Are Arterial Blood Gas (ABG), Pulmonary Function Tests (PFT), and pulmonology clearance necessary for all scoliosis correction surgeries?

Preoperative Pulmonary Evaluation for Scoliosis Surgery

No, ABG, PFT, and pulmonology clearance are not required for all scoliosis correction surgeries—these tests should be reserved for patients with specific risk factors rather than performed universally. 1

Risk-Stratified Approach to Pulmonary Evaluation

The Congress of Neurological Surgeons guidelines explicitly state there is insufficient evidence to support routine preoperative pulmonary testing for all spine surgery patients. 1 Instead, testing should be targeted based on clinical presentation and risk factors. 1

Patients Who DO NOT Require Routine Testing

For adolescent idiopathic scoliosis (AIS) with moderate curves undergoing posterior spinal fusion, preoperative PFTs are not necessary. 2

• In a study of 133 AIS patients undergoing posterior fusion with mean thoracic Cobb angle of 48°, 72.9% had normal PFTs and only 2.3% developed postoperative pulmonary complications. 2
• There was no correlation between abnormal preoperative PFT results and postoperative pulmonary complications in this population. 2
• The only risk factor identified was thoracoplasty performance, not baseline pulmonary function. 2

Patients Who REQUIRE Preoperative Pulmonary Evaluation

Obtain PFTs and consider pulmonology consultation for patients with:

High-Risk Patient Factors

• Neuromuscular scoliosis (most critical risk factor) 3, 4
• Functional dependence 1
• Advanced age ≥65 years 1
• Chronic obstructive pulmonary disease (increases pneumonia risk 2.7-4 fold) 1
• Congestive heart failure (doubles reintubation risk) 1
• Obstructive sleep apnea 1
• Recent weight loss 1

High-Risk Curve Characteristics

• Cobb angle ≥76° (strongly predicts need for postoperative ventilation) 4
• Congenital scoliosis (more severe pulmonary impairment than idiopathic) 5
• Age of onset <10 years 5
• Thoracic curve location (more pulmonary impact than lumbar) 6
• ≥7 vertebrae involved 5
• Spinal segments involved ≥11 (predicts postoperative ventilation) 4

High-Risk Surgical Factors

• Anterior spinal fusion (higher complication rates than posterior) 2
• Combined anterior-posterior procedures 7
• Planned thoracoplasty 2

Specific Testing Thresholds

When PFTs Predict Prolonged Ventilation

Order preoperative PFTs if considering these critical thresholds: 3

• FEV1 <40% predicted (strongest independent predictor of prolonged mechanical ventilation ≥3 days) 3, 4
• FVC <60% predicted 3
• Vital capacity <38% predicted (unable to extubate) 4
• Total lung capacity <60% predicted 3
• Inspiratory capacity <30 mL/kg 3
• Maximal inspiratory pressure <60 cm H₂O 3

When Pulmonology Clearance Is Indicated

Refer to pulmonology at least 2 months before surgery for: 1

• Neuromuscular disease patients (especially Duchenne muscular dystrophy) 1
• Active pulmonary symptoms requiring optimization 1
• Suspected or confirmed sleep hypoventilation (obtain sleep study preoperatively) 1
• FEV1 <40% predicted to plan postoperative extubation strategy 3
• COPD requiring preoperative bronchodilator optimization 1

ABG Considerations

Arterial blood gas testing is NOT routinely indicated for scoliosis surgery. 1

• No evidence supports routine ABG testing for preoperative risk stratification. 1
• Consider ABG only if acute respiratory symptoms, suspected hypercapnia, or severe restrictive disease with FEV1 <40% predicted. 3

Critical Perioperative Planning

For High-Risk Patients Proceeding to Surgery

Even with severely reduced pulmonary function, surgery can proceed with appropriate planning: 1

• There are no absolute contraindications based on pulmonary function alone—some report good outcomes even with FVC 20% of predicted. 1
• Patients with abnormal sleep studies should begin nocturnal noninvasive ventilation before surgery and extubate to noninvasive ventilation postoperatively. 1
• Optimize cardiac, nutritional, and respiratory status preoperatively. 1
• Plan for aggressive postoperative airway clearance and respiratory support. 1

Common Pitfalls to Avoid

• Do not delay surgery in AIS patients solely based on mildly abnormal PFTs—curves >50° progress ~1°/year even after skeletal maturity, causing progressive pulmonary decline. 6, 8
• Do not assume Cobb angle alone predicts pulmonary function—chest wall deformities, curve location, and kyphosis component are equally important. 6, 5
• Do not forget that PFTs decline 60% immediately postoperatively with nadir at day 3—this should inform preoperative risk assessment. 7
• Do not overlook neuromuscular etiology—this is the single strongest predictor of prolonged postoperative ventilation, especially when combined with FEV1 <40%. 3