Biomedical Engineering Reference
In-Depth Information
4.4
Chapter 4.4
Anesthesiology
Luis Melendez and Raj Rane
To excel as a clinical engineer (CE) or biomedical engi-
neering technician supporting, the use of equipment in
anesthesia requires equally strong understanding of both
the clinical and technological components of the job. This
is an important distinction that anyone must face when
involved with anesthesia. Physiology and technology
meet
The CE wants to perform a couple of tests on the
machine but is concerned that asking for the time to do it
will add more tension. Wanting to solve the problem as
fast as possible, the CE does as told. Quickly, the CE is
out of the OR and off to find another machine. Mean-
while, they disconnect the patient from the machine,
start manual ventilation, and rearrange things in the OR
so that the CE can wheel the large device out and roll in
another in its place. The CE returns and leaves the new
machine just outside of the room, helps the physicians
move all items and drugs from the existing machine,
disconnects patient monitoring, gas-supply hoses, and
electrical connections. The CE wheels the machine out
of the room (careful not to touch sterile tables and
drapes, or else there would be even more upset people)
and moves the new machine in. With great care, things
are reconnected, and every detail is put back in its place.
The new machine and then the ventilator are turned on.
The very same problem is still there. The bellows do not
fill properly, even with a fresh gas-flow rate of 10 lpm.
Tension is building. The CE has done everything asked of
him, and there is nothing else that he can think of. The
physicians are growing even more upset. Not wanting to
be in the way, the CE decides that it is time to leave.
Back in the clinical engineering department, the CE
finds a co-worker and discusses the recent occurrence.
The co-worker convinces the CE that they both should
go to the OR. The first machine is still in the hallway.
They plug it in and turn on the oxygen cylinder. A quick
breathing circuit leak test and a functional ventilator test
indicate that nothing is wrong with that machine. In the
room, everyone is near an uproar because they cannot
ventilate adequately. The co-worker asks the physicians
to turn off the ventilator and to manually ventilate the
patient. They must use the oxygen-flush key just to keep
enough volume in the breathing circuit. The CE notices
the two cannot be separated. If you know the
technology well but have less than able comprehension of
medical terminology, human anatomy, and physiology, you
will have difficulty making efficient decisions to correct
a problem in the middle of surgery or to choose the best
technology to be used for the next 15 years. This chapter is
primarily dedicated to existing and present technology.
Future machines are not discussed in detail, as it would be
purely speculation as to what might work. Most discus-
sions are limited to principles and not specific detail.
This chapter is best introduced and summarized with
a case report. Events similar to the one described below
have happened, and will happen, at almost any in-
stitution. Suppose that in the middle of a total hip re-
placement in an operating room (OR) where ultraviolet
(UV) lights and laminar flow ventilation systems are used
to keep infection rates to a minimum, the CE is asked to
diagnose a large leak that has developed in the breathing
circuit during the case. The resident and attending phy-
sicians are concerned about the course of events, and the
CE can feel the tension upon entering the room. Alarms
are sounding, and it appears that the doctors are having
a difficult time ventilating the patient. The physiological
monitor is indicating poor oxygen saturation; it tells the
CE that the capnogram shows a poor waveform. The
ventilator is flashing a number of alarms. The attending
physician wants a new anesthesia machine, now. The CE
is told that the patient is paralyzed and that they will use
an Ambu bag (i.e., a manually operated resuscitator)
while the CE gets that broken machine out of the room.
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