| The medical profession has not been immune to the emergence
of wireless technology. Like most professionals, doctors, nurses,
and medical specialists are becoming more reliant on wireless
devices such as personal digital assistants (PDAs) to improve
the efficiency of their jobs.
That is only one manner in which advances in electronic technology
have improved the manner in which patients are treated. Stethoscopes,
thermometers, and heart monitors are just a few of the medical
devices whose capabilities have dramatically changed for the
betterment of patient care. Fortunately, this scenario also
creates a healthy opportunity for electronic design engineers,
as these medical devices now must provide exceptional audio
specifications while also have network integration tools previously
unheard of for medical devices.
One of the biggest benefits is in the
transfer of patient data and records. For example, EMTs and
healthcare professionals
can now transmit critical patient data from an ambulance or
helicopter to a receiving hospital’s cardiac care team
using a digital wireless network. This system utilizes a defibrillator
that Emergency Medical Services (EMS) personnel use to monitor,
and if necessary defibrillate, a patient suffering from a heart
attack. Once the patient has been stabilized, EMS personnel
acquire and transmit an ECG from the defibrillator to the receiving
hospital’s server via a PDA. The receiving hospital server
can then send the data to individual clinicians, such as the
cardiologist on call, using web-enabled PDAs or telephones.
All of the data transmission happens in just seconds, and in
this type of situation, seconds can save lives.
Improvements have also led to better
patient care in a day-to-day manner. Electronic stethoscopes
can now amplify heart, breath,
bowel or korotkoff sounds without amplifying outside noise.
In fact, electronic stethoscopes now have maximum amplitude
or sound pressure level output of 120 dB without distortion.
They also allow the healthcare professional to control the
frequency, so that they can switch the range between heart
sounds (45 Hz – 900 Hz) and breath sounds (50 Hz – 2000
Hz) for better results.
Electronic Records
The improved sound output of electronic stethoscopes allows
the physicians to once again use the PDA, this time for recording
a patient’s heart and lung sounds. Specialized software
captures the sound waves with synchronized ECG signals and
saves them as files that can be stored, retrieved, shared,
e-mailed, and analyzed at any time. This provides the physician
with a permanent record of auscultation and additional clinical
information. It also creates an objective record that complements
subjective information, thereby aiding in identifying specific
heart sounds and murmurs, as well as lung sounds such as
pneumonia, asthma and COPD (chronic obstructive pulmonary
disease).
An ancillary benefit of this capability is in educating the
next generation of healthcare professionals. The recording
and storing of these sounds can create real world examples
that can be used in the classroom to augment lectures and textbooks.
The continuous thread through all of these applications is
the ability to download patient data to a PDA or PC. As has
been outlined, this provides benefits to patient care but it
also creates advantages for the healthcare industry. One of
the major present themes, as part of streamlining the healthcare
program in the United States, is to create a more paperless
environment. Electronic medical records are being emphasized
as a means to improve efficiency, lower costs, and make the
overall healthcare experience less painful. This is much more
possible now than ever before.
In addition to the specific applications
outlined above, there are a host of other digital medical
devices, such as digital
heart monitors, that are now common. All of these instruments
can be integrated into the information technology (IT) of a
practice or hospital to create less paper and easier access.
Combining this capability with a PDA, a doctor can analyze
a patient’s records anywhere, anytime. So, a doctor attending
a conference in San Francisco can see the results of an exam
or test conducted on his patient in New York earlier that day.
Designing the Devices
Of course, access to this data is only
a benefit if the records are accurate. That is where the proper
design becomes important.
Because the audio quality is so vital to successfully downloading
patient records, as well as for physicians to correctly access
a patient’s condition, selection of the proper dynamic
speaker and receiver, as well as the microphone for PDAs,
is imperative.
Dynamic speakers and receivers used
in today’s medical
devices must combine high performance with compact size. They
must have a high SPL – sometimes referred to as sound
pressure – level. Typically, a dynamic speaker should
have a minimum SPL of 85 dB +/-3 dB at 0.3 W from a distance
of 10 cm. Some speakers can even achieve an SPL of 92.5 dB
+/-3 dB. They must also be ultra thin, measuring only 2.5 mm
high and having a diameter of only 13 mm in some cases.
Microphones used in the PDAs and other medical devices must
also squeeze high performance in a small package. Typically,
microphones used in medical applications must have a sensitivity
of at least -40 dB +/-3 dB and have a minimum signal-to-noise
(S/N) ratio of 58 dB. Working height of these devices needs
to be less than 3 mm.
Of course, since the microphones and receivers are being used
in medical applications, they must have extremely high reliability.
It is important for designers to consider this with audio components,
as some manufacturers have wide variations in component performance.
From a business perspective, using a
single source for these audio components is a wise move.
It reduces vendors, creates
a partner from which to work with, and eliminates any compatibility
issues that may otherwise arise. It’s a minor consideration
but one that can prove beneficial somewhere during the design
and manufacturing cycle.
Conclusion
The medical profession is one of many that is being aided by
the increased use of wireless technology and overall improved
electronics. It has led to better medical devices. Almost
as importantly, it has created a synergy between patient
care and administration that is leading to a paperless environment.
Therefore, healthcare professionals can better treat patients
because they will have greater access to more data than ever.
Selection of the proper components during the design stage
can maximize the potential of the electronic devices used in
the medical profession. Audio components should be evaluated
closely, as their performance is integral to the proper data
acquisition and subsequent downloading to PDAs, and enterprise
networks.
About the author: Christophe Naasz is the Business Development
Manager for Star Micronics America, Inc. He has been involved
in electronics for over 15 years. He can be reached at (732)
623-5500; or by email at:
cnaasz@star-us.com.
This article appeared in the November
15, 2004 edition of ECN magazine.
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