[Blood substitutes: state of the art and technical setbacks and why we are still disappointed].

Volume loading solutions used therapeutically (albumin, dextrans, modified gelatins and hydroxylstarches) are simple plasma substitutes and cannot ensure oxygen transport. The search for erythrocyte substitutes initially seemed utopian, but this goal is now within our reach, in the form of hemoglobin-based oxygen carriers (HBOC) for example. The clinical development of HBOC has been slowed by adverse effects, including an increase in arterial pressure due to the vasoconstrictive effect of cell-free hemoglobin in plasma, haemoprotein autoxidation leading to methemoglobin formation, and free radical generation that creates oxidative stress.