Sunday, January 22, 2006

I Have Trouble Remembering Which End to Use......
The stethoscope enters the 21st century: When a Heart Beats In a Noisy Hospital,Who Can Hear It?
At a medical conference in Florida last March, about 100 cardiologists found themselves stooped over little Plexiglas cubes, listening intently with a newfangled stethoscope.

Coming from the "sound boxes" were recorded heart and lung sounds, plus a lot of annoying hospital clatter. The doctors were conducting the equivalent of a taste test, comparing an experimental electronic stethoscope made by 3M Co. to traditional, acoustic stethoscopes made by the same company. The experimental stethoscope is designed to muffle outside noise.

It's a loud world. And the racket is rising in hospitals, according to recent research done by Johns Hopkins University in Baltimore. Acoustical engineers there took sound readings in the immediate vicinity of hospital patients and then compared results with those of historical noise studies. Since 1960, researchers found, average daytime hospital sound levels have risen from 57 decibels (roughly equivalent to a churning washing machine) to 72 (more like a grinding garbage disposal) today.

It's remarkably difficult to design a stethoscope that filters out environmental noise while still amplifying the subtle, vital sounds of the inner anatomy. For 3M and its smaller scope-making rivals, the prize is a chunk of a fairly big market. Global stethoscope sales are between $125 million and $150 million, with about half of the sales in the U.S. Relatively new, electronic scopes represent less than 10% of the market, 3M estimates.

The stethoscope has come a long way in its' near 200 years...
One of medicine's trustiest diagnostic devices, the stethoscope was invented in 1816 by a French physician, Rene Theophile Hyacinthe Laennec. His first model was simply a perforated wooden cylinder. Another clever inventor in 1880 made a trumpet-shaped model with a rubber end that doubled as a reflex hammer to rap on knees. Around the same time, the binaural, or twin-ear, stethoscope came onto the market, a major advance in reducing background noise.

But noise -- including human voices, the whoosh of air conditioning and heating systems, and the sounds of medical monitors -- continues to confound. The problem got worse in recent years after stethoscope companies tried to amplify the inner rhythms doctors really want to hear but inadvertently also raised the level of ambient racket.

Stethoscopes have long captured the body's wind and percussion sections: the lungs and heart. The instruments are either acoustic or electronic. The electronic ones amplify the sound. There were numerous attempts to design and patent amplifying stethoscopes in the early 1900s. But they didn't catch on until the late 1990s when they could be powered by small batteries.

A handful of companies have introduced electronic models in recent years, including the Echo Amplified sold by Trimline Medical Products Corp. and the Master Elite from Welch Allyn Inc. Electronic scopes tend to be used by cardiologists and respiratory specialists. Their manufacturers usually make some claim about filtering out environmental noise. The newer scopes certainly help amplify very faint sounds: gentle heart murmurs and subtle crackles and wheezes that can indicate heart disease, pneumonia and other serious ailments.

A doctor in Norway using one of the electronic scopes happened upon a high-frequency wheeze in a patient who was later found to have bronchial cancer. In a 2001 research paper, the doctor, Hasse Melbye, wrote: "I could scarcely have heard this sound with a [standard] stethoscope."
Pricey tools they are:
His stethoscope was made by Welch Allyn, a medical-instruments company in Skaneateles Falls, N.Y., which introduced the Master Elite Plus in 2000. The device's $446 price was easily twice that of many high-end stethoscopes. Garden-variety stethoscopes can run $65 or less. Then in 2003, Welch Allyn unveiled a moderately priced Master Elite for $245. The company generated some buzz by advertising that the scope used patented electronic-sensor technology to filter out unwanted noise.
3M has come out with a model as well:
Rival 3M, which markets the industry-leading Littmann electronic stethoscope, had its work cut out. Its researchers already had attacked noise-damping from several angles, at one point with special ear tips (patent no. 5,824,968) that made a tighter seal in the doctor's ear canal. 3M researchers next sounded out Bang & Olufsen, the maker of fancy sound systems. Working with the Danish company's acoustical specialists, the 3M scientists got busy designing a stethoscope that could gather environmental noise separately from the noises created by the patient.

To draw in sound from the air, designers experimented with a thin slit (0.040 of an inch) carved around the diameter of the chestpiece. Ambient noise, say a squeaky gurney, enters the device from the outside through that hole. There, it meets the same noise, which has been conducted through the patient's body. Because the scope is receiving the same vibrations from two different places, it cancels them out, leaving heart and lung sounds audible.

To satisfy the Food and Drug Administration, 3M began testing the new stethoscope on people about a year ago. The company, which makes products from Post-it notes to Scotch tape, brought doctors and patients to its headquarters in St. Paul, Minn. In a reverberation room -- a concrete chamber about the size of a one-car garage -- scientists re-created hospital cacophony from recorded sounds. Bells rang. Carts rolled. Bed rails squeaked. Respirators hummed. Voices mumbled incoherently in what 3M calls "hospital babble."

Heart specialists and other doctors conducted exams on real patients suffering from a variety of conditions, including a heart murmur and asthma. As doctors pressed stethoscopes to the patients, researchers assaulted the room with volumes of background noise from 60 to 80 decibels.

Feeling the new stethoscope sufficiently muffled unwanted noise, 3M next had to persuade doctors. Hospitals typically don't buy stethoscopes in bulk; doctors usually pick their own and pay for them.

3M devised the little sound boxes that cardiologists were bending over at the medical conference in Florida last spring. The plastic cubes were miniature versions of the reverberation room in Minnesota.

3M says tests show that its new stethoscope, introduced in November with FDA approval at a suggested retail price of $374, can reduce ambient noise by 75%.
Still a little pricey for my tastes. But if the price falls, I certainly can see the use for such a device in the trauma room. Tough to evaluate for Beck's Triad in the noisy ED.
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