Contributions to nephrology最新文献

Liver failure in the intensive care unit (ICU), whether acute or acute-on-chronic, remains a serious condition with reduced functions, various metabolite and toxin accumulation in the systemic circulation, and a high mortality rate. While transplantation remains the treatment of choice, the lack of organ transplants necessitates finding alternative solutions. Within the last years, several therapies aiming to support liver function have been developed in order to serve as a bridge to liver transplantation or as replacement therapy, allowing regeneration of the injured liver. In those therapies, nonbiological extracorporeal liver support devices are the most widely used, mainly based on detoxification by eliminating accumulated toxins notably by adsorption on specific membranes and/or with plasmapheresis. One of the most recent techniques is the double plasma molecular adsorption system combining plasma filtration and two specific adsorption membranes, which is largely described and studied in this chapter. This technique seems promising to remove deleterious toxins, cytokines and bilirubin in particular, is fairly simple to use, does not require a specific machine (it works on continuous renal replacement therapy machines), and has given encouraging results in the pilot studies published recently, in association with plasmapheresis or alone. However, further studies and evaluations are needed before this technique can be used routinely in ICU.

Patients with severe thermal injury require urgent specialized care in burn units. These units assure good coordination of a bundle of care including fluid resuscitation, nutritional support, respiratory care, surgical care and wound care, infection prevention, and rehabilitation. When severely injured, burn patients present a systemic inflammatory response syndrome, associated with a dysregulated immune homeostasis. This complex host response exposes patients to prolonged hospitalization with suppressed immune function, increased susceptibility to secondary infections, longer organ support, and increased mortality. To date, several strategies, such as hemoperfusion techniques, have been developed to mitigate immune activation. We propose herein a review of the immune response to burn injury and the rationale and potential applications of extracorporeal blood purification techniques such as hemoperfusion for burn patients' management.

Extracorporeal circulation (ECC) such as cardiopulmonary bypass or extracorporeal membrane oxygenation (ECMO) may induce a complex activation of the immune system. To date, strategies to mitigate this activation have failed to translate into meaningful improvement of clinical outcomes. Hemoperfusion is a blood purification technique, which relies on mass separation by a solid agent (hemoadsorption). It can be performed by adding a cartridge filled with adsorptive sorbent in the extracorporeal circuit. These devices have the theoretical advantage to enable the removal of excess pro- and anti-inflammatory molecules. Several studies have demonstrated the feasibility and safety of hemoperfusion during cardiac surgery. They have suggested that the procedure could decrease cytokine levels in situations where they were elevated. However, further studies are required to determine the clinical indications, timing, and duration of hemoperfusion during cardiac surgery. Although a similar rationale can apply to hemoperfusion in ECMO, available data in this situation are even more limited and results are conflicting. In this chapter, we discuss the rationale for hemoperfusion with ECC, how to practically do it, and the current level of evidence supporting this therapy.

Acute liver failure and acute-on-chronic liver failure are conditions in which the loss of metabolic function of the liver leads to the accumulation of several toxins such as bilirubin. Patients with sepsis or multiple organ dysfunction syndrome have a greater risk of developing liver failure, and hyperbilirubinemia is associated with poor prognosis. Bilirubin removal may not only alleviate signs and symptoms of liver dysfunction but also act as an index of removal of albumin-bound toxins. Conjugated and unconjugated bilirubin, due to their molecular weight and albumin-binding capacity, respectively, cannot be removed by classic dialysis; therefore, different extracorporeal techniques have been developed to remove bilirubin from the blood. Plasma adsorption perfusion is an extracorporeal liver support technique in which bilirubin is removed from the plasma through a specific adsorbing cartridge. Double plasma molecular adsorption system adds a broad-spectrum adsorption column for the removal of inflammatory mediators and antibodies and other medium toxins. Their use in the treatment of hyperbilirubinemia has been established with several emerging data indicating their efficacy when compared to other extracorporeal techniques. However, bilirubin adsorption kinetics has not been sufficiently elucidated, and more studies are needed to improve the quality of treatment in terms of timing and prescriptions.

The removal of soluble toxins from blood is necessary in patients with severe kidney failure. The majority of blood purification techniques are based on the use of semipermeable membranes, such as for dialysis treatment. But, whenever there is the need to remove small soluble molecules from blood, the use of such purification techniques may exhibit limited efficiency. This leads to a search for better-performing treatments. Hemoperfusion, given the recent strong advances in the sorption media biocompatibility with plasma (or blood), is considered a promising blood purification technique. This introductive chapter aims at briefly presenting the phenomenology of the adsorption process, also providing some basic elements related to how to use equilibrium load data to define an adsorption isotherm, which can be used to size a hemoperfusion cartridge.

In this chapter, anticoagulation treatments for adsorption techniques in continuous renal replacement therapy (CKRT) will be reviewed. Anticoagulation used with adsorption techniques is quite different than anticoagulation in classical CKRT with nonadsorptive therapies. Regional citrate anticoagulation (RCA) and unfractionated heparin (UFH) are the most common anticoagulation modalities for both nonselective adsorptive membranes - such as surface-treated acrylonitrile 69 membranes (AN69ST) and polymethylmethacrylate membranes - and selective adsorptive membranes such as AN69-oXiris. For these techniques, the efficacy of RCA seems to be superior to UFH. Regardless of the lack of large comparative studies in comparison to ones conducted for adsorptive filter techniques in CKRT, RCA and UFH will also be discussed for nonselective adsorptive sorbents like CytoSorb and Jafron HA. For selective adsorptive sorbents, such as polymyxin-B hemoperfusion, UFH and RCA seems to be the appropriate techniques; however, randomized controlled trials confirming this are yet to be conducted. Lastly, anticoagulation prophylaxis for more specific techniques like coupled plasma filtration adsorption and double plasma molecular adsorption system will be discussed.

The Jafron series of sorbent cartridges provides a comprehensive array of coated, highly biocompatible sorbent beads made of styrene-divinylbenzene copolymers. Such beads carry a mean diameter of 0.8 mm with a range from 0.60 to 1.18 mm. The maximal pore size of these coated beads and the volume of the cartridge vary according to the type of cartridge ranging between 50 Da and 60 kDa. The sorbents, the size of the cartridge, the volume of sorbent, and the pore size (which reaches 60 kDa with the HA330 cartridge) aim to take advantage of the principles of molecular adsorption in a variety of diseases from uremic toxin retention to poisoning and drug overdose, from kidney disease to liver failure, from acute respiratory distress syndrome to sepsis, from toxic skin injury to COVID-19. The preliminary data from ex vivo studies, animal investigations, and human pilot work look promising and justify a program of systematic investigation of these products to advance our understanding of how they may be incorporated into our therapeutic arsenal.