Strategies for reducing transfusions in major orthopaedic surgery

Blood is a valuable resource in the surgical setting and the limited supply of this resource makes it necessary to exploit all possible strategies to optimise its use. Salvage strategies are frequently employed: predeposit of autologous blood, pharmacological treatment (erythropoietin, tranexamic acid, low molecular weight heparin, etc), intra-operative blood salvage and post-operative blood salvage¹. The techniques for predepositing autologous blood require optimal conditions that guarantee the quality of the blood collected and its storage. For example it is crucial that the reinfusion is compatible with the treated patient’s erythropoietic capacity, and where this cannot be guaranteed, blood salvage techniques should be preferred to the predeposit strategy, for safety and efficacy reasons². Indeed, in major orthopaedic surgery, predeposit of autologous blood should only be recommended for selected patients who meet specific age and pre-operative haemoglobin (Hb) level criteria³.

Post-operative techniques of blood recovery following knee replacement surgery enable a significant reduction in the need for allogeneic transfusions. This is most evident for patients with pre-operative Hb levels between 12 and 15 g/dL; for patients with values above 15 g/dL the benefit is minimal, while for those with levels below 12 g/dL, it is useful to combine other transfusion sparing strategies with the post-operative blood salvage⁴. A recent study⁵ has indicated that techniques of peri-operative blood recovery should only be planned for patients with pre-operative Hb levels greater than 14 g/dL. However, another study found a non-significant difference in allogeneic transfusion needs between patients undergoing total knee arthroplasty, and those who were or were not treated with post-operative blood salvage, implying an unfavourable cost-benefit ratio for the blood salvage techniques⁶. It was not reported whether a tourniquet was used in these operations (a practice which affects both intra-operative and postoperative bleeding) and, more importantly the data were not analysed in relation to pre-operative levels of Hb, which would seem to be a fundamental element for determining the most effective strategy for sparing allogeneic blood transfusion, also in terms of cost. Other large studies have demonstrated a clear efficacy of post-operative blood salvage techniques in total knee replacement⁷, coupled with a good tolerability profile⁸. One interesting study showed the safety of blood salvage in patients undergoing total knee replacement who received loco-regional anaesthesia with ropivacaine: the amount of anaesthetic reinfused was well below toxic levels⁹.

While the tolerability and clinical safety profile of post-operative salvaged and filtered blood is good, the cost/benefit ratio has yet to be determined¹⁰. Based on the available data in the literature, a cost/benefit analysis for transfusion-sparing techniques such as acute normovolaemic haemodilution, predeposit and peri-operative salvage is difficult¹¹. Moonen et al. did however find that treatment with erythropoietin was more effective but significantly more expensive, than blood salvage techniques in patients with a pre-operative Hb in the range between 10–13 g/dL; this fact was even more evident for total knee arthroplasty than for hip replacement surgery¹².

The optimisation of peri-operative blood salvage programmes must not only consider the conditions (pre-operative Hb, type of operation, etc.) but also the costs of these techniques, in terms of both equipment and the human resources necessary for their management.

In this issue of Blood Transfusion, Singh et al.¹³ reports the results of a prospective non randomised study evaluating the use of an interesting therapeutic device (CellTrans™) for the postoperative recovery of blood, proposed as an extremely simple and practical instrument compared with similar instruments on the market.

The study recruited 70 patients undergoing elective primary total knee arthroplasty who were divided into two groups according to the type of drain used: normal suction drain or CellTrans™ drain. All operations were performed by the same team following a standardised surgical procedure to ensure homogeneity between the two groups of patients.

In this study, in patients undergoing total knee arthroplasty, transfusion of autologous blood collected using appropriate drain device for recovery of blood significantly reduces the need for postoperative allogeneic blood transfusions.

To fully evaluate this new technique, one aspect that should be looked at in future experiments is the presence of free Hb in the plasma after reinfusion of the salvaged blood, which seems to be a critical point of this system (passive with a peak suction at 100 mmHg) compared to other systems (active with constant and modifiable suction). There was however no clinically relevant presence of free Hb, white blood cells, or C3, in the filtered product to be reinfused, either with the CellTrans™ device or with others, according to reports in the literature⁸, with the exception of a study by de Jong¹⁴, who hypothesised a possible thrombogenic effect of filtered postoperative salvaged blood.

In conclusion, the CellTrans™ device can be considered interesting for its simplicity and ease of use, combined with potential cost-saving with regards to the instrument itself and its management. It is to be hoped that critical points of this and similar devices (e.g. free Hb in the serum following reinfusion of the shed blood) is the subject of future studies.