Local anaesthesia and Bellovac ABT.

Evidence suggests that local anaesthesia after total knee replacement (TKR) provides better knee function in the postoperative period with less post-operative complications like nausea and vomiting as compared to conventional ways of pain treatment (i.e.opioids). Good clinical results have been obtained with and without the use of indwelling catheters. The Bellovac ABT system; a technique to collect, filter and reinfuse blood and tissue fluid, is also often used in TKR. Bellovac ABT is used as an alternative to allogeneic blood transfusion. A combination of both techniques however, is not common yet. Before routinely combining local anaesthesia with the Bellovac technique we want to quantify the amount of local anaesthetic (if any) in the collected and retranfusable blood and tissue fluid. On the basis of these data the safety of combining local anaesthesia with the retransfusion of blood and tissue fluid will be assessed.

To quantify the amount of local anaesthetic in blood and tissue fluid in the Bellovac ABT system and in the blood circulation of the patient. The primary objective is to quantify the cumulative ropivacaine level when the blood should be retransfused to the patient. As a secondary objective the quality of postoperative anaesthesia will be evaluated.

During hospitalisation.

Administration of local anaesthetic (single shot and continuous infusion) in TKR. Blood and tissue fluid will be collected in a Bellovac ABT system and by venous sampling and used for quantification of local anaesthetics.