Blood purification
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During sepsis, there is release of various endotoxins from microorganisms which more or less activates cascade systems including release of cytokines such as tumor necrosis factor alpha and interleukin 6 and complement components. This causes impairment of vascular integrity and permeability which may progress into septic shock and a disseminated intravascular coagulation which progresses into multiorgan failure, including acute renal failure and subsequent death. Although most endotoxins and cytokines have a molecular size < 50 kD, there is little efficacy in removal of them by hemofiltration filters used for acute dialysis. ⋯ In contrast, these studies showed a survival rate of about 75% by addition of such therapeutic interventions to the conventional intensive care unit treatment. The substitution of the removed plasma products must be considered to include products important for the host defense and coagulation process and to avoid infections, bleeding, or increased coagulation. This type of removal is unselective and probably in the future will include addition of absorption techniques which may add further benefit to the outcome.
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Review Historical Article
The role of hemofiltration in the critically-ill intensive care unit patient: present and future.
The development of acute renal failure (ARF) in intensive care unit (ICU) patients carries a poor prognosis. Today, most cases are no longer an isolated organ dysfunction but are part of a multiple system organ failure syndrome. Recently developed renal replacement therapies allow adequate metabolic control, even in highly catabolic and hemodynamically unstable patients. ⋯ Although hemofiltration has been shown to improve hemodynamics of experimental septic shock, convincing evidence that hemofiltration improves outcome of ICU patients is lacking. Available data suggest that high ultrafiltrate volumes may be needed to achieve clinically important beneficial effects of hemofiltration in these patients. Prospective, randomized trials in homogeneous patient groups are needed to assess the role of hemofiltration in patients with septic shock or multiple system organ failure.
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Tumor necrosis factor is a cytokine made by macrophages, monocytes and T cells that has been formed to play an important role in shock, cachexia and inflammation. The importance of this cytokine eliciting shock and cachexia in mammals is reviewed.
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Case Reports
Hypoventilation in a dialysis patient with severe metabolic alkalosis: treatment by hemodialysis.
A patient with end-stage renal disease (ESRD) developed metabolic alkalosis and alkalemia from protracted vomiting. As a result of the absence of the alkali excretory capacity in this patient with ESRD, the alkaline load accumulated rapidly. Once the amount of acid lost from vomiting exceeded the amount of acid gained from metabolism, alkalemia supervened. ⋯ In this report, the extent of compensatory hypoventilation in the setting of metabolic alkalosis in patients treated for ESRD and therapeutic approaches to this problem will be discussed. Treatment was aimed at correcting the primary disorder, namely metabolic alkalosis. Conventional bicarbonate dialysis was shown to be effective in improving acid-base homeostasis in this patient.
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Comparative Study
Acetate-free biofiltration: hemodiafiltration with base-free dialysate.
Bicarbonate dialysis has several clinical advantages compared to conventional acetate hemodialysis. However, the use of bicarbonate in the dialysate requires complicated hardware with considerable maintenance and servicing. We have developed a new dialysis technique, a modification of hemodiafiltration, called acetate-free biofiltration (AFBF), with no base replacement agents in the dialysate and with the infusion of bicarbonate solution in postdilution fluid. ⋯ In the chronic part, 880-910 HCO3 mEq was infused per session and there was an increase in mean pretreatment plasma bicarbonate from 18.1 +/- 2.2 upon starting to 22.8 +/- 0.4 mEq/l by the end of the 12-month period. A very low incidence of intradialytic hypotension and stable serum chemistries were achieved with this technique as compared with standard hemodialysis despite a reduction of 3 h in weekly treatment time. AFBF is an easy-to-use, safe alternative to bicarbonate dialysis thanks to the absence of pyrogen reactions and comparatively low-cost maintenance.