The efficacy of bedside chest ultrasound: from accuracy to outcomes

Abstract

For many respiratory physicians, point-of-care chest ultrasound is now an integral part of clinical practice. The diagnostic accuracy of ultrasound to detect abnormalities of the pleura, the lung parenchyma and the thoracic musculoskeletal system is well described. However, the efficacy of a test extends beyond just diagnostic accuracy. The true value of a test depends on the degree to which diagnostic accuracy efficacy influences decision-making efficacy, and the subsequent extent to which this impacts health outcome efficacy. We therefore reviewed the demonstrable levels of test efficacy for bedside ultrasound of the pleura, lung parenchyma and thoracic musculoskeletal system.For bedside ultrasound of the pleura, there is evidence supporting diagnostic accuracy efficacy, decision-making efficacy and health outcome efficacy, predominantly in guiding pleural interventions. For the lung parenchyma, chest ultrasound has an impact on diagnostic accuracy and decision-making for patients presenting with acute respiratory failure or breathlessness, but there are no data as yet on actual health outcomes. For ultrasound of the thoracic musculoskeletal system, there is robust evidence only for diagnostic accuracy efficacy.We therefore outline avenues to further validate bedside chest ultrasound beyond diagnostic accuracy, with an emphasis on confirming enhanced health outcomes.

FIGURE 1

Levels of diagnostic test efficacy [8] depicting the available evidence for bedside chest ultrasound at each level and the relative clinical impact.

FIGURE 2

Selected chest ultrasound images. a) Sea-shore sign. Granular “sea-shore” appearance of normal lung sliding on M mode. b) Barcode sign. Horizontal “bar-code” appearance with loss of lung sliding on M mode. c) B-lines. Asterisks indicate comet tail artefacts arising from the pleural line (B-lines). d) Simple pleural effusion. “E” indicates anechoic free-flowing effusion. “L” indicates compressed atelectatic lung. “D” indicates diaphragm. e) Consolidation. “C” indicates consolidation. “D” indicates diaphragm. “L” indicates liver. “S” indicates serrated distal margins of the consolidation. Arrows indicate air bronchograms. f) Lung tumour. The arrow indicates the smooth distal margin of the mass.

FIGURE 3

Chest ultrasound syndromes: available evidence at each level of efficacy. Grey shading indicates a substantial body of evidence for that level of efficacy.