Abstract
Bleeding is an inevitable consequence of most surgical interventions. Total blood loss resulting from an operation can be calculated from the observed drop in haemoglobin and haematocrit levels, taking into account the amounts of blood transfused. Total blood loss is partly accounted for by the measurable external blood loss, during operation and in the drains, but there is also occult blood loss in the tissues, which is often as much as or even greater than the measurable external blood loss; occult blood loss is often underestimated; it has been found to represent on average 30% of the total blood loss after THR, and 45 to 60% after TKR.
Blood loss may be important enough to require compensatory measures. Transfusion of homologous blood has been for a long time the method of choice, but its use has been restricted for a number of reasons, among which the fear of viral transmission, although it has decreased dramatically over the past few years.
There are several possible ways to reduce the requirement for allogenic blood transfusion in surgery. They can be distributed under the following headings:
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Reduce perioperative blood loss
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Increase the preoperative erythrocyte volume
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Lower the transfusion trigger
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Use autologous blood
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Use blood substitutes
These topics will be covered by the participants to this symposium, each of whom has been involved in major clinical studies and is a recognised expert on one or several aspects of this blood management strategy.
As we will see, transfusion of homologous blood can be avoided in a high proportion of cases through judicious use of the various possibilities available.
Before any given operation, the first step must be to evaluate the anticipated total blood loss, and to figure out whether this is higher or lower than the allowable blood loss for that specific patient. The allowable blood loss will depend on the preoperative blood volume and haematocrit of that patient, and also on the haematocrit that is to be preserved postoperatively, taking into account specific features of that patient, such as coronary heart disease. If the anticipated blood loss is greater than the allowable blood loss, some form of action is necessary in order to reverse the balance. This can be achieved by reducing blood loss and/or by improving the preoperative haematocrit of the patient, together with either autologous blood predonations – if the patient’s condition permits - and/or re-infusion of recuperated shed blood. Blood substitutes have not yet reached a stage of clinical applications.
The management of blood loss must be given appropriate consideration in all surgical procedures; it requires a customised approach, from the preoperative consultation until the postoperative period.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
