is the specialized application of ultrasound
by emergency responders
, such as paramedics, to guide immediate care and first aid
procedures. Like conventional ultrasound, it is a device that produces cyclic sound pressure
to penetrate a medium (usually flesh, in this instance) and reveal details about the inner structure of the medium.
Differences between emergency ultrasound and conventional ultrasound
Many emergency physicians now view screening ultrasound as a tool, and not a proceedure or study. It is primarily used to quickly and correctly ascertain a limited set of internal injuries, specifically those injuries where conventional methods of determining them, such as trauma to the torso or heart, would either take too long, require too much time to prepare, or introduce greater risk to the patient.
While conventional ultrasound can be a lengthy process, and is usually conducted with non-mobile units and advanced image filtering and manipulation built into the unit, emergency ultrasound is as simple and quick to operate as possible, and narrowly focused on a small set of criteria.
Uses of emergency ultrasound
The primary uses of emergency ultrasound are determining the severity of fluid or trauma to the midsection, determining immediate trauma or penetration of the heart, and to process sources and extent of internal bleeding. Specific implementations vary, some areas use the German originated FAST SCAN system which focuses on fluids in the paracolic gutter and the Douglas and Morrison pouch. Others focus more on cardiac ultrasounds.
Emergency ultrasound procedures
In most cases, EMT's will deploy a portable unit. In every instance, an attempt is made to find the area best suited to an ultrasound and utilize bare skin if possible. Resolution is vastly decreased if soundings must be made through any form of clothing.
There are two main areas of emergency ultrasound. The FAST system focuses on trying to ascertain if there is internal bodily fluid in blunt abdominal trauma, in the areas between organs, which is a sign of severe internal injury. CARDIASOUND is used to attempt to find blockages, clots, or penetrations of the heart. Both systems are scanning methodologies, they use identical equipment.
Strengths of emergency sonography
- It images muscle, soft tissue, and bone surfaces very well and is particularly useful for delineating the interfaces between solid and fluid-filled spaces, unlike most other methods of trauma diagnosis, which are little more than educated guesses.
- It renders "live" images, where the operator can dynamically select the most useful section for review, and narrows down the problem area, rather than having to wait until the patient is at the hospital.
- It has no known long-term side effects and rarely causes any discomfort to the patient.
Weaknesses of emergency sonography
- Sonographic devices have trouble penetrating bone. For example, sonography of the adult brain is very limited. This means that in terms of trauma diagnosis involving concussions, sonography will not work.
- The depth penetration of ultrasound is limited, making it difficult to image structures deep in the body, especially in obese patients, which can be compounded by thick or obscuring clothing that can't be removed out of fear of harming the patient.
- The method is operator-dependent. A high level of skill and experience is needed to acquire good-quality images and make accurate diagnoses, which is one more skill that a limited EMT team must develop. Since most EMT teams are small and suffer high turnover, retaining qualified personnel can be difficult.