Lung Transplantation¶

Chapter 309 | Part 7: Disorders of the Respiratory System

KEY CLINICAL POINTS¶

Lung transplantation is indicated for end-stage lung disease, with the Lung Allocation Score (LAS) and Composite Allocation Score (CAS) systems guiding organ prioritization.
Contraindications include active infections (e.g., HIV, hepatitis), uncorrectable organ dysfunction, and severe comorbidities like cirrhosis or irreversible psychiatric disorders.
Donor selection prioritizes age <55 years, Pao2/Fio2 >300, no smoking history, and absence of chronic lung disease. Ex vivo lung perfusion (EVLP) expands use of donors after cardiac death (DCD).
Post-transplant complications include primary graft dysfunction (PGD), infections, and chronic lung allograft dysfunction (CLAD). Immunosuppression with calcineurin inhibitors and corticosteroids is critical.
Pre-transplant evaluation includes the BODE index, pulmonary function tests (PFTs), and multidisciplinary assessment of psychosocial and nutritional status.

1. DEFINITION & OVERVIEW¶

Lung transplantation is a treatment for end-stage lung disease, with the Lung Allocation Score (LAS) and Composite Allocation Score (CAS) systems guiding organ prioritization. The LAS (2005) and CAS (2023) systems prioritize patients with higher acuity, older age groups, and diseases affecting survival. Idiopathic pulmonary fibrosis (IPF), a restrictive lung disease, has become a common indication due to antifibrotic therapies. The transition to CAS aims to improve equity in access and reduce wait-list mortality.

Table 309-1: Contraindications to Lung Transplantation¶

ABSOLUTE CONTRAINDICATIONS	RELATIVE CONTRAINDICATIONS
Surgical considerations	Anatomic abnormalities not amenable to transplant procedure
Functional status	Immobility, inability to participate in physical therapy/rehabilitation
Nutritional	BMI <18 or >30–35
Psychosocial	Untreatable, irreversible psychiatric disorder with potential to impact transplant outcome
Active substance abuse	Other circumstances that would impede ability to participate in and comply with posttransplant care
Active malignancy or malignancy with insufficient remission period	Uncontrolled viral infection (HIV, hepatitis)
Active bacterial bloodstream infection	Untreatable, irreversible organ dysfunction

1.1 Indications¶

Indications include IPF, pulmonary hypertension, restrictive lung disease, and progressive fibrosing interstitial lung diseases. Forced vital capacity <80% predicted or diffusing capacity <40% predicted, failure to respond to therapy, and functional decline are key indicators. The BODE index (Body Mass Index, Airflow Obstruction, Dyspnea, Exercise Capacity) guides referral, with scores ≥ 5 indicating evaluation and ≥ 7 indicating listing.

1.2 Contraindications¶

Absolute contraindications include active infections (e.g., HIV, hepatitis), uncorrectable organ dysfunction, and severe comorbidities. Relative contraindications include advanced age, frailty, and irreversible psychiatric disorders. Patients with uncontrolled viral infections or substance abuse are at higher risk for poor outcomes.

2. EPIDEMIOLOGY¶

The average life expectancy for IPF patients before antifibrotic therapy was 3–5 years, making transplantation a survival benefit. The CAS system prioritizes patients with higher acuity and older age groups. Functional capacity, as assessed by 6-minute walk distance, inversely correlates with wait-list and post-transplant mortality. Nutritional status has a U-shaped relationship with outcomes, with underweight (BMI <18) and obesity (BMI >35) increasing mortality risk.

2.1 Demographics¶

Patients with IPF and other restrictive lung diseases are prioritized due to antifibrotic therapies. Older patients with significant comorbidities face higher risks, but functional status (e.g., 6-minute walk distance) is a stronger predictor of outcomes than absolute disease severity.

2.2 Risk Factors¶

Risk factors include advanced age, comorbidities (e.g., diabetes, HIV), and poor nutritional status. Patients with cystic fibrosis (CF) or bronchiectasis face unique risks from resistant infections like Burkholderia cepacia complex.

3. ETIOLOGY & PATHOPHYSIOLOGY¶

Lung transplantation is indicated for end-stage lung disease, including IPF, pulmonary hypertension, and restrictive/obstructive diseases. Pathophysiology involves disease progression, immune suppression, and complications like infection. Antifibrotic therapies slow decline but do not reverse disease, necessitating transplantation for IPF. Ischemia-reperfusion injury and immune rejection are key post-transplant challenges.

3.1 Disease Mechanisms¶

Progressive fibrosing interstitial lung diseases (e.g., IPF) and pulmonary hypertension are primary indications. Antifibrotic therapies slow decline but do not reverse disease. Infections (e.g., Pseudomonas, Burkholderia) and immune dysfunction contribute to transplant failure.

3.2 Immunosuppression¶

Calcineurin inhibitors, corticosteroids, and purine modulators are used to prevent rejection. However, these drugs increase infection risk and nephrotoxicity. Steroid use must be minimized to avoid wound healing complications.

4. CLINICAL FEATURES¶

Clinical features include respiratory failure, pulmonary hypertension, and complications from infections. Functional decline, as measured by the BODE index or 6-minute walk test, is a key indicator. Patients with CF or bronchiectasis face risks from resistant bacterial colonization (e.g., Burkholderia cepacia).

4.1 Symptomatology¶

Symptoms include progressive dyspnea, hypoxemia, and right heart failure. Patients with IPF may develop secondary pulmonary hypertension, requiring vasodilator therapy. Infections (e.g., Pseudomonas, CMV) are common post-transplant.

4.2 Complications¶

Complications include primary graft dysfunction (PGD), infections, and chronic lung allograft dysfunction (CLAD). Acute exacerbations and worsening right ventricular function are critical risks in pulmonary hypertension.

5. DIFFERENTIAL DIAGNOSIS¶

Differential diagnoses include other restrictive lung diseases (e.g., sarcoidosis, connective tissue disorders) and obstructive diseases (e.g., COPD). The BODE index and PFTs help distinguish between conditions. Infections (e.g., CMV, Pseudomonas) must be ruled out in transplant candidates.

5.1 Key Differentiators¶

IPF is distinguished by restrictive physiology and honeycombing on imaging. COPD is characterized by obstructive PFTs. Infections (e.g., Burkholderia in CF) require specific antimicrobial stewardship.

6. INVESTIGATIONS & DIAGNOSIS¶

Diagnosis involves the LAS and CAS systems, PFTs, and imaging. The BODE index guides referral. Donor evaluation includes chest imaging, bronchoscopy, and serologic tests for CMV, EBV, and HIV. EVLP is used to assess marginal DCD donors.

6.1 Diagnostic Criteria¶

The LAS and CAS systems prioritize patients based on acuity and survival metrics. PFTs (e.g., FEV <25% predicted) and the BODE index are key tools. Donor evaluation includes chest x-ray, bronchoscopy, and exclusion of chronic lung disease.

6.2 Imaging & Lab Tests¶

Noncontrast imaging assesses donor lungs. Arterial blood gases, CMV/EBV/HIV testing, and bronchoscopy are required. EVLP is used to rehabilitate DCD donor lungs.

7. MANAGEMENT & TREATMENT¶

Management includes antifibrotic therapy for IPF, immunosuppression (calcineurin inhibitors, corticosteroids), and ECMO support. Post-transplant care involves infection prophylaxis, diabetes management, and monitoring for PGD. EVLP expands donor pool for DCD lungs.

7.1 Pre-Transplant¶

Optimize medical therapy (e.g., antifibrotics, vasodilators), manage comorbidities (e.g., diabetes, HIV), and ensure nutritional status. Multidisciplinary evaluation includes psychosocial and financial assessments.

7.2 Post-Transplant¶

Immunosuppression with calcineurin inhibitors, corticosteroids, and purine modulators. Monitor for infections (e.g., CMV, Pseudomonas) and PGD. Use ECMO for prolonged support and EVLP for DCD donors.

8. PROGNOSIS & COMPLICATIONS¶

Prognosis is influenced by PGD severity, infection rates, and immune suppression. CLAD is a long-term risk, with severe PGD at 72 h post-transplant correlating with higher mortality. Infections (e.g., fungal, viral) remain leading causes of morbidity and mortality.

8.1 Post-Transplant Outcomes¶

PGD severity (Pao2:Fio2 <100) at 72 h predicts chronic dysfunction. Infections peak 10–28 days post-transplant, with fungal infections peaking at 10–28 days. Steroid use must be minimized to avoid wound healing complications.

8.2 Long-Term Risks¶

CLAD and recurrent infections are major long-term risks. Immunosuppression increases infection susceptibility, requiring prophylaxis (e.g., trimethoprim-sulfamethoxazole for Pneumocystis).

9. SPECIAL CONSIDERATIONS¶

Nutritional status (BMI <18 or >35) and psychosocial factors (e.g., substance abuse, psychiatric disorders) impact outcomes. Patients with CF or bronchiectasis require specialized infection management. Financial and insurance coverage are critical for transplant access.

9.1 Nutritional & Psychosocial¶

Underweight or obese patients may require enteral feeding. Psychosocial support includes psychiatric evaluation and financial planning. Substance abuse and noncompliance are relative contraindications.

9.2 Comorbidities¶

Diabetes and HIV require optimized management pre-transplant. Patients with CF need specialized care for pancreatic dysfunction and infection control.

10. KEY POINTS & CLINICAL PEARLS¶

The transition to the CAS system improves equity in lung allocation. Donor evaluation includes EVLP for DCD lungs. Pre-transplant management of comorbidities (e.g., diabetes, HIV) is critical. PGD severity at 72 h predicts chronic dysfunction. Immunosuppression must balance rejection prevention and infection risk.