Many emergency physicians and paramedics now view point-of-care ultrasound as a tool, and not a procedure or study. It is primarily used to quickly and more correctly ascertain a limited set of internal physical findings to aid in emergent patient assessment and treatment.
While conventional ultrasound can be a lengthy process, and is usually conducted by highly trained and experienced sonographers with non-mobile units, prehospital ultrasound is a portable, simple and quick process that is narrowly focused on a small set of criteria.
There are many indications for the use of prehospital ultrasound. Often determining the severity of trauma to the chest and abdomen, determining and assessing trauma or penetration of the heart, and to identify extent of internal bleeding are starting points. Specific implementations vary across the country, some areas use the German originated FAST scan system which focuses on fluids in the paracolic gutter and the Douglas and Morrison pouch. Some focus more on cardiac ultrasounds while others only use it to start IVs. As a part of the FAST exam, it is common for the examiner to quickly image the sliding lung against the chest wall to rule out pneumothorax. If the visceral and parietal lung have separated, the lung sliding will disappear indicating a probable pneumothorax. If lung sliding is seen, there is no significant pneumothorax. This simple addition to the FAST exam can accurately identify lung collapse in only 1 additional minute. This Enhanced FAST exam is often called EFAST. Another useful indication is assessing intravascular volume by looking directly at the inferior vena cava (IVC). Large IVCs that don’t collapse during inspiration suggest that there is plenty of blood returning to the heart. Cardiac imaging can give the provider a sense of ejection fraction and heart function. Patients with pulmonary embolism can have a markedly enlarged right ventricle during the event, giving additional clues to the provider for correct diagnosis and treatment. A Recently appreciated exam is lung ultrasound. It can accurately differentiate COPD exacerbations from heart failure in seconds. AAA, cardiac and pleural effusions are fairly easy to identify. As time goes on, it is likely that there will be dozens of additional indications for field use.
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