Variation in Natremia Using Two Different Maintenance Intravenous Fluids in Postsurgical Hospitalized Children

Background: Despite prescription of maintenance IV fluids in hospitalized children is widely used since 1957 (Holiday & Segar), it is not always adequate for children with acute diseases, leading to hyponatremia. This mainly occurs due to a non-physiologic ADH secretion in this group of patients due to nausea, stress, pain, and surgical interventions, and the use of hypotonic maintenance IV fluids.

0.3% NaCl/dextrose 5%, is widely use as IV maintenance fluid in children after surgery. There is evidence suggesting that these IV fluids used in postsurgical hospitalized patients do not provide the adequate amount of sodium they require, leading to an increased risk of developing hyponatremia. Using 0.45% NaCl/dextrose 5% as IV maintenance fluid in these children would prevent hyponatremia, but this treatment has not been totally studied yet.

Study procedures: Hospitalized children who fulfill inclusion criteria and not having any of the exclusion criteria will be considered for the enrolment after written informed consent.

Venous blood samples will be taken at enrollment (baseline) for estimation of serum sodium. After randomization, one group will receive 0.3% NaCl/dextrose 5%, IV, at standard maintenance rate (100 ml/kg for the first 10 kg of body weight, 50 ml/kg for the next 10 kg, and 20 ml/kg for body weight exceeding 20 kg). The second group will receive 0.45% NaCl/dextrose 5%, IV, at the same rate.

Serum sodium will be estimated in both groups after 12 hours of intravenous fluid therapy.

Children who required oral fluids will be excluded from per-protocol analysis, and only analyzed for intention to treat.

Inclusion criteria

• Postsurgical children admitted to HGNPE Department of Surgery between january 2010 and october 2011.

Aged 1 month to 16 years. Initial plasma Na between 135-145 mmol/L. Primary route of fluid administration is anticipated to be intravenous, in the first 12 hours following surgery.

Informed consent of parent/guardian.

Exclusion criteria

• • Children with illness that have primary fluid and electrolyte imbalance such as:

• Shock: Defined as acute circulatory failure resulting in decreased tissue perfusion and manifesting as altered sensorium, hypothermia (<35oC), tachycardia, prolonged capillary filling time (>3 seconds), hypotension (BP < 5th percentile for age), oliguria (<0.5 ml/kg/hr), hypoxemia, hyperlactatemia, requirement of fluid bolus and/ or vasopressors.
• Diarrhea and Dehydration: Children presenting with diarrhea and features of dehydration: lethargy, irritability and altered sensorium, thirst, decreased urine output, sunken eyes & dry mucous membranes, loss of skin elasticity.; children with ongoing diarrhea will be excluded even if there is no dehydration.
• Fluid Overload: Cirrhosis, Congestive heart failure, Acute and Chronic renal failure, Nephrotic syndrome.

• Hyperglycemia: blood glucose > 180 mg/ dl.
• Require ICU admission.
• Severe Protein Energy Malnutrition: Defined as grade III (50-59% of expected weight for age) and grade IV (less than 50% of expected weight for age) as per IAP classification.
• Patients in whom either hypotonic or isotonic solutions may be contraindicated/necessary: i.e. specific neurosurgical patients (ie those at risk of increased ICP, e.g. requiring actual brain surgery, ICP monitor or external ventricular drain insertion), patients with diabetic ketoacidosis, acute (≤ 7 days) burns, pre-existing CHF, liver failure or cirrhosis, renal failure.
• Patients with known pre-existing risk of PNa derangements: DI or SIADH