Lung Ultrasound in Critical Care: A Narrative Review

Abstract

Lung ultrasound (LUS) has become a crucial part of the investigative tools available in the management of critically ill patients, both within the intensive care unit setting and in prehospital medicine. The increase in its application, in part driven by the COVID-19 pandemic, along with the easy access and use of mobile and handheld devices, allows for immediate access to information, reducing the need for other radiological investigations. LUS allows for the rapid and accurate diagnosis and grading of respiratory pathology, optimisation of ventilation, assessment of weaning, and monitoring of the efficacy of surfactant therapies. This, however, must occur within the framework of accreditation to ensure patient safety and prevent misinterpretation and misdiagnosis. This narrative review aims to outline the current uses of LUS within the context of published protocols, associated pathologies, LUS scoring systems, and their applications, whilst exploring more novel uses.

Keywords: COVID-19; acute respiratory failure; lung aeration; lung ultrasound; point-of-care ultrasound; weaning.

Figure 1

Normal lung ultrasound of aerated lung demonstrating ’bat wing’ appearance of ribs and A-lines.

Figure 2

(A) Confluent B-lines (arrow) consistent with pulmonary oedema and (B) consolidated and collapsed lung with shred sign (arrow).

Figure 3

(A) Complex pleural effusion with fibrin stranding (arrow) and (B) haemothorax with adherent haematoma on the diaphragm (arrow).

Figure 4

LUS findings on COVID-19 progression. (A) Normal aerated lung, (B) irregular pleural line with B-lines, (C) B-lines on >50% of image: ‘white lung’, (D) completely de-aerated collapsed lung.