The effect of acute normovolaemic haemodilution on blood gas parameters: a case report

Increased awareness of the risks related to homologous blood transfusions such as immunological reactions, transmission of infections, and immunosuppression, has necessitated exploration of alternative techniques to deal with the needs of intra-operative blood transfusion. Strategies that reduce or remove the risks associated with allogeneic transfusion include pre-operative autologous donation, peri-operative cell-salvage techniques, deliberate hypotension, and pharmacological interventions. Acute normovolaemic haemodilution is another such technique.

The effect of acute normovolaemic haemodilution on haemodynamics and blood gas parameters was studied in a male patient (58 y, 94 kg, American Society of Anesthesiologists physical status I) undergoing an orthopaedic surgical procedure for joint arthroplasty. After induction of general anaesthesia, 1600 ml of blood was collected and replaced with an equal volume of 6% hexaethyl starch.

Haemoglobin and haematocrit concentrations were significantly lower following haemodilution (14.9 and 9.2 g/dl for haemoglobin versus 45.0% and 31.7% for haematocrit). There was no significant change in the heart rate, blood pressure or end-tidal carbon dioxide tension throughout the operation period. Central venous pressure increased marginally from 5 to 90 min, but was within normal limits. There was no significant change in blood gas parameters following haemodilution. Platelet count decreased following haemodilution but the values were within normal limits.

Acute normovolaemic haemodilution with 6% hexaethyl starch is a safe procedure for blood conservation in selected operations. It did not cause any haemodynamic or blood gas parameters to change. It did not have any adverse effect on haemostatic mechanisms that could enhance the risk of bleeding at surgery.