When is a single lung transplant versus a double lung transplant recommended for patients with end-stage lung disease, considering factors such as disease progression, age, comorbidities, and pulmonary hypertension?

Single vs. Bilateral Lung Transplantation Decision Framework

For most patients with end-stage lung disease, the choice between single and bilateral lung transplantation depends primarily on the underlying disease etiology, with bilateral transplantation generally preferred for suppurative diseases (bronchiectasis, cystic fibrosis) and COPD in younger patients (<60 years), while single lung transplantation remains acceptable for pulmonary fibrosis and older COPD patients when organ scarcity is considered.

Disease-Specific Recommendations

Suppurative Lung Diseases (Bronchiectasis, Cystic Fibrosis)

• Bilateral lung transplantation is mandatory for patients with diffuse bilateral bronchiectasis or cystic fibrosis to prevent cross-contamination of the transplanted lung from the diseased contralateral native lung 1
• Single lung transplantation with contralateral pneumonectomy has been reported but is not standard practice 1
• Post-transplant survival for bronchiectasis shows 70% at 1 year and 54% at 5 years 1

Chronic Obstructive Pulmonary Disease (COPD)

• Bilateral lung transplantation is preferred for COPD patients younger than 60 years as it provides better long-term outcomes in this age group 1
• Single lung transplantation provides equivalent short- and medium-term results but bilateral shows slightly better long-term survival, particularly in COPD 2, 3
• The advantages of bilateral over single lung transplantation become less clear when considering mortality risk while on the waiting list 1
• COPD represents 35% of all lung transplants and approximately 12% of transplants are performed for emphysema secondary to alpha-1 antitrypsin deficiency 1

Idiopathic Pulmonary Fibrosis (IPF)

• No definitive recommendation exists - the ATS/ERS/JRS/ALAT guidelines explicitly state they "did not make a recommendation regarding single versus bilateral lung transplantation in patients with IPF" 1
• Pooled survival analysis of three observational studies showed no survival difference between single and bilateral transplantation (HR 0.47; 95% CI 0.19-1.17) 1
• Four additional studies confirmed no significant survival differences 1
• Single lung transplantation is most appropriate for pulmonary fibrosis patients based on historical practice patterns 4
• Most data support bilateral for COPD patients when available, and single for the majority of IPF patients 3

Pulmonary Hypertension

• Combined heart-lung transplantation is best for patients with right-heart failure secondary to vascular or parenchymal pulmonary disease 4
• Evidence of secondary pulmonary hypertension or cor pulmonale despite adequate oxygenation is a prognostic indicator for transplantation need 1

Critical Decision-Making Factors

Age Considerations

• Bilateral transplantation shows better long-term outcomes specifically in patients younger than 60 years 1
• Risks of transplantation generally increase with age, with patients above 65 years having an unfavorable risk-benefit mortality ratio 1
• For bronchiectasis, transplant referral is recommended for patients ≤65 years with FEV₁ <30% and significant clinical instability 5

Organ Scarcity and Ethical Considerations

• The shortage of organs is a universal problem - the decision to give bilateral transplantation to one patient rather than single-lung transplantation to two patients must consider health equity 1
• Recent developments suggest organ donor shortage may not be as severe as previously thought, making bilateral transplantation a possible alternative for more patients 2, 3
• Early referral to a transplant center is essential given scarcity of donor organs and prolonged waiting times 5

Functional and Survival Outcomes

• Actuarial 5-year survival following lung transplantation is approximately 50% overall 1
• Significant differences exist in actuarial survival at 1,2, and 3 years post-transplantation between single versus double lung transplant recipients for some conditions 1
• For bronchiectasis specifically, single lung transplantation showed lower 1-year survival (57%) compared to bilateral (73%) 1
• Transplant side (left vs. right) does not influence recipient survival, freedom from bronchiolitis obliterans syndrome, complications, or pulmonary function after single lung transplantation 6

Common Pitfalls to Avoid

Contraindications and Risk Factors

• Avoid bilateral transplantation in patients with septic pulmonary disease unless adequate cardiac function is present or recoverable 4
• Do not delay transplantation waiting for a "better-matched" donor lung on the opposite side, as transplant side does not influence outcomes 6
• Recognize that bronchiolitis obliterans syndrome is a strong negative predictor for survival (HR 6.78) regardless of single versus bilateral approach 6

Technical Considerations

• Replacement of native lung with ≥50% perfusion is more common in right-sided single lung transplantation recipients (47.1% vs 23.6% for left) 6
• The preferred side for single lung transplantation differs between fibrotic versus emphysema recipients 6
• Attention to technical detail and avoidance of perioperative corticosteroids increase likelihood of success 4

Timing Considerations

• List patients early enough to avoid extreme disability or pre-transplant death 5
• For IPF, refer based on diffusion capacity decline, progressive disease despite optimal medical management, severe functional impairment with oxygen dependency, and deteriorating physiologic course 5
• For COPD, consider listing when BODE index >7, FEV₁ <15-20% predicted, or three or more severe exacerbations in the preceding year 5