Page 83 - 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? 81
Results
Patients
Sixty-six lung US video clips were acquired in 11 patients, of whom eight women, with a mean age of 64.0 years (± 9.03). Their mean weight was 66.1 kg (± 9.30), and the mean body mass index (BMI) was 24.3 kg m–2 (± 2.98). Surgery was performed on the left and right chest in four and seven cases, respectively. All participants had a pneumothorax after the surgeon opened the thorax.
Observers
The video clips were observed by 15 physicians of whom 13 HEMS physicians (nine anesthesi- ologists, and four trauma surgeons) and two anesthesiology residents. These observers all had extensive experience (a mean of 7.1 years [± 3.58]) in lung ultrasonography.
Prior to the observations, six observers indicated to prefer a linear-array transducer for lung ultrasonography. Seven preferred a phased-array transducer and two had no preference. The curved-array transducer was preferred by none.
Each observer assessed the 66 cropped clips in a random order. There was no significant dif- ference between their different background for success rate (correct or incorrect diagnosis) or time they needed to assess the video clips.
In 10 of the 990 judged clips, an observer couldn’t decide on the diagnosis because the image quality was perceived to be too bad. Therefore, for data analysis where the diagnosis is a fac- tor we used the data on 980 clips. The time was recorded from the start of video playback to the moment the observer declared to be unable to state a diagnose.
Diagnostic performance
The overall sensitivity and specificity was 98.2% and 97.2%, positive predictive value (PPV) and negative predictive value (NPV) was 97.2% and 98.2%, respectively. A cross tabulation of the correct and incorrect diagnosis compared between transducers are displayed in Table 3.1.
The diagnostic performance measures for the different transducers for pneumothorax were calculated for 980 assessed clips and are displayed in Table 3.2.
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