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Apollo Medicine 2011 DecemberReview Article

Volume 8, Number 4; pp. 294–296

© 2011, Indraprastha Medical Corporation Ltd

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

Correspondence: Dr. Nameet Jerath, E-mail: dr_njerath@yahoo.comdoi: 10.1016/S0976-0016(11)60009-4

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

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

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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

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296 Apollo Medicine 2011 December; Vol. 8, No. 4 Kori and Jerath

© 2011, Indraprastha Medical Corporation Ltd

in the wards who do not have their serum electrolytes mea-sured and monitored frequently and have a higher chance of iatrogenic hyponatremia.

REFERENCES

1. Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics 1957;19:823–32.

2. Darrow DC, Pratt EL. Fluid therapy, relation to tissue compo-sition and expenditure of water and electrolyte. JAMA 1950;143:432–9.

3. Arieff AI, Ayus JC, Fraser CL. Hyponatraemia and death or permanent brain damage in healthy children. BMJ 1992;304:1218–22.

4. Arieff AI. Postoperative hyponatraemic encephalopathy follow-ing elective surgery in children. Paediatr Anaesth 1998;8:1–4.

5. Halperin ML, Bohn D. Clinical approach to disorders of salt and water balance. Emphasis on integrative physiology. Crit Care Med 2002;18:249–72.

6. Leaf A. Regulation of intracellular fluid volume and disease. Am J Med 1970;49:291–5.

7. Sharples PM, Seckl JR, Human D, Lightman SL, Dunger DB. Plasma and cerebrospinal fluid arginine vasopressin in patients with and without fever. Arch Dis Child 1992;67:998–1002.

8. Taylor D, Durward A. Maintenance fluid therapy—pouring salt on troubled waters. Arch Dis Child 2004;89:411–4.

9. Hoorn EJ, Geary D, Robb M, Halperin ML, Bohn D. Acute hyponatraemia related to intravenous fluid administration in hospitalized children: an observational study. Pediatrics 2004;113:1279–84.

10. Choong K, Kho M, Menon K, Bohn D. Hypotonic versus isotonic saline in hospitalised children: a systematic review. Arch Dis Child 2006;91:828–35.

11. Adrogue HJ, Madias NE. Hyponatremia. N Engl J Med 2000;342:1581–9.

12. Moritz ML, Ayus JC. Disorders of water metabolism in chil-dren: hyponatremia and hypernatremia. Pediatr Rev 2002;23:371–80.

13. Kannan L, Lodha R, Vivekanandhan S, Bagga A, Kabra SK, Kabra M. Intravenous fluid regimen and hyponatraemia among children: a randomized controlled trial. Pediatr Nephrol 2010;25:2303–9.

14. Yung M, Keeley S. Randomised controlled trial of intravenous maintenance fluids. J Paediatr Child Health 2009;45:9–14.

15. Montañana PA, Modesto i Alapont V, Ocón AP, López PO, López Prats JL, Toledo Parreño JD. The use of isotonic fluid as maintenance therapy prevents iatrogenic hyponatremia in pediatrics: a randomized, controlled open study. Pediatr Crit Care Med 2008;9:589–97.

16. Neville KA, Verge CF, Rosenberg AR, O’Meara MW, Walker JL. Isotonic is better than hypotonic saline for intravenous rehydration of children with gastroenteritis: a prospective ran-domized study. Arch Dis Child 2006;91:226–32.

17. Choong K, Bohn D. Maintenance parenteral fluids in the crit-ically ill child. J Pediatr (Rio J) 2007;83:S3–10.

18. Heer M, Baisch F, Kropp J, Gerzer R, Drummer C. High die-tary sodium chloride consumption may not induce body fluid retention in humans. Am J Physiol 2000;278:F585–97.

19. Skellett S, Mayer A, Durward A, Tibby SM, Murdoch IA. Chasing the base deficit: hyperchloraemic acidosis following 0.9% saline fluid resuscitation. Arch Dis Child 2000;83:514–6.

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