Anaesthesia for Lung Transplantation

Quick Answer

Lung transplantation is performed for end-stage lung disease refractory to medical therapy. Indications: COPD (30-35%), interstitial lung disease (25-30%), cystic fibrosis (15-20%), pulmonary hypertension (5-10%), retransplantation (5%). Key challenges: Pulmonary hypertension (PHT) and right ventricular (RV) dysfunction (major cause of early mortality), reperfusion injury, single vs bilateral transplant decision, intraoperative mechanical support (ECMO vs CPB). Monitoring: Arterial line, central venous catheter, PA catheter (controversial), TEE, cerebral oximetry. Induction: Avoid hypotension (coronary perfusion of RV), maintain preload (RV dependent), avoid hypoxia/hypercapnia (PHT). Ventilation: Protective strategy (6-8 mL/kg, PEEP 5-10 cm H₂O), avoid high airway pressures (RV afterload), permissive hypercapnia if needed. Bypass/ECMO: ECMO preferred (better preservation of RV function, less inflammation), CPB alternative. Post-reperfusion: Gradual ventilation, protective strategy, ECMO weaning, rejection surveillance. [1-15]

Pathophysiology

Common Indications for Lung Transplantation

Chronic Obstructive Pulmonary Disease (COPD) - 30-35%:

• Pathophysiology: Emphysema (alveolar destruction), chronic bronchitis (airway inflammation)
• Gas exchange: Severe V/Q mismatch, hypoxemia, hypercapnia
• Mechanics: Dynamic hyperinflation, auto-PEEP, increased work of breathing
• PHT: Secondary to chronic hypoxia (vasoconstriction), mild-moderate typically
• Timing: BODE index >7, FEV₁ <20%, frequent exacerbations
• Outcomes: Good survival (best among indications), often single lung sufficient

Interstitial Lung Disease (ILD) - 25-30%:

• Types: Idiopathic pulmonary fibrosis (IPF, most common), nonspecific interstitial pneumonia, connective tissue-associated ILD
• Pathophysiology: Alveolar inflammation → fibrosis → stiff, non-compliant lungs
• Mechanics: Restrictive pattern, reduced TLC, FRC, decreased compliance
• Gas exchange: Severe hypoxemia, often normal or low PaCO₂ (hyperventilation)
• PHT: Common and severe (fibrotic destruction of pulmonary vasculature)
• Timing: FVC <80% predicted with significant decline, DLCO <40%
• Outcomes: Higher mortality than COPD; bilateral transplant preferred

Cystic Fibrosis (CF) - 15-20%:

• Pathophysiology: CFTR mutation → thick secretions → chronic infection, bronchiectasis
• Organisms: Pseudomonas aeruginosa (most common), Burkholderia cepacia (contraindication to transplant in many centers), MRSA, fungal
• Mechanics: Obstructive pattern, severe bronchiectasis
• Other organs: Pancreatic insufficiency (malabsorption, diabetes), liver disease, osteoporosis
• PHT: Moderate, secondary to chronic hypoxia
• Timing: FEV₁ <30%, frequent exacerbations, declining BMI
• Outcomes: Better with bilateral transplant (infection control), sinus disease persists

Pulmonary Hypertension (PHT) - 5-10%:

• Types: Idiopathic PAH (IPAH), congenital heart disease, chronic thromboembolic
• Pathophysiology: Elevated PVR, right heart failure (cor pulmonale)
• Cardiac: Severe RV dysfunction, tricuspid regurgitation, low LV output (septal bowing)
• Timing: NYHA Class III-IV, declining 6-minute walk, rising BNP
• Outcomes: High early mortality (RV failure); bilateral transplant or heart-lung; intraoperative support critical

Retransplantation - 5%:

• Indications: Chronic lung allograft dysfunction (CLAD), refractory acute rejection, airway complications
• Outcomes: Worse than primary transplant; careful patient selection

Other Indications:

• Alpha-1 antitrypsin deficiency: Emphysema pattern
• Lymphangioleiomyomatosis (LAM): Young women, cystic lung disease
• Sarcoidosis: Stage IV fibrotic
• Connective tissue diseases: Scleroderma, systemic lupus

Pulmonary Hypertension and Right Ventricular Dysfunction

Pathophysiology of PHT:

• PVR elevation: Remodeling of pulmonary vasculature (medial hypertrophy, intimal fibrosis, plexiform lesions)
• Afterload mismatch: RV cannot overcome high afterload
• RV adaptation: Hypertrophy (compensated) → dilation (decompensated)

RV Physiology:

• Thin-walled: Low-pressure pump normally (systolic PA pressure 15-25 mmHg)
• Coronary perfusion: Occurs during systole and diastole (unlike LV)
  • RV ischemia risk with hypotension (decreased perfusion pressure)
• Afterload sensitive: Cannot acutely adapt to increased afterload
• Preload dependent: Requires adequate filling (but not excessive - causes septal bowing)

RV Failure in PHT:

• Acute decompensation: During induction (anesthesia vasodilation), clamping (acute increase in afterload), reperfusion
• Signs: Hypotension, elevated CVP, TR, decreased cardiac output, septal bowing on TEE
• Management: Inotropes (milrinone preferred - pulmonary vasodilation + inotropy), vasopressors (noradrenaline for coronary perfusion), inhaled NO or epoprostenol (selective pulmonary vasodilation)

Interventricular Dependence:

• Septal bowing: Dilated RV pushes septum into LV
• Effect: Reduces LV compliance, decreases LV filling, reduces cardiac output
• Management: RV decompression, maintain LV preload

Reperfusion Injury

Pathophysiology:

• Ischemia-reperfusion: Donor lung ischemic during procurement/preservation
• Inflammatory cascade: Activated by reperfusion
  • Free radicals, cytokines, neutrophil activation
  • Endothelial injury, increased permeability
• Manifestation: Non-cardiogenic pulmonary edema, hypoxemia, pulmonary infiltrates

Primary Graft Dysfunction (PGD):

• Definition: Acute lung injury within 72 hours post-transplant
• Grading (PaO₂/FiO₂ ratio):
  • Grade 0: >300
  • Grade 1: 200-300
  • Grade 2: 100-200
  • Grade 3: <100
• Radiographic: Diffuse alveolar infiltrates, pulmonary edema pattern
• Risk factors: Prolonged ischemic time, donor smoking, recipient PHT, large recipient size
• Management: Protective ventilation, ECMO support if severe, diuresis, inhaled NO
• Outcomes: Grade 3 associated with increased mortality

Prevention:

• Donor management: Optimal lung procurement, protective ventilation in donor
• Preservation: Cold preservation solution (Perfadex, Papworth), short ischemic time (<6-8 hours ideal)
• Reperfusion strategy: Controlled reperfusion (low FiO₂ initially, protective ventilation)
• ECMO: Provides support during reperfusion period

Single vs Bilateral Lung Transplant

Single Lung Transplant (SLT):

• Advantages: Shorter procedure, less immunosuppression (one lung), if second lung fails still have one, shorter waitlist time (only need one donor)
• Disadvantages: Native lung can cause problems (infection in CF, pneumothorax in COPD), less reserve if graft fails, PHT may persist
• Best for: COPD, older patients, ILD without severe PHT, limited donors

Bilateral Lung Transplant (BLT/Sequential BLT):

• Advantages: Better lung function, no native lung complications, better for CF (removes infected tissue), allows higher PA pressures
• Disadvantages: Longer procedure, more immunosuppression, longer ischemic time for second lung, harder to find two donor lungs
• Best for: CF, severe PHT, ILD, younger patients, large recipients

Heart-Lung Transplant:

• Indication: Irreparable cardiac defect with lung disease, Eisenmenger syndrome with unreparable shunt
• Rare: Most PHT can be managed with bilateral lung transplant alone (PVR falls with new lungs)

Clinical Presentation

Preoperative Recipient Assessment

Disease-Specific Evaluation:

• Severity: FEV₁, FVC, DLCO, 6-minute walk test
• Gas exchange: ABG on room air and supplemental O₂
• PHT: Echocardiography (RV function, TR velocity), right heart catheterization (confirm PVR, cardiac output)
• Infection: Sputum cultures, CF patients (organisms, sensitivities)
• Nutrition: BMI (CF often low, COPD may be cachectic or overweight)

Cardiovascular:

• LV function: Echocardiography (rule out coronary disease if risk factors)
• RV function: Critical in PHT (severe dysfunction predicts early mortality)
• Coronary angiography: If age >50 or risk factors
• PADP (Pulmonary artery diastolic pressure): <15 mmHg favorable; >20 mmHg concerning

Other Organ Systems:

• Renal: Creatinine clearance (immunosuppression nephrotoxic)
• Hepatic: Function, portal hypertension (contraindication)
• GI: GERD (common in CF, worsens aspiration risk; may need Nissen)
• Bone: Osteoporosis (steroids post-transplant increase fracture risk)
• Psychosocial: Compliance, support system, understanding of lifelong immunosuppression

Absolute Contraindications:

• Malignancy <2 years (except basal cell, squamous cell skin)
• Untreatable advanced organ dysfunction (renal, hepatic)
• Active infection (systemic)
• Active substance abuse (smoking, alcohol, drugs)
• Non-compliance, psychiatric instability
• BMI >35 or <16-18 (varies by center)
• Significant chest wall/spinal deformity (restrictive after transplant)

Risk Stratification:

• LAS (Lung Allocation Score): US system prioritizing sickest patients
• Risk factors for poor outcome: RV dysfunction, high PVR, retransplantation, ventilator/ECMO bridge, CF with resistant organisms

Donor Lung Assessment

Selection Criteria:

• Age: Ideally <55-60 years
• Smoking history: <20 pack-years (controversial - survival benefit even with smoking donors)
• Gas exchange: PaO₂ >300 mmHg on 100% FiO₂ and PEEP 5 cm H₂O
• Chest X-ray: Clear
• Bronchoscopy: Minimal secretions, no purulence
• Ischemic time: <6-8 hours ideal (longer acceptable in experienced centers)
• Size matching: Donor/recipient TLC ratio 0.8-1.2

Extended Criteria Donors:

• Older age (60-70)
• Mild smoking history
• Mild CXR abnormalities
• Prolonged ischemic time (8-12 hours)
• Hepatitis C positive (now acceptable with modern treatments)
• Can increase donor pool significantly with acceptable outcomes

Ex Vivo Lung Perfusion (EVLP):

• Purpose: Assess and treat marginal donor lungs
• Technique: Donor lungs perfused with Steen solution, ventilated, evaluated
• Benefits: Can improve lungs (treatment of edema, inflammation), extend ischemic time, increase donor pool
• Results: Non-inferior to standard criteria donors

Management

Preoperative Preparation

Informed Consent:

• High-risk procedure (mortality 10-20% at 1 year varies by indication)
• Need for lifelong immunosuppression
• Possible need for ECMO/CPB
• Possibility of primary graft dysfunction
• Risk of rejection, infection

Medications:

• Immunosuppression: Induction therapy (basiliximab, ATG, or alemtuzumab) given intraoperatively
• Antibiotics: Prophylaxis based on recipient/donor cultures
• Sedation/anxiolysis: Light (preserve respiratory drive if not intubated)

Equipment:

• ECMO: Circuit primed and ready (if plan or backup)
• Blood products: 6-10 units PRBC, FFP, platelets available
• Cell saver: Autotransfusion
• Inhaled NO: Available for PHT
• TEE probe: Sterilized and ready

Patient Arrival:

• Timing: Donor lungs confirmed viable, timing coordination with procurement team
• Preoperative status: May be intubated (bridge to transplant), on nasal cannula, or room air
• Optimization: Last-minute ABG, electrolytes

Induction and Intubation

Key Principles:

• Avoid precipitating RV failure: Smooth, gradual induction
• Maintain coronary perfusion: MAP >65-70 mmHg (higher in PHT)
• Avoid hypoxia/hypercapnia: Both increase PAP
• Prevent acidosis: Increases PVR

Monitoring:

• Standard: ECG, NIBP, SpO₂
• Arterial line: Pre-induction (continuous BP, ABG)
• Large bore IV: 14-16 gauge × 2
• CVP: For venous access, RA pressure monitoring
• PA catheter: Controversial (risk of arrhythmia, PA rupture in PHT); some centers routinely place, others use TEE
• TEE: Essential for RV function, filling, PA pressures

Induction Strategy:

• Pre-oxygenation: 100% O₂, 3-5 minutes
• Etomidate: 0.2-0.3 mg/kg (hemodynamically neutral, good for RV dysfunction)
• Ketamine: Alternative (sympathomimetic, maintains BP, bronchodilation)
• Propofol: Use cautiously (vasodilation, myocardial depression) - reduce dose or avoid in severe PHT
• Opioid: High-dose (fentanyl 10-20 μg/kg or remifentanil infusion) - blunts sympathetic response

Intubation:

• Muscle relaxant: Rocuronium 0.6-1 mg/kg or suxamethonium (if full stomach)
• Airway: Left double-lumen tube (DLT) for single lung transplant; single lumen for bilateral (requires ECMO/CPB usually)
• Positioning: Lateral decubitus for single lung; supine for bilateral
• Confirmation: Fiberoptic bronchoscopy to confirm position

Pulmonary Hypertension Management:

• Pre-induction: Consider pulmonary vasodilators if severe PHT
  • Inhaled NO (20-40 ppm)
  • Epoprostenol (intravenous or inhaled)
  • Sildenafil
• Induction: Maintain preload, avoid hypotension
• Vasopressors: Have ready (phenylephrine, noradrenaline, vasopressin)

Single Lung Transplant Procedure

Positioning:

• Lateral decubitus: Recipient side up (right lung transplant = left lateral)
• Double-lumen tube: Allows independent lung ventilation

Monitoring:

• Arterial line: Continuous
• CVP: Access and monitoring
• TEE: RV function, PA pressures
• Pulse oximetry: Both limbs (right hand preductal, left lower postductal - check differential if patent foramen ovale)

Phases:

1. Native Lung Pneumonectomy:

• Access: Thoracotomy (posterolateral or anterolateral)
• Pleural adhesions: Common in ILD, CF; may cause bleeding
• PA dissection: Identify and prepare for clamping
• PV dissection: Identify pulmonary veins
• Bronchus: Dissect and prepare for transection
• Heparin: 300-500 IU/kg before PA clamping (timing critical - avoid coagulopathy before anastomoses)

2. Donor Lung Implantation:

• Sequence: Bronchus first (airway), then PA (reperfusion), then left atrial cuff (venous drainage)
  • Some variations exist
• Anastomoses:
  • Bronchial: Running suture, telescoping technique (donor bronchus inside recipient)
    • Wrap with omentum or pericardium (vascularized tissue for healing)
  • PA: End-to-end anastomosis
  • LA cuff: Left atrial anastomosis (donor PV cuff to recipient LA)
• De-airing: Critical (TEE guidance, Trendelenburg position)
• Reperfusion: Gradual release of PA clamp, controlled reperfusion

3. Hemostasis and Closure:

• Bleeding: Common (pleural adhesions, anticoagulation)
• Blood products: PRBC, FFP, platelets as needed
• Two chest drains: Apical and basal
• Closure: Standard thoracotomy closure

Ventilation Strategy:

• Transplanted lung:
  • Protective: VT 6-8 mL/kg, PEEP 5-10 cm H₂O, FiO₂ 50-100%
  • Avoid high plateau pressure (<30 cm H₂O)
• Native lung (SLT):
  • May require different settings
  • Adjust to match compliance differences
• Post-reperfusion: Gradual recruitment, avoid derecruitment

Bilateral Lung Transplant Procedure

Approach:

• Clamshell incision: Bilateral anterior thoracotomies with transverse sternotomy
• Alternative: Sequential single lung via bilateral thoracotomies (sternum intact)

ECMO vs CPB:

• ECMO (preferred):
  • Veno-arterial (VA-ECMO) - drains venous blood, returns to arterial system
  • Advantages: Preserves pulsatile flow, less inflammatory response than CPB, can continue postoperatively
  • Cannulation: Femoral or central (RA to PA or aorta)
• CPB (alternative):
  • Traditional cardiac bypass circuit
  • Advantages: Full cardiac support if needed
  • Disadvantages: Non-pulsatile flow, more hemodilution, inflammatory response
• Decision factors: Severity of PHT, RV function, institutional preference

Sequence:

• First lung: Side with worse native lung (usually right, easier to collapse)
• Second lung: After first lung stable
• Ischemic time: Second lung longer ischemic time (concern for PGD)

Anaesthetic Considerations with ECMO/CPB:

• Anticoagulation: Heparin (ACT >400-480 seconds for CPB, >300 for ECMO)
• Hemodilution: CPB prime volume
• Blood pressure: ECMO flow-dependent; maintain adequate flow for perfusion
• Ventilation: Discontinued during full bypass/ECMO flow
• Rewarming: If hypothermic bypass used

Post-Reperfusion Management

Immediate:

• Ventilation: Protective strategy as above
• Hemodynamics: Support RV (milrinone, inhaled NO), maintain MAP >65 mmHg
• TEE: Assess RV function, rule out LA cuff obstruction
• ABG: Assess oxygenation (PaO₂/FiO₂ ratio)
• Chest X-ray: Assess lung inflation, rule out pneumothorax

Weaning ECMO/CPB:

• Gradual: Reduce flow, increase ventilation
• Criteria: Adequate oxygenation, hemodynamic stability, acceptable bleeding
• Decannulation: In OR or delayed (ICU)

Hemostasis:

• Coagulopathy: Common (bypass, hemodilution, fibrinolysis)
• TEG/ROTEM: Guide component therapy
• Tranexamic acid: Often used (1-2 g IV)
• Re-exploration: If >300-500 mL/hour drainage

Emergence:

• Timing: Depends on graft function, hemodynamics, bleeding
• Strategy: Usually remain intubated (24-48 hours minimum)
• Exception: Excellent function, early extubation possible (some centers)
• Transport: ICU with ventilator, inotropes, monitoring

Postoperative Care

ICU Management:

Ventilation:

• Protective strategy: VT 6-8 mL/kg, PEEP 5-10 cm H₂O, limit plateau pressure <30 cm H₂O
• Permissive hypercapnia: Accept PaCO₂ 50-60 mmHg if pH >7.25
• FiO₂: Wean to 30-40% as tolerated
• Recruitment: Periodic recruitment maneuvers
• Extubation criteria:
  • Adequate oxygenation (PaO₂/FiO₂ >200)
  • Hemodynamic stability
  • Good cough, airway reflexes
  • Acceptable ABG

Hemodynamics:

• Goal: MAP >65 mmHg, adequate perfusion
• Inotropes: Milrinone often continued (pulmonary vasodilation + RV support), dobutamine, adrenaline if needed
• Vasopressors: Noradrenaline, vasopressin for vasoplegia or low SVR
• Pulmonary vasodilators: Continue inhaled NO or epoprostenol if used; wean gradually

Fluid Management:

• Restrictive: Lungs susceptible to edema (reperfusion injury, lymphatic interruption)
• Target: Even or negative balance
• Diuretics: Furosemide infusion or boluses
• Hemofiltration: If renal dysfunction

Rejection Surveillance:

• Biopsies: Transbronchial biopsies at intervals
• Grade acute cellular rejection: A0-A4, B0-B2 (airway inflammation)
• Antibody-mediated rejection: Less common, more severe
• Treatment: High-dose steroids, thymoglobulin, rituximab

Infection Prophylaxis:

• Bacterial: Perioperative antibiotics (broad-spectrum)
• Fungal: If colonized or high risk
• Viral: CMV prophylaxis (valganciclovir) if donor+/recipient-
• PJP: Trimethoprim-sulfamethoxazole prophylaxis

Complications:

Primary Graft Dysfunction (PGD):

• Management: As above, ECMO if severe
• Supportive: Diuresis, protective ventilation, nitric oxide

Airway Complications:

• Anastomotic dehiscence: Rare but serious (bronchopleural fistula)
  • Signs: Pneumothorax, subcutaneous emphysema, air leak
  • Management: Stenting, reoperation, prolonged chest drains
• Stenosis: Late complication (granulation tissue, fibrosis)
  • Management: Bronchoscopic dilation, stenting

Acute Rejection:

• Signs: Hypoxemia, fever, infiltrates, declining FEV₁
• Diagnosis: Biopsy
• Treatment: Methylprednisolone 500-1000 mg IV × 3 days

Infection:

• Bacterial: Early post-transplant (pneumonia)
• Viral: CMV, EBV, community respiratory viruses
• Fungal: Aspergillus, Candida
• Prophylaxis: Reduces but doesn't eliminate risk

Chronic Lung Allograft Dysfunction (CLAD):

• Definition: Decline in FEV₁ >20% from baseline lasting >3 weeks
• Bronchiolitis obliterans syndrome (BOS): Progressive small airway fibrosis
• Restrictive allograft syndrome (RAS): Restrictive pattern (pleuroparenchymal fibroelastosis)
• Management: Augmented immunosuppression, azithromycin, fundoplication if reflux, retransplantation

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Patients

Access and Equity:

• Geographic: Transplantation only in major centres (Sydney, Melbourne, Brisbane, Perth)
• Referral: May be delayed due to distance, comorbidities
• Assessment: Requires extended stay in metropolitan centre for workup

Health Disparities:

• Higher smoking rates: COPD prevalence
• Higher comorbidity: Diabetes, renal disease may complicate candidacy
• Infectious disease: Higher rates of some infections

Cultural Considerations:

• Consent: Complex procedure requires thorough explanation
• Family involvement: Extended family in decision-making
• Communication: Use interpreters if needed
• Aboriginal Liaison Officers: Essential support

Post-transplant:

• Compliance: Complex immunosuppressive regimen challenging
• Follow-up: Requires repeated travel to transplant centre
• Rejection surveillance: Bronchoscopies require travel
• Telemedicine: Useful for some follow-up (spirometry at local centre)

Māori Health Considerations

Health Inequities:

• Chronic lung disease: Disparities in COPD, asthma
• Access barriers: Geographic (North vs South Island)
• Transplant centre: Auckland (National Heart and Lung Transplant Service)

Cultural Safety:

• Whānau involvement: Essential for major life-changing procedure
• Communication: Risk/benefit in culturally appropriate manner
• Māori Health Workers: Liaison support

Practical Considerations:

• Assessment phase: Temporary relocation to Auckland for workup
• Post-transplant: Long-term follow-up requires ongoing coordination
• Rural follow-up: Telemedicine, local spirometry
• Support networks: Critical for medication adherence, lifestyle changes

Data:

• New Zealand has single national heart and lung transplant service
• Ensure equitable access across all populations
• Address barriers to referral and assessment

ANZCA Final Exam Focus

SAQ Patterns

Common Questions:

• "Describe the anaesthetic management for bilateral lung transplantation in a patient with pulmonary hypertension."
• "What are the indications for ECMO vs CPB during lung transplant?"
• "How would you manage primary graft dysfunction post lung transplant?"
• "Discuss the pathophysiology of right ventricular failure in pulmonary hypertension."
• "What are the risk factors for primary graft dysfunction?"

Marking Scheme Priorities:

• RV management (milrinone, inhaled NO, maintain coronary perfusion)
• Indications for single vs bilateral vs heart-lung
• ECMO vs CPB rationale
• Reperfusion injury and PGD management
• Postoperative ventilation strategy (protective)
• Anastomotic sequence and considerations

Viva Scenarios

Scenario 1: RV Failure During Clamping

• BP drops, CVP rises, TR on TEE during first lung transplant
• Management: Inotropes (milrinone), vasopressors (noradrenaline), inhaled NO, consider ECMO support

Scenario 2: Primary Graft Dysfunction

• Severe hypoxemia immediately post-reperfusion, infiltrates on CXR
• Management: Protective ventilation, ECMO if severe (PGD grade 3), diuresis, inhaled NO

Scenario 3: Reperfusion Strategy

• Discuss controlled reperfusion (low FiO₂ initially), protective ventilation, ECMO support
• Prevention of PGD

Scenario 4: Pulmonary Hypertension Management

• Severe PHT patient presenting for bilateral transplant
• Preoperative optimization, induction strategy, intraoperative management (avoid hypotension, maintain preload, pulmonary vasodilators)

Key Points for Examination Success

1. Indications: COPD (30-35%), ILD (25-30%), CF (15-20%), PHT (5-10%)
2. PHT/RV dysfunction: Major cause of early mortality; maintain MAP >70 mmHg, use milrinone, inhaled NO
3. ECMO vs CPB: ECMO preferred (less inflammation, preserves pulsatile flow, can continue postoperatively)
4. Anastomoses: Bronchus first, then PA, then LA cuff; wrap bronchus with vascularized tissue
5. Reperfusion injury: Inflammatory cascade from ischemia; PGD graded by PaO₂/FiO₂ ratio
6. Ventilation: Protective strategy (6-8 mL/kg, PEEP 5-10, plateau <30); permissive hypercapnia
7. Single vs bilateral: COPD can use single; CF, severe PHT, ILD require bilateral
8. Postoperative: Restrictive fluids, diuresis, surveillance for rejection (biopsies), infection prophylaxis
9. Airway complications: Anastomotic dehiscence rare but serious; stenosis late complication
10. Immunosuppression: Induction intraoperative, lifelong triple therapy post-transplant

Assessment Content

SAQ 1: Lung Transplant and Pulmonary Hypertension (20 marks)

Question: A 48-year-old woman with idiopathic pulmonary arterial hypertension (IPAH) is undergoing bilateral lung transplantation. Her baseline mean pulmonary artery pressure (mPAP) is 55 mmHg, and echocardiography shows severe right ventricular (RV) dilation with reduced function and moderate tricuspid regurgitation.

a) Outline the specific anaesthetic challenges posed by severe pulmonary hypertension in this patient. (6 marks) b) Describe your induction strategy to minimize the risk of RV failure. (6 marks) c) The patient's blood pressure drops to 55/35 mmHg and CVP increases to 18 mmHg immediately after pulmonary artery clamping for the first lung. Outline your immediate management. (8 marks)

Model Answer:

a) Anaesthetic challenges in severe PHT (6 marks):

• RV afterload mismatch: RV cannot overcome high PVR; thin-walled RV not designed for high afterload (1 mark)
• RV ischemia risk: Coronary perfusion occurs during systole; hypotension reduces perfusion (1 mark)
• Interventricular dependence: Dilated RV shifts septum into LV, reducing LV filling and cardiac output (1.5 marks)
• Preload dependence: RV requires adequate filling but excessive preload worsens septal bowing (1 mark)
• Acute decompensation risk: Anesthesia vasodilation, PA clamping (acute afterload increase), hypoxia, hypercapnia, acidosis all worsen PHT (1.5 marks)

b) Induction strategy (6 marks):

• Pre-induction optimization: Consider inhaled NO (20-40 ppm) or IV epoprostenol if severe (1 mark)
• Hemodynamic stability: Etomidate 0.2-0.3 mg/kg (hemodynamically neutral) or ketamine (sympathomimetic) (1.5 marks)
• Avoid: Propofol (vasodilation, myocardial depression) or use reduced dose cautiously (1 mark)
• High-dose opioid: Fentanyl 10-20 μg/kg or remifentanil to blunt sympathetic response (1 mark)
• Airway: Gentle laryngoscopy; have vasopressors ready (phenylephrine, noradrenaline) (1 mark)
• TEE: Essential for monitoring RV function, filling (0.5 marks)

c) Management of RV failure during clamping (8 marks):

Immediate hemodynamic support:

• Increase MAP: Noradrenaline or phenylephrine to maintain coronary perfusion (target MAP >70-75 mmHg) (1.5 marks)
• RV inotropy: Milrinone (pulmonary vasodilation + inotropy) (1.5 marks)
• Pulmonary vasodilation: Inhaled NO 20-40 ppm or IV epoprostenol (1.5 marks)

ECMO consideration:

• Initiate ECMO: If refractory to medical therapy (1 mark)
• VA-ECMO: Provides RV support, maintains systemic perfusion (1 mark)

Communication:

• Inform surgeon: May need to proceed rapidly with implantation or consider ECMO (0.5 marks)
• Optimize: Preload (ensure adequate but not excessive), check for tamponade (0.5 marks)

Monitoring:

• TEE: Assess RV function, septal position, TR severity (0.5 marks)

SAQ 2: Primary Graft Dysfunction (20 marks)

Question: Following bilateral lung transplantation for idiopathic pulmonary fibrosis, a 62-year-old man develops severe hypoxemia (PaO₂ 65 mmHg on 100% FiO₂) immediately after weaning from ECMO. Chest X-ray shows diffuse bilateral alveolar infiltrates consistent with pulmonary edema.

a) What is the most likely diagnosis? What is the grading system for this condition? (4 marks) b) What are the risk factors for developing this complication? (4 marks) c) Outline the management of severe primary graft dysfunction (grade 3). (8 marks) d) How can this complication be prevented? (4 marks)

Model Answer:

a) Diagnosis and grading (4 marks):

• Primary graft dysfunction (PGD) (1 mark)
• Grading system (PaO₂/FiO₂ ratio):
  • Grade 0: >300 (0.5 marks)
  • Grade 1: 200-300 (0.5 marks)
  • Grade 2: 100-200 (0.5 marks)
  • Grade 3: <100 (patient has Grade 3: 65/1.0 = 65) (0.5 marks)
• Timeframe: Within 72 hours post-transplant (1 mark)

b) Risk factors (4 marks):

• Donor factors: Prolonged ischemic time (>6-8 hours), smoking history, trauma, aspiration (1 mark)
• Recipient factors: Severe PHT, ILD diagnosis, large recipient size mismatch (1 mark)
• Surgical factors: Prolonged bypass/ECMO time, poor lung preservation (1 mark)
• Reperfusion: Uncontrolled reperfusion (high FiO₂, high pressure) (1 mark)

c) Management of severe PGD (8 marks):

• Reinitiate ECMO: Veno-venous or veno-arterial ECMO for gas exchange support (2 marks)
• Protective ventilation: VT 6 mL/kg, PEEP 10-15 cm H₂O, plateau pressure <25 cm H₂O (1.5 marks)
• Permissive hypercapnia: Accept PaCO₂ 50-70 mmHg if pH >7.20 (0.5 marks)
• Fluid management: Restrictive, diuretics (furosemide), negative balance (1 mark)
• Pulmonary vasodilators: Inhaled NO or epoprostenol (reduce PVR, improve RV function) (1 mark)
• Steroids: Methylprednisolone (reduce inflammation) (0.5 marks)
• Antibiotics: Broad-spectrum (rule out infection) (0.5 marks)
• Prone positioning: If no ECMO, may improve V/Q (0.5 marks)
• Avoid: Nephrotoxic drugs, excessive fluid (0.5 marks)

d) Prevention (4 marks):

• Donor management: Optimal lung procurement, protective ventilation in donor (1 mark)
• Preservation: Cold preservation solution, minimize ischemic time (<6-8 hours) (1 mark)
• Controlled reperfusion: Low FiO₂ (30-50% initially), low pressure, gradual (1 mark)
• EVLP: For marginal lungs (can improve grafts before implantation) (0.5 marks)
• Size matching: Appropriate donor/recipient size match (0.5 marks)

Viva Scenario: ECMO vs CPB Decision

Examiner: "You are planning bilateral lung transplantation for a patient with severe pulmonary hypertension. Discuss the rationale for choosing ECMO versus CPB."

Candidate: "ECMO is generally preferred over CPB for lung transplantation. The primary advantage of ECMO is that it maintains pulsatile blood flow, which is beneficial for right ventricular function and coronary perfusion. CPB produces non-pulsatile flow, which can contribute to myocardial dysfunction. ECMO also generates less inflammatory response than CPB - there's less hemodilution, less complement activation, and reduced cytokine release, which may reduce the risk of primary graft dysfunction. Additionally, ECMO can be continued postoperatively in ICU if the patient requires ongoing support, whereas coming off CPB requires reversal of anticoagulation and decannulation in the operating room."

Examiner: "When would CPB be preferred?"

Candidate: "CPB might be preferred in specific circumstances - if there's severe cardiac dysfunction requiring full cardiac support, if there are major intracardiac shunts that need repair, or in some reoperative cases with severe adhesions where cardiac manipulation is extensive. Some centers also prefer CPB for bilateral lung transplants in small children. However, for most adult lung transplants, particularly with severe pulmonary hypertension, ECMO has become the standard at experienced centers."

Examiner: "How would you manage anticoagulation with ECMO?"

Candidate: "ECMO anticoagulation is less intensive than CPB. During the procedure, we maintain ACT around 300-350 seconds, compared to greater than 480 seconds for CPB. This reduces bleeding risk, which is important given the extensive dissection and anastomoses in lung transplantation. Postoperatively, if ECMO is continued, we transition to heparin infusion titrated to anti-Xa levels or PTT rather than ACT, typically targeting moderate anticoagulation since bleeding remains a concern in the postoperative period."

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