Page 49 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars
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Diaphragmatic rupture
Diaphragmatic rupture occurs in up to 5% of blunt abdominal trauma patients and may be present despite a negative FAST scan.56 Ultrasonographic signs may be poor movement (on M-mode) or elevation of the diaphragm, a liver sliding sign (at the right chest wall), sub- phrenic effusion, or the presence of an intrathoracic spleen or liver.57–59 In addition, Ganga- har introduced Rip’s absent organ sign as an indirect marker: nonvisualization of the spleen or heart caused by displacement of abdominal contents anteriorly to these organs.60,61
B – Gastric tube
The only indication for a gastric tube (GT) in the prehospital setting is to relieve gastric dis- tention that is often caused or aggravated by bag-valve-mask ventilation. Traditionally, cor- rect positioning is verified by injecting air in the tube while listening for air bubbles, or by aspiration of gastric contents. These methods are unreliable, especially in the noisy prehos- pital environment, and the recommended pH measurements and chest X-rays are not feasi- ble.62 Chenaitia et al. estimated the diagnostic accuracy of PHUS confirming GT placement in 130 prehospital intubated patients, compared to in-hospital chest X-ray. They positioned the probe subxiphoidal in the transverse plane, oriented towards the left hypochondrium to visualize the GT tip in the gastric antrum. Examination time was limited to 1 minute. Sensi- tivity and specificity were 98.3% and 100%. PPV and NPV were 100% and 85.7%.63
In a follow-up study they added an esophageal view at the anterior neck during and after GT insertion. In case the GT was visualized in the esophagus but not in the stomach 50ml of air was inserted. An intragastric position of the tip was visualized or assumed when gastric air entry was observed as dynamic fogging: an expanding volume of hyperechoic ‘fog’. Sensitiv- ity and specificity were both 100% compared to in-hospital chest X-ray.64 When US is only performed after GT insertion, it is as fast as the traditional air insufflation and aspiration method.
C – Circulation – cardiac arrest
Current European resuscitation guidelines state that there is no doubt that focused cardiac ultrasound (FoCUS)—using specific protocols for US evaluation—has the potential to detect reversible causes of cardiac arrest.12 FoCUS can help distinguish the PEA type, identify the cause of the arrest, choose a suitable treatment, and make the right decision on cardiopulmo- nary resuscitation (CPR) termination.65 In 75% of the patients with pulseless electrical activi- ty (PEA) FoCUS showed coordinated cardiac motion (pseudo-PEA) in a prehospital peri-re- suscitation care study.66 Pseudo-PEA is strongly associated with increased survival compared
ABCDE of prehospital ultrasonography 47
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