ITBM-RBM最新文献

The oxygenator design demands three issues : function, hematologic compatibility and hemodynamic compatibility. The function of an oxygenator is to assure the gaz transfer of oxygen and dioxydic of carbon throught a microporous membrane. The hematologic compatibility emerges on biocompatibility to inhibit the inflammatory respons. The hemodynamic compatibility manages the interaction of the device with the natural circulation. This issues are linked and determine the industrial choices : membrane type, fiber weaving, coating, volume, blood path length, pressure drop.

The ideal extracorporeal oxygenator transfers oxygen into and carbon dioxyde out of the body at physiologic blood flow rates without blood trauma and a small priming volume. Compared with natural lungs, artificial lungs have much smaller surface areas and are limited by diffusion. Despite improved oxygenators designs that offset these differences somewhat, the maximum oxygen transfer of even the most efficient artificial lungs is less than half that of normal lungs. Nevertheless the progress realized for 50 years allowed a considerable improvement of oxygenators. From more than two liters, the priming volumes reache now less than 200 ml of bloodless solutions.

The biocompatibility was recently improved by the complete suppression of the blood-air interface because of continuous polymethylpentene membranes employment with gaz transfers of 02 and C02 equal to those of the microporous polyethylene membranes. The coated surfaces by heparin, phosphorylcholine or cyclosiloxane decrease the cell and the non cell blood activation. The devices of deairing by trap and filter are optimized in the oxygenator, enhancing the safety . The miniaturization of the cardio pulmonary bypass circuits goes on with the incorporation of a centrifugal pump head in the design of the oxygenator.

A recent article in a famous medical journal has questionned the safety of aprotinin utilization in cardiac surgery. As opposed to this observational study, we are reporting meta-analysis on antifibrinolytic therapy efficacy and safety.

Four meta-analysis published between 1994 and 2006 are concerned. They show the efficacy of aprotinin and tranexamic acid for decreasing the number of allogeneic blood-transfusions (PRC) and the patients receiving at least one unit of PRC. Aprotinin also decreased of incidence of reoperations for bleeding. Antifibrinolytic therapy did not influence mortality and perioperative complications such as myocardial infarction, stroke and acute renal failure. By contrast the data issued of 18 trials demonstrated a reduction of strokes with aprotinin therapy. The results of the recent observational study are discussed. Physicians therapeutic choice should be lead by randomised trials when such data exist.

The aim of this study was to evaluate the blood volume saved after rinsing of the circuit of extracorporeal circulation with a physiologic solution at the end of cardiac operations. The blood volume saved in patients in whom the circuit was rinsed (n = 219), was greater than in control group (n = 184), respectively, 733 ± 204 ml and 585 ± 187 ml (difference: 148 ml, p < 0.001). The best results were obtained in patients who had haemofiltration during surgery (difference: 244 ml, p < 0.001) and in patients operated for valvular disease (difference: 20 ml, p < 0.001). In patients with coronary disease the difference was lower but statistically significant (76 ml, p = 0.025).

Before the beginning of cardiopulmonary bypass (CPB), the manipulation of the oxygenator requires priming, then a deairing done with a tough care, a stake in load (responsibility) and a rigorous surveillance. The choice of the membrane depends on the patient (age, size, weight) and on its pathology to be treated.

Contact system was thought to be an accessory pathway for thrombin generation. It appears that this system participate to fibrinolysis, vascular tone and capillary permeability regulation. These actions are mediated by FXII and bradykinin generated from high molecular weight kininogen. C1-inhibitor is the main regulatory protein. During cardiopulmonary bypass, activation of contact system occurs with secondary fibrinolysis, capillary leak syndrome and vasopl6gie. CI-inhibitor consumption leads to acquired deficit and therapeutic use may be of interest.

Weaning from cardiopulmonary bypass may be difficult in some patients due to altered left ventricular contraction, inadequate preload, inappropriate rate and rhythm, and obstruction to inflow. Optimization of the weaning process is accomplished by diligent monitoring of hemodynamics parameters.

Du fait de l'accroissement de l'espérance de vie et des pathologies cardiovasculaires avec l'âge, la chirurgie du rétrécissement valvulaire aortique s'est beaucoup développée.

Patients. —

Les progrès de la médecine ont permis une diminution de la mortalité opératoire qui est analysée à partir d'un groupe de 442 patients âgés de 80 ans et plus opérés entre le 1^er, janvier 2000 et le 31 décembre 2004. Le remplacement valvulaire était isolé (n = 344) ou associé à une revascularisation coronarienne (n = 86), une plastie mitrale (n = 5) ou une chirurgie de l'aorte ascendante (n = 7). Un deuxième groupe de 621 octogénaires opérés avant le 31 décembre 2000 a fait l'objet d'une analyse visant à déterminer les résultats à long terme.

Résultats.—

La mortalité opératoire est de 7,5 % (n = 33). Les facteurs indépendants de mortalité opératoire sont : une insuffisance aortique (30 %, p < 0,004), la classe NYHA IV (20,5 %), p < 0,001), une défaillance ventriculaire gauche ou droite (11,5 % et 19,4 %, p < 0,02), une insuffisance rénale chronique (18,5 %, p < 0,04), l'urgence (37,5 %, p < 0,001, OR = 4,7), la fraction d'éjection ventriculaire gauche (21,1 %, p < 0,004, OR = 0,9) et une chirurgie redux (35,3 %, p < 0,001, OR = 6). La mortalité opératoire est majorée par une revascularisation coronarienne (11,6 %), une chirurgie mitrale ou tricuspide (20 %) et une chirurgie de l'aorte ascendante (25 %). La survie globale des 621 opérés était de 85 % à un an, 71 % à 3 ans et 60 % à 5 ans.

Conclusion. —

L'excellent résultat tant en termes de longévité que de qualité obtenue au prix d'un risque opératoire raisonnable justifie le remplacement valvulaire aortique chez les octogénaires. La décision doit être personnalisée en tenant compte de l'état général du patient et de ses fonctions supérieures.

Increasing life expectancy coupled to an increasing incidence of cardiovascular disease with age is leading to an ever increasing number of elderly referred for aortic valve replacement.

Patients. —

Hospital mortality has been analysed and updated according to a group of 442 patients aged ⩾80 years who underwent an aortic valve replacement between January 2000 and December 2004 either isolated (n = 344) or associated with coronary revascularisation (n = 86), mitral valvuloplasty (n = 5) or aortic surgery (n = 7). A group of 621 octogenarians operated before December 2000 was analysed in order to determine long term results.

Results. —

Operative mortality is 7.5% (n = 33). Independent predictive factors of mortality were : aortic insufficiency (30%, p < 0.004), NYHA class IV (20.5%, p < 0.001), left and right heart failure