key: cord-0925865-1oybwfhk authors: Kulkarni, S.; Down, B.; Jha, S. title: Point-of-care (POC) lung ultrasound in intensive care during the COVID-19 pandemic date: 2020-05-13 journal: Clin Radiol DOI: 10.1016/j.crad.2020.05.001 sha: 799a9e86692061583ec7984e661e967aaacc7e47 doc_id: 925865 cord_uid: 1oybwfhk Abstract Coronavirus disease 2019 has spread to every inhabited continent in the world. So far, plain radiography and computed tomography have been the mainstay of imaging methods used. The present analytical paper on the role of point-of-care lung ultrasound in this pandemic examines its diagnostic accuracy, clinical utility, and physical practicality in the intensive care unit. Lastly, the common advantages of ultrasound still apply: the test is cheap, uses no ionising radiation, and the results are available instantly. (8, 9) The literature on POCUS in COVID-19 has grown in the pandemic, although it comprises predominantly of case reports, opinion pieces, and tutorials. The present analysis stems from seven articles, outlined in Box 1. These constitute all of the articles present on Medline regarding POCUS in COVID-19 at the time of writing. Evidence was also included from articles on POCUS published prior to where this would supplement the readers' understanding of the topic. Interstitial syndrome and consolidation Interstitial syndrome refers to processes (water, infection, infiltration) in the pulmonary interstitium. In COVID-19, interstitial syndrome most likely results from acute respiratory distress syndrome (ARDS) or pneumonia.(11) Interstitial syndrome is characterised by B lines, which are vertical hyperechoic reverberations between the ribs, in contrast to the horizontally oriented A lines, which are seen in the normal lung. Further, subpleural consolidation presents as indistinct hyperechoic areas with surrounding B lines. In severe cases, consolidation can resemble the liver, which is known as hepatisation of the lungs. (17) Although non-specific, B lines are common in COVID-19, with Peng et al. (9) first to report their appearance. This was confirmed by other groups. (10, (14) (15) (16) In severe disease with significant oedema or consolidation, a "white lung" can be present. (11) For the detection of interstitial syndrome in non-COVID patients, the accuracy of ultrasound (95%; sensitivity 98%; specificity 88%) surpasses chest radiography (72%; sensitivity 60%, specificity 100%) and auscultation (55%; sensitivity 34%; specificity 90%). (18) Ultrasound can also distinguish between cardiogenic and noncardiogenic pulmonary oedema (8) and can be deployed rapidly to exclude alternative causes of hypoxia in intensive care. (19) For consolidation, ultrasound has an accuracy of 97% (sensitivity 93%; specificity 93%), compared with 75% for chest radiography (sensitivity 68%; specificity 95%) and 36% for auscultation (sensitivity 8%; specificity 100%). (18) Pleural inflammation Inflammation of the pleura causes pleural thickening and disruption, which can be visualised on ultrasound. Pleural thickening has been observed in COVID-19 pneumonitis. (10) (11) (12) (14) (15) (16) Although pleural thickening appears to be sensitive for COVID-19 pneumonitis, it is non-specific, being present to some degree in all forms of pneumonia. There is a paucity of literature on the ultrasonographic assessment of recovery from COVID-19. Peng et al. (9) report the re-appearance of A lines following treatment. Their re-appearance indicates a reduction in interstitial infiltration. Before the COVID-19 outbreak, ultrasound had been used in critical care to assess treatment response and for prognostication. In a clinical trial, Bouhemad et al. (20) showed that POCUS could titrate ventilator settings in positive end-expiratory pressure (PEEP)-induced lung recruitment. Haddam et al. (21) showed that POCUS enables monitoring of aeration during prone ventilation; however, it did not predict oxygenation response. Lastly, the lung ultrasound score (LUS), a quantitative measurement of noncardiogenic pulmonary oedema, quantifies disease severity and is prognostic in ventilated ICU patients with ARDS.(22) It is reasonable to suggest that these findings will also be true in COVID patients, who otherwise have POCUS findings similar to other forms of pneumonia. There are several causes of hypoxia in the ICU. Distinguishing between them is important as it enables the correct treatment to be given. The present review will demonstrate the advantage of using POCUS to distinguish between ARDS and pleural effusion will be used to illustrate this. Pleural effusion appears white on a chest radiograph and can be difficult to differentiate from consolidation. Furthermore, effusion of <500 ml is difficult to detect on chest radiography; in a ventilated ICU patient lying on their back, the fluid will be even more difficult to detect due to its dependent nature. (17) These factors result in a diagnostic accuracy of 47% (sensitivity 39%; specificity 85%) for pleural effusion diagnosis on chest radiography. (18) Conversely, pleural effusion is an anechoic rectangular region between the visceral and parietal pleura. The diagnostic accuracy of POCUS for pleural effusions is 93% (sensitivity 92%; specificity 93%), superior to chest radiography (above) and auscultation (accuracy 61%; sensitivity 42%; specificity 90%). (18) Pleural effusions are uncommon in COVID-19.(9) Therefore, its presence may indicate that another diagnosis should be considered, such as bacterial pneumonia or congestive cardiac failure. There are barriers to using POCUS in hospitals. Firstly, ultrasound is inherently userdependent. Inadequate training could lead to inadequate assessment and high interoperator variability. In a report on the Italian experience of POCUS in COVID-19, Vetrugno et al. (15) suggested that basic training and 25 supervised examinations was minimum to achieve basic proficiency. Although this training is time-consuming in the short-term, it provider greater yields in the long-term. On the question of time, decontamination of equipment between patients may add to the workload of intensive care physicians; however, compared to a portable X-ray or CT machine, ultrasound machines are faster to decontaminate due to their small size. Italian physicians have minimised decontamination time by using portable, hand-held ultrasound probes attached to sheathed tablet devices. (10, 13) HOW CAN HOSPITALS IMPLEMENT POCUS? The implementation of POCUS requires ultrasound machines, which can range from handheld devices to freestanding machines on wheels. All are portable, easy to decontaminate, and are a fraction of the cost of CT machines. Hospitals can repurpose ultrasound machines from departments running on reduced capacity due to COVID-19, such as in outpatient clinics, and also re-deploy technologists/radiologists to ICUs. CONCLUSION POCUS has a high sensitivity for the pulmonary manifestations of COVID-19, such as ARDS and consolidation. Furthermore, POCUS can be used to monitor treatment response. POCUS is an asset to hospitals as it minimises nosocomial spread of the disease. In centres with lack of expertise in POCUS, radiologists are encouraged to provide this service. 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How to perform lung ultrasound in pregnant women with suspected COVID-19 infection Proposal for international standardization of the use of lung ultrasound for COVID-19 patients; a simple, quantitative, reproducible method Lung ultrasound findings in a 64-year-old woman with COVID-19 Our Italian experience using lung ultrasound for identification, grading and serial follow-up of severity of lung involvement for management of patients with COVID-19 Lung ultrasound and computed tomographic findings in pregnant woman with COVID-19 Practical approach to lung ultrasound Comparative diagnostic performances of auscultation, chest radiography, and lung ultrasonography in acute respiratory distress syndrome Critical care ultrasonography differentiates ARDS, pulmonary edema, and other causes in the early course of acute hypoxemic respiratory failure Bedside ultrasound assessment of positive end-expiratory pressure-induced lung recruitment Lung ultrasonography for • POCUS minimises nosocomial spread.• POCUS can prognosticate and assess response to therapy.• In centres with lack of expertise in POCUS, radiologists are encouraged to provide this service. ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: