Osmotic production of sterile oral rehydration solutions--an economic, low-technology method

A sterile oral rehydration solution can be produced by immersing in water a semi-permeable cellulose tube containing glucose and salts. Osmotically-driven ultrafiltration excludes all microbes and particulate matter even when the immersion water contains 45 x 10(6) cfu/ml of Pseudomonas aeruginosa, 25 x 10(7) cfu/ml of Staphylococcus aureus or 20 x 10(7) cfu/ml of Escherichia coli. Solutions of consistent composition can be obtained by having a standard amount of glucose-electrolytes in a cellulose tube of appropriate dimensions and immersing this in a fixed volume of water for a minimum period of time. The method is simple, inexpensive, low-technology and requires no external source of power. It has potential for producing sterile solutions for injections and intravenous use in situations with very limited and simple resources, in emergencies and during natural disasters. Further studies are now needed to determine whether the method can be adapted to provide the large quantities of oral rehydration fluid needed in field conditions.