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Pulmonary Risk Assessment

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Pulmonary Risk Assessment

Comprehensive perioperative pulmonary risk assessment including OSA screening, COPD optimization, postoperative pulmonary complication prediction, and management strategies

complete
Updated: 2025-12-25
High Yield Overview

PULMONARY RISK ASSESSMENT

ARISCAT Score | OSA Management | COPD Optimization | Postoperative Pulmonary Complications

2-5%postoperative pneumonia in orthopaedics
26 pointsARISCAT intermediate risk threshold
4 weekssmoking cessation minimum for benefit
24%undiagnosed OSA prevalence in surgery

ARISCAT RISK STRATIFICATION

Low Risk
PatternARISCAT under 26
TreatmentStandard care
Intermediate Risk
PatternARISCAT 26-44
TreatmentEnhanced monitoring, physiotherapy
High Risk
PatternARISCAT over 44
TreatmentHDU/ICU, respiratory support

Critical Must-Knows

  • ARISCAT score predicts postoperative pulmonary complications - seven risk factors including age, SpO2, respiratory infection
  • OSA affects 24% of surgical patients - STOP-BANG greater than 5 requires CPAP continuation perioperatively
  • Smoking cessation under 4 weeks may worsen outcomes - minimum 4 weeks required for pulmonary benefit
  • PFTs rarely change management in asymptomatic patients - reserve for moderate-severe COPD or unexplained dyspnea
  • Neuraxial anesthesia reduces pulmonary complications by 30% compared to general anesthesia in lower limb surgery

Examiner's Pearls

  • "
    ARISCAT includes: age, SpO2 under 96%, respiratory infection in last month, preop anemia, upper abdominal/thoracic surgery, duration over 2 hours, emergency procedure
  • "
    STOP-BANG: Snoring, Tired, Observed apnea, Pressure (BP), BMI over 35, Age over 50, Neck over 40cm, Gender male - score 5-8 = high OSA risk
  • "
    FEV1 under 50% predicted or FEV1/FVC under 0.7 indicates moderate-severe COPD needing optimization
  • "
    Continue CPAP perioperatively for known OSA - reduces atelectasis and hypoxemia

Critical Pulmonary Risk Assessment Exam Points

ARISCAT Score

Gold standard for pulmonary risk prediction. Seven factors: age over 50 (3-16 points), SpO2 under 96% (8 points), respiratory infection in last month (17 points), preop anemia Hb under 100 (11 points), upper abdominal/thoracic surgery (15 points), duration over 2h (16 points), emergency (8 points). Score over 44 = high risk (42% complication rate).

OSA Screening and Management

STOP-BANG over 5 = high OSA risk. Continue CPAP/BiPAP perioperatively. Avoid opioids in PACU. Neuraxial preferred over general anesthesia. Semiupright positioning. Extended monitoring 24-48h. Undiagnosed OSA major cause of postop respiratory failure.

COPD Optimization

Optimize 4-6 weeks before surgery. Bronchodilators, inhaled corticosteroids if FEV1 under 60%. Smoking cessation minimum 4 weeks. Antibiotics if acute exacerbation. Physiotherapy and incentive spirometry. Delay surgery if active infection or poorly controlled.

PFT Indications

PFTs rarely change management unless moderate-severe COPD (FEV1 under 60%), unexplained dyspnea, or lung resection planned. Do NOT order routinely. Clinical assessment (exercise tolerance, symptoms) more predictive than spirometry for elective orthopaedics.

At a Glance

The ARISCAT score is the gold standard for predicting postoperative pulmonary complications, incorporating seven factors: age, SpO₂ less than 96%, respiratory infection in last month, preoperative anemia, upper abdominal/thoracic surgery, duration greater than 2 hours, and emergency procedure. Scores greater than 44 indicate high risk (42% complication rate). OSA affects 24% of surgical patients; STOP-BANG greater than 5 indicates high risk requiring perioperative CPAP continuation. Smoking cessation requires minimum 4 weeks for pulmonary benefit—cessation less than 4 weeks may paradoxically worsen outcomes due to increased secretions. PFTs rarely change management in asymptomatic patients—reserve for moderate-severe COPD (FEV1 less than 60%) or unexplained dyspnea. Neuraxial anesthesia reduces pulmonary complications by 30% compared to general anesthesia in lower limb surgery.

Mnemonic

ASTHMA RARISCAT Risk Score - 7 Predictors

A
Age
50-80 years = 3 points, over 80 years = 16 points
S
SpO2 saturation
91-95% = 8 points, under 90% = 24 points (room air)
T
Thoracic/upper abdominal surgery
15 points - proximity to diaphragm impairs ventilation
H
Hemoglobin low
Anemia Hb under 100 g/L = 11 points (impaired oxygen delivery)
M
Month - respiratory infection
Within last month = 17 points (residual inflammation)
A
Acute/Emergency procedure
8 points - no time for optimization
R
Run time over 2 hours
2-3 hours = 16 points (prolonged anesthesia and atelectasis)

Memory Hook:Patients with ASTHMA R factors need enhanced pulmonary care! Score under 26 = low risk, 26-44 = intermediate, over 44 = high risk.

Mnemonic

STOP-BANGSTOP-BANG Score for OSA Screening

S
Snoring
Loud snoring (louder than talking or heard through closed door)
T
Tired
Tired, fatigued, or sleepy during daytime
O
Observed apnea
Witnessed breathing stopped during sleep
P
Pressure - hypertension
High blood pressure or on treatment for hypertension
B
BMI over 35
Body mass index greater than 35 kg/m�
A
Age over 50
Age greater than 50 years
N
Neck over 40cm
Neck circumference greater than 40 cm (measure at cricothyroid membrane)
G
Gender male
Male gender (2x risk of OSA vs females)

Memory Hook:Use STOP-BANG to catch OSA before they crash! Score 0-2 = low risk, 3-4 = intermediate, 5-8 = high risk. High risk needs CPAP perioperatively.

Mnemonic

PRAPSPostoperative Pulmonary Complications

P
Pneumonia
Most serious PPC - 2-5% in orthopaedics, 30-day mortality 20%
R
Respiratory failure
Hypoxemia requiring reintubation or NIV - associated with OSA
A
Atelectasis
Most common PPC - alveolar collapse from hypoventilation and secretions
P
Pleural effusion
Fluid accumulation - common after upper abdominal/thoracic surgery
S
Severe bronchospasm
Exacerbation of reactive airway disease - COPD/asthma

Memory Hook:Watch for PRAPS after surgery - these pulmonary complications kill! Early mobilization and physiotherapy prevent most.

Overview and Core Principles

Why Pulmonary Risk Assessment Matters

Postoperative pulmonary complications (PPCs) are a leading cause of perioperative morbidity and mortality, particularly in orthopaedic surgery where patients are often elderly with multiple comorbidities. PPCs include pneumonia, respiratory failure, atelectasis, bronchospasm, and pleural effusion. These complications:

  • Occur in 2-5% of elective orthopaedic procedures, 10-40% in high-risk patients
  • Increase 30-day mortality by 2-20 fold depending on severity
  • Prolong hospital stay by 5-10 days on average
  • Cost an additional $20,000-50,000 per episode
  • Are largely preventable through systematic risk assessment and optimization

The goals of pulmonary risk assessment are to: (1) identify high-risk patients requiring enhanced monitoring and intervention, (2) optimize modifiable risk factors before surgery, (3) guide anesthetic technique selection (neuraxial vs general), and (4) inform postoperative care planning (ward vs HDU/ICU).

Risk Stratification Tools

  • ARISCAT score: validated PPC prediction (most widely used)
  • AROZULLAR score: respiratory failure prediction
  • STOP-BANG: OSA screening (8-item questionnaire)
  • Gupta MICA: myocardial infarction or cardiac arrest
  • Clinical assessment: exercise tolerance most predictive

Modifiable Risk Factors

  • Smoking cessation: minimum 4 weeks preoperatively
  • COPD optimization: bronchodilators, steroids if FEV1 under 60%
  • Weight loss: BMI reduction if over 40
  • Respiratory infections: delay surgery 4-6 weeks after infection
  • OSA management: CPAP continuation perioperatively

ARISCAT Risk Score

ARISCAT Components and Calculation

The Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) score is the most validated tool for predicting postoperative pulmonary complications. Developed from a multicenter cohort of 2,464 patients undergoing noncardiac surgery, it identifies seven independent risk factors.

ARISCAT Score Components and Point Values

Risk FactorCategoryPointsRationale
AgeUnder 50 / 50-80 / Over 800 / 3 / 16Decreased respiratory reserve, comorbidities
Preoperative SpO2Over 96% / 91-95% / Under 90%0 / 8 / 24Baseline hypoxemia indicates lung disease
Respiratory infection in last monthNo / Yes0 / 17Residual inflammation and secretions
Preoperative anemiaHb over 100 / Hb under 100 g/L0 / 11Impaired oxygen delivery to tissues
Surgical incisionPeripheral / Upper abdominal or thoracic0 / 15Proximity to diaphragm impairs ventilation
Duration of surgeryUnder 2h / 2-3h / Over 3h0 / 16 / 23Prolonged anesthesia and atelectasis
Emergency procedureNo / Yes0 / 8No time for optimization

ARISCAT Risk Stratification

1.6% PPC rateLow Risk - ARISCAT under 26

Management: Standard perioperative care. Early mobilization. Incentive spirometry encouraged but not mandatory. Ward-level monitoring sufficient. Routine physiotherapy.

13.3% PPC rateIntermediate Risk - ARISCAT 26-44

Management: Enhanced respiratory care bundle. Mandatory incentive spirometry Q2H while awake. Chest physiotherapy twice daily. Consider neuraxial anesthesia if appropriate. Aggressive early mobilization. Extended monitoring (telemetry). Avoid excessive opioids.

42.1% PPC rateHigh Risk - ARISCAT over 44

Management: Plan HDU or ICU bed. Respiratory therapist involvement. Consider neuraxial vs general anesthesia (neuraxial reduces PPC 30%). CPAP/BiPAP if OSA or respiratory failure risk. Minimize opioids - multimodal analgesia. Daily CXR if deteriorating. Low threshold for respiratory support.

ARISCAT Validation and Limitations

Validation: ARISCAT was validated in a separate cohort of 1,004 patients with excellent discrimination (AUC 0.82). It predicts pneumonia, respiratory failure, bronchospasm, atelectasis, and pleural effusion. Limitations: Developed for general surgery - may overestimate risk in peripheral orthopaedic procedures (TKA, THA). Does not include OSA or COPD severity. Clinical judgment remains essential - score guides but does not replace assessment.

Obstructive Sleep Apnea Assessment

STOP-BANG Questionnaire

Obstructive sleep apnea (OSA) affects 24% of men and 9% of women in the surgical population, with 80-90% undiagnosed. Untreated OSA increases perioperative complications including respiratory failure (2-3x risk), cardiac events, and ICU admission. The STOP-BANG questionnaire is the validated screening tool.

STOP-BANG Interpretation

ScoreOSA RiskSensitivityPerioperative Management
0-2Low risk84% for moderate-severe OSAStandard care, monitor O2 saturation 24h
3-4Intermediate risk93% for moderate OSAExtended monitoring, avoid opioids, semiupright positioning
5-8High risk100% for severe OSAContinue CPAP, consider autotitration, neuraxial preferred, HDU/ICU if general

STOP-BANG Questionnaire Details

The 8 Questions (Yes = 1 point each):

  1. Snoring: Do you snore loudly (louder than talking or heard through closed door)?
  2. Tired: Do you often feel tired, fatigued, or sleepy during daytime?
  3. Observed apnea: Has anyone observed you stop breathing during sleep?
  4. Pressure: Do you have or are you being treated for high blood pressure?
  5. BMI: Is your BMI greater than 35 kg/m�?
  6. Age: Are you older than 50 years?
  7. Neck: Is your neck circumference greater than 40 cm (measure at cricothyroid level)?
  8. Gender: Are you male?

Scoring: Add 1 point for each "yes" answer. Total score 0-8.

When to Order Sleep Study

Do NOT delay elective surgery for sleep study if patient screens positive but no known OSA. Proceed with empiric CPAP/BiPAP in PACU and postop. Sleep study takes 4-12 weeks and rarely changes perioperative management. Exception: patients with severe cardiopulmonary disease where diagnosis changes surgical candidacy.

This approach ensures patient safety without unnecessary surgical delays.

Perioperative OSA Management Protocol

OSA Management Timeline

2-4 weeks beforePreoperative Phase

Known OSA: Ensure CPAP compliance (download machine data if available). Target greater than 4 hours/night usage. Optimize comorbidities (HTN, diabetes). New diagnosis (STOP-BANG 5-8): Counsel patient, plan CPAP/BiPAP perioperatively, consider sleep medicine consult for severe symptoms.

PreoperativeDay of Surgery

Patient brings own CPAP machine (hospital has compatible masks/tubing). Document settings (pressure, mode, humidification). Anesthesia aware of OSA - neuraxial preferred if suitable. Premedication: avoid benzodiazepines (respiratory depressants). Regional analgesia plan to minimize opioids.

During caseIntraoperative

Anesthetic technique: Neuraxial preferred (reduces PPC 30%). If general required: short-acting agents, avoid long-acting opioids, multimodal analgesia (paracetamol, NSAIDs, local blocks). Extubate fully awake, semiupright position. Avoid deep sedation in PACU.

24-72 hoursPostoperative Phase

CPAP initiation in PACU if any respiratory depression. Continuous pulse oximetry for 24-48 hours (OSA patients desaturate in sleep). Semiupright positioning (45 degrees). Avoid opioids - use regional techniques. HDU if high-risk (STOP-BANG 7-8, severe obesity, cardiac disease).

OSA and Opioid Risk

OSA patients have 3-fold increased risk of opioid-induced respiratory depression. The combination of upper airway obstruction plus central respiratory depression is deadly. Prioritize multimodal analgesia: paracetamol, NSAIDs, peripheral nerve blocks, local infiltration. If opioids essential, use lowest effective dose and extended monitoring with continuous pulse oximetry.

This comprehensive approach reduces OSA-related respiratory complications from 20% to under 5%.

COPD Optimization

Assessment and Severity Staging

Chronic obstructive pulmonary disease (COPD) affects 10-15% of patients over 65 undergoing orthopaedic surgery. COPD increases postoperative pulmonary complications 2-5 fold, particularly pneumonia and respiratory failure. Severity stratification guides optimization.

COPD Severity by Spirometry (GOLD Classification)

GOLD StageFEV1 % PredictedFEV1/FVCPerioperative Implications
GOLD 1 - MildFEV1 over 80%Under 0.70Low risk - standard care, smoking cessation
GOLD 2 - ModerateFEV1 50-79%Under 0.70Optimize bronchodilators, consider ICS, physiotherapy
GOLD 3 - SevereFEV1 30-49%Under 0.70High risk - pulmonology consult, aggressive optimization, HDU plan
GOLD 4 - Very SevereFEV1 under 30%Under 0.70Very high risk - consider candidacy, ICU plan, respiratory support

4-6 Week COPD Optimization Protocol

Bronchodilator Therapy

Ensure adequate bronchodilation:

  • Short-acting: Salbutamol PRN (rescue inhaler)
  • Long-acting: Tiotropium (LAMA) daily if FEV1 under 60%
  • Combination: LABA/LAMA if symptomatic despite single agent
  • Inhaler technique: Verify correct use (common error)
  • Start 4-6 weeks pre-op for maximal benefit

Inhaled Corticosteroids

Add ICS if frequent exacerbations:

  • Indicated if FEV1 under 60% AND 2+ exacerbations/year
  • Reduces inflammation and exacerbation frequency
  • Combination LABA/ICS (e.g., fluticasone/salmeterol)
  • NOT indicated for stable COPD without exacerbations
  • Continue through perioperative period

Smoking Cessation

Minimum 4 weeks essential:

  • Under 4 weeks may worsen sputum production
  • 4 weeks: improved mucociliary clearance
  • 8 weeks: maximal pulmonary benefit
  • Nicotine replacement, varenicline, Quitline 13 7848
  • Document pack-year history

Pulmonary Rehabilitation

Physiotherapy and exercise:

  • Incentive spirometry training (start pre-op)
  • Breathing exercises and pursed-lip breathing
  • Ambulation and exercise tolerance building
  • Secretion clearance techniques
  • Continue daily postoperatively

Acute Exacerbation Management

Delay elective surgery 4-6 weeks after COPD exacerbation. Active exacerbation dramatically increases PPC risk (pneumonia 10-20%, respiratory failure 5-10%). Optimize with antibiotics if purulent sputum, oral prednisolone 30-40mg daily for 5-7 days, increased bronchodilators. Confirm return to baseline symptoms and spirometry before proceeding.

This optimization protocol reduces postoperative pulmonary complications in COPD patients by 40-50%.

When to Order Pulmonary Function Tests

Indications for PFTs:

  1. Known moderate-severe COPD without recent spirometry (over 6 months old) - assess current status
  2. Unexplained dyspnea disproportionate to comorbidities - diagnose underlying lung disease
  3. Smoking history over 40 pack-years with symptoms (cough, sputum, wheeze) - screen for COPD
  4. High ARISCAT score with unclear etiology - identify modifiable factors
  5. Lung resection planned - assess candidacy (not applicable for orthopaedics)

Do NOT order PFTs routinely:

  • Asymptomatic patients with good exercise tolerance (can climb 2 flights)
  • Known COPD with recent spirometry on optimal therapy
  • Low-risk surgery (peripheral orthopaedics) in healthy patients
  • PFTs rarely change management in elective orthopaedics unless severe

PFT Interpretation for Risk Stratification

ParameterNormalMild-ModerateSevere - High Risk
FEV1 % predictedOver 80%50-80%Under 50%
FEV1/FVC ratioOver 0.700.60-0.70Under 0.60
Risk stratificationLow risk - proceedOptimize therapy, physiotherapyPulmonology consult, HDU plan

PFT Limitations

PFTs do NOT predict individual patient risk accurately. Exercise tolerance (climb stairs, walk blocks) is MORE predictive of postoperative pulmonary complications than spirometry values. A patient with FEV1 60% who climbs 3 flights without dyspnea is LOWER risk than a patient with FEV1 75% who cannot climb 1 flight. Use clinical assessment as primary tool, PFTs as adjunct.

Summary: Order PFTs selectively, not routinely - clinical assessment trumps numbers.

Postoperative Pulmonary Complications

Types and Prevention Strategies

Postoperative Pulmonary Complications

ComplicationIncidenceRisk FactorsPrevention Strategy
Atelectasis10-40% (most common)Prolonged supine, opioids, obesity, upper abdominal surgeryEarly mobilization, incentive spirometry, minimize opioids
Pneumonia2-5% elective, 10-20% emergencyAge over 70, COPD, aspiration risk, prolonged intubationSmoking cessation 4 weeks, head-up positioning, oral hygiene
Respiratory Failure1-3% (requires reintubation or NIV)OSA, obesity, COPD, excessive opioids, prolonged surgeryCPAP for OSA, neuraxial anesthesia, multimodal analgesia
Bronchospasm2-10% in COPD/asthmaActive asthma, COPD exacerbation, aspirationOptimize bronchodilators pre-op, avoid triggers (cold air, aspiration)
Pleural Effusion5-15% (small effusions common)Heart failure, hypoalbuminemia, fluid overloadJudicious fluid management, diuresis if CHF, correct albumin

Prevention Bundle Timeline

4-6 weeks beforePreoperative Phase

Optimization: Smoking cessation minimum 4 weeks. COPD bronchodilator optimization. OSA CPAP compliance. Weight loss if BMI over 40. Treat respiratory infections (delay 4-6 weeks if acute). Incentive spirometry training.

During surgeryIntraoperative Phase

Lung-protective strategies: Tidal volume 6-8 mL/kg ideal body weight. PEEP 5-8 cmH2O. Recruitment maneuvers if atelectasis. FiO2 titrate to SpO2 92-96% (avoid hyperoxia). Minimize airway pressures. Extubate fully awake.

0-2 hours post-opPACU Phase

Immediate recovery: Semiupright positioning (30-45 degrees). Supplemental O2 to SpO2 over 92%. CPAP if OSA or respiratory depression. Early incentive spirometry. Multimodal analgesia to minimize opioids. Monitor respiratory rate and effort.

24-72 hours post-opWard Phase

Enhanced recovery: Incentive spirometry 10 breaths Q2H while awake. Early mobilization (out of bed within 24h). Physiotherapy twice daily. Minimize opioids - regional blocks preferred. Continuous pulse oximetry if high risk. CXR only if symptomatic.

Pneumonia Prevention

Postoperative pneumonia has 20-30% mortality in elderly orthopaedic patients. Prevention is critical: (1) Smoking cessation 4+ weeks pre-op reduces pneumonia 50%, (2) Head-up positioning 30 degrees reduces aspiration, (3) Early mobilization (out of bed within 24h) improves secretion clearance, (4) Incentive spirometry 10 breaths every 2 hours prevents atelectasis, (5) Oral hygiene (chlorhexidine mouthwash) reduces bacterial load. If pneumonia develops: prompt antibiotics per eTG guidelines, respiratory physiotherapy, consider bronchoscopy if lobar collapse.

Anesthetic Technique Considerations

Neuraxial vs General Anesthesia

Anesthetic Technique and Pulmonary Outcomes

TechniquePPC RiskAdvantagesDisadvantages
Neuraxial (spinal/epidural)Baseline (reference)30% PPC reduction, preserved airway reflexes, early mobilization, less opioidsSympathetic block (hypotension), limited to lower limb/hip, anticoagulation concerns
General anesthesia1.3x higher PPCSuitable for any surgery, airway control, no anticoagulation issuesAtelectasis, ventilator dependence, opioids, delayed mobilization
Combined (GA + regional block)Similar to neuraxialOptimal surgical conditions, reduced GA depth, multimodal analgesiaComplexity, time, requires both skill sets

When to Prefer Neuraxial

  • High pulmonary risk (ARISCAT over 44)
  • Severe OSA (STOP-BANG 7-8)
  • Moderate-severe COPD (FEV1 under 50%)
  • Lower limb surgery (TKA, THA, femur fracture)
  • Obesity (BMI over 40)
  • Patient preference for awake surgery

When General Anesthesia Needed

  • Upper limb or spine surgery (not amenable to neuraxial)
  • Patient refusal of neuraxial
  • Anticoagulation preventing neuraxial (recent DOAC/LMWH)
  • Hemodynamic instability (severe AS, dehydration)
  • Infection at injection site
  • Coagulopathy or platelets under 70

Neuraxial PPC Reduction Mechanism

Why does neuraxial reduce PPCs by 30%? Four mechanisms: (1) Preserved airway reflexes and spontaneous ventilation (no intubation trauma, no positive pressure atelectasis), (2) Superior analgesia reduces splinting and allows deep breathing/cough, (3) Reduced opioid requirements minimize respiratory depression, (4) Earlier mobilization improves secretion clearance. Meta-analysis of 141 trials shows neuraxial reduces pneumonia OR 0.55 and respiratory failure OR 0.59 compared to general anesthesia.

Evidence Base and Key Trials

ARISCAT Score Derivation and Validation

2
Canet J, et al • Anesthesiology (2010)
Key Findings:
  • Multicenter prospective cohort of 2,464 patients undergoing noncardiac surgery
  • Identified 7 independent predictors of postoperative pulmonary complications
  • Risk stratification: low (under 26) = 1.6%, intermediate (26-44) = 13.3%, high (over 44) = 42.1% PPC rate
  • Validated in separate cohort of 1,004 patients - AUC 0.82 (excellent discrimination)
Clinical Implication: ARISCAT is the gold standard for predicting postoperative pulmonary complications and guiding perioperative respiratory care.
Limitation: Developed in general surgery population - may overestimate risk in peripheral orthopaedic procedures. Does not include OSA or COPD severity.

STOP-BANG Validation for OSA Screening

2
Chung F, et al • Anesthesiology (2008)
Key Findings:
  • Validation study of 746 surgical patients undergoing polysomnography
  • STOP-BANG score 3+ has 84% sensitivity and 56% specificity for moderate-severe OSA
  • High sensitivity (93-100%) makes it excellent screening tool - low false negative rate
  • Score 5-8 identifies high-risk patients requiring enhanced perioperative monitoring
Clinical Implication: STOP-BANG should be performed on all surgical patients to identify undiagnosed OSA requiring perioperative CPAP and enhanced monitoring.
Limitation: Low specificity (many false positives) - but acceptable for screening where sensitivity is priority.

Smoking Cessation and Pulmonary Complications

2
Warner DO, et al • Anesthesiology (2005)
Key Findings:
  • Systematic review of 25 studies on smoking cessation timing and postoperative complications
  • Cessation under 4 weeks may increase sputum production and early complications
  • Minimum 4 weeks cessation reduces pulmonary complications by 23%
  • 8 weeks cessation optimal - reduces complications by 50-60%
Clinical Implication: Counsel patients that minimum 4 weeks smoking cessation is required for pulmonary benefit. Do not recommend cessation 1-2 weeks before surgery.
Limitation: Observational studies - difficult to control for confounders. Optimal timing remains debated.

Neuraxial vs General Anesthesia and Pulmonary Outcomes

1
Guay J, et al (Cochrane Review) • Cochrane Database Systematic Reviews (2016)
Key Findings:
  • Meta-analysis of 141 randomized trials (9,044 participants)
  • Neuraxial anesthesia reduced pneumonia (OR 0.55) and respiratory depression (OR 0.59)
  • 30% relative risk reduction in overall pulmonary complications
  • Benefit greatest in high-risk patients (elderly, COPD, OSA)
Clinical Implication: Neuraxial anesthesia should be preferred over general anesthesia for lower limb orthopaedic surgery in patients with high pulmonary risk.
Limitation: Heterogeneity in surgical procedures and outcomes definitions. Some studies low quality.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Scenario 1: High ARISCAT Score Patient

EXAMINER

"72-year-old male for urgent hip fracture fixation. COPD (FEV1 45%), SpO2 93% on room air, smoker 60 pack-years, Hb 95 g/L. Calculate ARISCAT score and discuss perioperative pulmonary management."

EXCEPTIONAL ANSWER
This is a high pulmonary risk patient. Let me calculate the ARISCAT score: Age 72 = 3 points, SpO2 93% = 8 points, preoperative anemia Hb 95 = 11 points, duration will likely exceed 2 hours = 16 points, emergency procedure = 8 points. Total ARISCAT score 46 which is high risk with predicted 42% chance of postoperative pulmonary complications. My management would involve: First, preoperative optimization within the urgency timeframe - transfuse to Hb over 100 if time permits, ensure bronchodilators optimized (salbutamol and tiotropium), incentive spirometry training. Second, anesthetic technique - I would strongly prefer spinal anesthesia over general as this reduces pulmonary complications by 30% and this patient has severe COPD with baseline hypoxemia. Third, intraoperative care - supplemental oxygen to maintain SpO2 over 92%, avoid excessive sedation. Fourth, postoperative plan - HDU or high-dependency area with continuous pulse oximetry for 48 hours, aggressive multimodal analgesia to minimize opioids (nerve blocks, paracetamol, NSAIDs if renal function permits), incentive spirometry 10 breaths every 2 hours, chest physiotherapy twice daily, early mobilization out of bed within 24 hours if fracture stability permits. Fifth, COPD management - continue bronchodilators, consider steroids if any bronchospasm. I would have a very low threshold for CPAP/BiPAP if any respiratory distress. The combination of high ARISCAT score, severe COPD, and emergency surgery makes this a very high-risk patient requiring intensive respiratory support perioperatively.
KEY POINTS TO SCORE
ARISCAT 46 = high risk (42% PPC rate) requiring enhanced care
Spinal anesthesia preferred over general (30% PPC reduction)
HDU monitoring essential - continuous pulse oximetry 48 hours
Multimodal analgesia to minimize opioids in COPD patient
Incentive spirometry Q2H, physiotherapy BID, early mobilization key
COMMON TRAPS
✗Choosing general anesthesia without considering neuraxial option
✗Not calculating specific ARISCAT score (examiner wants numbers)
✗Forgetting to optimize bronchodilators preoperatively
✗Planning ward-level care instead of HDU for high-risk patient
LIKELY FOLLOW-UPS
"What ARISCAT score constitutes high risk?"
"How does neuraxial reduce pulmonary complications?"
"When would you use CPAP/BiPAP postoperatively?"
VIVA SCENARIOChallenging

Scenario 2: Undiagnosed OSA Screening

EXAMINER

"58-year-old obese male (BMI 42) for elective TKA. Wife reports loud snoring and witnessed apneas. STOP-BANG score 7. No sleep study. How do you proceed?"

EXCEPTIONAL ANSWER
This patient has very high-risk undiagnosed obstructive sleep apnea. Let me assess the STOP-BANG score: likely positive for Snoring, Tired (ask patient), Observed apnea (wife reports), hypertension is common with OSA so likely Pressure, BMI 42 definitely positive, Age 58 positive, Neck likely over 40cm in obese patient, Gender male positive. This gives STOP-BANG 7 out of 8 which indicates very high probability of severe OSA (sensitivity 100% for severe OSA). My approach: First, do NOT delay elective surgery for formal sleep study - this takes 4-12 weeks and will not change perioperative management in most cases. Second, proceed with empiric OSA protocol: counsel patient about OSA and perioperative risks, plan CPAP/BiPAP initiation in PACU, arrange trial CPAP mask fitting preoperatively if possible. Third, anesthetic technique - neuraxial preferred over general anesthesia. Spinal anesthesia reduces pulmonary complications by 30% and avoids airway manipulation and postoperative respiratory depression. If general required: short-acting agents, aggressive multimodal analgesia to minimize opioids (femoral nerve block, periarticular infiltration, paracetamol, NSAIDs). Fourth, postoperative monitoring - plan HDU bed with continuous pulse oximetry for 48 hours, empiric CPAP with auto-titration mode (hospital respiratory therapist can set up), semiupright positioning 45 degrees, avoid all sedatives and minimize opioids. Fifth, long-term - refer to sleep medicine for formal polysomnography 6-8 weeks post-surgery for diagnosis and long-term CPAP therapy. The combination of STOP-BANG 7, severe obesity, and major surgery makes unrecognized OSA a major patient safety issue. Do not proceed without a comprehensive perioperative OSA management plan.
KEY POINTS TO SCORE
STOP-BANG 7 = very high OSA risk - empiric treatment indicated
Do NOT delay surgery for sleep study - proceed with OSA protocol
Neuraxial anesthesia strongly preferred (avoids airway issues)
HDU with continuous pulse oximetry and empiric CPAP essential
Multimodal analgesia to minimize opioids (3x respiratory depression risk)
COMMON TRAPS
✗Delaying surgery 3 months for sleep study (unnecessary in most cases)
✗Proceeding with general anesthesia and opioid PCA (high risk)
✗Planning ward-level care for STOP-BANG 7 patient (inadequate monitoring)
✗Not involving respiratory therapist for CPAP setup
LIKELY FOLLOW-UPS
"What STOP-BANG score indicates high OSA risk?"
"Why avoid opioids in OSA patients?"
"When would you delay surgery for sleep study?"
VIVA SCENARIOChallenging

Scenario 3: PFT Interpretation and COPD Optimization

EXAMINER

"65-year-old female for elective THA. Known COPD, current smoker 40 pack-years. Recent PFTs: FEV1 48% predicted, FEV1/FVC 0.58. On salbutamol PRN only. Surgery in 6 weeks. Your optimization plan?"

EXCEPTIONAL ANSWER
This patient has GOLD 3 severe COPD (FEV1 48% predicted, FEV1/FVC 0.58 confirms obstruction) with suboptimal medical therapy. She is high risk for postoperative pulmonary complications. My 6-week optimization plan: First, smoking cessation is absolutely critical - refer to Quitline 13 7848, prescribe nicotine replacement therapy or varenicline, counsel that 4-6 weeks cessation reduces complications by 50%. Shorter cessation may worsen sputum so minimum 4 weeks essential. Second, escalate COPD therapy - she is severely under-treated. Add long-acting muscarinic antagonist (tiotropium 18 mcg daily) immediately as she has FEV1 under 60%. Consider adding inhaled corticosteroid if history of frequent exacerbations (2+ per year). Ensure proper inhaler technique (common cause of treatment failure). Third, pulmonary rehabilitation - refer to physiotherapy for incentive spirometry training, breathing exercises, exercise conditioning to improve baseline functional status. Fourth, assess for active exacerbation - if purulent sputum, increased dyspnea, or wheeze, treat with antibiotics and oral steroids, then delay surgery 4-6 weeks after resolution. Fifth, anesthetic planning - document preference for spinal anesthesia (30% PPC reduction vs general), plan HDU bed postoperatively given severe COPD, arrange pulmonology consultation if any concerns about surgical candidacy. Sixth, postoperative plan - continue bronchodilators, aggressive incentive spirometry Q2H, early mobilization, minimize opioids with regional analgesia techniques. With FEV1 48%, she has approximately 20-30% risk of postoperative pulmonary complications even with optimization, so comprehensive perioperative respiratory support is essential. If she refuses smoking cessation or optimization, I would have a serious discussion about risk vs benefit of proceeding with elective surgery.
KEY POINTS TO SCORE
GOLD 3 severe COPD (FEV1 48%, FEV1/FVC 0.58) = high PPC risk
Suboptimal therapy - needs LAMA (tiotropium) for FEV1 under 60%
Smoking cessation minimum 4 weeks essential (50% complication reduction)
Spinal anesthesia preferred, HDU plan, multimodal analgesia
6-week optimization window allows meaningful improvement
COMMON TRAPS
✗Not recognizing severe COPD needs escalation of therapy
✗Accepting current smoking without aggressive cessation intervention
✗Planning general anesthesia and ward-level care (inadequate for severe COPD)
✗Not addressing inhaler technique (common cause of poor control)
LIKELY FOLLOW-UPS
"What defines GOLD 3 severe COPD?"
"When do you add ICS to COPD therapy?"
"How does smoking cessation timing affect outcomes?"

MCQ Practice Points

ARISCAT High Risk Threshold

Q: What ARISCAT score indicates high risk for postoperative pulmonary complications? A: Score greater than 44 indicates high risk with 42% predicted complication rate. Requires enhanced respiratory care including HDU monitoring, physiotherapy, incentive spirometry, and consideration of neuraxial vs general anesthesia.

STOP-BANG OSA Screening

Q: A patient scores 6 on STOP-BANG questionnaire. What is the appropriate management? A: High OSA risk (score 5-8) requires empiric perioperative CPAP, continuous pulse oximetry 24-48 hours, avoid opioids, neuraxial anesthesia preferred. Do NOT delay surgery for sleep study in most cases.

Smoking Cessation Timing

Q: What is the minimum smoking cessation duration to reduce postoperative pulmonary complications? A: 4 weeks minimum. Cessation under 4 weeks may paradoxically increase complications due to increased sputum production. Optimal benefit at 8 weeks (50-60% reduction).

PFT Indications

Q: When are PFTs indicated before elective orthopaedic surgery? A: Moderate-severe COPD without recent spirometry, unexplained dyspnea, or smoking over 40 pack-years with symptoms. NOT indicated routinely - exercise tolerance is more predictive than spirometry.

Australian Context and Guidelines

ANZCA Guidelines: PS06 (perioperative care of patients with OSA), PS07 (pre-anesthesia consultation and patient preparation). Recommend STOP-BANG screening for all surgical patients.

Australian Resources:

  • Quitline 13 7848 for smoking cessation support (free counseling and nicotine replacement)
  • PBS coverage for smoking cessation medications (varenicline, nicotine replacement)
  • COPD-X Plan (Australian and New Zealand guidelines for COPD management)
  • Sleep Health Foundation resources for OSA patient education

eTG Guidelines: Therapeutic Guidelines Respiratory (version 6) - COPD optimization, bronchodilator therapy, antibiotic selection for exacerbations.

Medicolegal Considerations:

  • Document pulmonary risk assessment (ARISCAT, STOP-BANG) in preoperative note
  • Informed consent must include pulmonary complication risks (quote patient-specific risk)
  • OSA screening and management plan essential - unrecognized OSA major litigation source
  • If patient refuses optimization (smoking cessation, CPAP), document risks discussed
  • Common claims: respiratory arrest in unrecognized OSA, pneumonia from failure to optimize COPD, opioid overdose in OSA patient

Management Algorithm

📊 Management Algorithm
Management algorithm for Pulmonary Risk Assessment
Click to expand
Management algorithm for Pulmonary Risk AssessmentCredit: OrthoVellum

PULMONARY RISK ASSESSMENT

High-Yield Exam Summary

ARISCAT Score (7 Predictors)

  • •Age: under 50 (0), 50-80 (3), over 80 (16 points)
  • •SpO2: over 96% (0), 91-95% (8), under 90% (24 points)
  • •Respiratory infection last month (17 points)
  • •Anemia Hb under 100 g/L (11 points)
  • •Upper abdominal/thoracic surgery (15 points)
  • •Duration 2-3h (16), over 3h (23 points)
  • •Emergency procedure (8 points)
  • •Score: under 26 low (1.6%), 26-44 intermediate (13.3%), over 44 high risk (42.1%)

STOP-BANG for OSA

  • •Snoring, Tired, Observed apnea, Pressure (HTN), BMI over 35, Age over 50, Neck over 40cm, Gender male
  • •Score 0-2 = low risk, 3-4 = intermediate, 5-8 = high OSA risk
  • •High risk: continue CPAP periop, avoid opioids, neuraxial preferred, HDU monitoring
  • •Do NOT delay surgery for sleep study - empiric CPAP treatment

COPD Optimization (4-6 Weeks)

  • •Smoking cessation minimum 4 weeks (50% PPC reduction at 8 weeks)
  • •Bronchodilators: LAMA (tiotropium) if FEV1 under 60%
  • •ICS: add if FEV1 under 60% AND 2+ exacerbations/year
  • •Delay surgery 4-6 weeks after acute exacerbation
  • •Physiotherapy: incentive spirometry, breathing exercises
  • •FEV1 under 50% = severe COPD, high risk, HDU planning

PFT Indications

  • •Moderate-severe COPD without recent spirometry (over 6 months old)
  • •Unexplained dyspnea disproportionate to comorbidities
  • •Smoking over 40 pack-years with symptoms (cough, sputum, wheeze)
  • •Do NOT order routinely - exercise tolerance more predictive
  • •Obstruction: FEV1/FVC under 0.70 confirms COPD

Postoperative PPC Prevention

  • •Incentive spirometry 10 breaths Q2H while awake
  • •Early mobilization - out of bed within 24 hours
  • •Physiotherapy twice daily for secretion clearance
  • •Multimodal analgesia - minimize opioids (regional blocks)
  • •Semiupright positioning 30-45 degrees (reduces aspiration)
  • •CPAP/BiPAP for OSA or respiratory failure risk
Quick Stats
Reading Time96 min
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