Continuous haemodynamic monitoring using transoesophageal Doppler during acute normovolaemic haemodilution in patients with coronary artery disease

Abstract

Transoesophageal Doppler monitoring allows non-invasive assessment of stroke volume. We studied haemodynamic changes during acute normovolemic haemodilution (ANH) in anaesthetised patients with coronary artery disease. Twenty patients were randomly assigned to either ANH or a control group. During ANH, a mean (SD) blood volume of 15.3 (3.4) ml.kg-1 was withdrawn decreasing systemic oxygen delivery from 12.7 (3.3) to 9.3 (1.8) ml.kg-1.min-1 (p < 0.001). In the control group, haemodynamic data remained unchanged, whereas in the ANH group, stroke volume and central venous pressure increased significantly (mean = +21 ml [95% CI: 18-25 ml.min-1]; mean = +2.5 mmHg [95% CI: 2.2-2.8 mmHg], respectively) and heart rate decreased (mean = -6 beat.min-1 [95% CI: 6-8 beat.min-1], p < 0.05). According to the Frank-Starling relationship, individual changes in stroke volume compared with central venous pressure fitted a quadratic regression model (R2 > 0.91). A reduced viscosity associated with ANH resulted in improved venous return, higher cardiac preload and increased cardiac output. In summary, this study demonstrated that ANH to a haemoglobin value of 8.6 g.dl-1 was well tolerated in patients with coronary artery disease.