Minimising changes in plasma calcium and magnesium concentrations during plasmapheresis

Abstract

Hypocalcaemic tetany is a known complication of plasmapheresis. It has two causes. Intravenously administered 4.5% human albumin solution (HAS) has no calcium or magnesium, so the replacement of plasma with this fluid depletes these ions. The citrate in fresh frozen plasma (FFP) chelates divalent cations, so the exchange with this at the end reduces the proportion of calcium and magnesium that is ionised. We studied the effect of supplementing HAS with 2 mmol/l calcium chloride and 0.8 mmol/l magnesium sulphate on the changes in ionised and total calcium and magnesium concentrations throughout plasmapheresis. The supplements prevented the falls in these concentrations that is otherwise seen during the HAS infusion, and, thus, the transient fall in ionised calcium concentration induced by the citrate in the FFP was not so profound, reaching 0.92 instead of 0.78 mmol/l (P = 0.002). Supplementation with calcium and magnesium during HAS maintains their balance and prevents tetany during the FFP infusion.

Prophylactic infusion of calcium gluconate to prevent a symptomatic fall in plasma ionized calcium during therapeutic plasma exchange: A comparison of two methods

“…The supplementation of the albumin replacement fluid with 0.5 g (1.12 mmol) of calcium gluconate per 500 mL of albumin was highly effective at maintaining a stable level of [Ca 2+ ] throughout the TPE procedures, but we cannot be certain that the same could have been achieved using less calcium gluconate. Krishnan and Coulthard supplemented a 4.5% human albumin solution with 2 mmol/L of calcium chloride in the pediatric setting and achieved results similar to ours . However, in the present study, the infusion of 1 g (2.325 mmol) of calcium gluconate per hour during TPE was almost as effective, resulting in a significant, but small (~5%) decrease in plasma [Ca 2+ ] by the end of TPE.…”

“…A fall in plasma [Ca 2+ ] of only 5% would not be expected to be associated with symptoms. [1][2][3][4]6,8 In fact, only 2 of the 47 TPE procedures in our study were associated with symptoms of hypocalcemic toxicity.…”

“…The rapid infusion of pharmaceutical albumin is the major factor responsible for lowering of plasma [Ca 2+ ] during TPE . The supplementation of the albumin replacement fluid with 0.5 g (1.12 mmol) of calcium gluconate per 500 mL of albumin was highly effective at maintaining a stable level of [Ca 2+ ] throughout the TPE procedures, but we cannot be certain that the same could have been achieved using less calcium gluconate.…”

“…A mean of approximately 140 mL of ACD-A was returned to our patients during the TPE procedures ( [17][18][19] The rapid infusion of pharmaceutical albumin is the major factor responsible for lowering of plasma [Ca 2+ ] during TPE. [1][2][3][4]13 The supplementation of the albumin replacement fluid with 0. A fall in plasma [Ca 2+ ] of only 5% would not be expected to be associated with symptoms.…”

“…Hypocalcemic toxicity during therapeutic plasma exchange (TPE) principally results from the infusion of pharmaceutical albumin, which avidly binds plasma ionized calcium ([Ca 2+ ]), as the colloid replacement fluid. [1][2][3][4] We and others have shown that supplementation of the albumin replacement fluid with calcium gluconate is effective in preventing this usually mild, but frequent, complication. [5][6][7] The fall in plasma [Ca 2+ ] that occurs during donor apheresis procedures, or cytapheresis procedures such as peripheral blood hematopoietic progenitor cell collection, results from the return of plasma carrying a citrate-based anticoagulant to the donor or patient.…”