Study: Impact of Lung Ultrasounds in the Prehospital Setting

How prevalent is acute heart failure (AHF)? Is this a major problem in the U.S.?

More than a million patients are hospitalized with AHF annually. AHF refers to the rapid onset or worsening of signs of heart failure with symptoms that include severe shortness of breath, swelling in the legs and abdomen, and fatigue. AHF has a high healthcare cost burden accounting for over 20 billion dollars annually.

A leading cause of unplanned hospitalizations in the U.S., AHF is triggered by various factors, including medication non-compliance, diet non-compliance, heart attacks, and high blood pressure. As symptoms are similar to other conditions, such as chronic obstructive pulmonary disease (COPD), pneumonia, or asthma, AHF is challenging for first responders to diagnose correctly. Delayed diagnoses and treatments lead to poor outcomes for many patients - more than a quarter of patients diagnosed with AHF will die within 12 months.

How can ultrasound imaging help with AHF?

Lung ultrasound (LUS) can significantly help diagnose AHF and allows for quicker identification of AHF cases, compared to waiting for other diagnostic test results such as chest X-rays. It has also been shown to be more accurate than traditional diagnostic methods such as patient history, physical examination, and blood tests.

How common is it for paramedics to receive ultrasound training?

Ultrasound is not yet a standard skill for most paramedics in the U.S, although it has been adapted in prehospital settings for decades in other countries. In the U.S., field use of ultrasound is in a developmental stage, with ongoing research and implementation efforts. Within the last decade, the onset of more affordable, portable, all-in-one ultrasound probes – like the ones we used in our study—have made paramedic adoption increasingly feasible, supporting this transition toward a new standard of care.

What about staff in other prehospital settings?

In Europe, prehospital physicians are commonly using prehospital ultrasound to help guide care in patients with shortness of breath. Other studies have shown that, with modest investments in training and equipment, ultrasound could prove helpful for flight nurses or critical care paramedics, trauma assessments, and mass casualty incidents. Really, handheld ultrasound could be used in nearly any situation where healthcare providers and other medical staff need to quickly get an idea of what’s happening within the body.

Are there any challenges associated with paramedics having ultrasound technology on their ambulance? What is the financial burden?

One challenge we encountered during our study was that about 20% of patients whose symptoms qualified them for the study did not receive LUS when one was available on the ambulance. We theorize that some paramedics might have been less confident in their skill with use of the handheld ultrasound device or did not save images or interpretations.

Ongoing training would likely be the largest investment an emergency services provider would need to make, as the cost of the devices themselves is relatively affordable as medical equipment goes – just a couple thousand dollars.

Can you talk about the results with us? Was any of this surprising?

Our study looked at training a group of 26 full-time paramedics to diagnose AHF using a handheld portable ultrasound device from Butterfly Network. The training consisted of 30 minutes of classroom education, followed by 30 minutes of hands-on scanning. Participants also had to pass a written test and demonstrate competent use of the Butterfly device.

We found that paramedics with little to no prior training in LUS were able to use this tool accurately in the pre-hospital setting and that advanced diagnostic tools increased correct diagnoses of AHF by paramedics from 23% to 71%, with a very small 2.5% rate of false positives.

The significantly higher level of accuracy achieved by paramedics with relatively minimal training was impressive. This was not unexpected as we know LUS is easy to learn and can be performed by non-physicians. From a patient care perspective, there was a significant reduction in average time to treatment – from almost three hours to just 21 minutes when paramedics used the LUS device. Since we know that earlier treatment of AHF is associated with better outcomes, this could have a significant positive impact on mortality.

Will there be further studies done with additional EMS teams?

We purposefully limited the size of this pilot study to determine if handheld ultrasound devices could be adapted into prehospital management of patients experiencing AHF. More research is needed with a larger cohort of patients and with other EMS agencies. We also have plans to evaluate paramedic performed LUS with an AI augmented interpretation to evaluate diagnostic accuracy.