgery and on the first postoperative day. Measurements were made of central and peripheral circulation, ventilation and fluid balance. All patients were maintained with controlled ventilation for the first 24 hours postoperatively. There were no deaths and the results indicated stable conditions in the majority of the patients with an unchanged oxygen uptake and insignificant changes in cardiac index. Stroke index decreased and was accompanied by an increase in heart rate. Pulmonary artery and left atrial pressures decreased continuously. Pulmonary and peripheral vascular resistances were mainly unchanged. Venous admixture corresponded to 16–20% and was not assjciated with a change in dynamic compliance. All patients showed a positive fluid balance. The small circulatory changes observed could probably be explained on the basis of insufficient blood replacement in spite of a positive balance. Low cardiac output syndrome was not observed in any patient.