Page 77 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars
P. 77

                 Which ultrasound transducer type is best for diagnosing pneumothorax in pre-hospital care? 75
Introduction
In the critically ill and injured patient, an accurate physical examination is essential in the care of the patient. However, auscultating for breath sounds in a respiratory distressed pa- tient is often difficult or even impossible, especially in a noisy accident scene, or patient compartment of a (moving) ambulance or helicopter.
The sensitivity of auscultation for the diagnosis of hemothorax, hemopneumothorax, and pneumothorax is only 58–66%.1–3 Unilateral decreased or absent breath sounds are often in- terpreted as a pneumothorax. However, conditions such as splinting from rib pain, lung contusion, atelectasis, pneumonia, pleural effusion, and tumor growth may account for the same abnormal auscultation.
Lung ultrasonography (US) for the diagnosis of pneumothorax was first described in 1986.4 It may rule-in pneumothorax with a sensitivity ranging from 81–98% and rule it out with a specificity approaching 99–100%.5–7 Additionally, pleural effusion, lung contusion, and at- electasis may be detected.7 It has even been suggested that US might one day replace the stethoscope.8,9
US is feasible in the prehospital setting including inside ground ambulances and a heli- copter emergency medical service (HEMS).10–12 Similar to most diagnostic and therapeutic procedures, US requires training and regular practice. Time-pressure and limited working space are additional challenges.12 To facilitate the best possible images, it is important that optimally set-up US equipment is readily available. In an optimal configuration, the most suitable transducer is connected to the US machine.
Lung US can be performed with either high-frequency linear-array, curved-array, or phased-array transducers. However, it is not known which one is preferable and provides the best images.
We hypothesized that a linear-array transducer is the optimal transducer for the appreci- ation of the pleural line for diagnosing pneumothorax. The aim of the study is to compare three transducer types on diagnostic accuracy, speed of the diagnosis, and image quality in the assessment for pneumothorax.
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