Anesthesiologists and Critical Care Physicians are confronted with the differential diagnoses of dyspnea, complications of mechanical ventilation or rapid assessment of trauma patients on a nearly daily basis. This requires the timely diagnosis or exclusion of a wide variety of disease processes including pleura effusion, pneumonia, pneumothorax as well as thoracical or abdominal bleeding. Furthermore, the anaesthesiologist or intensivist often makes decisions leading to invasive procedures like thoracentesis or percutaneous dilatational tracheostomy. Bedside ultrasound as the "visual stethoscope" of the acute care physician offers an alternative to other imaging modalities like X-ray and CAT scan and can reduce associated high-risk transportation of mechanically ventilated patients. In this article, we introduce a new training module based on the DGAI curriculum.

The development of modern critical care lung ultrasound is based on the classical representation of anatomical structures and the need for the assessment of specific sonography artefacts and phenomena. The air and fluid content of the lungs is interpreted using few typical artefacts and phenomena, with which the most important differential diagnoses can be made. According to a recent international consensus conference these include lung sliding, lung pulse, B-lines, lung point, reverberation artefacts, subpleural consolidations and intrapleural fluid collections. An increased number of B-lines is an unspecific sign for an increased quantity of fluid in the lungs resembling interstitial syndromes, for example in the case of cardiogenic pulmonary edema or lung contusion. In the diagnosis of interstitial syndromes lung ultrasound provides higher diagnostic accuracy (95%) than auscultation (55%) and chest radiography (72%). Diagnosis of pneumonia and pulmonary embolism can be achieved at the bedside by evaluating subpleural lung consolidations. Detection of lung sliding can help to detect asymmetrical ventilation and allows the exclusion of a pneumothorax. Ultrasound-based diagnosis of pneumothorax is superior to supine anterior chest radiography: for ultrasound the sensitivity is 92-100% and the specificity 91-100%. For the diagnosis of pneumothorax a simple algorithm was therefore designed: in the presence of lung sliding, lung pulse or B-lines, pneumothorax can be ruled out, in contrast a positive lung point is a highly specific sign of the presence of pneumothorax. Furthermore, lung ultrasound allows not only diagnosis of pleural effusion with significantly higher sensitivity than chest x-ray but also visual control in ultrasound-guided thoracocentesis.

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