RESUMO
BACKGROUND: Home hemodialysis is associated with lower costs to the health care system compared with conventional facility-based hemodialysis because of lower staffing and overhead costs, and by transferring the treatment cost of utilities (water and power) to the patient. The purpose of this study was to determine the utility costs of home hemodialysis and create a formula such that patients and renal programs can estimate the annual patient-borne costs involved with this type of treatment. METHODS: Seven common combinations of treatment duration and dialysate flows were replicated 5 times using various combinations of home hemodialysis and reverse osmosis machines. Real-time utility (electricity and water) consumption was monitored during these simulations. A generic formula was developed to allow patients and programs to calculate a more precise estimate of utility costs based on individual combinations of dialysis intensity, frequency and utility costs unique to any patient. RESULTS: Using typical 2014 utility costs for Edmonton, the most expensive prescription was for nocturnal home hemodialysis (8 h at 300 mL/min, 6 d/wk), which resulted in a utility cost of $1269 per year; the least expensive prescription was for conventional home hemodialysis (4 h at 500 mL/min, 3 d/wk), which cost $420 per year. Water consumption makes up most of this expense, with electricity accounting for only 12% of the cost. INTERPRETATION: We show that a substantial cost burden is transferred to the patient on home hemodialysis, which would otherwise be borne by the renal program.
RESUMO
Generating renewable energy while sequestering CO2 using algae has recently attracted significant research attention, mostly directing towards biological methods such as systems biology, genetic engineering and bio-refining for optimizing algae strains. Other approaches focus on chemical screening to adjust culture conditions or culture media. We report for the first time the physiological changes of algal cells in response to a novel form of mechanical stimulation, or a pulsed wave at the frequency of 1.5 MHz and the duty cycle of 20%. We studied how the pulsed wave can further increase algal lipid production on top of existing biological and chemical methods. Two commonly used algal strains, fresh-water Chlorella vulgaris and seawater Tetraselmis chuii, were selected. We have performed the tests in shake flasks and 1 L spinner-flask bioreactors. Conventional Gravimetric measurements show that up to 20% increase for algal lipid could be achieved after 8 days of stimulation. The total electricity cost needed for the stimulations in a one-liter bioreactor is only one-tenth of a US penny. Gas liquid chromatography shows that the fatty acid composition remains unchanged after pulsed-wave stimulation. Scanning electron microscope results also suggest that pulsed wave stimulation induces shear stress and thus increases algal lipid production.
