Can village mothers prepare oral rehydration solution?

Both the prepackaged glucose-electrolyte powder and the domestic rehydration solution have received wide publicity, yet there has been little evaluation of how accurate the mother can be in preparing the mixture. The 2 studies described here attempted to measure this human factor in actual field situations in India and Trinidad. The 1st study attempted to quantify the variability in the size of the 2-finger and thumb pinch of salt. The 2nd study measured the different concentrations when mothers diluted a standard packet of glucose and electrolytes in domestic vessels. In India and Trinidad, mothers of children with diarrhea were instructed about making up local salt-sugar-water mixtures for home treatment. They were shown how to take a 2-finger and thumb pinch of salt in a way which had previously been agreed upon. Multiple pinches--5 in Trinidad and 10 in India--were then weighed on standard laboratory scales to find the average salt picked up. The fingers of the mothers were measured to see if the weight of salt picked up correlated with hand size. Other factors which could influence the pinch size were also considered: type and quality of salt available and the relative humidity. In the packet dilution study, mothers in rural India were instructed in the local language by an indigenous nurse who used diagrams in the teaching. The glucose concentrations of the mixture made up by 66 village mothers were analyzed in the field by a pocket refractometer. The finger-pinch method of measuring salt was very inaccurate in field tests. At least 1 mother in 20 would pick up double the amount of salt intended. There was no statistical correlation between finger size and the weight of a pinch of salt. In the packet dilution study there was a wide range of concentrations, but over 83% of the mothers mixed the solution to within 40 mmol/liter of the "correct" value.