AUTOTRANSFUSION AFTER OPEN-HEART-SURGERY - THE OXYGEN DELIVERY CAPACITY OF SHED MEDIASTINAL BLOOD IS MAINTAINED

Autotransfusion of mediastinal shed blood after open heart surgery has become a common and accepted procedure in reducing the need for homol ogous transfusion during the last 15 years. The objectives of the pres ent study were to investigate the oxygen delivery capacity of autotran sfused shed mediastinal blood, compared to patient-blood, during cardi opulmonary bypass and in the postoperative period. Ten consecutive pat ients undergoing elective cardiac surgery were studied. Mediastinal sh ed blood was collected in the cardiotomy reservoir and retransfused du ring the first 18 postoperative hours. The oxygen delivery capacity of the blood to the tissues was calculated by use of the oxygen status a lgorithm (OSA 2.0) programme and measurement of the 2,3-diphosphoglyce rate (2,3-DPG) concentration. Autotransfusion volume ranged from 450-1 530 mi per patient (median 824 mi). Shed blood had a mean haemoglobin level of 8.8 g/dl and 7.4 g/dl at 1 h and 6 h of autotransfusion, resp ectively. There were no significant changes of 2,3-DPG concentration i n the patient-blood during cardiopulmonary bypass or after autotransfu sion compared to preoperative values. P50 for oxygen (3.6 and 3.6 Wa) and 2,3-DPG concentrations (5.3 and 5.1 mikromol/ml erythrocyte) in sh ed mediastinal blood (Ih and 6h postoperatively) were not significantl y different compared to patient-blood. The results demonstrate that th e oxygen delivery capacity of shed mediastinal blood is maintained and that the oxygen affinity of patient-blood is not influenced by autotr ansfusion.