The gold standard in challenging differential diagnoses of pulmonary pathology in chest X-rays is the CT scan. To reduce undue risk to the patients, like unintended extubation and dislocation of central venous catheters during transport, a noninvasive bedside tool would be preferable. The accuracy of ultrasound in diagnosing pulmonary pathology such as pleural effusion, consolidation, or pneumothorax has already been demonstrated [1, 2]. In the normal lungs, ultrasound can usually identify the pleural line. The horizontal lines under the pleural line are separated by regular intervals that are equal to the distance between the skin and the pleural line. These lines are artifact lines and reflect the presence of elements with high acoustic impedance gradient (air and pleural tissue in this case), and they are called A lines (Figure 3). In a comparative study by Lichtenstein et al., it has been shown that the accuracy of ultrasound in patients with ARDS was 93% for pleural effusion, 97% for consolidation, and 95% for alveolar interstitial syndrome compared with 47%, 75%, and 72%, respectively, for chest X-rays [2]. In children, ultrasound was demonstrated to be of equal clinical value compared to CT scanning in detecting parapneumonic effusions [3]. In 2008, an algorithm (the so-called BLUE protocol) for lung ultrasound was published which reached an immediate diagnosis in acute respiratory failure of > 90% [4]. We would like to promote the use of bedside ultrasonography in the emergency department and critical care departments as a reliable, low-cost, and radiation-free tool to differentiate the main potential pulmonary diagnoses. The physical properties of the ultrasound give a good access to the pleural space pathology, such as air or fluid in the lung, or a consolidated adhesive lung. This tool has seen a significant progression in the field of critical care over the last 10 years, particularly in the case of central venous line insertion, echocardiography, and ultrasound of the lung.