Hypotonic fluids are commonly prescribed for maintenance fluid therapy in children. This has been associated with a higher incidence of iatrogenic hyponatremia, sometimes with significant neurological sequelae including death. The use of isotonic fluid for maintenance therapy is likely to reduce this complication and is strongly recommended.

1. Choosing the right maintenance intravenous fluid in children

2. Apollo Medicine 2011 December
Review Article
Volume 8, Number 4; pp. 294–296
Choosing the right maintenance intravenous fluid in children
Manish Kori*, Nameet Jerath**
*Fellow, Paediatric Critical Care Unit, **Senior Consultant, Paediatric Critical Care and Pulmonology, Indraprastha Apollo Hospitals,
Sarita Vihar, New Delhi – 110076, India.
ABSTRACT
Hypotonic fluids are commonly prescribed for maintenance fluid therapy in children. This has been associated with
a higher incidence of iatrogenic hyponatremia, sometimes with significant neurological sequelae including death.
The use of isotonic fluid for maintenance therapy is likely to reduce this complication and is strongly recommended.
Keywords: Hyponatremia, hypotonic fluid, isotonic fluid, maintenance fluid
INTRODUCTION
Intravenous (i.v.) fluids are designed to provide the water and
electrolyte requirements for children. Many of these chil-dren
are unable to or not allowed to take orally either partially
or completely. The i.v. fluid used for maintenance in most
paediatric units is a hypotonic solution of 0.18% or 0.2%
saline in 5% dextrose, widely prescribed as Isolyte-P in India.
The ‘P’ has erroneously been associated with ‘Paediatric’ and
has become widely used all over the country as the standard
maintenance fluid for children both by paediatricians and
by other health care providers, often without much thought
behind the selection.
The choice of resuscitation fluid for extracellular space
expansion is agreed to be an isotonic crystalloid 0.9%
saline or Ringer’s lactate solution. There is little dispute in
this and will not be discussed further.
FLUID AND ELECTROLYTE REQUIREMENTS
Holliday and Segar described the fluid requirements in chil-dren
based on their study of healthy children in 1957.1 They
derived the free water requirements based on the calorie
expenditure equating 1 mL of water with a fixed consump-tion
of 1 Kcal. This results in a convenient estimate of
100 mL/100 Kcal and the frequently used fluid calculation
of 100 mL/Kg for the first 10 Kg, 50 mL/Kg for the next 10 Kg
and 20 mL/Kg for subsequent body weight. The sodium
Correspondence: Dr. Nameet Jerath, E-mail: dr_njerath@yahoo.com
doi: 10.1016/S0976-0016(11)60009-4
© 2011, Indraprastha Medical Corporation Ltd
and potassium requirements of 3 and 2 mEq/100 Kcal/24 h,
respectively, were based on the urinary excretion of electro-lytes
in breast-fed healthy infants.2
CONCERNS WITH TRADITIONAL
‘HOLLIDAY–SEGAR’ METHOD
The recommendations by Holliday and Segar are based
on studies on healthy children who were enterally fed.
Extrapolating this to i.v. requirements is flawed. These
fluid requirements have been shown to be an overestimate
of the actual requirements. In fact, the energy requirements
in critically ill children may be as low as 50–60 Kcal/Kg/
day reducing the associated water requirements.3,4 Endo-genous
water production due to catabolism in acute illness
is also ignored which reduces the exogenous water
requirement.
Similarly, the electrolyte requirements were calculated
and recommended based on the urinary excretion of elec-trolytes
in breast-fed infants.1 However, electrolyte require-ments
may vary a lot in the disease. The gut acts as a
selective barrier in terms of ‘choosing’ electrolytes. This
advantage is lost in i.v. fluid administration where the fluid
and electrolytes are compulsorily infused into the intravas-cular
compartment. When the fluid is infused in the intra-vascular
compartment, the most important function of
sodium is to maintain tonicity and not just to replace sodium
losses.5 A normal sodium concentration and hence the

3. Choosing the right maintenance intravenous fluid in children Review Article 295
© 2011, Indraprastha Medical Corporation Ltd
tonicity in the cellular milieu are important to maintain
cellular homeostasis.6
FLUID HOMEOSTASIS IN AN UNWELL
CHILD
Antidiuretic hormone (ADH) has an overriding effect on
urine flow rates, an effect which is exaggerated in disease
states. Due to the effects of ADH, the body tends to hold on
to free water in an apparent effort to maintain intravascular
space.5 The increased ADH response, earlier termed inap-propriate
(SIADH), is seen in many situations including
respiratory infections—bronchiolitis, pneumonias, asthma,
gastrointestinal infections and neurological conditions—
injury, encephalitis, meningitis, postoperative period, and
other factors such as stress, pain or opioid use.5,7 These
account for almost all of the paediatric admissions in any unit.
The current commonly practiced fluid regimen tend
to overestimate the fluid requirements, underestimate the
effect of ADH on fluid balance and incorrectly estimate
the electrolyte requirements in the i.v. fluid being adminis-tered.
All of these predispose the ill child to develop
hyponatremia.8
HOW COMMON IS HYPONATREMIA?
Hyponatremia is not just a theoretical concern. Various
studies do demonstrate a high incidence of hyponatremia in
ill children ranging from 10% to almost 100%.9,10 There are
many reports of deaths and neurological sequelae in chil-dren
because of hospital-acquired hyponatremia induced by
hypotonic fluid administration.10
WHY IS HYPONATREMIA BAD?
Administration of hypotonic fluid and associated hy ponat-remia
causes fluid shifts, the effects of which are most pro-nounced
and frightening in the brain. A hypotonic milieu
results in neuronal swelling with symptomatic hyponatrem ia
related to the central nervous system dysfunction. This
is typically characterized by headache, nausea, vomiting,
muscle cramps, lethargy, restlessness, disorientation, and
depressed reflexes.11 This can be severe enough to cause sei-zures,
respiratory arrest, permanent neurologic dysfunction
and death, resulting from cerebral edema and brainstem
herniation. Children in particular are more prone to these
effects of cerebral edema because of a higher brain-to-skull
size ratio, which leaves less room for brain expansion.12
THE SOLUTION LIES IN THE SOLUTION
The use of isotonic fluids for maintenance is likely to
prevent the iatrogenic hyponatremia and its associated
complications in children. This indeed has been observed
in many studies with lower incidence of hyponatremia
in the isotonic fluid group in varied disease states.13–16
A meta-analysis by Choong et al showed that hypotonic
solutions significantly increased the risk of developing
hyponatremia.10
There would certainly be conditions where isotonic
fluid may not be the best fluid, as in cases of free water
deficit, but these scenarios would be occasional.17 Most of
the children in paediatric wards do not have their sodium
levels monitored frequently and this is the group which is
most commonly prescribed hypotonic fluids putting them
at a high risk of iatrogenic hyponatremia. Routine use of
hypotonic fluid as maintenance fluids in children should
therefore be discouraged. The current evidence and under-standing
suggest the use of isotonic fluids.
The use of isotonic fluids will increase the daily sodium
intake to 2- to 3-fold. The concern that this would lead to
hypernatremia has not been shown in studies.18 This is
because the fluid infused has the same sodium concentra-tion
as in the plasma. Moreover, isotonic fluids have been
used in the adult patients for decades where isotonic fluid
administration is the norm without an outbreak of hyper-natremia.
8 Massive fluid boluses for resuscitation too have
not been associated with hypernatremia in spite of signifi-cant
sodium load.19
The search for the right isotonic solution for mainte-nance
fluid therapy continues; 0.9% saline has a higher
chloride load and is responsible for hyperchloremia though
this might not be of any consequence.18,19 Some consider
the Ringer’s lactate solution to be better because of the lower
chloride load.8
CONCLUSION
The traditional fluid and electrolyte calculations are poten-tially
harmful in children. The safest approach would be to
use isotonic fluids for maintenance fluid therapy in children.
This is even more important in unwell children admitted

4. 296 Apollo Medicine 2011 December; Vol. 8, No. 4 Kori and Jerath
in the wards who do not have their serum electrolytes mea-sured
and monitored frequently and have a higher chance of
iatrogenic hyponatremia.
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© 2011, Indraprastha Medical Corporation Ltd
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