Blood oxygen transport function in cardiopulmonary bypass surgery for acquired heart valvular diseases.

Intraoperative analysis of the principal parameters of oxygen transport was carried out in 123 cardiosurgical patients before and after radical correction of an acquired heart valvular disease of rheumatic origin. The study was carried out in two groups of patients operated on under ataralgesia (n = 74) and total intravenous anesthesia (n = 49). The principal parameters that reflect oxygen homeostasis at various stages of the operation are heart productivity, oxygen supply and consumption. Reduced cardiac output, that most frequently develops directly before cardiopulmonary bypass onset, results in impairment of oxygen supply. To maintain metabolism under such conditions, oxygen extraction from the blood is increased. Analysis of correlations helped determine the critical level of oxygen supply: 350 ml/min/m2; a lower level of oxygen supply involves reduction of oxygen consumption, formation of oxygen debt, and lactate accumulations. Limited oxygen supply is more incident in the patients operated on in conditions of ataralgesia including nitrous oxide. Administration of the drugs stimulating heart productivity in the early postperfusion period effectively correct disordered oxygen transport function of the blood in the patients with reduced oxygen supply, whatever the anesthetic method employed. Dopamine infusions in dose 5-7 micrograms/kg/min help compensate for oxygen debt, which fact is proved by a positive time course of blood lactate levels.

Glucose metabolism and insulin activity during cardiac surgery.

Disorders of glucose metabolism were investigated in 177 patients undergoing cardiac surgery. In group I patients, the cardiopulmonary bypass (CPB) priming fluid contained glucose. Patients in group II received neither glucose nor insulin during the operation. Group III received insulin-glucose therapy (IGT) during the operation (insulin, 1 U/kg/h, glucose, 0.5 g/kg/h). At the onset of CPB in group I, hyperglycemia was produced by the glucose load and by a relative reduction in insulin secretion. In group II, the start of the operation was accompanied by a rise in the titer of insulin antibodies. IGT resulted in normalization of the blood glucose level after CPB and stability of the insulin antibody titer during the investigation. The indices of myocardial contractility in group III were better than those of the "glucose-free" group II before and after CPB. In group II, indices of beta-cell function were moderately depressed 16 to 18 hours after the operation. Insulin and c-peptide level measurements demonstrated insulin production in group III on the first postoperative day. The results demonstrate that IGT has some potential benefit for glucose metabolism and myocardial function during cardiac surgery.