Characterisation of aluminium release by the enFlow® fluid-warming system in crystalloids and blood products

The use of uncoated aluminium-heated plates in an intravenous fluid-warming system has been shown to produce high levels of aluminium in Sterofundin 1/1E, a balanced crystalloid solution. However, the effect of this fluid-warming device on other balanced crystalloid solutions and blood products has not been studied. Using mass spectrometry we measured aluminium levels in Plasma-Lyte 148, compound sodium lactate solution, 4% human albumin solution, expired resuspended packed red cells and fresh frozen plasma that were pumped through an enFlow^® fluid-warming system at 2 ml.min^-1 . Samples were taken at baseline before heating and then at 10-min intervals up to 60 min with the system set to warm the fluids to 40 °C. High concentrations of aluminium were found for Plasma-Lyte 148 and compound sodium lactate solutions (mean (SD) 223 (0.6) μmol.l^-1 and 163 (0.2) μmol.l^-1 at 60 min, respectively); both concentrations were significantly greater than the United States Food and Drug Administration recommended maximum limit for aluminium in intravenous nutrition of 25 μg.l^-1 (0.9 μmol.l^-1 ). Lower aluminium levels were found in 4% human albumin solutions, expired resuspended red cells and fresh frozen plasma at 60 min (mean (SD) 5.7 (0.1) μmol.l^-1 , 2.7 (0.0) μmol.l^-1 and 2.3 (0.4) μmol.l^-1 , respectively). The process allowing addition of aluminium to be added to Sterofundin 1/1E by the enFlow fluid warmer also occurs in Plasma-Lyte 148 and compound sodium lactate solutions and to a lesser degree in blood products. The exact mechanism facilitating this process and its clinical significance remain unclear.