August 5, 2020

Is it time to ditch the stethoscope?

Daily Briefing
    Editor's note: This popular story from the Daily Briefing's archives was republished on March 23, 2021.

    As Covid-19 "reshapes how medicine is practiced in" America, it could deal the final blow needed to send "one iconic tool" of the trade to "the dustbin of medical history": the stethoscope, hospitalist Larry Istrail writes in a STAT News opinion piece.

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    America's coronavirus epidemic has continued to worsen, and in light of the virus' unrelenting spread, a lot of clinicians have decided that the "ratio of useful information to infection risk does not favor employing a stethoscope on any patient with even a whiff of Covid-19 related illness," Istrail writes.

    Instead, doctors are increasingly turning to the "budding dark horse of modern bedside medicine: the portable, and increasingly affordable, [point-of-service] ultrasound," he writes. According to Istrail, the handheld, radiation-free, point-of-service ultrasound uses high-frequency sound waves to "digitally peel back the skin and observe the ecosystem of internal organs functioning in real time, an ability our forefathers and stethoscope-monogamous colleagues could infer only through skin changes, audible noises, and subjective symptoms."

    Ultrasounds are more accurate than stethoscopes, researchers found

    Further, Istrail writes that "there are many clinical scenarios in which point-of-care ultrasound provides more and better information than a stethoscope," and perhaps the most illuminating example is a study, published in Nature, comparing lung examinations performed with a stethoscope and with an ultrasound.

    When doctors used stethoscopes to detect whether patients had pulmonary edema—a buildup of fluid in the lungs, typically caused by congestive heart failure, that can cause a "crackling sound" when patients take a breath—the doctors picked up 46% of cases, and only 67% of the patients presenting with that crackling sound actually had congestive heart failure. In comparison, point-of-care ultrasound accurately detected 97% of cases, with only 2% of false positives.

    Similar differences in sensitivity and specificity were found when the methods were compared for other conditions, such as asthma or COPD, or pleural effusions, Istrail notes.

    The researchers concluded that lung auscultation, or stethoscopes, should only be used "in resource limited settings, with a high prevalence of disease and in experienced hands." They added that, in most cases "better diagnostic modalities" should replace stethoscopes.

    Moreover, according to Istrail, stethoscopes are also known to carry dangerous bacteria and are cleaned infrequently. In fact, stethoscopes were connected to a coronavirus outbreak in a South African hospital, he notes.

    And in the era of Covid-19, Istrail writes that the "point-of-care ultrasound has proven invaluable." He explains that ultrasounds are more sensitive than chest X-rays in detecting Covid-19, and the devices can limit the number of health care workers that come into contact with one patient by equipping one physician to do the initial evaluation and the imaging.

    In addition, "in patients with a high suspicion for Covid-19 but a negative nasal swab test, ultrasound provides valuable objective information to determine if that negative test warrants a repeat, as these tests still have notoriously high false-negative rates," Istrail writes.

    'Time is life'

    Given the proven benefits of using point-of-care ultrasounds, why are we still clinging to stethoscopes, Istrail asks.

    According to Istrail, very few internal medicine physicians use ultrasounds, usually due to a "lack of formal training and cost." He notes that one ultrasound system can cost between $2,000 and $50,000 compared with $400 for a "top-of-the-line" stethoscope.

    But "[w]hile the stethoscope is certainly more available and affordable, it fails to provide accurate data, the most crucial measure of a good screening assessment," he writes—noting, after all, that inaccuracy could be the difference between life and death.

    "Time is life when you can find in a patient with plummeting blood pressure a large pericardial effusion compressing the heart," he writes. "Time is life when you can detect a large blood clot brewing in the leg before it has broken off and traveled to the lung, causing a life-threatening pulmonary embolism."

    In addition, Istrail writes that point-of-care ultrasounds are becoming more affordable. One ultrasound that connects to a smartphone is 20 times cheaper than traditional ultrasounds, he notes.

    Ultimately, if ultrasounds become widely used, stethoscopes can be banished to the "dustbin" once and for all, according to Istrail. "I believe that given the remarkable diagnostic accuracy of point-of-care ultrasound, every patient presenting to a clinic or hospital should have a focused ultrasound to augment their clinician's physical exam findings," he writes. "There is just no excuse not to" (Istrail, STAT News, 7/15).

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