Content area
Full Text
NICOLA BATES discusses the clinical effects and management of salt and sodium bicarbonate overdose in adults and children
This article has been subjected to double-blind peer review
Sodium chloride and sodium bicarbonate are widely used both pharmaceutically and in the home. Each can cause hypernatraemia, defined as a sodium concentration greater than 150mmol/L, in overdose. Sodium bicarbonate can also cause other metabolic disturbances, particularly metabolic alkalosis. This article outlines the clinical features and management of sodium chloride and sodium bicarbonate overdose.
Osmolality is the concentration of osmotically active particles in solution and is expressed as osmoles of solute per kilogram of solvent. The normal range is between 286 and 296 mOsm/kg water. Sodium contributes to about 90 per cent of extracellular fluid osmolality. An increase in sodium concentration results in extracellular fluid becoming hypertonic and water moving from intracellular to extracellular space. The net result is cellular dehydration and vascular overload. In the central nervous system this causes vascular stasis, thrombosis, brain shrinkage and shearing of intracerebral vessels with subsequent haemorrhage (Smith and Palevsky 1990).
SODIUM CHLORIDE
Sodium chloride (NaCl) is widely available and has many uses. Cooking salt is the most common source of salt ingested accidentally or by administration of salt water emetics. Some bottle sterilising fluids, water softeners and bath salts also contain high concentrations. Dishwasher salt, used to prevent machine scaling rather than in the dishwashing process, is another potential source.
Sodium chloride poisoning is serious and frequently fatal, and hypernatraemia from exposure has occurred in many different circumstances. Administration of salt water emetics is a particular problem (Barer et al 1973, Roberts and Noakes 1974, Gresham and Mashru 1982, Streat 1982, Smith and Palevsky 1990) but is now relatively rare due to a decrease in the practice. However, cases of salt water induced hypernatraemia are occasionally reported (Litovitz et al 2001) as many people still perceive a salt water emetic as an appropriate first aid measure for victims of suspected poisoning. In any potential poisoning case where emesis has been induced, it is always advisable to ask the method used to assess risk of hypernatraemia.
Accidental ingestion of salt may also occur as children explore their environment or where children have fed salt to younger siblings (Calvin et...