Speaker's Highlight

• Don Sin University of British Columbia, St. Paul Hospital (Canada)
  Kenneth R. Chapman Toronto General Hospital Research Institute (Canada)
• Parameswaran Nair McMaster University (Canada)
  Carolyn Calfee UCSF (U.S.A.)
• Gregory P. Downey University of Colorado School of Medicine (U.S.A.)
  David A. Schwartz University of Colorado School of Medicine (U.S.A.)
• Neil Schluger Tuberculosis Control Branch, California Department of Public Health (U.S.A.)
  Nick Kim Critical Care & Sleep Medicine, University of California San Diego (U.S.A.)
• Nicola Hananiah Baylor College of Medicine (U.S.A.)
  Jae-Joon Yim Seoul National University College of Medicine (Republic of Korea)
• Koichiro Asano Tokai University School of Medicine (Japan)
  Diahn-Warng Perng Taipei Veterans General Hospital (Taiwan)
• Konstantinos Kostikas University of Ioannina (Greece)
  Karin Klooster University Medical Center Groningen (Kingdom of the Netherlands)

• Pulmonary complications after haematopoietic stem cell transplantation

  Haematopoietic stem cell transplantation (HSCT) can offer curative treatment for leukaemia, lymphoma, myeloma and selected marrow failure syndromes. The lungs remain vulnerable throughout the transplant journey because conditioning therapy, immune suppression, infection, graft-versus-host disease (GVHD) and fluid shifts can affect the airways, alveoli, pleura and pulmonary circulation.

  Pulmonary complications of haematopoietic stem cell transplantation may appear within days or develop months or years later. In Australia, early recognition is particularly important when patients move between metropolitan transplant units in Sydney, Melbourne, Brisbane, Perth or Adelaide and local hospitals or general practices. Clear communication helps clinicians distinguish an urgent transplant-related problem from asthma, influenza, COVID-19 or a routine chest infection.

  Why the transplanted lung is vulnerable

  Conditioning chemotherapy and radiotherapy can injure the respiratory epithelium before engraftment occurs. Neutropenia, mucosal damage and impaired cellular immunity increase the risk of bacterial, viral and fungal infection. Donor-derived immune cells may later attack recipient tissues, producing pulmonary forms of chronic GVHD.

  The clinical picture is often complicated by several processes occurring together. A patient with breathlessness may have infection, pulmonary oedema, diffuse alveolar haemorrhage, medication toxicity or thromboembolism. Reduced exercise tolerance can also be mistaken for expected post-transplant fatigue, delaying investigation.

  Early respiratory problems

  During the pre-engraftment and early post-engraftment periods, fever, cough, hypoxia and new infiltrates require prompt assessment. Common causes include bacterial pneumonia, respiratory viruses, invasive fungal disease and reactivation of organisms such as cytomegalovirus. Neutropenic sepsis may progress rapidly, even when chest signs are mild.

  Non-infectious conditions are equally important. Peri-engraftment respiratory distress can involve capillary leak, pulmonary oedema and inflammatory lung injury. Diffuse alveolar haemorrhage may present with falling haemoglobin, fever and worsening oxygenation, with or without obvious haemoptysis. Drug reactions and transfusion-associated lung injury should also be considered.

  Later airway and interstitial disease

  Bronchiolitis obliterans syndrome is a serious late complication associated with chronic GVHD. Progressive narrowing and scarring of the small airways cause exertional dyspnoea, dry cough, wheeze and air trapping. Spirometry may show a sustained fall in forced expiratory volume, sometimes before symptoms become prominent.

  Other late problems include organising pneumonia, restrictive interstitial changes, pleural disease and pulmonary hypertension. Some survivors develop persistent susceptibility to infection because immune recovery is incomplete. Smoking, vaping, occupational dust and bushfire smoke can add further stress to already damaged lungs, making avoidance particularly relevant during Australian fire seasons.

  Assessment in Australian practice

  Evaluation usually combines oxygen saturation, a chest examination, full blood count, renal and liver tests, inflammatory markers and chest imaging. High-resolution CT can identify ground-glass change, consolidation, nodules, air trapping or fibrosis more clearly than a plain radiograph. Pulmonary function testing should include spirometry, lung volumes and diffusion capacity when the patient is stable enough to perform the tests.

  Bronchoscopy with bronchoalveolar lavage may be needed for unexplained infiltrates, suspected fungal infection, alveolar haemorrhage or unusual pathogens. Results should be interpreted alongside the transplant timeline, immunosuppressive medicines and recent antimicrobial exposure. A falling diffusion capacity, new obstruction or decline in exercise capacity may provide an early signal of chronic lung injury.

  Patients should bring an up-to-date medicine list and transplant summary to every emergency or respiratory review. Australian centres may use different referral pathways, so the treating team should identify the transplant unit, after-hours contact and nearest hospital capable of managing severe immunosuppression-related illness.

  Treatment and prevention priorities

  Management depends on the cause and severity. Antimicrobial treatment may need to cover resistant bacteria, moulds or viral disease, while non-infectious inflammation may require corticosteroids or adjustment of immunosuppression. Oxygen, non-invasive respiratory support or intensive care can be necessary for acute hypoxaemic respiratory failure.

  Prevention includes vaccination when immune recovery permits, careful hand hygiene, food and water precautions, and prophylaxis prescribed by the transplant team. The Australian Immunisation Handbook guides timing, although individual schedules vary. Patients should avoid tobacco smoke and vaping, check local air-quality alerts during bushfires and wear a well-fitted mask in crowded indoor settings during periods of high respiratory virus circulation.

  Protective measures that support lung health

  • Keep influenza, COVID-19 and other recommended vaccines up to date
  • Report fever, new cough or breathlessness promptly
  • Avoid smoking, vaping, mould and dusty renovation work
  • Follow antifungal, antiviral and antibacterial prophylaxis exactly

  Warning signs that need urgent review

  Symptoms after HSCT can change quickly. A normal temperature does not exclude severe infection in a person taking corticosteroids or other immunosuppressants. Home pulse oximetry may be useful for monitoring when recommended by the clinical team, but a reassuring reading should not override rapidly worsening symptoms.

  Australian patients should call emergency services on 000 for severe breathing difficulty, blue lips, confusion, collapse or inability to speak in full sentences. For less dramatic changes, contacting the transplant unit or hospital early is safer than waiting for a routine appointment, especially when the patient lives several hours from a tertiary centre.

  Symptoms that should not be ignored

  • New or worsening shortness of breath
  • Oxygen saturation below the patient’s agreed threshold
  • Fever, rigors, chest pain or coughing blood
  • A persistent dry cough or falling exercise tolerance

  Coordinating long-term follow-up

  Long-term respiratory surveillance should continue after hospital discharge. Baseline pulmonary function tests, repeat testing when symptoms arise and periodic review for chronic GVHD can help identify decline early. Rehabilitation, graded activity and nutrition support may improve conditioning, while specialist advice is important before returning to strenuous work or remote travel.

  Care also needs to reflect the realities of daily life in Australia. A patient in regional Queensland may need telehealth and a local pathology plan, while someone in Melbourne or Sydney may have easier access to specialist testing but greater exposure to crowded public transport. Medicare arrangements, state-based hospital services and PBS-listed medicines can influence how quickly treatment is obtained, so discharge plans should state which costs, prescriptions and referrals apply.

  A practical pathway after discharge

  Every patient should leave the transplant service with written instructions covering warning symptoms, infection precautions, medication changes and emergency contacts. The plan should also record baseline lung function, oxygen requirements, vaccination timing and the threshold for hospital review. Family members and carers need the same information because they may notice subtle changes before the patient does.

  At the next transplant or respiratory appointment, review symptoms, smoking or vaping exposure, bushfire or occupational exposure, medication adherence and functional capacity. The concrete next step is to ensure the patient’s GP and transplant unit share an updated respiratory monitoring plan before the next episode of cough or breathlessness.

  Richard Russell Nuffield Department of Clinical Medicine, University of Oxford (United Kingdom)
• Mona Bafadhel King’s College London (United Kingdom)
  David Jackson Guy’s and St Thomas’ Hospital, King’s College London (United Kingdom)
• James Chalmers University of Dundee (United Kingdom)
  David Price University of Aberdeen (United Kingdom)