Difference between revisions of "Posterior spinal fusion"

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(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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{{Infobox surgical procedure
{{Infobox surgical procedure
| anesthesia_type =  
| anesthesia_type = General
| airway =  
| airway = ETT
| lines_access =  
| lines_access = Large bore IV (bolus/resuscitation), 2nd PIV (infusions), A-line
| monitors =  
| monitors = Standard, neuromuscular monitoring (e.g. SSEV)
| considerations_preoperative =  
| considerations_preoperative = Starting Hb, pulmonary function (restrictive physiology)
| considerations_intraoperative =  
| considerations_intraoperative = Nerve injury, significant blood loss, controlled hypotension
| considerations_postoperative =  
| considerations_postoperative = Nerve injury, pain control
}}
}}


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 Harrington rods were the original method but are no longer current as segmental implants allow surgeons more control and early mobilization without the need for bracing.  
'''Posterior spinal fusion''' is an orthopedic procedure performed to correct idiopathic scoliosis. It is the most common treatment for idiopathic scoliosis. The surgery involves placement of implants (an array of hooks, screws, and wires) which are attached to disc segments and tightened to straighten the spine. Bone grafts are placed between vertebrae and encourage spine fusion.


== Overview ==
== Overview ==


=== Indications ===
=== Indications ===
Generally indicated for severe scoliosis (Cobb angle >50 degrees).
Generally indicated for severe scoliosis (Cobb angle >50 degrees). Even after skeletal maturity, such severe Cobb angles can progress to extreme curvature of up to 80 degrees.
 
Such severe deviation of spine curvature can lead to chronic back pain and decreased pulmonary function (akin to restrictive lung physiology).  


=== 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 and graft bone. Bone grafts are used between vertebrae to stimulate growth and ultimately spinal fusion.  Controlled hypotension (MAPs no greater than the 70s, sometimes lower) limits bleeding during this part of the procedure.
Tightening of the wire implants stretches/distracts the spine 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.  


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|-
|-
|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 54:
|-
|-
|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 67:


=== 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. --> ===
A pre-op Hb as well as Type and Screen should be drawn pre-procedure. ABG monitoring can be performed if significant blood loss is observed. ABGs 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
#Tranexamic acid infusion for bleeding, blood pressure agents (norepinephrine infusion for hypotension, nitroglycerin infusion for hypertension)


=== 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.  
=== Regional and neuraxial techniques<!-- Describe any potential regional and/or neuraxial techniques which may be used for this case. If none, this section may be removed. --> ===


== 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 (SSEP) 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. --> ===
Patient is prone during hardware placement and flipped to supine after skin closure is complete.


=== 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. --> ===
''Bleeding''
Generally, a bolus of tranexamic acid followed by a continuous tranexamic infusion is started to limit excessive blood loss. 
''Maintenance of anesthesia''
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.
Administering ketamine may be considered to improve SSEV signals.


=== 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 the surgeons begin with deep dermal suturing. This will help with faster emergence. Wean the gas when skin closure is finished and the patient 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. --> ===
Admit 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 gtt 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 from spine distraction. Significant blood loss leading to hypovolemic shock and increasing risk for spinal cord ischemia/damage.


== Procedure variants<!-- This section should only be used for cases with multiple approaches (e.g. Laparoscopic vs. open appendectomy). Otherwise, remove this section. Use this table to very briefly compare and contrast various aspects between approaches. Add or remove rows as needed to maximize relevance. Consider using symbols rather than words when possible (e.g. +, –, additional symbols such as ↑ and ↓ are available using the "Ω" tool in the editor). --> ==
== References ==
 
{| class="wikitable wikitable-horizontal-scroll"
|+
!
!Variant 1
!Variant 2
|-
|Unique considerations
|
|
|-
|Position
|
|
|-
|Surgical time
|
|
|-
|EBL
|
|
|-
|Postoperative disposition
|
|
|-
|Pain management
|
|
|-
|Potential complications
|
|
|}


== References ==
# Peterson LE, Nachemson AL. Prediction of progression of the curve in girls who have adolescent idiopathic scoliosis of moderate severity. Logistic regression analysis based on data from The Brace Study of the Scoliosis Research Society. J Bone Joint Surg Am 1995; 77:823.
# Weinstein SL. Adolescent idiopathic scoliosis: prevalence and natural history. Instr Course Lect 1989; 38:115.
# Weinstein SL, Ponseti IV. Curve progression in idiopathic scoliosis. J Bone Joint Surg Am 1983; 65:447.
# Lonstein JE. Adolescent idiopathic scoliosis. Lancet 1994; 344:1407.
# Ascani E, Bartolozzi P, Logroscino CA, et al. Natural history of untreated idiopathic scoliosis after skeletal maturity. Spine (Phila Pa 1976) 1986; 11:784.
# Sponseller PD. Bone, joint, and muscle problems. In: Oski's Pediatrics: Principles and Practice, 4th ed, McMillan JA, Feigin RD, DeAngelis CD, Jones MD Jr (Eds), Lippincott Williams & Wilkins, Philadelphia 2006. p.2488.
# Winter RB, Lovell WW, Moe JH. Excessive thoracic lordosis and loss of pulmonary function in patients with idiopathic scoliosis. J Bone Joint Surg Am 1975; 57:972.
# Roach JW. Adolescent idiopathic scoliosis. Orthop Clin North Am 1999; 30:353.
# Newton PO, Wenger DR, Yaszay B. Idiopathic scoliosis. In: Lovell and Winter's Pediatric Orthopaedics, 7th ed, Weinstein SL, Flynn JM (Eds), Lippincott Williams & Wilkins, Philadelphia 2014. p.629.
# Stasikelis PJ, Pugh LI, Allen BL Jr. Surgical corrections in scoliosis: a meta-analysis. J Pediatr Orthop B 1998; 7:111.
# Sarwark JF. Idiopathic scoliosis: New instrumentation for surgical management. J Am Acad Orthop Surg 1994; 2:67.
# Geck MJ, Rinella A, Hawthorne D, et al. Comparison of surgical treatment in Lenke 5C adolescent idiopathic scoliosis: anterior dual rod versus posterior pedicle fixation surgery: a comparison of two practices. Spine (Phila Pa 1976) 2009; 34:1942.
# Newton PO. Thoracoscopic anterior instrumentation for idiopathic scoliosis. Spine J 2009; 9:595.
# McNicol ED, Tzortzopoulou A, Schumann R, et al. Antifibrinolytic agents for reducing blood loss in scoliosis surgery in children. Cochrane Database Syst Rev 2016; 9:CD006883.
# Goobie SM, Zurakowski D, Glotzbecker MP, et al. Tranexamic Acid Is Efficacious at Decreasing the Rate of Blood Loss in Adolescent Scoliosis Surgery: A Randomized Placebo-Controlled Trial. J Bone Joint Surg Am 2018; 100:2024.
# Reames DL, Smith JS, Fu KM, et al. Complications in the surgical treatment of 19,360 cases of pediatric scoliosis: a review of the Scoliosis Research Society Morbidity and Mortality database. Spine (Phila Pa 1976) 2011; 36:1484.


[[Category:Surgical procedures]]
[[Category:Surgical procedures]]

Latest revision as of 14:44, 6 April 2023

Posterior spinal fusion
Anesthesia type

General

Airway

ETT

Lines and access

Large bore IV (bolus/resuscitation), 2nd PIV (infusions), A-line

Monitors

Standard, neuromuscular monitoring (e.g. SSEV)

Primary anesthetic considerations
Preoperative

Starting Hb, pulmonary function (restrictive physiology)

Intraoperative

Nerve injury, significant blood loss, controlled hypotension

Postoperative

Nerve injury, pain control

Article quality
Editor rating
In development
User likes
0

Posterior spinal fusion is an orthopedic procedure performed to correct idiopathic scoliosis. It is the most common treatment for idiopathic scoliosis. The surgery involves placement of implants (an array of hooks, screws, and wires) which are attached to disc segments and tightened to straighten the spine. Bone grafts are placed between vertebrae and encourage spine fusion.

Overview

Indications

Generally indicated for severe scoliosis (Cobb angle >50 degrees). Even after skeletal maturity, such severe Cobb angles can progress to extreme curvature of up to 80 degrees.

Such severe deviation of spine curvature can lead to chronic back pain and decreased pulmonary function (akin to restrictive lung physiology).

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 and graft bone. Bone grafts are used between vertebrae to stimulate growth and ultimately spinal fusion. Controlled hypotension (MAPs no greater than the 70s, sometimes lower) limits bleeding during this part of the procedure.

Tightening of the wire implants stretches/distracts the spine 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

A pre-op Hb as well as Type and Screen should be drawn pre-procedure. ABG monitoring can be performed if significant blood loss is observed. ABGs should generally include lytes and iCa.

Operating room setup

  1. A-line
  2. 2 PIV, one large bore (16 gauge) for resuscitation and bolus of meds, one for infusions
  3. Standard monitors/equipment including temperature probe/bear hugger (important given prolonged exposure
  4. Ancillary equipment: Cell-saver, neuromuscular monitors
  5. Tranexamic acid infusion for bleeding, blood pressure agents (norepinephrine infusion for hypotension, nitroglycerin infusion for hypertension)

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

  1. Evoked potentials (SSEP) are followed by a technologist.
  2. Continuous arterial line blood pressure is monitored to ensure precise blood pressure control.
  3. 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

Patient is prone during hardware placement and flipped to supine after skin closure is complete.

Maintenance and surgical considerations

Bleeding

Generally, a bolus of tranexamic acid followed by a continuous tranexamic infusion is started to limit excessive blood loss.

Maintenance of anesthesia

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.

Administering ketamine may be considered to improve SSEV signals.

Emergence

Consider slowly starting to wean the Propofol infusion when the surgeons begin with deep dermal suturing. This will help with faster emergence. Wean the gas when skin closure is finished and the patient 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

Admit to inpatient.

Pain management

Ketamine gtt and opiate PCA. Valium prn.

Potential complications

Nerve injury from spine distraction. Significant blood loss leading to hypovolemic shock and increasing risk for spinal cord ischemia/damage.

References

  1. Peterson LE, Nachemson AL. Prediction of progression of the curve in girls who have adolescent idiopathic scoliosis of moderate severity. Logistic regression analysis based on data from The Brace Study of the Scoliosis Research Society. J Bone Joint Surg Am 1995; 77:823.
  2. Weinstein SL. Adolescent idiopathic scoliosis: prevalence and natural history. Instr Course Lect 1989; 38:115.
  3. Weinstein SL, Ponseti IV. Curve progression in idiopathic scoliosis. J Bone Joint Surg Am 1983; 65:447.
  4. Lonstein JE. Adolescent idiopathic scoliosis. Lancet 1994; 344:1407.
  5. Ascani E, Bartolozzi P, Logroscino CA, et al. Natural history of untreated idiopathic scoliosis after skeletal maturity. Spine (Phila Pa 1976) 1986; 11:784.
  6. Sponseller PD. Bone, joint, and muscle problems. In: Oski's Pediatrics: Principles and Practice, 4th ed, McMillan JA, Feigin RD, DeAngelis CD, Jones MD Jr (Eds), Lippincott Williams & Wilkins, Philadelphia 2006. p.2488.
  7. Winter RB, Lovell WW, Moe JH. Excessive thoracic lordosis and loss of pulmonary function in patients with idiopathic scoliosis. J Bone Joint Surg Am 1975; 57:972.
  8. Roach JW. Adolescent idiopathic scoliosis. Orthop Clin North Am 1999; 30:353.
  9. Newton PO, Wenger DR, Yaszay B. Idiopathic scoliosis. In: Lovell and Winter's Pediatric Orthopaedics, 7th ed, Weinstein SL, Flynn JM (Eds), Lippincott Williams & Wilkins, Philadelphia 2014. p.629.
  10. Stasikelis PJ, Pugh LI, Allen BL Jr. Surgical corrections in scoliosis: a meta-analysis. J Pediatr Orthop B 1998; 7:111.
  11. Sarwark JF. Idiopathic scoliosis: New instrumentation for surgical management. J Am Acad Orthop Surg 1994; 2:67.
  12. Geck MJ, Rinella A, Hawthorne D, et al. Comparison of surgical treatment in Lenke 5C adolescent idiopathic scoliosis: anterior dual rod versus posterior pedicle fixation surgery: a comparison of two practices. Spine (Phila Pa 1976) 2009; 34:1942.
  13. Newton PO. Thoracoscopic anterior instrumentation for idiopathic scoliosis. Spine J 2009; 9:595.
  14. McNicol ED, Tzortzopoulou A, Schumann R, et al. Antifibrinolytic agents for reducing blood loss in scoliosis surgery in children. Cochrane Database Syst Rev 2016; 9:CD006883.
  15. Goobie SM, Zurakowski D, Glotzbecker MP, et al. Tranexamic Acid Is Efficacious at Decreasing the Rate of Blood Loss in Adolescent Scoliosis Surgery: A Randomized Placebo-Controlled Trial. J Bone Joint Surg Am 2018; 100:2024.
  16. Reames DL, Smith JS, Fu KM, et al. Complications in the surgical treatment of 19,360 cases of pediatric scoliosis: a review of the Scoliosis Research Society Morbidity and Mortality database. Spine (Phila Pa 1976) 2011; 36:1484.

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