Acute Dyspnea Assessment: Portable Ultrasound Better Than CXR?

Emma Hitt, PhD

October 24, 2012

ATLANTA, Georgia — With minimal training, internal medicine house staff can successfully use hand-held ultrasound devices in the diagnosis of acute dyspnea, according to a new report.

Ravindra Rajmane, MD, from the New York University Langone Medical Center in New York City, and colleagues reported the study findings in a poster presentation here at CHEST 2012: American College of Chest Physicians Annual Meeting.

"The technology of sonography has improved markedly over the past few years," Dr. Rajmane told Medscape Medical News. "Our study underscores the ease of transporting and effectively applying this technology with minimal training," she said. "Our residents were able to successfully learn the basics of lung ultrasonography with a 1-hour didactic lecture followed by 1 hour of hands-on training. Unstructured training was also provided during ICU [intensive care unit] rounds."

According to the researchers, acute dyspnea is normally assessed with a combination of history taking, physical examination, electrocardiography, chest x-ray, and lab work. Lung ultrasound is increasingly being used to assess acute respiratory conditions because it is faster, less invasive, and more sensitive.

The researchers assessed the ability of medical residents to learn to perform and interpret lung ultrasonography with minimal training.

For the study, 6 medical residents took the 1-hour training course outlining ultrasound images (A-lines, B-lines, lung sliding, and pleural effusions) related to causes of acute dyspnea. Residents supervised by a principal investigator performed lung ultrasound on patients in a mobile ICU.

Residents were able to identify more than 70% of A-lines, more than 80% of B-lines, and almost 90% of lung sliding. Lung ultrasound confirmed the clinical diagnosis in almost 95% of patients. Chest x-ray and lung ultrasound findings were aligned in more than 63% of cases. Ultrasound was more accurate in 1 case, suggesting that the faster, less-invasive option could replace the standard use of chest x-ray in the diagnosis of causes of acute dyspnea.

Results May Change the Face of Training

"This study will lead to better and more prompt patient care. It will also begin the dialog with internal medicine residency programs to incorporate ultrasonography as a key component of the physical exam and vital part of residency curriculum," Dr. Rajmane said.

According to Dr. Rajmane, lung ultrasonography provides immediate information on the causes of respiratory failure. "Ultrasonography provides a richer window into ailing physiology. We can look at a failing heart, hidden fluid collections, and optimal sites for invasive procedures," she added.

Independent commentator Michael Blaivas, MD, from the University of South Carolina School of Medicine in Charleston, and editor-in-chief of the Critical Ultrasound Journal, thinks that, on the basis of these findings, the method is effective and convenient.

"The convenience part is somewhat inferred," he explained. However, "ultrasound was more sensitive than chest x-ray for some findings, like pleural effusion, that are easily seen on ultrasound but missed on chest x-ray."

According to Dr. Blaivas, this is a bedside or point-of-care test that uses no radiation, can be performed very rapidly, and can be performed by relative novices. "Thus, the clinician may be able to, in the future, take an ultrasound device from their pocket and decide if the patient has pulmonary edema or congestive heart failure as the cause of their dyspnea — usually acute or at least exacerbation of chronic," he told Medscape Medical News.

This could be done in a matter of minutes, not the hours it takes to send the patient to a radiology suite (or have a portable machine brought from the radiology department), and shoot, develop, and review a chest x-ray, he explained.

Bedside Ultrasound in Other Settings: Europe Ahead of North America

It remains to be seen how well this technique will be integrated outside of the hospital, in settings such as a private office or clinic and in emergency departments (EDs). It is also unclear what to do in cases where ultrasound is more accurate than chest x-ray, which appears to be not infrequent, Dr. Blaivas said. "Do we go to CT scan and a lot more radiation, or just believe the ultrasound even if one is still getting experience with the technique after initial training and hospital credentialing?" he asked.

There are a lot of data "on the benefits of lung ultrasound in clinical practice, and our colleagues in Europe are probably ahead of us here in North America. As ultrasound use by clinicians will naturally lead to increasing use at the bedside in the ICU, floor, ED, and other settings," he said.

The study was not commercially funded. Dr. Rajmane and Dr. Blaivas have disclosed no relevant financial relationships.

CHEST 2012: American College of Chest Physicians Annual Meeting. Abstract 2177. Presented October 24, 2012.