Page 160 - Biomedical Engineering and Design Handbook Volume 2, Applications

DESIGN OF RESPIRATORY DEVICES 139

respiratory system may not be entirely normal, and the operation of the device can be viewed with
suspicion.
Another patient may enter the hospital with a severe pulmonary condition. She/he may suffer
from extreme dyspnea, can be nearly unconscious, and may exhibit symptoms of panic. Movement
to standard pulmonary function testing equipment may require too much exertion, and he or she
may be too preoccupied to fully cooperate. Special breathing maneuvers may not be within his/her
capabilities. The operation of the device must be fast and able to occur where he/she is located, and,
unlike the first patient, the instrument offers hope, not a threat.

The Technician. The technician is highly trained, but not in the way an engineer is trained. The
technician is oriented toward the patient, and can coax and cajole the best effort and the best mea-
surements from the patient. The technician can also add consistency to the measurement, because
he/she often adds a great deal of discrimination when it comes to deciding whether a measurement
should be kept or repeated.
The technician does not coax and cajole instruments very well. Operation of the instrument is ide-
ally automatic up to the point where a decision is made whether or not to repeat a test. Too many but-
tons and choices take too much attention away from the patient, which the technician may not like.
The Physician. The physician shoulders the ultimate responsibility for diagnosis and treatment.
She/he is busy, and has little time to devote to undependable instrumentation. The medical device,
like the technician, must do what she/he wants instead of the other way round. The physician must
have confidence in both the technician and the device in order that she/he may be able to rely on
measurement results and make a determination of the problem without wasting unnecessary time.
The device should give unequivocal results whenever possible so as not to create confusion or uncer-
tainty. The physician generally prefers new medical devices that are familiar and relate to other
devices and methods she/he has used in the past. Once accepted by the physician, the assumption is
made that the new medical device gives accurate results. In reality, the device does not always need
to be extremely accurate, but it must be consistent.

The Engineer. It is the engineer who knows each flaw in the measurement. She/he wants to be
proud of the instrument, and wants it to be perfect. The engineer wishes to be appreciated for all the
bits of creativity and insight that have been incorporated into the machine and is disappointed when
these are not appreciated. Her/his tendency, in the face of a compromise between machine and
patient, is to require more of the patient. This tendency must be resisted. The engineer must have
faith in her/his abilities, patience with those in the medical profession, and care in her/his approach.
Above all, she/he must realize that the medical world is different from her/his own, and that, while
nothing can stand between medicine and a technique that it craves, there is no path more strewn with
obstacles than the path toward acceptance of a new medical device.

4.7.10 Physical Characteristics

Aesthetic design is important for device acceptance. Many respiratory devices are relatively small,
and compactness is usually a positive attribute. There was a time when the very size and massive
appearance of a device connoted robustness, but styles change, and now the appearance of elegance
is in vogue. The device must look clean, small, lightweight, and sanitary. Computer displays should
have an appearance similar to popular computer programs of the day. The color of the device should
be rather neutral instead of gaudy.
Most medical devices are accepted better if they are lightweight. Respiratory devices may be used
in the home, and home may be located up several flights of stairs. Even hospital equipment must be
moved for cleaning or storage, so lighter devices are appreciated. Portability is beneficial.
Medical devices should be quiet. They should not appear to be contraptions to nurses and tech-
nical staff, and they should not cause loss of confidence in patients. They should not add to the din
of a hospital environment, especially during emergencies, when communications among healthcare
professionals are most critical.