I Gusti Bagus Oka Wijaya, I Nyoman Teri Atmaja
Poliklinik Radiologi RSU Wisma Prashanti, Tabanan, Bali, Indonesia
ABSTRACT
COVID-19 needs a fast and accurate diagnosis. The imaging procedure commonly used is chest X-ray and chest CT scan. But those techniques have relative immobility and risk of radiation exposure. Other method of lung evaluation is ultrasound. Ultrasound is safe with no absolute contraindication, easy to use because the device is mobile and portable. Lung ultrasound can be used for detection and diagnosis of lung abnormalities. I Gusti Bagus Oka Wijaya, I Nyoman Teri Atmaja. Emergency Lung USG in COVID-19 Era
Keywords: COVID-19, lung ultrasound
In December 2019, in the city of Wuhan, Hubei Province, China, 41 cases of pneumonia of unknown etiology were reported. The world health authority (WHO) on December 31 2019 announced an outbreak of pneumonia cases in China. Then on January 9 2020 WHO stated that the disease was caused by a new type of corona virus or called the 2019 new coronavirus (2019nCoV); The disease was named coronavirus disease 2019 or COVID-19.
The number of COVID-19 cases continues to increase, along with the expansion of screening and diagnostic examinations, until now the cumulative total worldwide is more than 34.8 million confirmed cases with more than 1 million deaths; most were reported in the Americas (55%), followed by Europe (23%). In the last week, the Americas, Southeast Asia and Europe added up to 91% of new cases. Five countries (India, United States, Brazil, Argentina, and France) reported 60% of new cases, while Israel recorded the highest incidence (3,717 new cases per 1 million population). Globally, the highest percentage of cases is reported in the 25-39 year age group, around 50% of cases in the 25-64 year age group. However, the percentage of deaths increases with age, around 75% of deaths occur at the age of 65 years and over. 3 As of October 6 2020, Indonesia has reported 311,176 confirmed COVID 19 patients; There were 11,374 deaths related to COVID-19 and 236,437 patients were declared cured.
COVID-19 manifests with a wide clinical spectrum ranging from no symptoms, mild symptoms, manifesting in several parts of the body, to septic shock and multiorgan dysfunction. 5 COVID-19 is classified based on its clinical manifestations, namely mild, moderate, severe and critical symptoms. The most common symptoms are fever, fatigue, dry cough, and diarrhea. Meta-analysis Fu, et al, 7 found that the most frequent symptoms were fever (83.3%), cough (60.3%), and fatigue (38.0%), followed by increased phlegm production, shortness of breath, and myalgia, with an estimated prevalence of each below 30%.
Common supporting examinations are rapid tests, PCR swabs, and chest photos or chest CT scans. Initial imaging is by plain chest x-ray (CXR); If there is doubt, computed tomography (CT) can be performed as a diagnostic tool. However, most imaging results of COVID-19 patients are found to be normal, especially during admission; in the early phase, 18% of patients had normal CXR or CT. CXR examination usually shows diffuse asymmetric opacity, similar to pneumonia but more peripherally located; The abnormality that differentiates this disease from other diseases is ground glass opacity (GGO) on CT examination. CT scan findings in COVID-19 patients are bilateral, subpleural GGO, with unclear margins, predilection in the right lower lobe. The appearance of pleural effusion, large small pulmonary nodules, and lymphadenopathy rarely indicates a diagnosis of COVID 19, but these images provide a differential diagnosis of pneumonia or pulmonary TB infection. However, the initial presentation is usually less specific and can resemble other diseases such as H1N1 influenza, cytomegalovirus pneumonia, and other atypical pneumonias. Over time, the radiological pattern evolves from a focal unilateral abnormality to a bilateral diffuse opacity so that a definitive diagnosis can be made. CT scan images of massive consolidation are often found in almost all patients who require intensive care (ICU).
Sesak napas merupakan kasus yang sering muncul di situasi emergensi. Saat menangani pasien kritis, klinisi seringkali dituntut untuk melakukan diagnosis dan tatalaksana secara cepat. Pada pasien tersebut anamnesis dan pemeriksaan fisik saja kurang tegas untuk diagnosis, dan CXR dapat mengecoh ataupun terlambat; pada saat demikian ultrasonografi dapat dijadikan alat untuk membantu diagnosis klinis karena alatnya portabel dan mobile. Ultrasonografi paru telah digunakan pada situasi di luar rumah sakit dan di daerah terpencil ataupun lokasi sulit untuk membantu diagnosis kelainan paru.
ULTRASONOGRAPHY OF THE LUNGS
Ultrasonography has been used as an imaging technique for more than 50 years; however, it is still widely considered limited for the diagnosis and treatment of respiratory tract diseases because the air-filled thoracic structure and rib cage hinder examination. Currently, lung ultrasonography is a rapid diagnostic tool for lung disorders such as pulmonary edema, pleural effusion, pneumothorax and lung consolidation. Lung ultrasound can be an alternative screening or diagnostic tool for COVID-19.
Technique
During a lung ultrasound examination, several signs must be understood, including:
1. Identify the pleural line (Figure 1, white line) and lung sliding (on ultrasonography, horizontal movement of the pleural line indicates that there is no pneumothorax).
2. A-line (Figure 1, yellow line, horizontal line extending from the pleural line); A-lines and sliding indicate normal lungs; A-lines without sliding indicate pneumothorax.
3. Lung point indicates pneumothorax.
4. B-lines (Figure 2, white arrow) indicate interstitial syndrome originating from the pleura. B-lines appear as 2 or 3 lines radiating from the pleura that eliminate the A-lines and extend the ultrasound image to the edge of the examination field.
5. Consolidation is confirmed as a fractal/shred sign (Figure 3, white arrow). Consolidated lung tissue appears as a subpleural hypoechoic region that looks like liver tissue with irregular and thick edges.
6. Signs of pleural effusion include quad and sinusoid signs (quad signs consist of 4 lines representing the pleura, ribs, fluid and lungs, while sinusoid signs indicate lung respiratory movements with atelectasis). These two signs have high sensitivity and specificity for pleural effusion (Figure 4).
Figure 1.
Ultrasound examination shows pleural line (white arrow), A line (yellow arrow), and rib cage (white star)
Figure 2
Ultrasound examination shows multiple B-lines (white arrows).
Figure 3
Ultrasound examination shows shred sign with fractal line (white arrow), lung consolidation (white star).
Figure 4
Ultrasound examination of lung consolidation with hepatization (white stars), air bronchograms (yellow arrows); pleural line (white arrow), rib cage (yellow star).
Lung Ultrasonography in COVID-19
COVID-19 has an ultrasound appearance that can mimic lower respiratory tract infections caused by other viruses; However, several characteristic features can differentiate it from other lung disorders. Research shows that lung ultrasound is superior to clinical evaluation and plain radiographs to aid in the diagnosis of COVID-19.
Imaging findings of COVID-19 on lung ultrasonography, namely B lines with varying shapes, irregular or fragmented shapes of the pleural lines, and minimal peripheral lung consolidation. This imaging is characterized by clustered glowing artifacts appearing from the normal pleura, disappearing, replacing the A-line of normal lung. B-lines imaging in COVID-19 pneumonia can be variable. COVID-19 has clusters of B-lines which are usually separate, but can cluster together, giving the appearance of white lungs. These lines may appear at one point from the pleura and from peripheral consolidation; This light shines to the end of the examination area. This imaging is a typical sign of COVID-19 pneumonia, but can sometimes be found in several other lung disorders. This imaging picture is always found in the early phase of COVID-19. This imaging can be an early sign of GGO in active COVID-19 cases, when the lesions are still limited and the lung parenchyma is still healthy. Chinese researchers describe this imagery as a waterfall sign. However, in Western countries it is more considered an artifact lesion as a light beam that disappears and appears during inspiration and expiration. As a note, it is better to use a convex probe with a wide beam and low frequency to get a clearer light beam image. Care should also be taken to position the focus at the pleural level to avoid vertical artifacts.
Buda, et al, studied the course of COVID-19 disease with lung ultrasound. In the early phase of COVID-19, examinations are generally still normal, but B-line artifacts can be found. As the disease progresses, the number of B-lines will increase and begin to form interstitial syndrome with a B-line appearance resembling a light beam. Along with inflammation, acute respiratory distress syndrome (ARDS) can occur. On ultrasonographic images of lungs with severe clinical conditions, massive consolidation can be seen and lung sliding is no longer found. This pathological process is usually found in the middle and lower lobes of the lungs on the lateral-posterior side. In the improvement phase, the interstitial lesions will slowly disappear, then the number of B-lines and consolidations will slowly decrease, until they finally become A-lines which are usually found in normal lungs. However, the lung process cannot completely recover, so a picture of fibrosis is found in the healing phase.
Massive/large consolidation lesions can indicate co-infection with bacteria, consolidation lesions in COVID-19 are generally minimal, and massive pleural effusions are also rare, but minimal effusions can still be found in areas not exposed to air.
Lung ultrasound is sometimes used to diagnose cases of respiratory disorders such as cardiogenic and non-cardiogenic pulmonary edema, pulmonary embolism, or bacterial pneumonia, these diseases have a similar appearance to COVID-19 pneumonia, so they are a differential diagnosis. In this case, the clinician must take the patient’s history, physical examination, and other findings as a diagnostic tool. Although the lung ultrasound picture of COVID-19 has several distinctive characteristics, not all COVID-19 patients have this ultrasound picture. To compare the lung ultrasonography image of COVID-19 with other diseases, see table 1.
Figure 5
Comparison of ultrasound images with CT: Normal (A), B-lines appear (B and C), mild peripheral consolidation (D), severe consolidation (E). The red area in (C) shows GGO on CT correlating with B-lines on ultrasound.
Table 1
Differences in lung ultrasound findings in COVID-19 and other diseases.
Use of Lung Ultrasonography in Emergency Cases
The advantages of lung ultrasonography in emergency cases include bedside use with fast availability due to mobile and portable devices, no radiation exposure, easy re-examination, and almost no absolute contraindications. Thus, children, pregnant patients, and patients who cannot get out of bed can be examined easily. In addition to being a diagnostic tool, ultrasound can also guide therapeutic and invasive procedures such as drainage of pleural or pericardial effusion. The main limitation is that it depends on the skill of the examiner, which means that ultrasound training is a requirement to obtain appropriate results. The main purpose of ultrasonography for emergency cases is the initial assessment of the patient to guide further intervention, both diagnostic and therapeutic.
The recommended protocol is the COVID-19 Lung Ultrasound in Emergency (CLUE) protocol, which will later be scored based on the lung ultrasound scoring system (LUSS).
The following are the inspection steps in an emergency situation:
The COVID-19 pandemic has many clinicians considering the use of lung ultrasound to reduce the risk of exposure to infection; Lung ultrasound has been reported to be very useful in decision making in COVID-19 patients. However, currently lung ultrasound examination in COVID-19 patients does not yet have definite diagnostic criteria, prognostic value, and cut-off value for diagnosis, as well as indications and timing of examination (every day, twice a day, based on clinical conditions). Clinicians must make decisions carefully, avoiding rash decisions based on unclear data.
It is recommended that the scan be performed systematically as 12 zones, six zones for the right lung (R1 to R6) and six
zone for the left lung (L1 to L6, Figure). Scanning the posterior zones (R5, R6, L5, L6) will increase the sensitivity of lung ultrasonography, because most abnormalities occur in the posterior lung. For safe scanning, the patient sits facing away from the clinician. The posterior, lateral (R3, R4, L3, L4), and anterior (R1, R2, L1, L2) zones are scanned by the doctor from behind the patient. If the patient is in the supine position, the posterior zone is replaced with an area close to the posterior axillary line. It takes less than 10 minutes to perform a lung ultrasound. During the examination, it is recommended to carry out infection control and disinfection protocols.
LUSS is a valid score for assessing lung aeration in patients with ARDS and can be used in COVID-19 pneumonia with a similar interpretation. In each zone, the LUSS score ranges from 0-3, where a score of 3 indicates massive changes in lung structure. Based on scoring in 12 zones, the severity of the disease is divided into mild (score 1-5), moderate (>5-15), and severe (>15), normal lungs have a score of 0.
CONCLUSION
Pulmonary and pleural ultrasonography is essential in the assessment of patients in the emergency department. Ultrasonography is safe for all groups, free from radiation, dynamic, cheap, and can be done anywhere. Devices can be protected with plastic to reduce the risk of contamination and simplify the sterilization process. Several conditions can be evaluated with lung and pleural ultrasonography, including consolidation, pulmonary edema, pneumothorax, and pleural effusion. Ultrasonography can be used for both detection and diagnostics of patients with COVID-19.
