Hypotonic Versus Isotonic Parenteral (HIP) Fluid Trial

Research Question:

In general pediatric surgical patients, do isotonic PMS compared to hypotonic PMS, result in a lower risk of acute hospital acquired plasma sodium derangements, occurring at any time during the study intervention? Primary efficacy objective -To determine the impact of postoperative administration of isotonic compared to hypotonic PMS on the risk of hospital acquired PNa derangements in pediatric surgical patients, occurring at any time during the study intervention.

Secondary efficacy objectives: a) To determine the impact of postoperative administration of isotonic compared to hypotonic PMS on clinical sequelae related to acute PNa changes, in pediatric surgical patients. b) the independent predictors of hospital acquired PNa derangements will be explored.

Study Design:

This is a double-blind randomized controlled trial. Participants, health care providers, data collectors, and judicial assessors of outcomes will be blinded to the study intervention.

Setting: McMaster Children's Hospital.

Trial Intervention:

Enrolled patients will be randomized postoperatively to receive either one of the following parenteral maintenance solutions: 1) hypotonic PMS, or 2) isotonic PMS. For the purposes of this study the hypotonic PMS will be 0.45%NaCl, and the Isotonic PMS will be 0.9% NaCl. Enrolled patients will receive their allocated treatment (provided there are no safety issues or concerns) until they are fully orally fed and the PMS rate is no greater than a rate required to "keep vein open (KVO)", to a maximum duration of 48 hours. The physician can thereafter administer the maintenance solution of their choice. The following parameters will be monitored in each study participant during the treatment period: hourly urine output, strict intake and output, 12 hourly fluid balances and daily weights. Blood and urine samples will be obtained on study patients every 12 hours until they are fully orally fed and the IV rate is at KVO, for a maximum of 48 hours. Any additional investigations ordered by the caring physician during the treatment and follow up period will also be recorded. Patients will be followed for clinical outcomes for 48 hours after the study intervention is discontinued, or until the time of discharge.

Inclusion criteria

• Pediatric patients, 6 months corrected age -16 years, undergoing surgery.
• Within 6 hours of the immediate post-operative period.
• Post-operative stay anticipated to be more than 24 hours.
• Primary route of fluid administration is anticipated to be intravenous, in the first 24 hours following surgery.
• Informed consent of parent/guardian.
• Consent to participate from surgeon.

Exclusion criteria

• Patients under 6 months of age
• Patients equal to or over 17 years of age
• Patients with hemodynamic instability , defined as a requirement for continuous vasoactive infusion (e.g. epinephrine, dopamine, norepinephrine, phenylephrine, milrinone, or Dobutamine) to maintain blood pressure at the end of surgery.
• Patients admitted into the "short stay" post-operative unit
• 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
• Chronic diuretic use - defined as use of any oral or intravenous diuretics for ≥ 7 days.
• Known, uncorrected PNa derangement (PNa < 134 or > 146 mmol/L), identified peri-operatively (i.e. within 12 hours of surgery or during surgery).
• Prior enrolment in this study
• Patients or their guardians objecting to give consent.