Potential Deleterious Interactions between Certain Chemical Compounds and a Thermoplastic Polyurethane Heat Exchanger Membrane Oxygenator.

Extracorporeal membrane oxygenation (ECMO) has become a powerful tool in the race to reverse failure to rescue events. Rapid implementation set the stage for the advent of the 30-day wet-priming storage as a standard practice. A recent alert regarding methylene blue (MB) unidirectional leach from patient's circulation through the oxygenator thermoplastic polyurethane (TPU) heat-exchanger membrane into the heater-cooler unit (HCU) water bath led us to believe that despite reassurances, the reverse process might be possible. To that effect, we performed a pilot in vitro experiment. We tested three adult ECMO sets (Adult Quadrox iD Oxygenator, Getinge, Doral, FL) probing for the transfer of MB between the water bath of a Sarns Dual Heater Cooler (Terumo Corporation, Ann Arbor, MI) and the circuit stored wet-primed for 30 days. In each test, 1,500 mg of reconstituted MB (HiMedia, Mumbai, India) were added to the 7.5 L of water in the HCU, circulated for 6 hours on which the water lines were disconnected and the setup was stored for 30 days. The primed circuit was tested for MB transfer at days 0, 13, and 30 by means of optical density (OD) at 665 nm and 26.5°C. Transference of MB from the HCU water bath into the ECMO circuit could be detected as early as day 13 after setup, achieving significant values by day 30 (median OD .019 (.014-.021). Expected OD if no diffusion present: 0. The complete separation of water interfaces between the patient's circuit and the HCU water bath may prove to be more dogma than fact when certain chemical substances are used in conjunction with TPU membrane oxygenators. Whether the transfer of substances is due to chemical processes or molecular weight needs further evaluation. Meanwhile, the use of chemicals for the cleaning of the HCU should be mindful of potential noxious effects.

Technical-environmental optimisation of the activated carbon production of an agroindustrial waste by means response surface and life cycle assessment.

In this study, a simultaneous optimisation of technical and environmental parameters for activated carbon production from soybean shells is presented. A 23 factorial design was developed to explore the performance of the technical responses yield and iodine number, and the single score of ReCiPe endpoint method, which was evaluated by means the life cycle assessment. The independent factors included in the design of experiments were the impregnation ratio, temperature, and time activation. Three quadratic equations were obtained and simultaneously optimised by maximisation of the overall desirability function. The principal results of the individual responses indicate that the iodine number is practically independent of the activation temperature in a range of 450 ºC-650 ºC; the yield is inversely proportional to activation time and exhibits minimum values between 500 ºC-600 ºC; and the environmental response single score presents the lowest value at a temperature and time activation of 450 ºC and 30 min, respectively. The most polluting stage of activated carbon production from soybean shells production is the impregnation stage, mainly for the use of ZnCl2 as activating agent and the energy consumption. The simultaneous optimisation of the three responses indicates that the optimal activated carbon should be produced at 180 min, 650 ºC, and an impregnation ratio of 1 g soybean shell g ZnCl2-1.