A Randomized Controlled Pilot Study to Examine the Effects of Goal-directed Fluid Therapy on Post-operative Outcomes in Children Undergoing Scoliosis Repair

Written informed consent from parent/guardian and assent from the patient will be obtained.

Each patient will be randomized into either the control arm or Cardio Q directed fluid therapy arm.

The following standard monitors will be placed before induction of anesthesia: electrocardiography, non-invasive blood pressure and pulse oximetry. The patient is anesthetized in the supine position using a standardized anesthetic technique. All attempts will be made to maintain normothermia

Following induction of anesthesia, the following will be placed: invasive arterial cannula, large bore intravenous cannula, Bispectral index monitor, temperature probe and central venous cannula (if needed).

Cardiac output monitor: Following induction of anesthesia and after placement of appropriate lines and monitors, a transoesophageal doppler (TED) probe will be inserted through the mouth into the esophagus and positioned correctly. A normal saline infusion will be started once the patient is anesthetized at 0.5 ml/kg/hour in the line where the drugs will be infused.

Control Group: In this group, fluid administration, using boluses of 5ml/kg of plasmalyte at the anesthesiologist's discretion will be used. Anesthesiologists will be blinded to the cardio-Q numerics on the monitor. The flow waveform and sound will be available to optimize probe position.

Intervention groups: Boluses of 5ml/kg plasmalyte will be given when: either MAP drops 20% from baseline or stroke volume drops 15% from baseline. If the patient is fluid responsive, a further 5ml/kg of fluid will be given.

Vasopressor use: MAP (and stroke volume) becomes unresponsive to a fluid bolus then a bolus of phenylephrine or ephedrine may be given at the anesthesiologist's discretion.