Objective: The detection of abnormal airs is important but not always easy on ultrasonography at the emergency room. Our study is to evaluate the different techniques to detect the abnormal airs from various etiologies on ultrasonography.
Methods: From 2002 to 2007, fourteen patients of abnormal airs from various etiologies were imaged on ultrasonography at our emergency room. All of them were scanned using three different techniques (in sequence) that classed to the traditional scan (3-5MHz), the high frequency ultrasound (10-15MHz), and the change in body position. And all of the cases were conformed by subsequent X-ray, barium study, computed tomography (CT) images, surgical findings, or pathologic findings. We analyze the images in retrospect to find the best technique in each situation.
Results: Ten of the fourteen cases (71.4%) revealed abnormal airs by the traditional scan technique alone. Five of the fourteen cases (35.7%) were got useful information by the high frequency ultrasound. Six of the fourteen cases (42.9%) were best imaged by the change in body position. Traditional scan seemed to detect more positive cases than other techniques. However, high frequency ultrasound was clearer to small amount or superficial airs and only the change in body position can recognize the two cases of pneumoperitoneum in our study.
Conclusions: None of each technique alone could detect all abnormal airs on ultrasonography at our emergency room. Different techniques may play different roles in different situations. Understanding of these techniques may result in better clinical application.