Essays on Future Trends in Anaesthesia

102 Pages·1972·2.56 MB·English

by  Antonio Boba M. D. (auth.)

Anaesthesiology and Resuscitation
Anaesthesiologie und Wiederbelebung
Anesthesiologie et Reanimation
61
Editors
Prof. Dr. R. Frey, Mainz . Dr. F. Kern, St. Gallen
Prof. Dr. O. Mayrhofer, Wien
Managing Editor: Prof. Dr. M. Halmagyi, Mainz
A. Boba
Essays on Future
Tr ends in Anaesthesia
With 48 Figures
Springer-Verlag Berlin Heidelberg New York 1972
ANTONIO BOBA, M. D.
Director of Anesthesia, The Southern Illinois Medical Center,
Mount Vernon, Illinois 62864, USA
ISBN-13: 978-3-540-05798-7 e-ISBN-13: 978-3-642-65377-3
DOl: 10.1007/978-3-642-65377-3
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© by Springct-Vetlag Berlin. Heidelberg 1972. Library of Congress Catalog Card Number 72-76388.
Preface
Lest the reader be discouraged, let us state unequivocally and at the very
beginning that this is not, nor will it develop into, a treatise on information
or decision or communication theory. It is true that on occasion some ideas
or concepts will be borrowed from these areas, and it is also true that on
some other occasions we might offer examples of what communication
theory, or decision theory, are all about. Nevertheless, this will be done for
the primary purpose of showing where and how further exploration of
these areas of endeavour might lead to further and better understanding of
our problems, and possibly lead the way to sounder planning and more
workable solutions.
The more sophisticated will find a paucity of illustrations and a minimal
mathematical treatment of the subject. This has been done for two specific
reasons; the first being that additional graphic representation or mathema
tical manipulations would not have contributed materially to a better under
standing of the subject, at least in the context in which it is being presented.
The second reason is that graphic representation or mathematical mani
pulation implies the knowledge that there exists a conceptual isomorphism
between the subject under discussion and the graphic or mathematical
models being presented. This can hardly be justified at this time and of this
subject and we have chosen to rely to a large extent on verbal representa
tion which, precisely because of its redundancy and imperfections, lends it
self more readily to the description of imprecise objects or relationships.
Historically, this approach is entirely justified. Indeed, the solution of
even the simplest form of equation, when not using our present mathe
matical notation, requires a considerable amount of ingenuity and verbali
zation, a feat which did not discourage Diophantus but which we may find
rather tiresome. In more recent times we find that correct verbal represen
tation and solution of calculus problems, with a minimum of symbolic
notation, as we see in Leibnitz precedes by far its entirely symbolic treatment.
What the above remarks mean is that before a subject can be abstracted
and presented, using a wholly symbolic or mathematical notation, it must
be thoroughly understood in terms of its more prosaic verbal representation.
Failure to do so would lead to the harmful strait-jacketing of an incompletely
understood idea into a uniform that does not fit and which because it does
not fit may indeed stunt its further growth.
Dedication
These essays are dedicated to those past, present and future students of
mine who have led me to an understanding of the fact that what is expected
of me is not to teach them what I know. Rather, I have realized that what is
expected of me is that I should teach how I came to know what I do know
so that, in turn, they may begin to learn what they want to know.
This is as much a blow to the myth of true knowledge as it is an acknowl
edgement of the fact that new individuals are borne every day, whether we
like it or not. To that extent let us all then be cheerful midwives.
Table of Contents
I. Anaesthesia and the Anaesthetist . . . . 1
II. The Administration of Anaesthesia - a Process 6
A) General Comments 6
B) Monitoring . 6
C) The Message . . . 7
D) The Decision 11
E) Interactions between Message and Decision 15
F) The Optimizing Process 18
G) General Conclusions ..... . 20
III. A Special Tool for a Special Purpose 22
A) General Comments 22
B) Vaporizers . . . . . . . . . . 22
C) Recording . . . . . . . . . . 26
D) New Tools and New Knowledge 28
E) A Blueprint 30
F) Two Examples 34
G) Conclusions 37
IV. First Hand Experience 40
A) General Comments 40
B) The Blood Pressure . 40
C) Some Results 46
D) Second Generation Data 50
E) The Pulse Pressure Contour 56
F) Breathing Patterns 60
G) Conclusions ..... 65
V. The Future of Anaesthesia 67
A) General Comments 67
B) Monitoring the Circulation 67
C) Monitoring the Respiration 68
D) Recording . . . . . . 70
E) Agents and Vaporizers 71
F) Programmed Anaesthesia 72
G) Conclusions ..... 79
x
Table of Contents
Appendices
A) On Isomorphism . . . . . 81
B) Arterial Puncture Data 81
C) Second Generation Data (1) 85
D) Second Generation Data (2) 90
I. Anaesthesia and the Anaesthetist
Traditionally, the anesthetist is viewed as the man who "walks into the
operating room, reaches for the anesthesia machine, turns a few dials and
puts the patient to sleep".
There are many who share this image of the anesthetist. Interestingly
enough, this image is essentially wrong apart from and beyond the obviously
improper use of everyday language. In fact, sleep is not anesthesia and
anesthesia is not sleep.
Patients, the majority of them anyway, see the anesthetist in the light
of the man who puts them to sleep. Indeed, it is not uncommon to find the
patient who, subconsciously or openly, objects to routine questions during
the preoperative visit on the grounds that "all I want is that you should
put me to sleep". Frequently even some of the more sophisticated patients
answer the routine questions with some bemusement, because deep in their
minds the fact remains that eventually all the anesthetist will do is "put them
to sleep", and in this light the questioning is both inane and beside the
point.
Our surgical colleagues, at all levels of training and experience, also
share this image and we are continuously asked to "do something about
it", even when it is perfectly obvious that careful observation and watching
are the only reasonable courses of action.
Unfortunately, it is all too frequent that this is also the image which
the anesthetist has of himself; even though this fact is betrayed more by
what he does than by what he says. Just by way of example one could men
tion that it is all too common to see residents, during their first week of
residency, taken to the operating room and there, under the eager guidance
of an instructor, they are "taught" how to administer a spinal anesthetic
and then, in quick succession, how to insert an endotracheal tube, and so
on, and so on. The medical students rotating through anesthesia also come
to the operating room eager to "do a spinal" or "intubate a patient". The
fact that these endeavours are aided and abetted by their teachers confirms
the previous statement to the effect that the anesthetist, himself, sees him
self as the man who "puts the patient to sleep".
What strikes me as odd, at least now because at the beginning I was as
guilty as anybody else, is the fact that we do not see surgical residents, at
the same level of training, dragged to the operating room and there "taught"
how to fix a hernia or remove a gall bladder. Rather, the view is taken that
as the resident learns of the surgical art and of the science of surgery,
2 Anaesthesia and Anaesthetist
whatever there is of it, then he will also and in a natural way fix hernias and
remove gall bladders. All of this should not be taken to mean that all
surgical training is good and all anesthesia training is bad. Rather, it is
intended to support the argument that in the mind of the instructor the
"putting the patient to sleep" is most important and this attitude is in turn
transferred to the trainee.
From a historical viewpoint, it might be worthwhile to recount how my
interest in this subject was developed. Early in my experience as a teacher,
I discovered that the correct handling of the great majority of distress calls
from trainees did not require of me the performance of unusual or extra
ordinary feats of manual labor or of dexterity. Rather, what was required
was the making of a decision at an intellectual level, which decision was
then followed by the performance of a manual task of a most trivial nature
(i. e., turning a knob slightly clockwise, or injecting a drug via an already
existing intravenous route).
In due course of time it became obvious that the true nature of the
distress was a breakdown in the decision making process, which had not
been taught or discussed, rather than in the task performance process, which
had been overemphasized. This slow accumulation of rather trivial occur
rences was what led to the viewing of the administration of anesthesia
primarily as a continuous decision making process with an associated, and
dependent, continuous task performance process. This shift in philosoph
ical approach then led to a reevaluation of those factors which are of im
portance in the decision making process and eventually to some insight
into the structure and intricacies of decision making.
It may well be worthwhile to keep in mind that the true nature of the
process of administering an anesthetic requires a smaller number of manual
skills than any equivalent procedure in medicine. To that extent it may be
both dangerous and misleading to place major emphasis on the manual
task performance aspect of the process.
The nature of the decision making process in anesthesia has often been
conceived as being analogous to a feedback loop. Indeed, the very concept
of "servo-anesthesia" rests on the acceptance of the existence of a concep
tual isomorphisml between the process of anesthesia administration and
feed-back theory. It is very likely that the fact that but little progress has
been made in the field of servo-anesthesia is more related to the fact that
such isomorphism does not exist, rather than to inadequate development
of hardware.
1 The very concept of isomorphism aud the process of constructing a model,
which is one of its natural consequences, need additional clarification as their na
ture and limitations are frequently not fully appreciated (see appendix A).
Anaesthesia and Anaesthetist 3
A somewhat clearer insight into some of the mechanics of the process
of anesthesia administration may be had by considering Figures 1 and 2.
OPERATOR ~----------~
~
MACHINE
~
PATIENT
Fig. 1. Simplified diagram of the relationship commonly held to exist between
anesthetist, machine and patient.
Note how the cycle supposedly begins with the anesthetist establishing con
tact with the machine. The patient feeds back noise into the anesthetist only after
the machine establishes contact with him.
The fact that the patient feeds back noise into the anesthetist has undoubtedly
contributed a great deal to the assumption that we are dealing with a "feed back
loop". The many pitfalls of this assumption will be discussed in the third essay
Figure 1 is a diagramatic representation of the relationships between
anesthetist, anesthesia machine and patient as they are commonly accepted.
There the anesthetist reaches for the machine and then administers some
thing to the patient. Whatever the effects of this maneuver are, the patient
then feeds-back to the anesthetist some kind of noise, which noise in turn
causes the anesthetist to reach for some other dials on the machine and
there the process starts again. This process can be viewed as a feed-back
type of process and analyzed in the light of what is known of the behavior
of feed-back loops. We shall return to this issue later on.
By comparison Figure 2 typifies an entirely different process. Note here
that the first step is the transfer of information from the patient to the
anesthetist. To a large extent the anesthetic process may not begin until
such a time that enough information has been gathered to establish the
fact that the patient needs an anesthetic. As soon as enough information
has been gathered by the anesthetist to justify an action (or the withholding
of an action) the effects of this decision are transferred to the patient.
However, by now the patient has changed because of the combined effects
of the passing of time and/or previous actions by the anesthetist. To that
extent, any decision to act by the anesthetist always affects any patient at a
time when the patient is known to the anesthetist only throught prediction
by extrapolation. This fundamental "uncertainty" of the system leads to the
requirement that additional information be immediately acquired and trans-