Scoliosis surgery

Surgical approach

• Usually posterior spinal fusion with segmental instrumentation (pedicle screws/hooks/rods) over multiple vertebral levels
  • Midline posterior incision; subperiosteal dissection to expose posterior elements
  • Placement of screws/anchors; rod insertion; deformity correction (derotation/translation/compression-distraction)
  • Decortication + bone grafting to achieve fusion; wound closure ± drains
• Alternative/adjuncts (less common depending on centre/patient): anterior approach, thoracoscopic release, staged procedures, osteotomies (e.g. Smith-Petersen, pedicle subtraction) for rigid deformity
  • Anterior thoracic approach may require one-lung ventilation and has higher pulmonary impact
• Intra-operative spinal cord monitoring commonly used: SSEPs ± MEPs; wake-up test is now uncommon but may be a backup

Anaesthetic management (headline)

• Type of anaesthesia: General anaesthesia (TIVA commonly to facilitate MEPs/SSEPs); regional techniques usually adjunct only (e.g. wound infiltration/erector spinae plane block in selected centres)
• Airway: cuffed ETT (reinforced often helpful); secure well (prone positioning). SGA not appropriate
• Duration: typically 4–8 hours (can be longer with severe curves, osteotomies, revision surgery)
• Pain: severe (multi-level bony surgery, muscle dissection). Plan multimodal analgesia + PCA/opioid infusion ± ketamine; consider HDU/ICU
• Key intra-op priorities: prone safety, blood conservation (TXA, cell salvage), neuromonitoring-compatible anaesthesia, temperature control, large-bore access, arterial line, careful ventilation and haemodynamics

Indications and patient groups

• Idiopathic adolescent scoliosis (most common), congenital scoliosis, neuromuscular scoliosis (e.g. cerebral palsy, muscular dystrophy, SMA), syndromic (Marfan, NF1), degenerative adult scoliosis
• Surgery considered for progression, significant Cobb angle (often >45–50° in adolescents), pain/functional limitation, cardiopulmonary compromise, imbalance

Pre-operative assessment

• History: exercise tolerance, dyspnoea/orthopnoea, recurrent chest infections, OSA symptoms, reflux/aspiration risk, pain meds, previous anaesthetics, bleeding history, transfusion refusal
• Examination: airway (limited neck movement, braces, syndromic features), cardiopulmonary exam, baseline neuro status (document), nutritional status, pressure area risk
• Respiratory investigations: spirometry (restrictive pattern common). Consider ABG if severe restriction/hypoventilation; CXR; sleep study if suspected OSA; consider NIV assessment in neuromuscular disease
  • Risk increases with low FVC (particularly <50% predicted) and thoracic curves; neuromuscular patients at highest risk of post-op ventilation
• Cardiac: ECG; echo if severe deformity, symptoms, pulmonary HTN suspicion, or syndromic disease (e.g. Marfan)
• Bloods: FBC (optimise Hb), coagulation profile, U&E, group & save/crossmatch; consider iron studies and pre-op optimisation (iron ± EPO in selected pathways)
• Medication planning: continue most meds; consider stress-dose steroids if chronic steroid use; manage anticonvulsants; neuromuscular disorders—avoid triggers for rhabdomyolysis/hyperkalaemia
• Consent/discussion: blood loss/transfusion, ICU/HDU, neurological injury risk, post-op ventilation, pain plan, lines and monitoring, potential for wake-up test

Physiology and anaesthetic implications of scoliosis

• Respiratory: restrictive lung disease (↓FVC, ↓TLC), V/Q mismatch, reduced chest wall compliance; severe curves can cause chronic hypoventilation and pulmonary hypertension
• Cardiovascular: cor pulmonale in advanced disease; right heart strain; reduced exercise tolerance; potential congenital heart disease in syndromic/congenital scoliosis
• Airway/positioning: difficult positioning; limited neck extension; risk of ETT displacement when turning prone; facial/airway oedema with prolonged prone surgery

Intra-operative monitoring and access

• Standard monitoring + invasive arterial pressure (beat-to-beat, blood sampling) and temperature; urinary catheter; consider depth of anaesthesia monitoring (TIVA)
• IV access: 2 large-bore cannulae; consider central venous access if poor peripheral access/anticipated vasoactive infusions (not routine)
• Blood management: crossmatched blood available; cell salvage (unless contraindicated); point-of-care coagulation testing (TEG/ROTEM) if available

Induction and maintenance (including neuromonitoring)

• Induction: IV induction typical; consider aspiration risk (reflux, neuromuscular) and plan RSI if indicated
• Maintenance for neuromonitoring: TIVA (propofol + remifentanil) commonly used; avoid/limit volatile agents as they depress SSEPs and especially MEPs
  • If volatile used, keep low MAC and stable; communicate with neurophysiology team
• Neuromuscular blockade: allow intubation dose, then avoid further NMB if MEPs required; if only SSEPs, a low stable block may be acceptable (centre dependent)
• Haemodynamic goals: maintain spinal cord perfusion (avoid hypotension/anaemia); treat signal changes with MAP augmentation, optimise oxygenation/ventilation, check anaesthetic depth and NMB, correct temperature and electrolytes

Ventilation strategy (prone)

• Lung-protective ventilation: moderate tidal volumes, appropriate PEEP; monitor plateau pressures (reduced compliance). Aim normocapnia unless specific strategy agreed
• Prone positioning can improve oxygenation but abdominal compression increases venous pressure and bleeding—ensure abdomen free (frame positioning)

Positioning and prone safety

• Team brief before turn; secure ETT and all lines; eye protection; check bite block; ensure no pressure on eyes (risk of peri-operative visual loss is rare but catastrophic)
• Pressure care: face, breasts, iliac crests, knees, toes; pad ulnar nerve; avoid excessive shoulder abduction; document positioning checks
• Haemodynamics after prone: reassess ventilation pressures, ETCO2, arterial waveform; ensure abdomen not compressed

Blood loss and blood conservation

• Blood loss can be large (often 500–3000 mL+ depending on levels/osteotomies/revision). Anticipate dilutional coagulopathy and hypocalcaemia with transfusion
• Tranexamic acid (TXA): commonly used (local protocols vary). Typical regimens include loading dose then infusion; check contraindications (e.g. active thrombosis, seizure risk considerations at high doses)
• Cell salvage: reduces allogeneic transfusion; consider leucocyte depletion filters if concern about contaminants (follow local policy)
• Controlled hypotension: sometimes requested to reduce bleeding but must be balanced against spinal cord perfusion and neuromonitoring reliability; avoid in high-risk patients
• Coagulation management: use TEG/ROTEM if available; replace fibrinogen early if low; maintain platelets; warm patient; correct ionised calcium

Fluids, temperature and metabolic issues

• Aim euvolaemia; balanced crystalloids; use blood products guided by Hb/physiology and coagulation; avoid excessive crystalloid (tissue oedema, airway swelling)
• Active warming: forced-air warming where possible, fluid warmers; hypothermia worsens coagulopathy and neuromonitoring signals
• Electrolytes/ABGs: monitor lactate, base deficit; watch for citrate-related hypocalcaemia during massive transfusion (treat with calcium as needed)

Analgesia

• Multimodal: paracetamol + NSAID (if acceptable) + opioid (PCA/infusion) ± ketamine infusion; consider clonidine/dexmedetomidine as adjuncts (centre dependent)
• Neuraxial analgesia: epidural is uncommon with extensive instrumentation and neuromonitoring; may mask neurological deficits and is technically challenging
• Regional fascial plane blocks (e.g. erector spinae plane) may reduce opioid use in some pathways; ensure not interfering with neuro assessment and follow local practice

Emergence and post-operative care

• Plan extubation vs post-op ventilation: consider duration, blood loss, hypothermia, facial oedema, respiratory reserve (FVC), neuromuscular disease, OSA, opioid requirements
• Neurological assessment: wake patient for motor assessment early where feasible; document baseline and post-op findings; liaise urgently if deficit suspected
• Destination: HDU/ICU commonly for major fusions, significant comorbidity, or high transfusion requirement
• PONV prophylaxis: high risk (opioids, long surgery). Use multimodal antiemetics; consider TIVA benefit

Complications (anaesthetic and surgical relevance)

• Neurological injury: spinal cord ischaemia/traction; respond to neuromonitoring changes promptly (raise MAP, correct anaemia/hypoxia, reduce correction, check technical factors)
• Major haemorrhage and coagulopathy; transfusion reactions; hypocalcaemia; hypothermia
• Respiratory: atelectasis, pneumonia, post-op ventilation, aspiration; higher risk in neuromuscular scoliosis
• Position-related: pressure sores, peripheral nerve injury, ocular injury/visual loss (rare), airway oedema, tongue/lip injury
• VTE risk (adolescents lower than adults but not zero); balance chemoprophylaxis with bleeding risk and surgeon preference