Page 44 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars

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Chapter 2
The LCI, triple scan, and BLUE protocol all might be relevant and valuable in the prehospital setting because of simplicity and nominal time investment. With the help of these protocols the EMS caregiver can accurately differentiate between causes to direct treatment and avoid unnecessary or harmful interventions.
Besides the diagnosis of dyspnea, lung US may be used to support prehospital continuous positive airway pressure (CPAP) treatment.41. In 20 ADHF patients, a physician-staffed EMS sonographically assessed 15 chest wall regions before and after CPAP treatment compared to standard treatment. The number of B-lines (explained in Table 2.1 and shown in Figure 2.1 and Figure 2.2) was significantly lower in the CPAP group, and their respiratory and hemo- dynamic variables improved after CPAP. The number of B-lines correlates with the amount of extravascular lung water (EVLW) and NT-proBNP levels and thus with the severity of ADHF. They develop at a pulmonary artery occlusion pressure (PAOP) > 18 mmHg.42
Figure 2.1 Normal lung
A normal lung ultrasound image acquired with a 15-6 MHz linear transducer. The ribs are visible with their anechoic shadows on both sides of the image. The pleural line is shown in between the ribs, indicated with two horizontal arrows. Emanating down from the pleural line are comet-tails. B-lines (not visible here) also start at the pleural line, but extend all the way down to edge of the image.