Understanding and managing acute fluid and electrolyte disturbances

Abstract 

Fluid and electrolyte balance is important in infants and young children because of their high total body water content and basal metabolic rate. Excessive fluid losses lead to dehydration and hypovolaemia. Inadequate and delayed treatment lead to progressive deterioration in tissue perfusion, vascular collapse and progressive multiple organ failure. However, hasty rehydration may be just as devastating as dehydration in seriously ill paediatric patients with severe electrolyte imbalance. Rapid correction of sodium imbalance can produce cerebral oedema or osmotic demyelination. As a rule, sodium correction of 1–2mmol/l/h is recommended; rates higher than that may lead to death. Hyperkalaemia is an emergency that requires prompt correction medically or with dialysis. Hypocalcaemia, hypokalaemia and hypophosphataemia are increasingly recognized as critical, especially in septic patients. Fluid and electrolyte disorders should be approached by considering the deficit, the maintenance fluid and continuing losses, and a rate of replacement which will not produce severe neurological deficit.

Keywords:  hypovolaemia, dehydration, electrolytes, hypernatraemia, hyponatraemia, hyperkalaemia, hypokalaemia, hypophosphataemia, hyperphosphataemia