Pyrogen reactions to human serum albumin during plasma exchange

Is palmitate truly proinflammatory? Experimental confounders and context-specificity

Based primarily on cell culture results, saturated fatty acids (SFAs) are proposed to promote inflammation and contribute to metabolic dysfunction through Toll-like receptor activation. Studies are often complicated by a requirement for carriers (e.g., BSA) or solvents (e.g., ethanol) to increase SFA solubility. To ascertain whether these factors influence interpretations of SFA-associated inflammation activity, we measured responses of RAW264.7 monocyte/macrophages and C₂C₁₂ myotubes to various BSA, ethanol, and cyclodextrin (alternative FA carrier) conditions. Fatty acid-free, low-endotoxin BSA preparations (0.33% to 2% wt/vol) activated whereas 0.5-1.0% ethanol inhibited RAW264.7 TNFα release. Ethanol modestly increased IL-6 secretion in C₂C₁₂ myotubes. Cyclodextrins (0.3-6.0 mM) were tested as alternative carriers of palmitate, but their usefulness was limited due to toxicity and solubility issues. Using a lower-inflammation BSA source and no ethanol, ∼24-h sodium palmitate treatment (≤600 µM) failed to trigger RAW264.7 TNFα release and, in fact, significantly dampened BSA-induced inflammation by >50%. In C₂C₁₂ myotubes, only high palmitate concentrations (500-600 µM) elicited IL-6 secretion (>2.5-fold increase). Acute palmitate (200 or 500 µM) treatment did not activate MAP kinase pathways above that of fresh BSA-containing media alone in either cell type. These results highlight the importance of experimental conditions in studies exploring SFA inflammation effects. The limited (or even anti-inflammatory) effects of palmitate that we observed indicate that immunomodulatory effects of SFAs are context-specific. Thus, caution is needed when interpreting the literature related to putative proinflammatory effects of SFA.

Membrane-based Therapeutic Plasma Exchange: A New Frontier for Nephrologists

Therapeutic plasma exchange has long been utilized to manage a variety of immune-mediated diseases. The underlying principle is the removal of a circulating pathogenic substance from the plasma and substitution with a replacement fluid. Different methodologies of plasma separation include the use of centrifuge, which relies on the variation in the specific gravity of blood components, and membrane-based separation, which relies on particle size. With advancements in technology and clinical insight into disease pathophysiology, membrane technology has become more biocompatible, safer, and more adaptable to conventional hemodialysis and hemofiltration machines. As such, nephrologists, who are familiar with management of extracorporeal blood purification systems, are increasingly involved with membrane-based plasma separation. This review aims to highlight the technical aspects of membrane-based separation, review the prescription for therapy, and draw comparisons with the centrifuge-based technique when applicable.

Therapeutic apheresis: use of human serum albumin, fresh frozen plasma and cryosupernatant plasma in therapeutic plasma exchange

In therapeutic plasma exchange, patient plasma is removed and a colloid replacement solution is infused in its stead. A solution of 4-5% human serum albumin in saline is the recommended replacement solution in most instances, even though it leads to transient mild deficiencies of most plasma proteins. Albumin solutions are pasteurized to inactivate viruses, carry a very low risk of febrile and allergic reactions, and are convenient to store and administer. Fresh frozen plasma, which must be type specific and needs to be ordered in advance and thawed before use, carries a higher risk of reactions; however, it replaces all plasma constituents and is appropriate for patients with thrombotic thrombocytopenic purpura or a pre-existing coagulopathy. Neither cryosupernatant plasma, which is relatively depleted of the proteins in cryoprecipitate, nor pooled plasma that has been virally inactivated with organic solvents and detergents has been shown to be superior to fresh frozen plasma for any indication.

Methyl-beta-cyclodextrin: an alternative carrier for intravenous infusion of palmitate during tracer studies in swine (Sus scrofa domestica)

Fatty acid-free albumin has been the standard carrier for intravenous infusion of fatty acids to study in vivo lipid metabolism. However, subjects can have adverse reactions to infusion of albumin. We sought an alternative to albumin as a carrier for intravenous infusion of fatty acids, using the pig as a model. Cyclodextrins are naturally occurring water-soluble molecules that can serve as carriers for lipid-soluble compounds. 13C-palmitate was complexed to either 20% methyl-beta-cyclodextrin, 20% 2-hydroxypropyl-beta-cyclodextrin, or 5% porcine albumin (isotopic purity of infusates: 99.22+/-0.06%). 13C-palmitate-albumin was infused under fed conditions and 13C-palmitate-methyl-beta-cyclodextrin was infused under fasted and fed conditions in 50-kg pigs. Palmitate remained in solution at 4 degrees C in methyl-beta-cyclodextrin, but precipitated at 25-30 degrees C in 2-hydroxypropyl-beta-cyclodextrin. Pigs infused with 13C-palmitate-methyl-beta-cyclodextrin maintained normal body temperature and appetite; those infused with 13C-palmitate-albumin became anorexic and exhibited other negative side effects to albumin. Palmitate oxidation rates under fed conditions were similar using either 13C-palmitate-methyl-beta-cyclodextrin or 13C-palmitate-albumin complexes. Fasting increased 13C-palmitate-methyl-beta-cyclodextrin oxidation by approximately eight-fold. These data suggest that methyl-beta-cyclodextrin may be a suitable substitute for albumin in fatty acid metabolism studies in swine.

Pentastarch as partial replacement fluid for therapeutic plasma exchange: effect on plasma proteins, adverse events during treatment, and serum ionized calcium

We compared the safety, effect on plasma proteins, and contribution to hypocalcemic toxicity of 10% pentastarch vs. 5% albumin in plasma exchange. Thirty-two neurology patients underwent 161 plasma exchange procedures. Subjects were randomized to receive either 10% pentastarch (n = 17) or 5% albumin (n = 15) as the first (1/2) of colloid replacement. The second (1/2) of colloid replacement was 5% albumin in all cases. NaCl (plus small amounts of ACD-A) accounted for (1/4) of the total return fluid. Mean total exchange volume was 3,842.6 +/- 450 ml. Hemoglobin, platelet count, coagulation parameters, and plasma fibrinogen were similar between the two groups at the outset of plasma exchange and at the time of the last (4th or 5th) procedure of the series. Immunoglobulin levels were equivalent at the outset and were reduced by plasma exchange to the same extent in the two groups. Serum albumin concentration fell significantly faster in the group receiving pentastarch. On the other hand, serum calcium, corrected for the albumin concentration, fell significantly further in the control group than in the group receiving pentastarch. Mean serum ionized calcium fell approximately 25 % in procedures using only albumin but only approximately 16% when pentastarch was used (P < 0.0001). This was reflected in the occurrence of hypocalcemic toxicity in 33.3% of procedures performed using only albumin but in only 8.1% of those using pentastarch (P = 0.0002). Pentastarch may be suitable for partial colloid replacement in plasma exchange and would have saved our hospital $127,050 to $434,280 in 1998 if used in all procedures.

Safety of plasmapheresis in the treatment of neurological disease

BACKGROUND

Plasmapheresis is used as a treatment modality in several neurological disorders. Adverse reactions relating to vascular access, replacement fluid and anticoagulant use have been reported.

AIMS

To establish the incidence of complications of therapeutic plasmapheresis in the treatment of neurological diseases.

METHODS

A retrospective study was performed, in which case records of patients undergoing plasmapheresis for neurological indications between 1 April 1992 and 1 September 1996 were reviewed for fatalities and adverse reactions related to vascular access, transmission of Hepatitis B or C or Human Immunodeficiency Virus (HIV), fluid imbalance, allergic or febrile reactions, haematological complications, machine failure and citrate toxicity.

RESULTS

In the study period, 1283 plasmapheresis procedures were performed on 73 patients with neurological disease. There were no fatalities, no cases of Hepatitis B or C or HIV transmission, no allergic or febrile reactions, thrombosis, bleeding diathesis or severe citrate toxicity. Infections related to venous access occurred in 0.5 per cent of procedures with septicaemia in 0.2 per cent of procedures (4.1% of patients). Less serious complications included hypotension in 1.2 per cent of procedures (11% of patients) and citrate toxicity manifesting as nausea, vomiting, cramping or paraesthesia in 1.2 per cent of procedures. Machine failure occurred in 0.2 per cent of procedures.

CONCLUSIONS

Plasmapheresis is a safe procedure when performed for neurological indications by experienced personnel in a large pheresis unit. The most frequent adverse event is infection of the venous access site.

Mechanisms of adverse effects during hemapheresis

For over 20 years blood components have been collected from normal donors by automated hemapheresis. Cell separators have become increasingly sophisticated, and relatively pure component "concentrates" can be obtained quite safely. Cytapheresis donors are monitored carefully, and serious reactions are very rare. In contrast, therapeutic apheresis procedures may be technically demanding and frequently are performed on very sick patients. Large volumes of blood are rapidly removed from the patient, anticoagulated, and separated into components by the automated cell separator. The blood component containing the pathogenetic factor (e.g., plasma containing an antibody) is retained outside of the body, and the remaining components (e.g., red cells, white cells, and platelets) plus the replacement fluid are reinfused. Complications can occur in normal cytapheresis donors because of the technical challenges of the procedure (e.g., extracorporeal circuit to be filled, use of citrate anticoagulant, need for large bore intravascular access, and rapid blood flow rates). All of these factors apply also to therapeutic patients plus the additional requirement for replacement fluids, and the clinical features of the underlying illness for which each patient is being treated. Fortunately, even with therapeutic patients, most complications are of modest severity and are easily managed with only temporary slowing or interruption of the hemapheresis procedure.