Nadja N. Rehak

Controlled study of citrate effects and response to IV calcium administration during allogeneic peripheral blood progenitor cell donation

BACKGROUND: Leukapheresis procedures are generally performed at citrate anticoagulation rates extrapolated from shorter plateletpheresis procedures. However, neither the metabolic effects nor the management of associated symptoms have been critically evaluated during leukapheresis in healthy donors.

Comprehensive analysis of citrate effects during plateletpheresis in normal donors

BACKGROUND: Although plateletpheresis procedures are generally well tolerated, the clinical and metabolic consequences associated with rapid infusion of up to 10 g of citrate are underappreciated, and a comprehensive description of these events is not available.

Serum ionized magnesium: comparison of results obtained with three ion-selective analyzers.

Abstract In a two-center (Academic Medical Center, The Netherlands, and National Institutes of Health, USA) study, we compared ionized magnesium (iMg2+) results in serum determined with the AVL 988/4, KONE Microlyte 6 and NOVA CRT, which are the currently available analyzers equipped with a magnesium ion-selective electrode. The comparison was performed with frozen serum samples from normal individuals and patients. Imprecision and reference intervals were established. We found the best agreement between the KONE(x) and AVL(y) magnesium ion-selective electrodes (y = 0.972x−0.013; n = 138) with samples from patients. With samples from normals, all three analyzers reported significantly different results (p < 0.05). Best precision was found using the NOVA; coefficients of variation established at three levels were all < 4.0%. Coefficients of variation for the AVL and KONE were < 5% at normal and high iMg2+, but 10.7 and 9.4%, respectively, at iMg2+ ≈ 0.30 mmol/l. The reference intervals (mean ± standard deviation) based on measurements in fresh serum samples were different for each analyzer: 0.55–0.63 mmol/l for AVL, 0.470.57 mmol/l for KONE and 0.43–0.55 mmol/l for NOVA. Thus, significant differences among the ionized magnesium concentration obtained with the three analyzers, limit comparison of results in clinical practice, and need to be resolved (e.g. by improvement of specificity and standardization of calibrators).

Randomized placebo-controlled study of oral calcium carbonate supplementation in plateletpheresis: II. Metabolic effects.

BACKGROUND:  The metabolic effects of oral calcium (Ca) supplementation during plateletpheresis were evaluated in a randomized, placebo‐controlled trial.

Randomized placebo-controlled study of oral calcium carbonate administration in plateletpheresis: I. Associations with donor symptoms

BACKGROUND:  The effect of oral calcium (Ca) supplements in preventing citrate‐induced symptoms during plateletpheresis was evaluated in a randomized, blinded, placebo‐controlled trial.

Comparison of precision and effect of pH and calcium on the AVL and NOVA magnesium ion-selective electrodes.

We compared the precision of the AVL 988-4 and NOVA CRT instruments for determining ionized magnesium (iMg) and assessed the effect of pH and ionized calcium (iCa) concentration on the results Within-run and day-to-day precision for the iMg electrodes were determined using three levels of control material supplied by each manufacturer. The effect of pH on iMg results was assessed by analyzing anaerobic serum samples from patients, reanalyzing those same samples after pH was increased by in vitro loss of CO2 and comparing the results. To assess the effect of iCa concentration on the iMg results, we added CaCl2 to aqueous standards from both manufacturers and to a normal serum pool. The results show comparable coefficients of variation for the two iMg electrodes both within-run (0.68-2.05 for NOVA; 0.77-2.60 for AVL) and day-to-day (2.90-6.48 for NOVA; 1.71-4.93 for AVL). The AVL results were not affected by the increase in serum pH and agreed with the NOVA results that were adjusted to a pH of 7.4 (paired t-test; p > 0.2). There was a significant direct relationship between the iCa and iMg results for both analyzers, but the AVL slopes were smaller (0.026, 0.083) than the NOVA slopes (0.129, 0.165). Thus, these two iMg electrodes have comparable precision but differ in response to an increase in pH and iCa.

Placebo‐controlled study of intravenous magnesium supplementation during large‐volume leukapheresis in healthy allogeneic donors

BACKGROUND: Marked decreases in ionized magnesium (iMg) levels occur during large‐volume leukapheresis (LVL); however, the effect of intravenous (IV) magnesium supplementation in this setting has not been carefully studied.

Physical compatibility of magnesium sulfate and sodium bicarbonate in a pharmacy-compounded hemofiltration solution.

PURPOSE The physical compatibility of magnesium sulfate and sodium bicarbonate in a pharmacy-compounded hemofiltration solution was assessed. METHODS Two bicarbonate-buffered hemofiltration solutions (low- and high-magnesium formulations) were compounded in triplicate. The concentrations of magnesium (15 meq/L) and sodium bicarbonate (50 meq/L) in the high-magnesium formulation were chosen to be somewhat below the concentrations reported as being incompatible in a popular reference. The six hemofiltration bags were stored at 22-25 degrees C without protection from light for 48 hours. Physical compatibility was assessed by visual inspection and microscopy. The pH of the solutions was assayed 3-4 and 52-53 hours after compounding. Electrolyte and glucose concentrations of the solutions were assayed at 3-4 and 50-51 hours after preparation. RESULTS No particulate matter was observed by visual or microscopic inspection in the compounded hemofiltration solutions at 48 hours. The mean +/- S.D. pH values of the low-magnesium solutions were 8.01 +/- 0.02 and 8.04 +/- 0.02 at 3-4 and 52-53 hours after compounding, respectively. The mean +/- S.D. pH values of the high-magnesium solutions were 7.96 +/- 0.02 and 7.98 +/- 0.01 at 3-4 and 52-53 hours after compounding, respectively. The electrolyte and glucose concentrations in the low- and high-magnesium solutions were similar 3-4 and 50-51 hours after preparation. CONCLUSION Magnesium sulfate 1.5 meq/L and sodium bicarbonate 50 meq/L were physically compatible in a pharmacy-compounded hemofiltration solution for 48 hours when stored at 22-25 degrees C without protection from light.