[Hemorheology and hemodilution]

[Therapeutic erythrocytapheresis: technical aspects and clinical applications]

PURPOSE

Therapeutic erythrocytapheresis is a selective red cell-depletion aphaeresis technique.

CURRENT KNOWLEDGE AND KEY POINT

Using a discontinuous or continuous flow blood cell separator, the technique safely allows quickly and automatically collecting a large volume of red cells. The main obstacle of implementation is a poor peripheral venous access. The procedure is well-tolerated. Polycythemia vera, hereditary hemochromatosis, complicated sickle-cell-disease and retinal venous occlusion are the main clinical applications.

PROSPECT AND PROJECT

Therapeutic erythrocytapheresis is a more modern and more effective method than the classic patient-bleeding. It has to be preferred in the early treatment of patients with polycythemia vera and hereditary hemochromatosis.

[Place of normovolemic hemodilution in oncologic cervicofacial and ENT surgery]

OBJECTIVE

Evaluate the use of normovolaemic haemodilution in cervico-facial oncologic surgery.

STUDY DESIGN

Prospective, randomised, simple blinded study.

PATIENTS AND METHODS

38 ASA I and II patients were studied: a control group (n = 21) and a haemodilution group (n = 17) in whom 5.5-8 mL.kg-1 blood were withdrawn before induction, replaced by an equivalent amount of colloids. In both groups, the transfusional strategy was to keep the haemoglobin level above 100 g.L-1 throughout the procedure and the recovery phase, using in priority the autologous blood in the haemodilution group. Blood losses during surgery were evaluated by weighing the sponges and by measuring the aspirated blood.

RESULTS

Demographic and anaesthetic data, and blood losses were similar. The haemoglobin levels dropped significantly in the haemodilution group (138 +/- 10 g.L-1 to 107 +/- 11 g.L-1) as well as in the control group (131 +/- 11 g.L-1 to 110 +/- 10 g.L-1). Infectious complications were slightly higher in the haemodilution group, although this difference did not reach the level of significance.

CONCLUSION

Normovalaemic haemodilution does not seem to be indicated in cervico-facial and ENT oncologic surgery.

Comparative study of limited intentional normovolaemic haemodilution in patients with left main coronary artery stenosis

Intentional normovolaemic haemodilution is a blood saving technique which can be performed when major blood loss is expected. Severe coronary artery disease and particularly left main stenosis are considered a contraindication for intentional normovolaemic haemodilution. The effects and complications of limited intentional normovolaemic haemodilution in patients with left main coronary artery stenosis scheduled for coronary artery bypass grafting were evaluated. Patients were randomly allocated to two groups: group A (n = 15) underwent limited intentional normovolaemic haemodilution to a haematocrit of 34%; group B (n = 15), no intentional normovolaemic haemodilution was performed. In both groups succinyl-linked gelatin was used to maintain normovolaemia. Haemodynamic parameters were kept as constant as possible. In group A, a mean (SD) volume of 785 (250) ml of blood was withdrawn [range 500-1200 ml]. ST segment changes occurred on the ECG in three patients in each group. There were no statistically significant differences for frequency, maximum deflection and duration of ST-segment changes. Limited intentional normovolaemic haemodilution can be performed safely in patients with left main coronary artery stenosis. In this study it was not associated with increased frequency, severity or duration of ST-segment changes, or with arrhythmias or haemodynamic instability.

[Normovolemic hemodilution: application to the treatment of refractory cutaneous ulcers. Transfusion Techniques and Therapeutics Group]

Resistant cutaneous leg ulcers have a long evolution and are not easily cured by traditional therapeutics. Normovolemic haemodilution was proposed in 1984 by Guenneguez and Ouvry, who studied a small number of patients with good results, by using a local protocol, and a manual procedure. Recent data about physiopathology of cutaneous leg ulcers seem to confirm the benefit that Normovolemic Haemodilution should bring to the treatment of this pathology. Therefore a multidisciplinary group was created to lead a multicentric study about the treatment of resistant cutaneous leg ulcers by long term Normovolemic Haemodilution.

[Normovolemic hemodilution]

Transfusion of homologous blood to surgical patients is not without risks. Thus, strategies to prevent blood loss must be considered. This article deals with one of them: normovolaemic haemodilution together with its advantages, physiological consequences and technical aspects. In particular, it is important to follow certain inclusion criteria. The technique is safe, effective and relatively easy to implement. In the future, it could be used in non-surgical patients, when it is necessary to increase tissue perfusion.

[Programmed autologous transfusion in coronary surgery: experience with 106 patients]

Patients undergoing elective coronary bypass surgery can benefit from Preoperative Autologous Blood Donation (PAB), despite some opinions to the contrary, as a complement of intra-operative blood salvage techniques. We report herein 106 patients eligible for coronary bypass surgery included in our PAB program. We observed a very good tolerance owing to strict exclusion criteria, a close monitoring of vital signs, and as far as we are concerned, to the infusion of a macromolecular solution (Plasmion) in a 1:1 ratio, to maintain intra-vascular volume. We chose a volume replacement because the physiological adaptation to hypovolemia is altered by the beta-blocking and/or vasodilating agents which cannot be discontinued in patients with coronary heart disease. The changes in the hematological parameters are not different from those observed in other patients eligible for PAB. The postoperative hemoglobin level is satisfactory and compatible with a normal myocardial function inasmuch as the cardiopathy has been corrected. The efficiency of PAB is good since overall, 74% of the patients did not require homologous blood, this proportion rises to 84% for patients donating 3 or more units. Preoperative Autologous Blood Donation for patients with coronary heart disease implies a perfect coordination between the Blood Bank physicians and their colleagues from the Cardiology Department. Aside from its well known advantages, PAB allows a stimulation of erythropoiesis, a progressive normovolemic hemodilution perhaps beneficial to patients with coronary heart disease, and finally, a better psychological preparation to surgery.

[Original technic for preoperative hemodilution permitting deferred autologous transfusion (apropos of 106 cases)]

To carry out normovolemic haemodilution in the best security conditions we elaborate a new method of preoperative haemodilution. Collection of red cell concentrates and adequate compensation are made either in the blood bank or at the patient's bed side. There are two ways of proceeding: *manual plasmapheresis technic is used for the collection of less than 450 ml packed red cells; *collection of more than 450 ml packed red cells is carried out on a PCS Haemonetics cell separator. CPD autologous red cells concentrates prepared in that way can be stored to meet the patient's need during and after the operation. The patient is identified as donor and receiver as regards laboratory analysis and computer treatment as well. Information's transmission between blood bank hospital and clinics is secured with the same document. This method enables homologues transfusion save and completes autologous transfusion in 68% cases among 106 patients. It is to be noticed that none of the 98 haemodiluted patients suffered from thrombosis.