Risk of acute hyponatremia in hospitalized children and youth receiving maintenance intravenous fluids

Question 1

Which hospitalized children are at particular risk of developing nonphysiological ADH secretion?

Answer 1

1. Children undergoing surgery
2. Children with acute neurological infections (e.g. meningitis, encephalitis)
3. Children with acute respiratory infections (e.g. pneumonia, bronchiolitis)

Question 2

What are the clinical sequelae of acute hyponatremia?

Answer 2

Acute cerebral edema - lethargy, headache, seizures, respiratory and cardiac arrest due to brain stem herniation

Question 3

What are the definitions of sodium status?

Answer 3

1. Normonatremia 135-145
2. Hyponatremia <135
3. Severe acute hyponatremia <130 within 48h in child with normal baseline Na
4. Hypernatremia >145

Question 4

Who do the recommendations in this statement apply to?

Answer 4

1. Children >1m corrected age to 18yo
2. Excluding patients with:
   a) Renal disease
   b) Cardiac disease
   c) DKA
   d) Severe burns
   e) Underlying conditions that significantly affect electrolyte regulation

Question 5

What are the general principles regarding IVF management in hospital?

Answer 5

1. Oral fluids are generally very low in Na content (hypotonic). Where the total fluid intake (TFI) is a combination of oral and IV fluids, both need to be accounted for.
2. Because infants and young children have limited glycogen stores, dextrose should be part of the IV maintenance fluid prescription (eg, D5W.0.9%NaCl or D5W.0.45%NaCl) if no other source of glucose is provided.
3. The approach to prescribing IV fluids should be as cautious as that for medications, with close attention paid to indications, monitoring, the type of fluid and the volume/rate of administration.

Question 6

What are the recommendations re: monitoring in hospitalized children on IVF?

Answer 6

1. Baseline serum electrolytes (Na, K, glucose, urea, creatinine) should be measured when starting IV fluid therapy in hospitalized children.
2. Children receiving maintenance IV fluids should have their serum electrolytes checked regularly, with patients who may be at high risk of impaired renal water excretion checked daily if not more frequently.
3. All children receiving IV maintenance fluids should have their intake/output carefully monitored, as well as a daily weight measurement.
4. Clinicians should be aware of the symptoms of hyponatremia, which may include headache, nausea and vomiting, irritability, decrease in level of consciousness, seizures and apnea.

Question 7

What are the recommendations regarding prescription of IVF for maintenance requirements?

Answer 7

1. In children whose serum sodium is normal at baseline but who are considered to be at particularly high risk of ADH secretion (eg, peri- or postoperative; with respiratory or neurological infections) the use of isotonic saline (D5W.0.9% NaCl) is recommended.
2. For other hospitalized children whose serum sodium is normal, the options are D5W.0.9% NaCl or D5W.0.45% NaCl. The first option is preferred, especially when the serum Na is in the low normal range (135 mmol/L to 137 mmol/L inclusive).
3. Hypotonic IV fluids containing <0.45% NaCl should not be used to provide routine fluid maintenance and should not be generally available on paediatric wards.
4. When serum electrolyte results are not yet available, it is recommended that D5W.0.9% NaCl be initiated as the maintenance IV fluid.
5. If the serum sodium is 145 mmol/L to 154 mmol/L, then D5W.0.45% NaCl should be initiated and frequent monitoring of the serum sodium performed.
6. Ringer’s Lactate is commonly used in the operating room but the absence of dextrose and presence of lactate make it generally inappropriate for maintenance IV therapy, especially in young children.

Question 8

What is the sodium content (mmol/L) of commonly used IVF?

Answer 8

D5W0.9%NaCl = 154

D5W0.45%NaCl = 77

D5W0.2%NaCl = 33

2/3-1/3 = 45

Ringer’s Lactate = 130

Question 9

What is a summary of the recommended IVF based on plasma Na level?

Answer 9

If Na <138 isotonic

If Na 138-144 isotonic preferred but half isotonic solutions may be used

Perioperative period isotonic