Use of adsorptive mechanisms in continuous renal replacement therapies in the critically ill.

The pathophysiology of sepsis is becoming a more complicated scenario. In sepsis, endotoxin or other gram-positive derived products induce a complex and dynamic cellular response giving rise to several mediators known to be relevant in the pathogenesis of septic shock, such as specific mediators. substances responsible for up- or down-regulation of cytokine receptors and cytokine antagonists, inactivators of nuclear factor-kappaB or signal transduction pathways, and precursor molecules. In this article, we delve into some new concepts stemming from the use of sorbents in continuous plasma filtration. The rationale is based on the assumption that the nonspecific removal of several mediators of the inflammatory cascade and cytokine network may improve outcome in a rabbit model of septic shock and hemodynamics in a pilot clinical study. The importance of looking for innovative treatments specifically targeted for the special needs of the critically ill patients rather than using concepts and technology applied to the treatment of chronic renal failure is underlined.

Present and future options in continuous renal replacement therapies of sepsis and MOF.

Conventional continuous extracorporeal treatments such as hemofiltration and hemodiafiltration have not achieved significant reduction in cytokine plasma levels, in spite of their increasing popularity mainly related to the unnecessary fluid restriction thereby rendering adequate caloric intake possible (Actualités Nephrologiques, 1994). This is mainly due to reduced filtration, to saturability of the adsorption-related phenomena and to the absence of a convective mass transfer. New approaches have been more recently introduced. The concept of blood purification has been applied in some new innovative techniques that use non-selective or selective sorbents. We will focus on the criteria used by others and us to assess the efficiency in vitro and in animal models of sepsis of more recently introduced non-selective and selective devices. Among the innovative techniques, modalities aimed at the plasma treatment will receive emphasis. These modalities that are based on plasma filtration with the use of different sorbents. The preliminary results obtained from ongoing clinical trials will be presented. We will also expand on the technical, biological and clinical aspects that should be addressed in order to establish a new modality as innovative in the treatment of sepsis.

Results from ethical international surveys on the management of the continuous renal replacement therapy.

OBJECTIVE: To examine the ethical approach of clinicians to the continuous renal replacement therapy (CRRT). DESIGN: Review of international surveys. RESULTS: Many surveys have been carried out in order to evaluate the clinical approach and management of the continuous renal replacement therapy (CRRT). Nothing has been proposed in order to evaluate it from a bioethical point of view, even if many surveys dealt with the problem of the ethically correct administration of vital supports. These data demonstrate that an ethically correct approach to the management of life-saving support can be sometimes difficult. Results of a recent study on the ethical approach of intensivists and nephrologists to CRRT will be shown and discussed. CONCLUSIONS: Several ethical questions in the management of CRRT and other vital support are still unsolved. Practical and psychological aspects of the curing process are sometimes stronger than bioethical principles.

Achievements and new directions in continuous renal replacement therapies.

The evolution of renal replacement therapy has permitted the treatment of critically ill patients with acute renal failure. In intensive care settings, continuous renal replacement therapies have been shown to be better tolerated and clinically useful. Continuous hemofiltration is now performed with blood pumps and double-lumen venous catheters, thus avoiding the complications found in previous arteriovenous treatments. The use of countercurrent dialysate flow has overcome problems related to low treatment efficiency. High clearances can now be obtained during continuous hemodialysis or hemodiafiltration, and adequate blood purification can be achieved even in severely catabolic patients. New replacement solutions allow for a more effective correction of acidosis and electrolyte imbalances. Finally, newly designed machines permit continuous therapies while minimizing staff workload. Continuous therapies are today moving toward newer indications and applications. The ability to remove proinflammatory substances by filtration and/or adsorption has opened a series of potential indications. The concept that renal support and protection take place during hemofiltration suggests that very early use of this technique is desirable, even before the onset of oliguria or azotemia.