The management of autologous blood aims at reducing the need for allogenic transfusion. Blood requirement (autologous and/or allogenic) will depend on the pre-operative red blood cell stock and on the perioperative blood loss. The red cell stock is related to body weight and preoperative haemoglobin (haematocrit) level; it can be calculated accurately, whereas the perioperative blood loss (external and occult) is variable and unpredictable.

Preoperative donation of autologous blood, as well as intraoperative and/or postoperative recuperation and reinfusion of shed blood decrease the risk for allogenic transfusion in total hip replacement (THR) and total knee replacement (TKR) surgery. However, their efficiency and cost effectiveness are not optimal when applied to unselected patients.

Up to 50% of the predonated units of autologous blood are wasted after THR and THK surgery if patients have not been specifically selected to predonate blood.

In hip surgery the volume reinfused after intraoperative blood recuperation obviously depends on intraoperative bleeding; it averages 500 ml in a hip revision operation.

In TKR (with a tourniquet) the volume reinfused after postoperative recuperation depends on the amount of blood drained in the immediate postoperative period, which reflects both the amount of bleeding and the efficiency of the drainage. On average, 500 ml of shed blood with a haematocrit of 35% is reinfused, which increases the haemoglobin level by 1.0 gr/dl on average. The efficiency of this technique is unpredictable, with a wide dispersion of individual values (standard deviation: 208 ml) for the volumes reinfused. However, in patients with a body weight of 70 kg or less, the increase in haemoglobin level was more predictable and averaged 1.23 gr/dl.

In order to improve the efficiency of these two techniques (preoperative autologous blood donation and recuperation/reinfusion of shed blood), patients need to be targeted, taking into account:

- the calculated preoperative (day before surgery) red blood cell stock and the number of units of predonated blood,

- the lowest postoperative haemoglobin and haematocrit level clinically tolerable for that specific patient,

- the expected perioperative blood loss, which depends on such factors as duration of surgery, anticoagulant administration, use of a tourniquet,etc)

As a general rule, a haemoglobin level < 13 gr/dl, age > 65 years and weight < 70 kg all increase the risk to require autologous or allogenic blood transfusion, and would justify planning predonation of blood and/or recuperation/reinfusion of shed blood.