Citrate induced hypocalcaemia during cell separation

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.

Plasma separation for artificial liver support

A bioartificial liver (BAL) support system, using plasma separation, has been developed to support acute liver failure patients. This study examined 14 consecutive BAL treatments in nine patients with severe acute liver failure. We report methods to achieve and manage plasma separation for an extended period of time. The mean duration of a BAL treatment was 435 minutes, with 26-59 liters of blood processed. Ionized hypocalcemia resulting in muscle twitching was a side effect of the therapy. Ionized calcium levels decreased significantly (P < .02) after BAL treatment; however, total calcium levels increased (P < .05). No significant changes were noted in heart rate, electrocardiogram [Q-T (Q-Tc) interval], blood pressure, prothrombin time, partial thromboplastin time, hematocrit, platelet count and serum phosphorous, magnesium, glucose, and pH. Plasma fibrinogen levels decreased significantly (P < .002). Ionized hypocalcemia due to the chelating effect of sodium citrate was controlled by calcium chloride administration, adjustment of blood separation rates, and reduction of the blood-to-citrate ratio. This report demonstrates that intensive, large-volume plasma separation for long periods of time can be achieved safely in critically ill patients without serious adverse effects.

Citrate-induced impairment of neuromuscular transmission in human and experimental autoimmune myasthenia gravis

Two patients who underwent plasmapheresis for severe myasthenia gravis showed marked exacerbation of myasthenic weakness at the end of exchange sessions, in which citrate was used for anticoagulation. In one patient, improvement occurred after the administration of calcium but not after edrophonium. In rabbits and in rats with experimental autoimmune myasthenia gravis, decremental muscle response to 3 Hz repetitive nerve stimulation worsened significantly after injection of the citrate anticoagulant. The worsened neuromuscular transmission defect was reversed by the administration of calcium. When used for anticoagulation, citrate reduces serum ionized calcium levels and thus may aggravate myasthenic weakness and endanger patients during or immediately after plasmapheresis.

Regional anticoagulation: hemodialysis with hypertonic trisodium citrate

We have developed a simplified method for performing regional citrate anticoagulation during hemodialysis. High ultrafiltration rates and specialized equipment were obviated by the use of a 1.6-mol/L trisodium citrate solution and a standard calcium-containing dialysate. Thirty-six dialyses were performed with this technique on 14 stable and 22 high bleeding risk patients. There was no significant decline in plasma-ionized calcium during citrate dialysis, ie, 3.85 +/- 0.34 mg/dL (mean +/- SE) predialysis, to 3.31 +/- 0.26 postdialysis; furthermore, no patient developed neuromuscular symptoms or evidence of cardiovascular instability from hypocalcemia. Serum sodium rose with this procedure, but not to hypernatremic levels. This method of citrate dialysis is safe and effective during continuous blood flow (double-needle) hemodialysis, and is no more difficult to perform than conventional heparin dialysis. Single-needle (reciprocating blood flow) hemodialysis was successfully performed by the additional use of a calcium-free dialysate and separate calcium chloride infusion (10% calcium chloride), but risks the production of unexpected hypercalcemia.

Therapeutic apheresis. Applications and future directions

The past 10-15 years have been witness to major technological achievements in the field of therapeutic apheresis. Concurrently, a large number of diseases, primarily with an immunological basis, have been treated with apheresis. In this paper, we review the various applications of therapeutic apheresis, adverse reactions associated with the mode of therapy, and future research directions. Several representative diseases are also discussed in detail.

Adverse reactions to whole blood donation and plasmapheresis

Whole blood donation is recognized to be extremely safe, yet there have been reports of serious problems stemming from whole blood donation, and so-called "donor reactions" are regularly seen. While the physiologic causes of the common donor reactions are not completely understood, some effects of whole blood donation (such as transient iron deficiency) are understood but probably not significant. In order to avoid accepting any volunteer donor who might be at risk of a serious reaction, we may have been overly cautious in exclusion of potential donors. The pheresis donor is subjected to potential depletion of the protein or cellular elements being removed, problems caused by the device used for automated pheresis, or problems related to the infusion of potentially toxic substances. Documented benefit to the patient must balance these additional risks.

The role of intensive plasma exchange in the prevention and management of haemorrhage in patients with inhibitors to factor VIII

A strategy for the prevention and management of haemorrhage in patients with inhibitors to factor VIII by intensive plasma exchange and human factor VIII infusion is described. The advantages and disadvantages of this approach are discussed in the light of the authors' experience with the technique and the alternative methods of treatment described in the literature.

Intensive plasma exchange in the management of severe Rh disease

Fourteen high-risk cases of Rh alloimmunized women were treated by intensive plasma exchange on the cell separator throughout their pregnancies. The mean volume of plasma exchanged per week was 3.21 with a total volume of 10-123 1. The replacement fluid was mainly plasma protein fraction (PPF) supplemented with fresh frozen plasma (FFP). The mean duration of treatment was 131/2 weeks, ranging from 2 to 22 weeks, commencing at 12-30 weeks gestation. The complications encountered and the selection of the optimal time for delivery are discussed. The expected stillbirth rate in this series as determined by their past obstetric histories and anit-D levels was 62%. Intrauterine transfusion was given to only two of the infants and both were later stillborn. It was possible to reduce and maintain a lower level of anti-D in the serum of most of the patients and a successful outcome was achieved in nine of the 12 cases included for analysis (75%). Plasma exchange commenced early in pregnancy is recommended as a non-hazardous form of treatment in the management of severe Rh haemolytic disease. However, if the mean level of anit-D cannot be maintained at less than 35 iu/ml then the outcome is more likely to be fatal. Amniocentesis should be delayed where possible until 28 weeks gestation and intrauterine transfusion reserved for those cases where the anti-D level becomes uncontrollably high and the fetal death is imminent.