[Miniaturization, experimentation, and A.I. have unlocked
revolutionary potential in an old technology.]
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COULD ULTRASOUND REPLACE THE STETHOSCOPE?  
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Clifford Marks
January 20, 2023
The New Yorker
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_ Miniaturization, experimentation, and A.I. have unlocked
revolutionary potential in an old technology. _

, Illustration by Nicholas Konrad / The New Yorker

 

The patient, a man in his early twenties, hobbled into the E.R. on a
Wednesday morning, anxious and gasping, his shirt covered in blood.
Minneapolis in the nineteen-eighties was experiencing an increase in
violent crime that would later earn it the nickname Murderapolis; at
Hennepin County Medical Center, the city’s safety-net hospital,
stabbings and gunshot wounds had become commonplace. Doctors there had
treated dozens of patients with wounds to the chest, and the outcomes
had been dismal: roughly half had died, and many survivors suffered
brain damage.

The chest contains the heart, the lungs, and the body’s largest
blood vessels. The challenge for a doctor is figuring out which, if
any, organs have been injured, since each must be treated differently.
For decades, medical texts had advocated using a stethoscope for this
task: in theory, doctors could use a patient’s breath pattern to
detect a collapsed lung, or hear the muffled sounds of a heart filling
with blood. But in reality the stethoscope performed poorly in the
emergency room. It was dangerous to just treat and hope for the best:
by acting without a clear diagnosis, a doctor could harm or even kill
a patient, who might turn out to have only a superficial injury.

If the bloodied man at Hennepin had arrived a day earlier, he might
have died while his doctors continued to monitor him. But he had
stumbled into an experiment. A small group of Hennepin doctors had
decided to place an ultrasound machine in the E.R.’s trauma bay, to
see if they could quickly diagnose hemorrhaging in the heart.
Ultrasound lets clinicians see inside the body in much the same way
echolocation allows bats to navigate at night: a probe emits sound
waves at a frequency far beyond human hearing, and these waves bounce
off bone but pass through fluid, allowing the probe, which is also a
receiver, to sense the body’s interior. On an ultrasound screen,
bones appear bright white, flowing blood looks black, and most other
bodily tissues are visible in different shades of gray.

As doctors and nurses descended on the injured man, someone rolled the
half-ton ultrasound machine close and placed its probe on his chest.
Sound waves spread imperceptibly through his body, and an instant
later his heart filled the screen. It was surrounded by light gray:
blood was beginning to suffocate it. The man was rushed to the
operating room, where surgeons quickly drained the encroaching blood
and repaired the wounds to his heart. He recovered without significant
disability.

Ultrasound is an old technology, with roots in the sonar scanners used
during the Second World War. For decades, it’s been used mainly to
inspect fetuses while they’re still in the womb, and to examine
diseased hearts. But, in the past few decades, rapid advances in
computer technology, combined with the trial-and-error work of
clinicians, have transformed ultrasound into a powerful diagnostic
instrument for everything from damaged organs to tuberculosis. If
ultrasound’s evangelists are correct, it may soon replace the
stethoscope as the quintessential doctor’s tool. Its rise,
meanwhile, reveals something about how technology works. In some
cases, inventions arrive fully formed. But others reveal their true
potential slowly, truly coming into their own with the passage of
time.

Sonar uses pings that humans can hear. Ultrasonic frequencies, which
are higher and inaudible, were first employed in metal-flaw
detectors—machines that shipbuilders used to spot defects in their
hulls. At first, it wasn’t obvious how to adapt the technology for
medicine. One pioneer tried to use ultrasound to look at the brain;
unfortunately, that’s one of the organs least conducive to
ultrasonic imaging, since it’s encased in a skull of reflective
bone. The first ultrasound machines were enormous, in part because,
since air causes ultrasonic waves to scatter, patients had to be
submerged in water. (Today, clinicians use gel to create an air-free
interface between probe and patient.)

Most ultrasound trailblazers were engineer-physicians with a thirst
for experimentation. As a young medical officer in the Royal Air Force
during the Second World War, Ian Donald, a British obstetrician,
witnessed firsthand the power of both sonar and radar; later, he
wondered if ultrasound might be more effective than a physical exam at
distinguishing benign cysts from cancerous masses. He persuaded a
Glasgow boilermaker to let him turn its metal-flaw detector on two
trunkfuls of recently removed tumors, cysts, and fibroids. In 1956,
Donald and another young physician, John MacVicar, used a primitive
ultrasound machine of their own design on a patient who’d been
diagnosed with inoperable cancer. The diagnosis had been based on
X-rays and physical exams. The ultrasound, by contrast, suggested that
the mass was a large ovarian cyst —a benign growth that could be
removed easily through surgery. Doctors removed the cyst, and the
patient’s symptoms disappeared.

“From this point, there could be no turning back,” Donald
reportedly said. But his colleagues were not convinced. Early
ultrasound machines were hard to use and created murky pictures.
Donald’s team took the positive step of replacing the water bath
with a probe, but used olive oil to bridge the gap between probe and
body—a messy proposition for both patient and practitioner. To many
doctors, ultrasound seemed like a crutch for those who hadn’t
mastered the art of the physical exam. One physician told MacVicar
that ultrasound would only be of value “to a gynecologist who was
blind and had lost the use of both hands.”

The stethoscope, medicine’s most totemic object, had faced similar
obstacles. In 1816, a physician named René Laennec was treating a
young woman with cardiac disease; worried about the impropriety of
putting his ear directly to her chest, he rolled a piece of paper into
a tube, placing his ear at one end and his patient at the other. To
his surprise, he found he could hear heart and lung sounds more
clearly than with his ear alone. Laennec spent years refining and
improving his stethoscope—the name derives from the Greek words for
“looking” and “thorax”—before publishing a book describing
his findings. But adoption was slow. Critics argued that the tool was
too difficult to use, and that the training required was too
specialized. Even the Scottish physician John Forbes, who translated
Laennec’s treatise into English, wrote that he doubted the
stethoscope would “ever come into general use.” It took numerous
revisions to the device’s design—early models still resembled
rolled-up tubes—and the demonstration of replicable and meaningful
results for Laennec and his acolytes to overcome these objections.

In his book “The Diffusion of Innovations
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from 1962, the sociologist Everett Rogers identifies five
characteristics that explain the success or failure of new
technologies. The most obvious is relative advantage: a new invention
must offer a clear improvement over what has come before. But it must
also mesh with current practice patterns, be simple to use, and be
easy to try out. On those scores, early ultrasound failed miserably.
Even into the nineteen-sixties, ultrasound machines remained large and
difficult to transport, and required specially trained operators. They
produced grainy still images, initially captured on Polaroid film.
Obstetricians were open to ultrasound, because they wanted to avoid
exposing fetuses to the radiation created by X rays. Other doctors
adopted an attitude of wait and see.

The first wave of substantial improvements came through digitization.
As silicon chips replaced vacuum tubes, ultrasound benefitted from
Moore’s Law; image quality improved dramatically even as the size of
the machines shrank. Manufacturers simplified their user interfaces,
making the machines accessible to non-techies. In the
nineteen-nineties, _darpa_, the Defense Advanced Research Projects
Agency, awarded a grant to design an ultrasound unit that was portable
and durable enough to be carried onto the battlefield. In 1999, a
company called Sonosite released a commercial version—the first
handheld ultrasound device. The race toward miniaturization continued:
today, there are ultrasound machines that can plug into your
smartphone.

As a technology spreads, experimentation ensues, and new ideas get
refined and regularized. In the early nineteen-nineties, Grace
Rozycki, then a surgeon at Grady Memorial, a hospital in Atlanta,
studied how ultrasound could be used in evaluating trauma patients.
“Surgeons recognized rapidity as ultrasound's most valuable
quality,” Rozycki told me. She and her colleagues helped pioneer the
use of the _fast_ exam—for Focused Assessment for Sonography with
Trauma—to allow them to make treatment decisions sooner.

I learned to perform the _fast_ exam as an emergency-medicine
intern. I’ll never forget my first patient with a positive scan—a
person in their fifties who’d been struck by a car after they lay
down in the road, in a likely suicide attempt. The stretcher came
careening through the double doors of the ambulance entrance; as it
passed the threshold, a nurse rushed to put an I.V. in the patient’s
arm, while another connected them to a monitor that began displaying
their vitals. In a worrisome sign, the patient was becoming
increasingly confused.

I rolled the ultrasound machine to the bedside, squirted some gel
across the probe, and placed it on the right side of the patient’s
abdomen. Most probes radiate ultrasound waves outward in an arc, and
as a result the images have a phantasmagoric quality, as though a
flashlight is being shone into murky waters. When the patient’s
kidney came into view, it was surrounded by a pool of black—an
abdominal hemorrhage. In an instant, we knew that surgery and a blood
transfusion could make a life-changing difference.

Many early ultrasound boosters had envisioned this scenario. But
experimenters in fields as diverse as ophthalmology, rheumatology, and
orthopedics also seized on the technology, and they have pushed its
boundaries far beyond the emergency setting. In a few hours on a
recent shift in the emergency department, I used ultrasound to find a
broken bone in one patient and an abscess in another, and, in two
other cases, to rule out elevated pressure in the brain and a
gallbladder infection, respectively. Clinicians now use ultrasound to
diagnose pneumonia, cirrhosis, blood clots, tuberculosis, tendon
tears, detached retinas, bowel obstructions, appendicitis, bleeding in
the eye, rheumatoid arthritis, gout, aortic dissection, and kidney
stones, among other problems; they use it to site I.V.s in patients
with difficult-to-find blood vessels, and to provide targeted pain
injections that can reduce the need for opioids.

This versatility has proved particularly valuable in places with
limited access to medical care. “I basically bring the ultrasound
into every patient visit,” Ashley Weisman, an emergency-medicine
doctor who practices primarily in rural areas, told me. For a time,
Weisman worked at a small hospital in Kotzebue, Alaska—one of the
most remote hospitals in the United States. She began using ultrasound
for home visits and in village clinics. “You might have a patient in
their sixties or seventies with shortness of breath, but to get them
to a clinic—you have no ambulance, some of these villages don’t
even have roads,” she said. “But you can go to their house and do
lung ultrasound at the bedside, and figure out it’s their heart
failure that flared up, and change their meds. You don’t necessarily
have to strap them to the back of someone’s A.T.V. or put them on a
plane.” Tapiwa Kumwenda, who practices at a hospital in Lilongwe,
Malawi, where tuberculosis is endemic, told me that clinicians there
routinely use ultrasound to diagnose the disease. Traditional TB
testing can take days, and is often difficult to perform in remote
settings. “With the ultrasound, you can see the microabscesses and
the lymph nodes, and you know it is TB,” Kumwenda said. “You start
them on treatment and then two weeks later most of them will be
stabilized.”

The price of a handheld ultrasound today is around three to five
thousand dollars—low enough that a number of American medical
schools have begun giving handheld ultrasound probes to their
first-year students, in addition to the traditional gift of a
stethoscope. “I keep joking we’re going to have a big bonfire, and
we’re going to take all those stethoscopes and burn them, because
there aren’t many times a stethoscope helps us today,” Diku
Mandavia, an emergency-medicine doctor and early pioneer of
point-of-care ultrasound, told me. “But ultrasound—it’s
low-cost, no radiation, has so much value for patient care . . .
it’s going to be ubiquitous.”

And yet the path forward isn’t free of obstacles. Since the
nineteen-eighties, many radiologists have argued that ultrasound, by
ceding interpretive responsibility to non-radiologists, could lead to
incorrect diagnoses. At Hennepin County Hospital, radiologists
objected so strongly to ultrasound’s early use in the E.R. that the
affiliated medical school threatened to pull its residents if it
continued. The American Medical Association has made it much more
difficult for radiologists to block other specialties from using
ultrasound—but the fact remains that most new physicians don’t get
significant ultrasound training, and most specialties don’t yet
emphasize its use.

Ultrasound boosters argue the integration of artificial intelligence
will give the technology the momentum it needs to reach into primary
care and other areas of medicine where it’s not yet widespread. A
hospital where I worked last year purchased new ultrasound devices
that automatically calculate how much blood the heart pumps out to the
body with each beat—a critical piece of information in determining
whether a patient’s heart is failing. I used to estimate how much
blood was being pumped by watching the screen, or, if I wanted to be
more quantitative, by carefully measuring the movement of one of the
heart valves—a relatively time-consuming process. “I think the key
will be smart machines,” Michael Blaivas, an emergency-medicine
physician who focusses on ultrasound, said. “The machine has to meet
us partway. That’s how we really increase access on a mass scale.”

Ultrasound may also benefit from what Richard Hoppmann, a
rheumatologist who has spent years teaching ultrasound to medical
students, calls its “awe phenomenon.” “The first time these
students use ultrasound to look under the skin to see inside the body,
they have this incredible excitement,” he told me. Recently, I
taught an ultrasound seminar to a group of new medical students and
witnessed a similar reaction. It’s one thing to read about heart
valves, and another to put a probe to your chest and see your own
flapping with each passing beat. Patients can share this sense of awe.
Hoppmann helmed a project in which patients with high blood pressure
received periodic ultrasounds and were shown their own heart muscle
thickening—an indication that their uncontrolled blood pressure
might soon lead to heart failure. “The value of being able to see
the heart muscle thickening as it works against the blood pressure and
to point at what you’re talking about—that started making a
difference in terms of patients being compliant with their
medications,” he said. Now, whenever I perform a bedside ultrasound,
I try to show the patient and family what I am seeing and what I am
looking for. People in pain seek relief, but also answers; to be able
to see them along with your doctor, your faces upturned to the same
screen, is a gift.

Medicine has long grappled with an internal debate about how diagnosis
should happen. Some physicians argue that today’s doctors rely too
much on advanced imaging and lab tests, neglecting physical exam
techniques
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such as listening for heart murmurs; they maintain that more thorough
physical exams could curb the use of medical testing, which is
expensive, slow, and, in some cases, radioactive. They also lament the
effect of remote diagnostics on the physician-patient encounter.
Today’s physicians, they note, often spend more time placing orders
and reviewing charts in the electronic medical record
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they do interacting with patients.

Other doctors cite concerns about the reliability and reproducibility
of some parts of the physical exam. Even feeling for a pulse during a
potential cardiac arrest can be difficult. Ultrasound, unlike other
tests, can be used wherever the patient happens to be, in real time.
The physician and author Abraham Verghese
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proponent of increasing time spent with patients, views ultrasound as
a way to bring physicians back to the bedside. “The waning of the
bedside exam,” he said last year, might “find new life” through
ultrasound.

Improvements in A.I. and telemedicine raise another intriguing
possibility: patients could be given their own ultrasound machines,
which they could use to monitor chronic conditions at home. Guided by
A.I., a heart-failure patient who’s having difficulty breathing
could use a small ultrasound to see if fluid is accumulating in his
lungs, or to examine his heart; the images could be relayed to a
physician, who could decide whether to call the patient into the
hospital or update a medication. Blood-pressure devices, glucometers,
and dialysis machines all once resided exclusively in the hospital or
clinic, and now patients routinely employ them at home.

In fact, this approach is currently being tested two hundred and fifty
miles above Earth’s surface, where crew members aboard the
International Space Station are using ultrasound to assess themselves
for eye injuries, fractures, and other ills. With guidance from
physicians on the ground, the astronauts are capturing high-quality
images that help inform their own care, and also contribute to
research on how life in orbit affects the human body. “I don’t
have a medical background and didn’t know anything about sonography
when we started,” Leroy Chiao, a now retired astronaut who helped
run early ultrasound experiments aboard the I.S.S., told me. “But,
with a few hours of training, we were able to begin recognizing a good
ultrasound image versus a bad one.” Chiao said that he and the other
crew members quickly learned how to “image each other’s internal
organs, bones, and eyes in space.” Scott Dulchavsky, a surgeon,
recently led a number of _nasa_’s ultrasound research
investigations. If artificial intelligence progresses, he said, and if
the price of portable ultrasound devices continues to fall, “it’s
going to be ultrasound for dummies pretty soon.” Stethoscopes were
just for doctors. Ultrasound could be for everyone. ♦

CLIFFORD MARKS
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emergency-medicine physician at Beth Israel Deaconess Medical Center
and an instructor at Harvard Medical School.

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