SALT, WATER AND SURVIVAL - ACID TESTS AND BASIC ADVANCES IN FLUID THERAPY

Diarrhoea does not just cause fluid and electrolyte disturbances; fund amentally it is a failure of net enteric uptake of sodium and water. T he most lethal effects are dehydration, particularly loss of extracell ular (ECF) volume, also acidosis and hyperkalaemia. The importance of sodium in repairing ECF volume, and as the key constituent (alongside glucose) of oral rehydration solutions (ORS) was emphasised. Misconcep tions about the causes of hyponatraemia and hypernatraemia were clarif ied. The importance of bicarbonate precursors was reaffirmed and argum ents surrounding glycine were discussed. Glucose acts through cotransp ort with sodium, not as an energy source and the problem of energy def icit with conventional ORS was examined. Aspects of the composition of parenteral fluids were also discussed, notably sodium, potassium and bicarbonate precursors as well as the use of ORS in conjunction with p arenteral therapy. The opportunity to tailor therapy according to meas ured changes in plasma composition, especially acidosis, was identifie d as a major area of clinical progress. Impediments to progress includ e licensing constraints designed for receptor-active drugs and the ten dency for funding bodies to favour blue-sky research rather than genui ne improvements in deliverable health care.