Page 80 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars

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Chapter 3
Figure 3.2 The surgeon performs lung ultrasonography in a patient with a confirmed pneumothorax and the videoscope in situ
The video screen displays an image of the inside of the right hemi-thorax and the collapsed right lung. The surgeon is handling the wrapped-up ultrasound transducer. The ultrasound device is shown in the back of the image.
The Nijmegen physician-staffed HEMS carries a portable US machine since 2006. All HEMS physicians were trained in lung US either at the introduction of the US machine or at the start of their employment. They use lung US regularly in their prehospital practice.
We recruited all 13 HEMS physicians (except the author, RK) and two anesthesiology resi- dents with extensive experience in lung ultrasonography as observers to assess a randomized set of 66 15-second ultrasound clips. We used PotPlayer for Windows, version 1.7 (Kakao Corp., Jeju, South Korea) to separately randomize and playback the cropped set of clips for each observer (Figure 3.4). Before the observers assessed the set of video clips, they were informed about how we acquired the clips and about the two possible conditions (normal ventilation and pneumothorax). Due to the cropping and randomization, the observers were blinded for the diagnosis and for the transducer type.
The observers were requested to pause the playback themselves when they were certain about the diagnosis based on the presence or lack of lung sliding, A-line sign, or B-lines. The equal-