Background and method The use of thoracic ultrasound (TUS) by physicians is increasingly commonplace in light of recent BTS guidelines and changes to training curricula. At its simplest, TUS enhances patient safety during interventions through the identification of pleural fluid and underlying structures. However, TUS training documents in the UK (Royal College of Radiologists) and US (American College of Chest Physicians) acknowledge a need for the ultrasonographer to recognise features of underlying lung, including consolidation.
Pneumonia leading to respiratory failure is a common cause of admission to medical and intensive care units worldwide and associated with significant morbidity and mortality, particularly when diagnosis is delayed. Diagnosis can be challenging and existing tools (clinical examination, CXR or CT) have their recognised flaws. TUS may be an alternative solution, offering patients a bedside investigation that provides clinicians with instant feedback to inform treatment decisions.
We searched MEDLINE, EMBASE and the Science Citation Index Expanded (inception to October 2013) for studies relating to the diagnostic use of TUS in adults with acute respiratory failure due to radiographic consolidation, focusing on studies using CT as their reference standard. Two reviewers independently extracted data from eligible studies and assessed study quality using QUADAS-2.
Results Three cohort studies, all based in an ICU setting, with a total of 134 participants met inclusion criteria. Two studies were at high risk of potential bias, whilst the third had limitations of applicability. The reported sensitivity (0.91 to 1.00) and specificity (0.78–1.00) of TUS in expert hands for CT-detected consolidation was superior to that for CXR (sensitivity 0.38 and 0.68; specificity 0.89 and 0.95). Outside the inclusion criteria, a number of studies of patients with consolidation but no respiratory failure also suggested TUS might have greater diagnostic sensitivity than CXR.
Conclusion TUS remains, at present, a technology with limited evidence to support a front-line role in the assessment of patients with respiratory failure to detect lung consolidation. However, the evidence available is promising and well-designed clinical studies are necessary to ascertain whether TUS can influence relevant outcomes for patient benefit.