Maintenance fluids in critically ill children
Goal of maintenance fluids:
Preserve the extracellular volume while maintaining a normal electrolyte balance
Changes in last decade: Hyponatremia a new worry
- Hospital acquired hyponatremia and hyponatremic encephalopathy can cause
demise of patients in first 24-48 hours of fluid therapy
- Fluid overload (10%) has been associated with poor outcome in critically ill children
- Multiple disease states, physiological triggers and drugs which can cause arginine
vasopressin excess ( non- osmotic state ) increasing the risk of hyponatremia
- Hypotonic fluids have been found to add fuel to fire by increasing risk of
Hyponatremia encephalopathy: a worry in children?
Children have increased ratio of brain to intracranial volume with other common risk factors
like brain injury, hypoxemia making them high risk of hyponatremic encephalopathy.
Type of fluids:
Isotonic fluids have been looked as alternative and most of the guidelines prefer to use
them as maintenance fluids.
Normal saline, Ringer lactate and balanced salt solution (Plasmalyte) have been used.
Many of the studies suggested that restricting hypotonic fluid in critically ill state will
prevent hyponatremia, however they failed to justify in research and clinical practice.
Using isotonic fluids definitely reduced the risk of hyponatremia in hospital. However most
of the current studies have removed patients of heart failure, kidney injury, cirrhosis and
Complications of isotonic fluid:
Hyperchloremic metabolic acidosis has been a complication associated with normal saline.
Hypernatremia once thought to be associated with normal saline has now been refuted.
Fluid overload can happen with any type of fluid used.
Rate & amount of fluid administration:
This discussion is done after the child has been stabilized. Decision to administer
maintenance fluids to a sick child is an ongoing process. Fluid rate has to modified
depending upon the hemodynamic status, primary illness, day of illness, fluid balance and
electrolyte status. Though Holliday Segar overcalculates the amount of fluid, it remains the
most commonly used formula to start amount of fluid. Below is a rough guideline for
managing specific situations.
- CNS illness: Start with 100 percent fluids, titrate according to your input output and
sodium status. We may start with fluid restriction if clear cut evidence of SIADH is
there at admission (patients shifted from one hospital to other)
- Respiratory illness: start with 80 percent of maintenance fluids in pneumonia,
asthma and bronchiolitis.
- Congestive heart failure & myocarditis: 50 -60 percent of maintenance fluids is to
begin with in pure CHF, may