Pulmonary CT in Pneumonia Complicating Stroke

Pneumonia commonly complicates stroke and has a profound impact on clinical outcomes. Accurate and timely diagnosis of pneumonia complicating stroke remains a major challenge as several issues potentially confound diagnosis. Chest X-ray (CXR), a central component in the diagnostic work-up, may have limited utility in the early stages as they are often of suboptimal quality, and infrequently confirm typical diagnostic infiltrates. Blood biomarkers of the stress-immune response have received considerable attention, but interpretation has been limited by differing methodologies, including definition of pneumonia. Bacterial organisms in the oral cavity may also be of relevance as biomarkers of post-stroke pneumonia. Major challenges facing frontline clinicians are therefore whether to initiate antibiotics; if so, when and for how long. These issues have antibiotic stewardship implications for clinicians in terms of potential for under-treatment or over-treatment with antibiotics based on CXR appearances.

Pulmonary Computed Tomography (CT) could be of value as a radiological reference standard when pneumonia is suspected after stroke, and enable more rigorous evaluation of the diagnostic performance of CXR (and other candidate biomarkers) to inform decision-making when pneumonia is suspected.

The overall primary aim is therefore to investigate the feasibility and reliability of using pulmonary CT as a radiological reference standard for evaluating suspected pneumonia complicating stroke. The secondary aims are to explore the diagnostic accuracy of CXR and blood biomarkers (index tests) when pneumonia is suspected during hospital admission after stroke using pulmonary CT as a reference standard.

Pneumonia is a frequent complication of stroke, particularly within the first few days. The risk of pneumonia is increased in patients who are older, have a more severe stroke and in those who have swallowing problems as a result of their stroke. Patients who develop pneumonia have a higher risk of death and longer hospital stay. The diagnosis of pneumonia is not always easy, but it is important to identify pneumonia early in order to begin the most appropriate treatment in a timely fashion and avoid giving antibiotics unnecessarily. Chest x-ray, the standard test undertaken when pneumonia is suspected, infrequently shows changes and is of limited value.

Pulmonary Computed Tomography (CT) scans can be used to image the lungs in more detail than a standard chest xray. The Investigators plan to assess if it is feasible to perform pulmonary CT imaging in stroke patients within 48 hours of symptoms and who may be acutely unwell. The Investigators will also investigate how reliable CT is at diagnosing pneumonia by asking different x-ray doctors to review the scans. Comparing the result of the pulmonary CT imaging to the chest x-ray will allow assessment of their utility for the diagnosis of pneumonia. The Investigators will also record whether the CT informs clinical management e.g. stopping antibiotics if pneumonia is excluded.

Blood samples will be collected for measurement of inflammatory markers and mouth swabs will measure types of bacteria. The analysis will be conducted at Salford Royal NHS Foundation Trust (SRFT) and using new cutting-edge techniques performed by collaborators at ThermoFisher and Manchester Collaborative Centre for Inflammation Research. The Investigators will assess how useful these inflammatory proteins are in pneumonia diagnosis compared to the pulmonary CT scans. This research will help the Investigating team design larger studies to diagnose pneumonia earlier and more accurately, enabling more effective use of antibiotics.

Eligibility Criteria:
Inclusion Criteria:

* Inpatient in SRFT or RSUH with diagnosis of stroke current admission
* Within 24h of clinically suspected pneumonia occurring after admission
* Aged ≥18y
* Provision of informed consent from participant or personal consultee
* Able to undergo pulmonary CT within next 48h

Exclusion Criteria:

* Treatment for lower respiratory tract infection (LRTI) completed within the preceding month
* Mechanical ventilation planned or anticipated imminently
* End-of-life care planned or anticipated imminently