Pediatric Posterior and Anterior Spinal Fusion

Pediatric Posterior and Anterior Spinal Fusion

Introduction

The majority of these patients tend to be relatively healthy ASA 1 or 2 adolescents. Other types of scoliosis are congenital or neuromuscular scoliosis. These patients tend to be more complicated so their operative course as well as postoperative management tends to differ between these two groups and peri-operative planning needs to take into consideration these differences.

Preoperative

  • Determine the location and degree of spinal curvature
  • At 70 degrees curvature patients start to manifest objective restrictive pulmonary disease as seen during function testing; however they are usually asymptomatic.
  • When curvature approaches 110 degrees patient can have significant restrictive function and start to become symptomatic. Acute pulmonary problems such as asthma or respiratory tract infection warrant potential postponement of surgery.
  • Mitral valve prolapsed is found in 25% of patients with scoliosis compared to less than 10% of age matched controls. An increase association of scoliosis in children with congenital heart disease is well documented.

Labs

  • CBC, Coagulation labs, Type & Cross, any disease specific testing as required
  • Testing: PFT’s > 70 degrees, cardiac evaluation if known CHD, metabolic disorder or muscular dystrophies.

Intraoperative

Careful intraoperative preparation is essential for a successful procedure. The surgeon, anesthesiologist and the neurophysiologist each have an important role in the care of the patient.

  1. At timeout, the surgeon should discuss with the anesthesia and the neuromonitoring team details regarding the patient, the intended procedure, and surgical time frame and any other surgical concerns.
  2. The neuromonitoring team should discuss the plan for neuromonitoring, SSEP, MEP, EMG, etc.
  3. The surgeon and anesthesiologist will discuss the anesthetic plan intraoperatively, plan for postoperative pain management (epidural, dilaudid only infusion) and whether PICU or floor admission.

3. Hemodynamics

Maintaining adequate blood pressure is essential for spinal cord perfusion. A balance should be maintained to minimize intraoperative blood loss and transfusions, but maintaining adequate spinal cord perfusion. The mean arterial blood pressure is maintained 60-70 mmHg during exposure and placement of instrumentation. There may be patient variability, so the surgeon and anesthesiologist should discuss what would be appropriate blood pressure target range for individual patients.

Approximately 30 minutes before performing corrective maneuvers, the surgeon should notify the anesthesiologists to gradually elevate the MAP to > 70 mmHg to maintain cord perfusion during spinal manipulation and correction.

After correction, maintaining adequate blood pressure is essential for spinal cord perfusion. Mean arterial blood pressures 60-65 mmHG should be the goal or higher if neuromonitoring shows decrease or loss of signals.

4. Anti-fibrinolytics

Tranexamic acid helps to reduce estimated blood loss. Studies have demonstrated decreased estimated blood loss, reduction in the volume of PRBC’s transfusion as well as reduction in postoperative blood transfusions for idiopathic scoliosis repairs without any complications related to tranexamic acid.

Contraindications for tranexamic acid are active DIC, active intravascular clotting, patients with acquired defective color vision, or hypersensitivity to tranexamic acid or any of its ingredients.

Tranexamic acid 10 mg/kg (5 g max dose) loading dose over 15 minutes; followed by 1 mg/kg/hr. infusion (UCSF Adult spine protocol). The infusion can run as high as 10 mg/kg/hr. in pediatrics. (UCSF Adult spine protocol-discuss this with your attending).

Neuromonitoring-Neural Signal Changes

The SSEP/MEP signals must be continuously monitored throughout the procedure, especially during placement of instrumentation and deformity correction. Immediate action is required when damage to the spinal cord or peripheral nerve is suspected at any time during the procedure in response to changes of > 50% decrease in amplitude and > 10% increase latency in SSEP/MEP signals.

Immediately following identification of neuromonitoring signal changes, the hemodynamic and oxygenation status of the patient should be optimized in an effort to improve perfusion to the spinal cord.

  • The mean arterial blood pressure is elevated to > 80 mmHG or 20% above baseline values.
  • Hemoglobin is evaluated and corrected (Hct > 30-35) to increase the oxygen carrying capacity.
  • Euvolemia is important to maintain and any deficits should be corrected. Judicious use of intravenous fluid replacement or blood transfusion (if indicated).
  • Vasopressor when necessary to maintain cord perfusion. Dopamine or phenylephrine can be use to maintain mean arterial blood pressure if fluid replacement alone is insufficient.
  • Body temperature should be monitored and elevated to > 36.5 degrees Celsius to optimize neuromonitoring.
  • All these measures have shown to increase spinal cord perfusion.

Anesthetics for Neuromonitoring

Anesthetic choice must try to be compatible with neuromonitoring:

Inhalational agents: Sevoflurane, Desflurane MAC < 0.3 (often to achieve optimal MEP monitoring, even when using a high frequency stimulation technique, is to avoid inhalational gases.)

  • Avoid Nitrous: mainly for SSEPs
  • Remifentanil gtt 0.1-0.4 mcg/kg/min
  • Fentanyl gtt 1-2 mcg/kg/hr.
  • Propofol 100-200 mcg/kg/min
  • Alternative options to consider:
  • Ketamine 3-10 mcg/kg/min
  • Dexmedetomidine 0.2-.0.7 mcg/kg/hr.
  • Lidocaine 1.5 mg/kg/hr.

Post-operative Pain Management-Epidural

Posterior Spinal Fusion

Inquire with Dr. Diab or Berven if they can place epidural catheter at the end before they begin closure.

  • A dilaudid only infusion at 3-4 ug/kg/ hr.
  • No local anesthetic added to the infusion in order to allow neural exams.
  • Pediatric acute pain service will closely follow the patient and manage the epidural.
  • Epidural will typically be removed on POD #3.

Anterior spinal Fusion

  1. Thoroscopic Approach: PCA
  2. Thorocotomy Approach: Single lung ventilation will be requested. Depending on the size of the child, double lumen tube may be feasible. If the child is <30 kg, bronchial blocker may be more appropriate. Depending on the anatomy, epidural placement in the beginning may be feasible.
  • A Dilaudid only infusion at 3-4 ug/kg/hr.
  • No local anesthetic added to the infusion in order to allow neural exams.
  • Pediatric acute pain service will closely follow the patient and manage epidural.
  • Epidural will typically be removed on POD#3.

Post operative: Criteria for PICU admission

  • An intraoperative neurologic insult or significant neural signal change
  • Blood loss greater than 33% of blood volume
  • Neuromuscular Scoliosis or other coexisting cardiovascular, pulmonary or neurologic co-
  • morbidities.
  • Intubated and ventilator support
  • MAP >60 mmHg not sustainable without vasopressor.

 

Revised 7/2014

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This information is meant to serve as an educational resource. Clinicians should use their own professional judgment in the care of any individual patient as the guidance contained in this document may not be appropriate for all patients or all situations.