Lung Transplantation

Indications & Contraindications - Who Gets New Lungs?

Indications:

• End-stage lung diseases (COPD, IPF, CF, PAH)

  ⭐ COPD: most common indication.

• Life expectancy < 18-24 months
• Severe functional impairment (NYHA III-IV)
• PFTs: FEV1 < 30% (COPD/CF); FVC < 60% or DLCO < 50% (IPF)

Contraindications:

Donor Selection & Allocation - Gifting Breath Anew

• Ideal Donor Criteria:
  • Age < 55-65 yrs
  • ABO compatible
  • PaO2/FiO2 > 300 mmHg (on PEEP 5 cm H2O, FiO2 1.0)
  • Clear CXR; no aspiration/trauma
  • No active malignancy/systemic infection
  • Smoking < 20 pack-years
• Extended Criteria Donors (ECD): Increasingly used to expand donor pool; criteria less stringent.
• Lung Allocation Score (LAS):
  • Prioritizes candidates (≥ 12 yrs). Score 0-100 (↑score = ↑priority).
  • Balances waitlist urgency & post-transplant survival benefit.

⭐ Key LAS components: Forced Vital Capacity (FVC), PaO2, 6-minute walk distance (6MWD), pulmonary artery pressure, O2 requirement, age, BMI, creatinine, diagnosis.

Surgical Aspects & Techniques - The Big Swap

• Incisions:
  • Clamshell (bilateral anterolateral): DLT standard.
  • Posterolateral thoracotomy: For SLT.
  • Median sternotomy: Rare, specific cases.
• Procedure Types:
  • SLT: IPF, emphysema (non-suppurative).
  • DLT: CF, bronchiectasis (suppurative), PAH.
• Cardiopulmonary Bypass (CPB):
  • Often for DLT / unstable patients.
  • SLT: Off-pump preferred if stable.
  • ECMO: Bridge to transplant / intraop support.
• Anastomotic Technique:
  • Bronchial: Telescoping or end-to-end; membranous portion first, then cartilaginous.
  • Vascular: Pulmonary Artery (PA) typically end-to-end; Left Atrial (LA) cuff for pulmonary veins.

⭐ Sequence: Bronchus → Pulm. Artery → Pulm. Veins (LA Cuff). 📌 Breathe Air Via Lungs (Bronchus, Artery, Veins).

• Size Matching: Vital; donor lung often reduced if oversized.

Post-Transplant Care & Hurdles - Navigating New Normals

• Immunosuppression (Lifelong):

  • Standard: Triple therapy - Calcineurin Inhibitor (CNI), Antimetabolite, Corticosteroids.
    • CNIs (Tacrolimus, Cyclosporine): Nephrotoxicity, neurotoxicity. Tacrolimus target levels: 3-12 ng/mL (varies).
    • Antimetabolites (Mycophenolate Mofetil, Azathioprine): GI upset, myelosuppression.
    • Corticosteroids (Prednisone): Hyperglycemia, osteoporosis, infections.
  • Induction therapy (e.g., Basiliximab, ATG) may be used peri-operatively.

• Monitoring:

  • Pulmonary Function Tests (PFTs): Spirometry (FEV1, FVC) regularly.
  • Bronchoscopy with Transbronchial Biopsy (TBBx) & Bronchoalveolar Lavage (BAL): Surveillance for rejection/infection.
  • Imaging: Chest X-ray, CT scans as indicated.
  • Therapeutic drug monitoring for CNIs.

• Key Hurdles & Complications:

  • Primary Graft Dysfunction (PGD): Acute lung injury within 72 hours post-transplant; graded 0-3.
  • Rejection:
    • Acute Cellular Rejection (ACR): T-cell mediated. Dx: Biopsy. Rx: Pulse steroids, optimize immunosuppression.
    • Antibody-Mediated Rejection (AMR): Donor-Specific Antibodies (DSA). Dx: Biopsy (C4d), DSA. Rx: IVIG, plasmapheresis, rituximab.
    • Chronic Lung Allograft Dysfunction (CLAD): Leading cause of late mortality.
      • Bronchiolitis Obliterans Syndrome (BOS): Airflow obstruction (↓FEV1). Most common form.
      • Restrictive Allograft Syndrome (RAS): Restrictive defects, fibrosis.

⭐ BOS, the most common phenotype of CLAD, is defined by a persistent decline in FEV1 to <80% of the post-transplant baseline. - Infections: High risk due to immunosuppression. + Bacterial: Pneumonia common early. + Viral: Cytomegalovirus (CMV) - prophylaxis/pre-emptive therapy (Valganciclovir). + Fungal: Aspergillus - prophylaxis (e.g., Voriconazole). - Other: Drug toxicities (renal, metabolic), malignancy (PTLD, skin cancer), cardiovascular disease.

High‑Yield Points - ⚡ Biggest Takeaways

• COPD, IPF, Cystic Fibrosis are key indications; DLT for suppurative diseases.
• Active malignancy & untreatable infections (e.g., B. cenocepacia) are absolute contraindications.
• Primary Graft Dysfunction (PGD) is a critical early complication from reperfusion injury.
• CLAD, notably Bronchiolitis Obliterans Syndrome (BOS), is the main cause of late graft failure.
• Standard immunosuppression is a triple-drug regimen (CNI, antimetabolite, steroids).
• CMV and Aspergillus are significant opportunistic infections post-transplant_._