Hyponatremia is the most common dyselectrolytemia in sick children; it can cause encephalopathy, death and permanent neurological sequelae. Holiday and Segar’s formula suggests adding 3 mEq of sodium per 100 mL of water for infants; this is equivalent to administering 0.18% normal saline, which is a hypotonic fluid and predisposes to development of iatrogenic hyponatremia. However, many pediatricians use the same fluid for older children as well, which is inappropriate even by the Holiday and Segar’s formula. There is increasing evidence showing the risk of hyponatremia with administration of hypotonic maintenance fluids in hospitalized children [3,4], but hypotonic fluids still remain the most commonly prescribed fluids for admitted children [5]. While administration of hypotonic fluids alone cannot explain hyponatremia [6], administration of isotonic maintenance fluid is associated with reduced incidence of hyponatremia amongst admitted children [7]. It is noteworthy that hyponatremia is related more significantly to the tonicity of administered fluid rather that volume [7]. Concerns regarding possibility of excessive sodium load and volume overload with administration of isotonic maintenance fluid have been allayed in various studies [7,8].

Fluid overload is associated with increased morbidity and mortality amongst sick children, independent of abnormalities in serum sodium levels [9]. Maintenance fluid volume calculated using the Holliday and Segar formula is based on normal urine output and energy expenditure in children. It does not take into account the effect of increased vasopressin level, reduced insensible fluid losses, reduced energy expenditures and increased tendency to fluid retention in a sick child. The formula consequently over-estimates the maintenance require-ments. This may predispose children to harmful effects of iatrogenic fluid overload, especially in circumstances such as Acute respiratory distress syndrome. The maintenance fluid requirement should be individualized based on energy expenditures, input-output balance and hemodynamic status.

In this issue of Indian Pediatrics, Shamin, et al. [10] provide further evidence of increased incidence of hyponatremia associated with commonly practiced method to calculate daily maintenance fluid requirement in hospitalized children. In a randomized controlled trial, the authors compared administration of hypotonic fluid at volume calculated using the Holliday-Segar formula with administration of isotonic fluid at 60% of the calculated volume. They also found that children in hypotonic fluid group had a weight gain as compared to isotonic fluid group who had weight loss, thus indicating a fluid overload state.

The reason to highlight the above points is to emphasize that the general approach to intravenous maintenance fluids is now being questioned. The method of calculation of volume and composition of maintenance fluids that has been used over half a century is now being considered inappropriate for sick children. The concept of a single formulation of fluid for all may be inappropriate, as each child is different. Intravenous fluids should be tailored according to child’s need and condition. The intravenous fluid prescriptions should be reviewed, based on electrolytes, fluid balance, hemodynamic status and weight monitoring at frequent intervals. The National Patient Safety Agency for England and Wales (UK) in 2007 published guidelines recommending the use of 0.45% NaCl or 0.9% NaCl as maintenance intravenous fluids, and to avoid 0.18% NaCl [11]. Despite this recommendation and growing evidence against use of hypotonic fluids, practice has not changed much.

To conclude, hyponatremia and fluid overload are common amongst hospitalized children and are associated with increased morbidity and mortality. There is enough evidence supporting the prevention of hyponatremia by use of isotonic maintenance fluids. It is time that we stopped using hypotonic fluids, especially 0.18% saline in 5% dextrose for maintenance intravenous fluid therapy in children in general pediatric care; the availability should be limited to critical care units and specialist wards, for use in limited numbers of scenarios. This information should be disseminated by the Academy; the professionals involved in care of sick children also need to be informed and trained adequately. At present, isotonic fluids are considered safe for maintenance fluid therapy and the use of hypotonic fluid should be completely curtailed, except in special circumstances where there is a need to administer extra free water.

Funding: None; Competing interests: None stated.

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