Page 79 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars
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                 Which ultrasound transducer type is best for diagnosing pneumothorax in pre-hospital care? 77
ultrasound video clips were recorded of normal ventilation at a respiratory rate of 20 min-1. The zone of interest was the pleural line with its two adjacent ribs. A typical clip was framed as shown in Figure 3.1.
Figure 3.1 Typical uncropped image of the pleural interface acquired with a linear-array transducer
Thirdly, after the chest was prepped and draped, ventilation of the non-dependent lung was interrupted while the surgeon opened the chest, introduced the videoscope and visually confirmed the collapse of the lung. Thereafter, the surgeon recorded three similar 15-second video clips of the established pneumothorax with the three transducers wrapped in sterile transducer covers (Figure 3.2). Hence, six clips were recorded in every patient. The time in- terval between the induction of the pneumothorax (reference test) and the performance of the three ultrasound video clips was no longer than two minutes. No adverse events occurred.
We cropped the video clips using iMovie for OS X, version 10.1.8 (Apple Inc., Cupertino, CA, USA). After we cropped and removed the text from the captured video clips, it was now no longer possible for the observers and the researchers to reliably recognize the transducer type by the image shape (rectangular or sector-shaped). An uncropped still image of the video clip and its cropped version are displayed in Figure 3.3.
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