Difference between revisions of "Posterior spinal fusion"
(Created page with "{{Infobox surgical procedure | anesthesia_type = | airway = | lines_access = | monitors = | considerations_preoperative = | considerations_intraoperative = | considerations_postoperative = }} Posterior spinal fusion is an orthopedic procedure performed to correct idiopathic scoliosis. It is the most common treatment for idiopathic scoliosis. It involves implants (an array of hooks, screws, and wires) being attached to segments of spine. Harrington rods were the o...") |
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Posterior spinal fusion is an orthopedic procedure performed to correct idiopathic scoliosis. It is the most common treatment for idiopathic scoliosis. | Posterior spinal fusion is an orthopedic procedure performed to correct idiopathic scoliosis. It is the most common treatment for idiopathic scoliosis. Involved are the placement of implants (an array of hooks, screws, and wires) which are attached to affected segments of spine. | ||
== Overview == | == Overview == | ||
| Line 17: | Line 17: | ||
=== Procedure === | === Procedure === | ||
Patients are initially supine for intubation, line placement, and monitors. Once complete, they are flipping to the prone position. A large midline incision is made cutting through the back muscles to expose the spine. The surgeon will clear the tissue from the spine in order to create a surface for hardware placement. Controlled hypotension (MAPs no greater than the 70s, sometimes lower) limits bleeding during this part of the procedure. | |||
Then, tightening of the wire implants stretches/distracts the spine, straightening it into midline position. It is important to maintain ''normotension'' once this begins in order to perfuse the spinal cord during distraction (which inevitably causes stretching of the nerves/nerve damage). Close neuromuscular monitoring by a technician allows surgeons to detect this early and stop manipulation. Steroids may be given if concern for nerve injury. | |||
If the spine remains off center from the pelvis, a pelvic fixation may also be performed. | |||
=== Other Interventions === | === Other Interventions === | ||
Harrington rods were the original method but are no longer current as segmental implants allow surgeons more control and early mobilization without the need for bracing. | |||
Anterior spinal fusion is another surgical method that comparatively has less blood loss and risk of neurologic injury. Advantages of posterior spinal fusion over anterior spinal fusion include avoidance of entering the thoracic cavity and potentially impairing pulmonary function. | Anterior spinal fusion is another surgical method that comparatively has less blood loss and risk of neurologic injury. Advantages of posterior spinal fusion over anterior spinal fusion include avoidance of entering the thoracic cavity and potentially impairing pulmonary function. | ||
| Line 30: | Line 37: | ||
|- | |- | ||
|Airway | |Airway | ||
| | |ETT. Prone positioning. | ||
|- | |- | ||
|Neurologic | |Neurologic | ||
| | |Intra-op neuromonitoring. Avoid NMB. Steroids for protection against nerve injury. | ||
|- | |- | ||
|Cardiovascular | |Cardiovascular | ||
| | |Controlled hypotension | ||
|- | |- | ||
|Pulmonary | |Pulmonary | ||
| | |Changes in compliance during surgical manipulation of spine | ||
|- | |- | ||
|Gastrointestinal | |Gastrointestinal | ||
| Line 45: | Line 52: | ||
|- | |- | ||
|Hematologic | |Hematologic | ||
| | |Anywhere between 300 to 3000 mL of blood loss from the scraping of the epidural veins of the spine | ||
|- | |- | ||
|Renal | |Renal | ||
| | |AKI from hypovolemia or prolonged hypotension | ||
|- | |- | ||
|Endocrine | |Endocrine | ||
| Line 58: | Line 65: | ||
=== Labs and studies<!-- Describe any important labs or studies. Include reasoning to justify the study and/or interpretation of results in the context of this procedure. If none, this section may be removed. --> === | === Labs and studies<!-- Describe any important labs or studies. Include reasoning to justify the study and/or interpretation of results in the context of this procedure. If none, this section may be removed. --> === | ||
ABG monitoring if observing significant blood loss. Should generally include lytes and iCa. | |||
=== Operating room setup<!-- Describe any unique aspects of operating room preparation. Avoid excessively granular information. Use drug classes instead of specific drugs when appropriate. If none, this section may be removed. --> === | === Operating room setup<!-- Describe any unique aspects of operating room preparation. Avoid excessively granular information. Use drug classes instead of specific drugs when appropriate. If none, this section may be removed. --> === | ||
# A-line | |||
# 2 PIV, one large bore (16 gauge) for resuscitation and bolus of meds, one for infusions | |||
# Standard monitors/equipment including temperature probe/bear hugger (important given prolonged exposure | |||
# Ancillary equipment: Cell-saver, neuromuscular monitors | |||
=== Patient preparation and premedication<!-- Describe any unique considerations for patient preparation and premedication. If none, this section may be removed. --> === | === Patient preparation and premedication<!-- Describe any unique considerations for patient preparation and premedication. If none, this section may be removed. --> === | ||
Generally patients receive muscle relaxers (i.e. Valium) to help with muscle spasm that inevitably occurs with such a large surgery. | |||
== Intraoperative management == | == Intraoperative management == | ||
=== Monitoring and access<!-- List and/or describe monitors and access typically needed for this case. Please describe rationale for any special monitors or access. --> === | === Monitoring and access<!-- List and/or describe monitors and access typically needed for this case. Please describe rationale for any special monitors or access. --> === | ||
# Evoked potentials (SSEV) are followed by a technologist. | |||
# Continuous arterial line blood pressure is monitored to ensure precise blood pressure control. | |||
# ABGs prn | |||
Keeping track of the patient's hourly fluid goal is important to maintain intra-op euvolemia. Consider setting up the following table (example for 52 kg patient): | |||
{| class="wikitable" | |||
|+ | |||
! | |||
!Deficit | |||
!Maintenance | |||
!Insensible losses | |||
!EBL | |||
!Hourly total | |||
!Cumulative total | |||
|- | |||
|Hour 1 | |||
|500 | |||
|x (can skip while replacing fluid deficit) | |||
|x | |||
|x | |||
|500 mL | |||
|500 mL | |||
|- | |||
|Hour 2 | |||
|500 | |||
|x | |||
|375 mL | |||
|200 mL (multiply by 2 to get necessary volume to replace, in this case 400 mL) | |||
|1275 mL | |||
|1775 mL | |||
|- | |||
|Hour 3 | |||
|x | |||
|92 mL | |||
|375 mL | |||
|x | |||
|467 mL | |||
|2242 mL | |||
|} | |||
Calculating expected blood loss will help guide when to check ABG and consider transfusing blood (for a healthy patient, generally at a Hb of 7 or 8): | |||
''Example: 52 kg patient with starting Hb of 12.6'' | |||
Estimated blood volume: 52 kg x 70 mL/kg = '''3500 mL''' | |||
Estimated cc per gram of Hb: 3500 mL divided by 12.6 g/dL = '''277 mL per g Hb''' | |||
To lose blood to go from Hb of 12.6 to 8.0: 12.6 - 8.0 = '''4.6 g/dL Hb''' | |||
Volume of blood to drop to reach transfusion threshold: 4.6 g/dL x 277 mL = '''1274 mL''' | |||
'''At an estimated blood loss of 1274 mL, the clinician can expect enough of a drop in Hb to transfuse blood.''' | |||
=== Induction and airway management<!-- Describe the important considerations and general approach to the induction of anesthesia and how the airway is typically managed for this case. --> === | === Induction and airway management<!-- Describe the important considerations and general approach to the induction of anesthesia and how the airway is typically managed for this case. --> === | ||
Standard induction with the addition of large doses of opiate (in preparation for significant pain of the procedure) followed by placement of ETT. Avoid paralysis. | |||
=== Positioning<!-- Describe any unique positioning considerations, including potential intraoperative position changes. If none, this section may be removed. --> === | === Positioning<!-- Describe any unique positioning considerations, including potential intraoperative position changes. If none, this section may be removed. --> === | ||
Prone. | |||
=== Maintenance and surgical considerations<!-- Describe the important considerations and general approach to the maintenance of anesthesia, including potential complications. Be sure to include any steps to the surgical procedure that have anesthetic implications. --> === | === Maintenance and surgical considerations<!-- Describe the important considerations and general approach to the maintenance of anesthesia, including potential complications. Be sure to include any steps to the surgical procedure that have anesthetic implications. --> === | ||
A MAC of 0.5 for inhalational agents is used to prevent interference with intra-op neuro monitoring. Iso-nitrous is often used with these procedures but sevo and iso at low MAC is still appropriate. A mix of gas and an IV Propofol infusion can lower the MAC needed to maintain general anesthesia. | |||
Ketamine may be considered to improve SSEV. | |||
=== Emergence<!-- List and/or describe any important considerations related to the emergence from anesthesia for this case. --> === | === Emergence<!-- List and/or describe any important considerations related to the emergence from anesthesia for this case. --> === | ||
Consider slowly starting to wean the Propofol infusion when surgeons begin throwing their deep dermal sutures which will help with faster emergence. Wean the gas when finished with skin and the patients is flipped back to supine positioning. | |||
Consider extubating in the OR to perform a neuro exam prior to leaving for the PACU. | |||
== Postoperative management == | == Postoperative management == | ||
=== Disposition<!-- List and/or describe the postoperative disposition and any special considerations for transport of patients for this case. --> === | === Disposition<!-- List and/or describe the postoperative disposition and any special considerations for transport of patients for this case. --> === | ||
Admitted to inpatient | |||
=== Pain management<!-- Describe the expected level of postoperative pain and approaches to pain management for this case. --> === | === Pain management<!-- Describe the expected level of postoperative pain and approaches to pain management for this case. --> === | ||
Ketamine and opiate PCA. Valium prn. | |||
=== Potential complications<!-- List and/or describe any potential postoperative complications for this case. --> === | === Potential complications<!-- List and/or describe any potential postoperative complications for this case. --> === | ||
Nerve injury. Significant blood loss. | |||
== References == | == References == | ||
[[Category:Surgical procedures]] | [[Category:Surgical procedures]] | ||
Revision as of 09:16, 10 July 2022
| Anesthesia type | |
|---|---|
| Airway | |
| Lines and access | |
| Monitors | |
| Primary anesthetic considerations | |
| Preoperative | |
| Intraoperative | |
| Postoperative | |
| Article quality | |
| Editor rating | |
| User likes | 0 |
Posterior spinal fusion is an orthopedic procedure performed to correct idiopathic scoliosis. It is the most common treatment for idiopathic scoliosis. Involved are the placement of implants (an array of hooks, screws, and wires) which are attached to affected segments of spine.
Overview
Indications
Generally indicated for severe scoliosis (Cobb angle >50 degrees).
Procedure
Patients are initially supine for intubation, line placement, and monitors. Once complete, they are flipping to the prone position. A large midline incision is made cutting through the back muscles to expose the spine. The surgeon will clear the tissue from the spine in order to create a surface for hardware placement. Controlled hypotension (MAPs no greater than the 70s, sometimes lower) limits bleeding during this part of the procedure.
Then, tightening of the wire implants stretches/distracts the spine, straightening it into midline position. It is important to maintain normotension once this begins in order to perfuse the spinal cord during distraction (which inevitably causes stretching of the nerves/nerve damage). Close neuromuscular monitoring by a technician allows surgeons to detect this early and stop manipulation. Steroids may be given if concern for nerve injury.
If the spine remains off center from the pelvis, a pelvic fixation may also be performed.
Other Interventions
Harrington rods were the original method but are no longer current as segmental implants allow surgeons more control and early mobilization without the need for bracing.
Anterior spinal fusion is another surgical method that comparatively has less blood loss and risk of neurologic injury. Advantages of posterior spinal fusion over anterior spinal fusion include avoidance of entering the thoracic cavity and potentially impairing pulmonary function.
Preoperative management
Patient evaluation
| System | Considerations |
|---|---|
| Airway | ETT. Prone positioning. |
| Neurologic | Intra-op neuromonitoring. Avoid NMB. Steroids for protection against nerve injury. |
| Cardiovascular | Controlled hypotension |
| Pulmonary | Changes in compliance during surgical manipulation of spine |
| Gastrointestinal | |
| Hematologic | Anywhere between 300 to 3000 mL of blood loss from the scraping of the epidural veins of the spine |
| Renal | AKI from hypovolemia or prolonged hypotension |
| Endocrine | |
| Other |
Labs and studies
ABG monitoring if observing significant blood loss. Should generally include lytes and iCa.
Operating room setup
- A-line
- 2 PIV, one large bore (16 gauge) for resuscitation and bolus of meds, one for infusions
- Standard monitors/equipment including temperature probe/bear hugger (important given prolonged exposure
- Ancillary equipment: Cell-saver, neuromuscular monitors
Patient preparation and premedication
Generally patients receive muscle relaxers (i.e. Valium) to help with muscle spasm that inevitably occurs with such a large surgery.
Intraoperative management
Monitoring and access
- Evoked potentials (SSEV) are followed by a technologist.
- Continuous arterial line blood pressure is monitored to ensure precise blood pressure control.
- ABGs prn
Keeping track of the patient's hourly fluid goal is important to maintain intra-op euvolemia. Consider setting up the following table (example for 52 kg patient):
| Deficit | Maintenance | Insensible losses | EBL | Hourly total | Cumulative total | |
|---|---|---|---|---|---|---|
| Hour 1 | 500 | x (can skip while replacing fluid deficit) | x | x | 500 mL | 500 mL |
| Hour 2 | 500 | x | 375 mL | 200 mL (multiply by 2 to get necessary volume to replace, in this case 400 mL) | 1275 mL | 1775 mL |
| Hour 3 | x | 92 mL | 375 mL | x | 467 mL | 2242 mL |
Calculating expected blood loss will help guide when to check ABG and consider transfusing blood (for a healthy patient, generally at a Hb of 7 or 8):
Example: 52 kg patient with starting Hb of 12.6
Estimated blood volume: 52 kg x 70 mL/kg = 3500 mL
Estimated cc per gram of Hb: 3500 mL divided by 12.6 g/dL = 277 mL per g Hb
To lose blood to go from Hb of 12.6 to 8.0: 12.6 - 8.0 = 4.6 g/dL Hb
Volume of blood to drop to reach transfusion threshold: 4.6 g/dL x 277 mL = 1274 mL
At an estimated blood loss of 1274 mL, the clinician can expect enough of a drop in Hb to transfuse blood.
Induction and airway management
Standard induction with the addition of large doses of opiate (in preparation for significant pain of the procedure) followed by placement of ETT. Avoid paralysis.
Positioning
Prone.
Maintenance and surgical considerations
A MAC of 0.5 for inhalational agents is used to prevent interference with intra-op neuro monitoring. Iso-nitrous is often used with these procedures but sevo and iso at low MAC is still appropriate. A mix of gas and an IV Propofol infusion can lower the MAC needed to maintain general anesthesia.
Ketamine may be considered to improve SSEV.
Emergence
Consider slowly starting to wean the Propofol infusion when surgeons begin throwing their deep dermal sutures which will help with faster emergence. Wean the gas when finished with skin and the patients is flipped back to supine positioning.
Consider extubating in the OR to perform a neuro exam prior to leaving for the PACU.
Postoperative management
Disposition
Admitted to inpatient
Pain management
Ketamine and opiate PCA. Valium prn.
Potential complications
Nerve injury. Significant blood loss.