PŘEHLEDOVÉ ČLÁNKY / REVIEW ARTICLES Imaging of COVID-19 in critical care with a focus on chest ultrasound 64 | ANESTEZIOLOGIE A INTENZIVNÍ MEDICÍNA / Anest intenziv Med. 2023;34(2):61-68 / www.aimjournal.cz from Wuhan in the early 2020 [30]. The Czech Society of Radiology has advocated for the use of CT on admission; however, the algorithm concedes to CT findings not being specific solely to the COVID-19 infection [17]. In contrast, due to the increased volume of CT examinations during the pandemic, a number of societal guidelines recommended against the use of CT as a screening tool [18–21]. A widespread use of CT in every patient with severe COVID-19 has been disregarded by several national and international radiology societies. The Radiologic Society of North America, the Canadian Society of Thoracic Radiology, and the Canadian Association of Radiologists have advocated against routine CT in every respiratory insufficiency due to unspecific findings and lack of sensitivity in the first 48 hrs. Instead, the diagnostic effort should be channelled towards appropriate sputum testing and CT should be limited to diagnosing complications such as lung abscesses or empyemas, or in cases where CT imaging can change the clinical management of the patient [18–20]. In summary, the pandemic era should not change the attitude of a critical care physician to chest CT in a patient with respiratory insufficiency. Alleged changes in therapy based on the calculated percentage of diseased lung parenchyma on radiology methods are not supported by any relevant clinical data. Moreover, in daily practice, we have seen multiple patients with a rather poor correlation between their radiology imaging findings and clinical status (Figs. 2 and 5). Detection of viral load, i.e. of a living virus, implies infectiousness, the need for virostatic therapy, and is not correlated to findings on chest imaging [31]. Physicians should avoid extremes supported by an inappropriate use of CT. An example is denying treatment to someone with excessive lung involvement on CT and with more than seven days of clinical findings, which has been part of some guidelines [32]. Coronavirus mutations (Beta, Delta) replicate often beyond 10 days, especially in an immunocompromised population where half of the patients may still be antigen positive [33, 34]. Therefore, parenchymal changes may also resolve slowly and, in many patients, may persist regardless of clinical resolution of the disease. Chest ultrasound CUS has demonstrated its usefulness during the pandemic when evaluating patients at the bedside for the evolution of the disease and the efficacy of treatment initiated for COVID-19 pneumonia. The ultrasound machine has become widely available in intensive care units and is easier to clean and disinfect than other radiographic imaging methods. This reduces the potential of complicated transport to the CT suite for imaging indicated for establishing the diagnosis of COVID-19. Unless other confounding factors are at play which can only be assessed by CT, CUS also reduces unnecessary infectious and radiation exposure of both personnel and patients [9, 23, 35, 36]. CUS should be performed systematically in an algorithmic way. The comprehensive 12-zone method (6 zones per hemithorax) of examining Fig. 5. The course of a severe global respiratory failure on bedside X-ray documents a poor correlation between CXR lung findings and disease severity: A CXR on Day 2 after cannulation of VV-ECMO for severe hypoxia in an intubated patient with severe COVID-19 ARDS; B CXR on Day 5 pre-extubation on VV-ECMO; note the radiographic worsening of the bilateral parenchymal opacities contrasting with grossly improved lung mechanics allowing for extubation; C CXR on Day 8, the patient is extubated on an oxygen face mask and with the ECMO cannulae removed, i.e. not seen on X-ray. Overall gross improvement is not followed by the bilateral lung findings on X-ray, similar to A (one day after admission) Fig. 4. COVID-19 on CT scans: four different patients with various disease severity: A oxygen by face mask (O2 mask); B non-invasive ventilation; note the asymmetry with predominant right lung ground-glass opacities; C IPPV and VV-ECMO, acute fibrinous organising pneumonitis; D IPPV and VV-ECMO, diffuse alveolar damage A O2 mask NIV IPPV, VV-ECMO IPPV, VV-ECMO B C D
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