Aluminium release and fluid warming: provocational setting and devices at risk.

BACKGROUND: Fluid warming, recommended for fluid rates of > 500 ml h-1, is an integral part of patient temperature management strategies. Fluid warming devices using an uncoated aluminium containing heating element have been reported to liberate aluminium resulting in critical aluminium concentrations in heated fluids. We investigated saline solution (0.9%), artificially spiked with organic acids to determine the influence of fluid composition on aluminium release using the uncoated enFlow® device. Additionally, the Level1® as a high volume fluid warming device and the ThermoSens® device were investigated with artificial spiked fluid at high risk for aluminum release and a clinically used crystalloid solution. RESULTS: Saline solution spiked with lactate more than acetate, especially at a non neutral pH, led to high aluminium release. Next to the enFlow® device, aluminium release was observed for the Level1® device, but not for the coated ThermoSens®-device. CONCLUSION: Uncoated aluminium containing fluid warming devices lead to potentially toxic levels of aluminium in heated fluids, especially in fluids with non-neutral pH containing organic acids and their salts like balanced electrolyte solutions.

Characterization of hot-dip coated steel by coupling of a flow cell with ICP-OES.

In this study, the successful coupling of a 3D printed electrochemical flow cell and online multi-element analysis by ICP-OES is presented. The feasibility of the coupled method is investigated on the basis of hot-dip coated steel sheet dissolution in diluted HCl (20%). At first a qualitative evaluation of the electrochemical and element information of the coated steel substrate and relating the results to a glow-discharge optical emission spectroscopy (GDOES) measurement is done. After the qualitative evaluation, the quantitative limits are assessed by validating the linearity, repeatability and reproducibility. Comparing the results to the standard method of bulk analysis shows that the method generates reliable results. In addition the method offers the opportunity of fully automated analysis not just limited to the sample preparation.

Aluminium release by coated and uncoated fluid-warming devices.

The use of fluid-warming systems is recommended for infusion rates > 500 ml.h-1 to avoid peri-operative hypothermia. Some fluid-warming devices use disposable aluminium-heated plates for heat transfer, but there is no protective coating to separate the fluid from the heated aluminium surface. It is unknown if this could promote release of aluminium into infusion fluids. We investigated a coated (Fluido compact) and an uncoated (enFlow) fluid-warming device using normal saline or balanced electrolyte solution as infusion fluids, pumped through the heated disposables at flow rates of 2, 4 and 8 ml.min-1 for 60 min each. Aluminium concentrations in the fluid samples were analysed using graphite furnace atomic absorption spectrometry. With saline the coated and uncoated devices yielded aluminium concentrations below the level of quantification (< 128 µg.l-1 ). Similarly, balanced electrolyte solution in the coated device yielded aluminium concentrations < 128 µg.l-1 . However, balanced electrolyte solution in the uncoated device yielded aluminium concentrations of up to 6794 (3465-8002 [1868-7421]) µg.l-1 . Repeating this last study at a flow rate of 2 ml.min-1 resulted in quite high aluminium concentrations when the uncoated device was not heated (~1000 µg.l-1 ) and higher concentrations after the device was heated. We conclude that using uncoated aluminium plates in fluid-warming systems can lead to a risk of administering potentially harmful concentrations of aluminium when balanced crystalloid solutions are used. The mechanism is unclear, but heat is in part involved. Coating for aluminium within medical devices in direct contact with infusion fluids should be recommended.

Investigation of volatile metabolites during growth of Escherichia coli and Pseudomonas aeruginosa by needle trap-GC-MS.

A new method for the growth-dependent headspace analysis of bacterial cultures by needle trap (NT)-gas chromatography-mass spectrometry (GC-MS) was established. NTs were used for the first time as enrichment technique for volatile organic compounds (VOCs) in the headspace of laboratory cultures. Reference strains of Escherichia coli and Pseudomonas aeruginosa were grown in different liquid culture media for 48 h at 36 °C. In the course of growth, bacterial culture headspace was analysed by NT-GC-MS. In parallel, the abiotic release of volatile organic compounds (VOC) from nutrient media was investigated by the same method. By examination of microbial headspace samples in comparison with those of uninoculated media, it could be clearly differentiated between products and compounds which serve as substrates. Specific microbial metabolites were detected and quantified during the stationary growth phase. P. aeruginosa produced dimethyl sulfide (max. 125 µg L(-1) < limits of quantification (LOQ)), 1-undecene (max. 164 µg L(-1)) and 2-nonanone (max. 200 µg L(-1)), whereas E. coli produced carbon disulfide, butanal and indole (max. 149 mg L(-1)). Both organisms produced isoprene.