Development of a regenerated carbon dioxide absorber for human life support systems during long space flights

In the development of life support systems for long-term space missions, the most important tasks are the absorption of carbon dioxide from the air, the production of carbon dioxide with a concentration above 98 %, and the production of oxygen from carbon dioxide by the Bosch – Sabatier process. To solve these problems, a regenerative carbon dioxide absorber adapted to space flight conditions is required. The article proposes a new method for the production of chemosorbents based on hydrated zirconium oxide using polyacrylates as a binder and polymer matrix. The regenerated absorber of carbon dioxide for its application in space flights must meet the regulatory requirements of sanitary-chemical and toxicological safety of materials intended for the equipment of inhabited sealed rooms, be resistant to radiation and to the effects of mold. In the study of the processes of “sorption – desorption” of carbon dioxide, we have established the relationship between the technological parameters of the synthesis of chemosorbents and the kinetic parameters of the processes of mass-sorption of sorbate in the “sorption – regeneration” cycles. It is found that the optimal weight ratio of the “adsorbent – filler/polymer matrix” 89÷94/11÷6 is optimal in terms of the performance characteristics of the developed absorbers. It is shown experimentally that the main operational characteristics of the developed materials do not change under experimental conditions during 2000 “sorption – regeneration” cycles. The resulting chemosorbents are investigated by physicochemical analysis. Employing methods of gas chromatography and chromatomass spectrometry, we have conducted sanitary and chemical studies and toxicological assessment of the quantitative and qualitative composition of the components of gas release of the developed regenerated carbon dioxide absorber and air-gas mixture formed during the regeneration of the regenerated carbon dioxide absorber. Also we have carried out microbiological tests of samples of the regenerated absorber of carbon dioxide for resistance of material to influence of mold mushrooms. The results obtained confirm the possibility of using the developed materials in life support systems of manned spacecraft for deep space exploration.

Preparation of the Siemens KION Anesthetic Machine for Patients Susceptible to Malignant Hyperthermia

Background Preparation of anesthetic machines for use with malignant hyperthermia-susceptible (MHS) patients requires that the machines be flushed with clean fresh gas. We investigated the washout of inhalational anesthetics from the KION anesthetic machine. Methods In part 1, halothane was circulated through KION anesthetic machines for either 2 or 12 h using a test lung. The times to washout halothane (to 10 parts per million [ppm]) first, from the internal circuitry and second, from the ventilator-patient cassette (without the carbon dioxide absorber) were determined at 5 and 10 l/min fresh gas flow (FGF). In part 2, the rates of washout of halothane or isoflurane from either the KION or Ohmeda Excel 210 machines were compared. The effluent gases were analyzed using calibrated Datex Capnomac Ultima (Helsinki, Finland) and a Miran LB2 Portable Ambient Air Analyzer (Foxboro, Norwalk, CT). Results Halothane was washed out of the internal circuitry of the KION within 5 min at 10 l/min FGF. Halothane was eliminated from the ventilator-patient cassette in 22 min at the same FGF. The times to reach 10 ppm concentration of halothane and isoflurane in the KION at 10 l/min FGF, 23 to 25 min, was four-fold greater than those in the Ohmeda Excel 210, 6 min. Conclusions To prepare the KION anesthetic machine for MHS patients, the machine without the carbon dioxide absorber must be flushed with 10 l/min FGF for at least 25 min to achieve 10 ppm anesthetic concentration. This FGF should be maintained throughout the anesthetic to avoid increases in anesthetic concentration in the FGF.