Page 48 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars
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Chapter 2
Detection of pneumothorax during flight
In some EMS systems, patients are evaluated and treated while in-flight in a helicopter or fixed-wing aircraft. In prehospital and flight medicine, lung US was found to be feasible and safe.16,24,48 For instance, M-mode (Figure 2 3 and Figure 2 5) ultrasonography was used to successfully evaluate a pleural interface model on board a helicopter while stationary, with rotor rotation before take-off, and at level flight.49 Madill reported the case of a blast injury patient in whom an in-flight chest US examination identified an untreated pneumothorax. This directed the decision to perform a successful in-flight thoracentesis and tube thoracos- tomy.50 In 2013, Roline reported to be the first to evaluate in-flight chest US in a helicopter emergency medical service (HEMS) operation.51 They performed 41 chest US examinations in 71 patients. Expert sonographers reviewed the images and reached substantial agreement with the providers. Image quality was good or poor in 54% and 46%, respectively. Challenges consisted of the lack of time, limited aircraft space, and, less frequently, the presence of pacer pads. They concluded that in-flight chest US is feasible, has a steep learning curve, and that additional training is needed to improve image quality. Quick et al. found that the diagnostic accuracy of in-flight US for pneumothorax is nearly similar to US in the ED: 91% and 96%, respectively.52
These reports suggest that PHUS augment the diagnostic capabilities of prehospital aero- medical providers, also when in-flight, and might lead to better outcomes.
Hemothorax
No studies with substantial data on the diagnostic performance of PHUS and hemothorax are available. Ketelaars described that PHUS detected one hemothorax in seven cases specif- ically assessed for hemothorax with 100% accuracy.4 In a 2007 best evidence topic report the authors concluded that ultrasound is a sensitive, specific, and accurate method to detect the presence of hemothorax in trauma patients.53 A more recent meta-analysis of hospital studies revealed a pooled sensitivity and specificity of 67% and 99% of PoCUS for hemothorax. For radiography, these were 54% and 99%.54 Therefore, PoCUS for hemothorax may be valuable in both in-hospital and prehospital settings. Future studies might demonstrate the added value of early, prehospital, detection of hemothorax although an early chest tube thoracostomy is rarely required.55 Still, PHUS yields valuable information to include in the prearrival notifi- cation to the receiving trauma center.
