Obstetric Analgesia and Anesthesia: A Manual for Physicians, Nurses and Other Health Personnel, Prepared for the World Federation of Societies of Anaesthesiologists

137 Pages·1972·2.82 MB·English

by  John J. Bonica M. D. (auth.)

Obstetric Analgesia
and Anesthesia
A Manual for Physicians, Nurses and Other Health Personne4
Prepared for the World Federation of Societies of Anaesthesiologists
Edited by
John J. Bonica
With 24 Figures
Springer-Verlag Berlin· Heidelberg· New York 1972
M. D.
JOHN J. BONICA,
University of Washington, School of Medicine, Department of Anesthe
siology and Anesthesia Research Center, Seattle/USA
Chairman, Ad Hoc Committee for Obstetric Anesthesia, and Scientific
Advisory Committee WFSA
ISBN 978-3-642-49523-6 ISBN 978-3-642-49813-8 (eBook)
DOl 10.1007/978-3-642-49813-8
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© by Springer-Verlag Berlin. Heidelberg 1972. Library of Congress Catalog Card Number 72-86713.
Introduction
The provision of the best possible anesthetic care to the-greatest number
of patients all over the world has always been the main goal of the
World Federation of Societies of Anaesthesiologists. In addition to the
establishment of Regional Anesthesiology Training Centers and the
organization of Regional and World Congresses, the distribution of
practical monographs on some important aspects of anesthesiology were
considered important for the attainment of this objective. In 1968, on
the occasion of the Fourth World Congress of Anesthesiology, held in
London, a monograph on "Emergency Resuscitation", compiled by the
Committee on Cardiopulmonary Resuscitation, chaired by Professor
HENNING POULSEN, was made available to our membership. Subsequent
ly, this excellent monograph was translated into Spanish, Russian, Ger
man and French and to this date over 100,000 copies of it have been
distributed to anesthesiologists and other interested physicians the world
over.
When looking for a suitable topic for a second monograph to commem
orate the 1972 World Congress of Anesthesiology to be held in Kyoto
this September, the subject of Obstetric Analgesia and Anesthesia was
the first choice of almost everyone consulted. For reasons that are hard
to condone, obstetric analgesia and anesthesia has often been the step
child among the anesthetic subspecialties. Considering that one fourth
to one third of all anesthesias administered are for the relief of child
birth, that obstetric anesthesia is in many cases "emergency" anesthesia,
and that not one but two lives are at stake, it is difficult to acquiesce in
the fact that in many communities this important function, deserving
the skill and devotion of the best specialists, is often relegated to poorly
trained medical and paramedical personnel.
In an attempt to alleviate this deplorable situation, an Ad Hoc Com
mittee for Obstetric Anesthesia was appointed and charged with the
task of compiling a brief, but comprehensive, practical monograph on
obstetric pain relief and infant resuscitation. This monograph is the
result of many hours of hard work contributed by the members of this
committee, ably directed by Professor John Bonica. It is our hope that
this concise volume will accomplish two objectives: It will arouse a
world wide interest in the sadly neglected field of obstetric anesthesia
and will serve as a practical guide for those planning to devote more
III
time, energy and sophistication to the relief of the suffering of parturients
and the improvement of chances of the newborn for a healthier and
thereby happier life.
FRANCIS F. FOLDES, M. D.
President
World Federation of Societies of Anaesthesiologists
IV
Preface
In recent years there has been an impressive surge of interest in obstetric
analgesia and anesthesia. This trend is exerting social and professional
pressures on physicians to provide parturients with better and more wide
spread pain relief during childbirth. Of the many factors for this trend
for greater demand for, and use of, anesthesia for childbirth, one of the
most important: has been the expectation of parturients. Today, gravidas
in many countries, having been made aware of the benefits of good ob
stetric analgesia by magazine articles, books, television and other news
media, have come to expect it just as they expect painless surgery and
painless dentistry. Thisincreased demand by patients and the realization
that lack of anesthesia or poorly administered anesthesia in themselves
cause maternal and perinatal mortality and morbidity have prompted
obstetricians in many parts of the world to demand better services by
anesthesiologists. This expectation is strongly supported by statistics from
those medical centers where obstetric anesthesia is provided by competent
personnel. These data show that optimal pain relief not only does not
contribute to, but actually reduces maternal and perinatal mortality and
morbidity by permitting better obstetric care. In response to this, more
and more physician-anesthetists are devoting some of their professional
time to obstetric anesthesia and some have become "obstetric anesthesio
logists," physicians with special training who are devoting all of their
efforts to this field.
This booklet is intended to provide guidelines to people who have the
serious responsibility of administering obstetric analgesia-anesthesia,
whether they be physicians, nurses or midwives. The importance of fun
damental knowledge in managing parturients cannot be overemphasized,
and is attested by the rather large amount of space devoted to Chapter 1.
Since normal vaginal delivery occurs in over three-fourths of births, a
commensurate amount of space is devoted to this aspect of obstetrics. The
sections on operative and complicated deliveries consider only the most
common problems. The scope of the brochure and space limitations pre
clude discussion of every drug and technique used throughout the world
or detailed review of the literature of the methods mentioned. The refer
ence list at the end of the brochure should be consulted for comprehensive
reviews.
v
I wish to thank the members of the Ad Hoc Committee, but especially
Doctors Gertie Marx and Sol Shnider, for their cooperation and help in
the development of this brochure. The Committee hopes that it will en
courage better anesthetic care for mothers and their offspring everywhere.
Seattle, June 1972
JOHN J. BONICA, M. D.
Chairman, Ad Hoc Committee for
Obstetric Anesthesia, and
Scientific Advisory Committee WFSA
VI
Table of Contents
Part A. Fundamental Considerations
Chapter 1. Physiologic and Pharmacologic Considerations 1
Maternal Physiology and Psychology 1
Physiology and Pharmacology of the Placenta
and Fetus ................... 14
Physiology of the Forces of Labor ....... 21
Pharmacology of Obstetric Analgesics, Anesthe-
tics and Related Drugs ............. 23
Part B. Analgesia-Anesthesia for Normal Labor and Vaginal Delivery
Chapter 2. General Considerations 29
Basic Principles 29
Antepartal Preparation 30
Preanesthetic Care 34
Intraanesthetic Care 35
Postanesthetic Care 35
Chapter 3. Non-Pharmacologic Methods of Obstetric Anal-
geSIa ......... 36
Psychologic Analgesia . . . . . 36
Acupuncture Analgesia . . . . . 42
Chapter 4. Simple Methods of Obstetric Analgesia 43
Management During Latent Phase . 43
Analgesia During the Active Phase of Labor 45
Chapter 5. Regional Analgesia-Anesthesia 48
Basic Considerations 49
Paracervical Block '. . . . . 54
Pudendal Block ...... 56
Subarachnoid (Spinal) Anesthesia 58
Spinal Epidural Block ...... 60
Caudal Block . . . . . . . . . . . 68
Cqp1plications of Regional Anesthesia 70
Chapter 6. General Analgesia-Anesthesia 75
Basic Considerations 75
Inhalation Analgesia 77
General Anesthesia . 82
VII
Part C. Analgesia-Anesthesia for Complicated Obstetrics
Chapter 7. Anesthesia for Operative Vaginal Delivery 87
Forceps Delivery 87
Breech Delivery .......... . 89
Multiple Delivery ......... . 92
Other Operative Obstetric Procedures 93
Chapter 8. Anesthesia for Cesarean Section 95
Elective Cesarean Section ..... . 95
Emergency Cesarean Section 100
Chapter 9. Anesthesia in the Presence of Complications 102
Toxemia of Pregnancy 102
Heart Disease 107
Diabetes Mellitus 111
Prematurity 113
Fetal Distress .. 114
Chapter 10. Management of Newborn 117
Basic Considerations 117
General Management 120
Resuscitation of the Depressed Newborn 122
References. . 127
VIII
Part A. Fundamental Considerations
Chapter 1. Physiologic and Pharmacologic Considerations
To provide optimal obstetric anesthetic care, it is essential for the
anesthetistl to kI,loW well the maternal physiologic alterations pro
duced by pregnancy, labor and parturition; physiology and pharma
cology of 'the fetal placental complex, and of the forces of labor and
how these are altered by analgesics and anesthetics. Unless this knowl
edge is properly applied, the anesthetist may make a grevious error
which may prove disastrous to the n:tother or the newborn or both.
This chapter includes a summary of current knowledge on: a) ma
ternal, physiologic and psychologic changes produced by pregnancy and
parturition; b) physiology and pharmacology of the placenta and fetus;
c) the physiology and pharmacology of the forces of labor. A summary
of the physiology of the newborn is contained in Chapter 10.
Maternal Physiology and Psychology
The process of pregnancy, labor and delivery produces remarkable
physiologic as well as psychologic changes in the mother. From the
viewpoint of the anesthetist, the changes involving respiration, circu
lation, acid-base and electrolyte balance, and gastrointestinal function
are the most important. These are consequent to hormones produced by
the placenta or are due to mechanical effects of the growing uterus or
both.
Respiration
Pregnancy produces impressive anatomic and physiologic changes in
volving the patient's airway, lung volumes, ventilation and the dy
namics of breathing.
Throughout this volume this term will be used to denote the person who admin
isters the anesthetic, whether he be a trained physician (anesthesiologist), registered
nurse anesthetist or other allied health personnel.
1
Anatomic changes. In the majority of pregnant women, capillary en
gorgement takes place throughout the respiratory tract so that the naso
pharynx, larynx, trachea and bronchi become swollen and reddened.
These changes simulate inflammation and often cause changes in the
voice and make nose breathing difficult for some women at term. They
are markedly aggravated in the presence of even minor upper respir
atory infection and toxemia of pregnancy. The growing uterus causes
the diaphragm to rise 4 cm, but does not impair its excursions and, in
fact, this is greater in pregnancy than in the puerperium. The abdominal
muscles have much less tone and are less active in the pregnant than
in the non-pregnant state. The cephalad displacement of the diaphragm
is effectively counterbalanced by an increase of 2 cm in the anterior
posterior and transverse diameters. of the thoracic cage and flaring of
the ribs all resulting in a 5 -7 cm increase in the circumference of the
thoracic cage. X-rays show increased lung markings which simulate
mild congestive failure.
Lung Volume. Lung volumes do not change until the fifth month of
gestation, after which there is a progressive decrease in expiratory re
serve volume (ERV), residual volume (RV), and functional residual
capacity (FRC). At term, ERV is about 100 mlless, and RV 200 ml
less than in the non-pregnant state. Consequently, FRC is about 300 ml
or 20 per cent lower than in the non-pregnant state. These changes are
accentuated by the recumbent position, obesity, and mitral valve dis
ease. The inspiratory capacity (IC) and the inspiratory reserve volume
(IRV) increase concomitantly with the result that total lung capacity
(TLC) remains unaltered. Vital capacity (VC) remains unaltered, but
occasionally increases. Maximum breathing capacity (MBC is little
affected by pregnancy as are timed vital capacity, peak flow rates, and
the velocity index. Lung compliance is unaffected, but total pulmo
nary resistance is significantly lower during pregnancy, primarily
due to decrease in airway resistance. Parturients in the supine or litho
tomy positions have decreased total and chest wall compliance which
rapidly increases after delivery of the infant. The mixing and distri
bution of inspired gas in the lung of the gravida remains normal.
Ventilation. Pregnancy is associated with a marked increase in minute
ventilation which at term is 50 % above normal. This is effected by a
40 % increase in tidal volume, and 15 % increase in respiratory rate. (Fig
ure 1). Since dead space remains normal, alveolar ventilation is about
70 % above normal at term. Until recently it was thought that the in
crease was progressive throughout pregnancy but recent data show that
almost maximum hyperventilation occurs as early as the second or third
2