Oxygen delivery and consumption during on-bypass cabg in htea and central analgesia

Objective. Despite some advantages, the use of high thoracic epidural anesthesia (HTEA) during on-bypass cardiac surgery may be discouraged by fear of adverse hemodynamic effects and associated disturbances of oxygen delivery.Aim. To compare oxygen delivery and consumption during on-bypass coronary artery bypass grafting in settings of HTEA and central analgesia (CA).Methods. 132 patients were assigned into two groups – study group (n=85), where the surgery was performed under HTEA and control group (n=47) - where the surgery was carried out under CA. Using data of transesophageal cardiac ultrasound and blood oximetry blood oxygen delivery (DO2), oxygen consumption (VO2), oxygen extraction coefficient (CEO2) were calculated at four stages of the surgery: after induction, sternotomy, cardiopulmonary bypass and at the end of the surgery.Results. In the initial stages of the surgery DO2 and VO2 were reduced relative to reference values with a tendency to increase in the course of the operation and achievement of the normal or supernormal level (VO2, study group) in the final stage. The decrease was due to moderate hypodynamic circulation and hemodilution. After sternotomy DO2 in the study group was higher than that of the control: 356 (279; 458) vs 317±89 ml·min-1·m-2, (р=0,021). After cardiopulmonary bypass oxygen saturation of venous blood (SatvO2,) in the study group was 71 ± 9 % compared with 68 ± 10 % in the control group. At the end of the surgery SatvO2 in the study group was 71 (66; 75) vs 59 (53; 70) % in the control (р = 0,005) and oxygen tension of venous blood (РvО2) was correspondingly 39 ± 6 and 33 (30; 38) mm Hg (р = 0,027). Despite the decrease in DO2 and VO2, oxygen extraction indices - CEO2, pvO2, SatvO2, and remained within the reference range, except that of the control group at the end of the surgery. Furthermore, at no stage lactate rise or acid-base deviations was observed in the both groups.Conclusions. In patients operated under high epidural anesthesia oxygen transport and consumption was better balanced compared to the patients operated under central analgesia