 Could
the humble stethoscope's days be numbered? The physician's
right- hand tool has some competition in hand-carried
ultrasounds (HCUs). Lightweight and battery-operated,
these devices are popping up in all kinds of medical settings,
from community clinics to ERs.
Once the domain of specialists,
echocardiography is now going mainstream. "The tool
of the few is now becoming the tool of the many because
it's getting smaller, it is getting more efficient and
it's getting more accessible," says Dr Normand Laberge,
Chief Executive Officer of the Canadian Association
of Radiologists.
But is this necessarily a good
thing? A review in the September issue of Chest
notes that studies have shown that ultrasounds improve
cardiologists' diagnostic accuracy by nearly 40%. But
how about letting non-cardiologists loose with these
devices?
TRAINING
WHEELS
The Chest study, conducted by Dr Robert J Siegel
and colleagues at Cedars-Sinai Medical Center in Los
Angeles, looked at 42 articles to assess the clinical
effectiveness of HCUs for diagnosing cardiac function.
They found that these devices increased diagnostic accuracy
when used in conjunction with a physical exam at first
patient contact. The HCU was particularly useful for
detecting global left ventricular dysfunction, but wasn't
as effective for diagnosing other abnormalities, including
right ventricular dysfunction and valvular lesions,
when used by less experienced operators.
Which brings us to the heart of
the matter. "It's a tremendous advance in technology,
but it's not a substitute for a full echocardiographic
examination," says Dr Harry Rakowski, professor of medicine
at the University of Toronto and past-president of the
American Society of Echocardiography (ASE). The ASE's
position statement on portable ultrasounds notes that
level-2 echocardiography training is a must. Dr Rakowski
worries that mistakes made by untrained operators will
devalue echocardiography.
Mr Laberge couldn't agree more.
He has some concerns himself that the spread of handheld
ultrasounds is preceding the knowledge of how to use
them. "The transfer of technology is the first thing
that happens, not the transfer of knowledge," he says.
"The machine becomes available because the advancement
of technology is faster than our teaching. Ultrasound
by itself is a useless and stupid thing, unless it's
attached to the right person."
To illustrate the point, Mr Laberge
offers an example from the Ottawa area, where CT referrals
jumped by 30% in just six months. The reason? Fast ultrasounds
were performed in the ER to check for fluid in the abdomen.
Finding nothing, the physicians referred patients for
a CT scan, stating on their order that an ultrasound
had already been done with no clear results. Mr Laberge
suspects that this increase stems from misuse of the
ultrasound equipment due to a lack of training.
QUALITY
QUERIED
And the devices themselves also deserve close scrutiny.
Portable units offer lower quality images and substandard
colouring, says Dr Rakowski, adding that most new devices
cannot provide detailed measurements because they can't
do continuous-wave Doppler imaging. Such as they are,
he thinks they won't be widely used in doctors' offices,
and are more practical in a hospital setting.
"That doesn't mean that it doesn't
have a role to play, as long as you don't think of it
as a substitute for a fully-featured, high-definition
system," he says. "In an urgent situation, if I want
to know if heart muscle function is normal, I can do
that with a handheld machine pretty accurately."
The Cedars-Sinai team suggests
that the HCU would be particularly effective for emergency
care, community testing and remote regions where patients
would normally have to travel for testing. The devices
are becoming more and more popular in Canadian hospitals,
but the price tag (roughly $15,000US) will likely prohibit
their spread to doctors' offices.
SCANNING
THE FUTURE
Down the line, HCUs will inevitably merge with existing
telehealth infrastructure, according to Mr Laberge.
In the near future, ambulance drivers could transmit
ultrasound readings to hospitals over cellphone lines
— a procedure that's already used in military settings.
In light of this technology's increasing
popularity, Dr Rakowski feels that issues of training,
functionality and availability still loom large. "I'm
a strong believer in the concept that small, portable
devices will be an important adjunct to how we manage
patients," says Dr Rakowski. "But we're not at that
stage yet. Right now we have devices that cost considerably
more, are heavy to carry, and they have a limited purpose
— they don't have the general purpose of being
something that every physician should have and take
to the bedside."
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