NOTES ON ANESTHESIA
COLLEGE OF SHYWANS - ht4D -SURGEONS
COLUMBIA UNIVERSITY, NEW YORK
In the absence of an adequate anestheeia textbook,
the following notes are offered as a supplement to the refer-
ences listed on the next page. The student who flnde that the
physiological mechanisms briefly referred to in this outline
are unfamlliar to him will do well to review them at this
time in his textbooks, and lecture notes of previoua courees.
     There are three people of great importance in the
conduct of the anestheeia: the patient,  the anesthetist and
the surgeon, The statements which follow take for granted an
ideal situation: an experienced surgeon who works quickly
and gently, and leaves the choice of the anesthetic agent
and technic and the conduct of the anesthesia to the ones-
thetist; a wholly capable anesthetist who knows how to choose
and use all the anesthetic agents and technics well, and who
understands fully the eurgeon's needs; and the most Important,
but also the most variable individual, the patient. He be-
comes lees unpredictable the more the surgeon and anesthetist
know about hie disease and how it affects him as a whole, The
anesthetist cannot adequately evaluate his patient unlees he
is first a good physician with a work- knowledge of physi-
ology,
SUGGESTED READING
1. Guedel, A. E. "Fundamentale of In%alation Aneetheeia"
2. Goodman and Gibn. "Phsrmacological Baaie of Therapeutics"
First 100 pagee, Chaps. 9, 12 and Seotion V.
3, American Medical Aseociation. '%undamentala of Aneetheela" 2nd Ed.
4. Cuflen, S. C. "Anesthesia in General Practice"
5. Cowville, C. B. '?Jntoward Reactims to Ritrous Oxide Anesthesia"
Excellent for pathology of anoxia.
6. Brinker, cb K. "Puhonary Edema and Inflamtnation"
    Good background for pulmomary compllcatione.
7. Miller, W. S. "The Lungt1
9. Adrfanf, John "Pharmacology of Anesthesia"
"Chemfatry of Aneetheaia"
"Technics and Procedure6 of Anesthesia"
10, "Anesthesiology, I' a monthly Journal
11. Gillespie, N. aEndotracheal Anesthesia" 2nd Ed.
12. Leigh, M.D. "Pediatric Anestheeia"
RES PIRATION
     It is most important that the anesthetist be thoroughly familiar with
the physiology of respiration since the lungs are the only site at which oxygen
may enter the body, the chief site of excretion of carbon dioxide, and the eite
of absorption and excretion of many of the anesthetic agents, The mechanics,
physical principles, and physiological control which cauae these gases and
vapors to enter and leave the lungs should therefore be well understood,  in
order that the aneathetist may recognize the changes which take place when the
nom1 state passes to the pathological,  or when consciousness is replaced by
progressively deepening anesthesia , Careful observation of all phaeee of respi-
ratim telle more about the depth of anesthesia than all the other eigne cm-
bined.
Control
The conscious control of respiration disappears entirely with the m-
set of the anesthetic state. Respiration becomes machinelikw, and variations in
it depend entirely on the mechanical or physiological changes produced by the
ane 8 th e t is t or 6 urge on.
The unconscious or automatic control is chiefly chemical in nature. It
i8 the oonoentration cjf the H ions in the respiratoaPy center whiob aff& aeomd
te aeclond osntr31 of respimtdon. Beosuse of the great diffwibility of earbon
dioxide through cell nembranes, it usually oauees these changes in pH, but they
may be due to lactic acid, unoxidized fatty acids, etc. Hyperpnea fOlhJ8 an
increase in acidity and diminished tidal volume follcwa a decrease in acidity.
When the reapiratory center is abnormally depressed by druga (anesthetic agent,
morphine, barbiturates, etc.) the site of automatic control ie probably shifted
to the carotid bodies. A low oxygen tension is now the respiratory etimulant,
2
not pH changes. Excess oxygen under these conditions will cause a period of
apnea, until either the hypoxic stimulus recurs, or the C02 teneion rises above
the level of the respiratory center's threshold.
Reflex control is present to a lesser extent. Copmnon sites of origin
or the afferent inpulses are the skin (pain, cold), the receptors of the vagus
in tho respiratory tract, the peritoneum, rectal sphincter, the carotid sinue,
aortic arch, and carotid body. The afferent impulae probably travel6 up the
peripheral or eamatic nerves to the respiratory center. The efferent impulse may
travel down the vagus to the larynx and bronobi to cause lar,vngoepaem Or bron-
chospasm, or dawn the cord to the cervical region (phrenics) and thoracic re-
gions innervating the intercostal musclee.
It ie an error to presuppose a noma1 reepiratory center in the eurgl-
cal patient, Although sometimes stimulated (pain, fever) it is more often de-
pressed, and its threshold to stimuli raised because of drugs wed,  or because
of abnormal metabolism arising from the patient's illness, In order of frequency,
the most cannon respiratory depreasants are the anesthetic agent, the premedice-
tion drugs, oxygen lack and a marked C02 excees.
The production of oxygen lack,  or carbon dioxide retention is ae In-
excusable as an overdose of premedication drugs or anesthetic agents. A relative
oxygen lack (hypoxia) is frequently present with certain diseases such a8 hyper-
thyroidism, aevem anemia, pulmonary fibroaie and poorly compeneated circulatory
systems, but the oxygen lack should be treated before operation is caneidered.
Anatmv
A knowledge of the anatmy of the reepiratory tract is Important eo
that we may predict and thereby prevent respiratory obstruction,  or looate it
prmptly should it occur. Respiratory obstruction is the ccomnoneet aneethetio
complication. Frequent causes for obstruction and their treatment are
listed on the next page.
3
Upper Re e@frat bry Tract
Treatment
Chaqing position of head;
artificial airway
Tongue against pharyngeal wall in
supine poeition
Large tone ila , pharyngea 1 t mors ;
pharyngeal edema
FluidrJ: mucus, blood, pue, vomitus
Laryngospasm: direct irritation aneethet-
ia agent, nucu~, vanitus, pus
Reflex laa!yngosp,sm
Nasal obetruotion plus tightly closed
mouth : adenoids, rhinltie,
weeping
   Lawer Beapiratorz Tract
Fluids : mucue, vmitus, blood, pus
Asthma; ref lex bronchospasm
S ubs te ma 1 thyroid, me dias t Ina 1
tumara canpressing trachea
Artif ioial airway beyond
point of obatruation
Prophylaxis, premedication,
head down, suction
Slower induction, uae of non-
irritating agent first, pre-
medication, properly fitting
airway, gravity and suction
Gentle suraery; adequately deep
anestheeia; avoidance of oxygen
  lack and GO2 excess
Preoperative shrinkage naeal
muc oua membrane ; ora 1 8 irway
early
Prophylaxis ; head down, suction
Proper selection aneathetic agent;
helium
Airway eetabliehed beyond
  obatruction; helium
Mechanics
Contraction of the diapbragm and external intercoatale producee the
negative pressure which pulla the lungs outwards, causing an inrueh of air. Re-
laxation of these muscles cause8 the reverse prooem, expiration. Only in foroed
expiration are the internal intercoetafs and the abdaminal musolee contracted.
Normally there is always a negative presaure in %he pleural apace, It can becane
more negative by inepiring against a cloaed glottis, or by produciq a rtaesive
atelectaais. It is more poaPtive with forced expiration against a aloeed glottic
(beginning of a cougfi) and with pneumothorax. The intrapulmonary presaure, in
tbe reeting phaee of respiration, ia the aam aa atmoepheric pressure. Dieturbed
4
intrathoracic pressure relations may embarrass thecirculatibn ae well as the
reepiration by altering; the venoue return to the heart. Maintenance of the
proper pressure relatime depends also on an Intact thoracic cage, with good
mobility at the coetovertebral and sternoclavicular joints o
Lung motion ia essentially passive. Active changes in bronchial lumen
and length may contribute to lung expaneion with inspiration and expiration is
aided by the elastic recoil of the lung tisaue. The beat aerated portions are
the lower lobes and anterior parts of the upper lobes. With inspiration the apex
and lung root move downward, the lung baee downward and outward, the remainder
of the lung outward and slightly upward.
Nwneroue factors may interfere with the meohanice of reapiratim,
causing a decrease in vital capacity, and thereby producirq inadequate transport
of anesthetic gase8, oxyeen and carbon dioxide to and from the blood atream.
Pathological:
Pulmonary.. . .Fibrosie of interstitial tissue
Chronic bronchitis; emphysema
Aathma
Tuberculosis
Pneumonia
Atelectasis
Pne moth orax
Ple ura 1 a dhes ions
Rilpyema
Skeletal. o . . .Oeteoarthritis of' spine
          Previoue rib reeections
        Kyph om olios is
Muecular. o o ..Residual poliomyelitis
diaphragmatic paralysis
intercostal paralyais
paralyzed spinal musclee with chest deformity
Diapkragina t ic hernia
Mediastinal. .Tuxtors substernal thyroid
Pericardia 1 effusion
5
Abdminal. . . .Distension of hollow viscera
       Pregnancy
       Ovarian cyst; fibroid uterue
         Ascites
       Bepato-.and splenmegalies
Produced during operation:
Change in position: head dawn, prone, lateral, Mdney bridge
Open chest for thoracic surgery
Weight of assfatant's arm on cheet
Rmwa 1 of riba , th orac oplaety
Retractore on coetal margin
Pad8 against diaphragm
Depreseion of muscular activity by aneathetic drugs
A te Is c t a s i 8
IIIEPLRATORY OBSTRUCTION
CIRCULATION
CSroulation is as important a8 reepiration in the proper distribution
of oxygen and the aneathetic agent to the tisauee, and in the excretion of
carbon dioxide and the anesthetic sent. Circulatory signs are not eepecially
helpful in determining the depth of anesthesia, but are of great aesistance In
dotemining the reaction of the patient to the operative trauma and the anesthe-
eiar Only with an accurate and frequent record of pulse rate by palpation, and
blood pressure by auscultation can a proper interpretation and prbgnoeie be made.
C ontsol
The control of the circulation ie like respiration in that the stimu-
lus ie chemical in nature, but unlike respiration,  in that the "paoemaker" ie in
a peripheral region rather than in the medulla. The eino-auricular node ie the
origin of tho heart beat, and change8 in acidity of the tiseues which make up
the S-A node influence the rhythm greatly. In the heart, the important chemical
stimuli are the inorganic ions, Ca, K and Na, not carbon dioxide. The condmting
tiesue of the heart ia quite different frcan the nervous tlssue carrying the
respiratory impulees, but in both system8 activity leads to a refractory period,
when further activation cannot take place.
Several neurological connections exist which contribute to the control
of c irc ulat i on .
a.
     The right and left vagus nerves supply the S-A and A-V mdee respec-
tively. Their normal action is one which keeps the heart in check. Stimulation
of the vagus produces a marked afming in rate, with  or without a heart block.
Tbe accelerator nerves, belonging to the sympathetic nervous Bystam,
b.
supply the heart much more diffusely. Their cell bodies are located in the tho,
raoic cord, frum T1 to TG and their first synapee occurs in any of the cervical
and upper five thoracic sympathetic ganglia. The postganglionic fibers may travel
in the cardiac plexus, or actually join the vagus nerve trunk. The aympathetics
and vagus tenti to balance one another normally, but stimulation of one eystem
depresses the activity of the other, and blocking of one system produces an exag-
geration of the si@ of activity of the other.
C. Both the diviaions of the autonmic nervous system supply the peri-
pheral arterioles . Vasmonstriction occure with eympathetic stimulation; vaaodi-
lation occurs loae forcefully but is probably mediated by the parasympathetic
system. Exceptions to thia gemral rule are the coronary and cerebral vessels,
which dilate with aympathetic stimulation. Capillaries apparently possess con-
trictility Quite independent of the state of the arterioles, ar neurological
connectione o
Afferent connections of the nervous aystem with the circulation exist
in many places * The morst important f olfm :
8. Carotid sinus : Receptors two preeent in tbe walls of the carotid ainue,
at the bifurcation of the ccgnmon carotid into its external and internal bramhes,
The afferent impulaea pas8 along the carotid 8inue nerve, a branch of the glaeeo-
pharyneeal nerve, and branchee of the vague and cervical sympathetlce. Reflexee
7
frm this region normally keep the blood pressure at a constant level. Pressure
changes inside or outside the sinus wall are the chief stimulating factors.
Overstimulation results in hypotension and bradycardia .
3.
Aortic arch: the afferent path is up the vagus nerve to the medulla.
Its reactions are similar to the carotid sinus reflexes.
All these impulses are collected by the vasomotor center in the me-
dulla, which synchronizes the circulatory reaction. Changes in respiration fre-
quently occur at the same time because of the cloae relation of the respiratory
and vasomotor centers.
Sh oc 1:
This  is the cmonest circulatory accident. The word is poorly chosen,
for many connotations have been ascribed to it. What is meant is a discrepancy
between the qirculating blood volume and the capillary bed. The sequence of
events in increasing shock la:
1.
2.
3.
4.
5-
5.
7.
8.
9-
10 .
Precipitating trauma : severe burn, hemorrhage, prolonged surgical
trauma, deep anesthesia
Capillary dilatatian and arteriolar constriction: trapping of much
blood in capillary bed making it unavailable for general circulation
Constriction 01 spleen to supply zilore blood
Increased heart rate, to deliver diminished volme better
Diminighed venous return
Increased reapirations (hypoxic etimulua to carotid body) to supply
more oxygen to overworking heart, until center damaged by hypoxia
Lose of proteins through capillary wall to tissues
Viscosity of blood greater - lcore difficult for heart aa a pump
Further capillary damage from prolonged hypoxia o IVm irreversible
Failure of myocardiura because of poor oxygenation
It is obvious that treatment of ahock must be prompt and rational. It
is directed tawards:
8
1. Supplying ample oxygen
2. Restoring blood volume
3. Restoring plaspls proteins
4.
Restoring RBC,  if blood has been lost
The anesthetist '8 inmediate reeponsibillty is to institute mans of providing
the patlent's tissues, ehpecially the oerebral tissues, with ample oxygen# and
to maintain optimal oxygenation while fluids, blood and blood substitutm~ are
obtained and administered by &hers. If help is not available the anesthetiet
should first set up a ~ouroe of excess axygen and an infallible alrway, befme
embarking on What may be a difficult and time-oonsuming venipundum in a pa-
tient with peripheral vascrmcrtor collapse.
There is no rationale in giving cardiao rstimulants. Adrenalin, Ana-
leptics (coramine, metrazol, etc .) and carbon dioxide stimulate heart muscle
ONLY if it is well oxygenated.
Ane a the t ic Ihp lic at i om
1.
Evaluation of the risk of a cardiac patient is merely the evaluation
of his compensation and reeerve. Any surgical operation or aneetheaia impoms a
strain on his circulatory system, and a careful history of his tolerance of
other kinds of strain will give better clues as to the length and eeverity of
the surgical procedure he car, tolerate, than phyeioal examination of his heart
and peripheral vessels . Determining the presence or absence of  murmur^, abnormal
rhythms, or vascular thickening cannot alone lead to an accurate prognosis 4s to
functional efficiency and adaptability of the circulatory system.
2.
     All anesthetic agente depress heart muscle directly, mklng it a less
effective pump. The deeper the anesthesia, the worse is the depression, Chloro-
form and ethyl chloride are the moet sevwe depreseants,
3.
Ether anesthesia, carried no deeper than second plane, is probably tbe
9
safest for a cardiec patient. Because of its irritating effect on the reepira-
tmy system, inspiration is stimulated which causes a better venous return to
the heart. Within certain limits, this meam an improved circulation.
11.
Oxygen lack is the worst depreseant for heart nuscle especially if it
is already danaged. (Myocarditis, rheumatic fever.) Ample oxygen MIET be sup-
plied to cardiac patients.
3.
The conduction system In %he heart is often affected by the agent.
Cyc lopropane frequently produces irregularities in rhythm wh fch are not perma-
nent. All druge, even procaine and the barbiturates, cause EXZ: changes.
5.
The vasomotor center is depressed especially by the non-volatile drug8 :
short-acting barbiturates
avertin. Deep anesthesia with the inhalation agents
11130 cauees a mrked depremion, so that compensation for impending shock, by
vasoconatriction, is completely lost.
Tbe anest21etist always attempta to keep the blood preeawe and pule6
at their normal leve18, in spite of the surgery. Following are some of the CQDS
mon reasons for changes  in them.
Increased Puleo Bate Rise in Blond Pressure
Oxygen want, early
Carbon dioxide excess
Eemorrhage
Ligh't anestheeia
Ether
Exceeeive sweating
Wreased adrena lin output
Fluids given too faet
AnaLept ice
Large doees atropine or scopolamine
Decreased Pulse Rate
Eigb epinaf anestheeia
Neasynephrine
Sudden, eevere anoxia
Carotid sinus reflex
Celiac plexus ref lex
Chloroform, ethyl chloride
cyclopropane
Poeition of patient
head dmn
lith ot coly
Oxygen want, earl?
Carbon dioxide exce8e
Manipulatian of toxic thgroid
Analeptics
Fluids
Fall ia Blood Pressure
Position of patient
aitt ing
change during anesthesia
prolonged Trendelenbur6
Ckygen want, late
Marked carbon dioxide excess
Deep anesthesia
10
Decreased Pulse Rate
Heart block
Vomiting
Drainage of cerebrospinal fluid
Procaine reaction
Fall in Blood Pressure
High spinal aneethesia
Avertin, i.v. barbiturate
vomit in$
Carotid sinus, celiac plexus
Prolonged operative trauma
Sympathectcrmy for hypertension
Hemorrhage
. Accidents1 i.v. procaine
' Sudden release of increased
abdominal pressure : pregnancy,
ascites, cysts
Decreased Pulse Pressure
Carotid sinus ref lex
Celiac plexus or other traction reflexes
Shift of mediastinum: thoracic surgery
High spinal anesthesia
Intracranial pre Gswe change8
fntracranial manipulation
CENTRAL IvERvuus SYm
A reversible and oontroUahle depression of the nervous system is the
aim of' any anssthesla. It would be desirable to limit the action of the drugs to
the nervous system alone, but by most technics this is impossible,  since the
drugs are carried by the blood stream. Only by regional blocks (spinal, psrw
blocks, local infiltration) are parts of the nekrvous system anesthetized di-
rectly.
      The inhalation agents cause an ascending paralysis of the spinal cord.
This means that the intercostal muscles, supplied by the thoracic cord are para-
kyzed before the diaphragm, with its cervical innervation. During deepening
anesthesia, the lower, then the upper interoostals and finally the diaphragm
lose their activity and tone, an8 during recovery frm deep anesthesia, them
musclea recover in the reverse order. Otservatian of the comparative activity of
these two groups of muscles gives UB one of our most important respiratory
signs .
                                                           11
     Concomitant with the ascending cord paralysis, deprespJim of the brain
progresses from ite most specialized to its least specialized centers. The cere-
brum is depressed first, with early loss in judpent and reason, followed by
loss of memory and consciousness. Of the special senee6, hearing remains intact
the longest, and recovers first. The cerebellum then shares in the depression as
evidenced by the ataxia of second stage. ObJective signs of further depression
are not obvious, but progress dawn through the thalamus, midbrain and medulla.
sgvere lnaduUary depression indicatea an approaching irreversibility of the  an.
esthesia.
'RlemOSt serious depressant for the nervous systm is oxygen lack. In
normal persons, it is a matter only Qf minutes (cerebrum, 8 min.; medulla, 30
min.) before permanent destruction takes place. In a person who is already in a
chronic hypoxic state (cardiac, pulmonary pathology, anemia, prolonged partial
obstruction of airway) this time interval is reduced to seconds. After a mvere
hypoxic episode, permanent sequellae, such as personality change#, visual dis-
turbances, and changes in muscle tonus, sensation and control of fine movements
may occur. Cerebral hypoxia in the newborn is known to be related to certain
types of mental deficiency and spastic states appearing during the child's de-
velopment. An eplsode of hypoxia severe enough to be inccaapatible with recovery
fa characteristically follcwed by failure to regain consciousness, restlessness,
convulsians, hyperthermia, cm and death. Since no treatment can change this
pictnre  once  it develops, prevention of oxygen want is the only mema of control-
ling thia problem.
AUTONOMIC NERVOUS SYSTEM
The autoncanic mrvoua system is one of tbe most cmpUcated and one of
the most fascinating ooncepts in physiology. For a clear presentation of the
problem, especially of that part relating to chemical mediatian of the nerve  im-
pulse, Chapter 19 in Goodman and Gihn,  is recammended.
None of the anesthetic drugs fits entirely into an adrenergic  0.1-
cholinergic classification but the common agents can be divided roughly as fol-
Adrenergic stimulation: ether, chlorof om, oxygen lack, C02 excess
Cholinergic stimulation: cyclopropane, barbiturates, morphine
Spinal or nerve blocks paralyze the sympathetic fibers to the part
anesthetized
Atropine and scopolamine depress cholinergic activity
Although a patient may be anesthetized to various stages of depression,
stimuli are not prevented frm reaching the nervous system and produciw re-
sponses. Most of these .reflexes are respiratory and circulatmy in nature and
are mediated by. the autonmic nervous system. Correctly speaking, this is solely
an effector system, but many afferent fibers run in autonomic nerve trunks
(splanchnic, vagus).. The cell bodies for these fibers are in the dorsal root
ganglia, or the vagus nucleus.
Origin of afferent impulses :
Traction on upper abdominal viscera, mesentery, cecum, pelvic organs,
Manipulation of recurrent and superior laryngeal nerves, phrenio nerves,
Periosteal sthulation - especially rib periosteum
Lung hilum stinulation
Stimulation of celiac plexus: manipulation of conanon duct, pads, retractors,
Stimulation of carotid sinus: neck infections, head dawn position, re-
perinem
vagi
elevated kidney rest
tractor in thyroid surgery, neck dissections, anesthetiet 's finger
   pressure, extreme  lateral flexion OT neck
Dilatation of rectum, vagina, cervix
Overdistention of lungs
Irritation of nasal or tracheal mucous membranes
Marked apprehension preoperatively; marked excitement stage
The efferent effects may be:
Respiratory: hryngospam, or adduction of vocal cords apnea, YMTegular
Circulatory: change in pulse rate, arrhythmia, hypotension, diminution in
Increase in puscle tanus, agnvulsions
re spire t i on, b ypo ypqea , br mch ospa 8m
pulse pressure, hypertensian
Treatment is mainly prophylactic
1.
2.
3, Adequate premedication to control psychic state and to diminish irri-
4,
5, Blocking of area of reflex activity with procaine
Deep anesthesia before traction ia exerted
3roduction of a8 little trauma as poesible, and if necessary gently
and steady, not sudden traction
tability of the nervous system (morphine)
Endotracheal airway for upper abdcaninal and neck surgery
Aner ref lex has occurred, treatment may be :
1.
2. Blocking the reeion with procaine locally
3.
4.
5.
Stopping trauma or traction when POSSible : reexerting traction slowly
and steadily
Changiw level of anesthesia, giving adequate oxygen, and removing
Supplementing light anesthesia with additional doses of morphine (with
me of some drug to cban&e the balance in the autonomic system: atro-
excess C02
mopolamine or atropine) for general reflex depreseion
pine
ephedrine, physostigmine, ergotamine : all have been succeesful
in @me cases
PHEMEDIC ATION
Premedication is as important in anesthesia as the choice of' agent or
technic. The reasons for using premedication are several:
1.
Psychic depression of patient: Abolition of undue alertness and anxiety
reduces the incidence of excitement during induction, and increases the eaee
with which subsequent anesthesias may be given to the same person. A atoMoy In-
duction usually leads to hyperactive ref lexes and increased secretions, come-
quently to a stormier uaintenance and recovery.
2.
To lower patient '8 ref-lex irritability, which parallels his metabolic
rate. Less anesthetic agent in actual amount is needed to produoe and maintain
surgical anesthesia if the starting paint of the anesthesia is at a relatively
low metabolic plane, Excretion of the agent and recovery frm anesthesia is
14
consequently more prmpt o If ref lex irritability is depressed by premedication,
there is less likelihood of such cmplications as vmiting during inductian,
breath holding and coughing with imitating agents, and reflex Larpgospasm.
3.
      To prevent excessive seoretime in the respiratory tract. The develop-
ment and retention of excessive secretions during anesthesia increases the ever-
the stimulation of secretions by ether that the tern itether pneumonia" was
coined. This misnamer is camonly applied to what starts a8 an atelectasils and
later develops into pnewaonia .
4.
To prevent the convulsant action of drug6 used for local, block or
spinal anestheaia. Acarding to experimental evidence the barbiturates are the
most effective o
   5. To coynteract autonomic nervous system effects of certain anesthetic
agents; i .e., intravenous barbiturates and cyclopropane are apparently cholin-
ergic drugs and are best preceded by scopolamine or atropine.
kPES OF DRUGS USED:
Barbiturates are best for psychfc depression, and for counteracting
the convulsant effects of the regional drugs. They are not satisfactory for
lowering reflex irritability. Alone, they cause increased secretions.
Morphine is the best drug for genere1 lletabolio depreaeion and
dim;irutirn of reflex lrritabillty, Dsrmerol is almost a8 satisfaatmy and ha
the addea advantage of produalng brcmchobilatien, leas reeplratary center
bapcssion and lees nausea an8 vdting t& comparable riosea qf mrgkir-e,
Atropine and sccrgolamine ere both good drugs for preventing eecmtians,
counteracting the respiratmy depression and the tendency to vamit after mor-
phine, and preventing excessive parasympathetic activity. The only important dif-
ference between the two drugs is their opposite effect on the cerebral centera:
atropine ie atikulating, causing increased alertness, while scopolamine is a
mild depressant causing drowsiness, and suinetimes amnesia .
Avertin is a premedicatim and not an anesthetic drug. It is desirable
from the patient's point of view because of the ease with which it produces un-
consciousness, but is undesirable because of the length of time protective
(cou&) reflexera are depressed. Used, however, only to produce amnesia, most or'
the ObJections to the drug are outweighed.
Intravenous barbiturates also produce prmpt and easy lOS8 of con-
sciousness but in moderate doses are preferable to averbin since they are meta-
bolized so quickly that laryngeal and cough reflexes return rapidly.
The dose of these drugs depends upon certain factors in the patient's
pathology and physiolog;!.
The following conditions are c~lllllon ones demanding
than average
doses of depressant drugs :
Fever Hyperactive personality
Pa in Muscular constitution
Ma rke d appm h e ns i on
Hyperthyroidism Pregnancy
Neurosis Adolescence
Manic type of psychosis. Determination to resist sleep
Chronic alcoholism
The following demand - less than average doses:
Anemia
Hemorrhage
Shock
Hypothyroidism
Chronic illness
Weight loss
Acute alcoholism
Cardiac diaease
Obesity
Ne ph r i t i s
Senility, infancy
Previ ou~ depressant drug
Jaundice
Mental deficiency
Sc h i z oph re nia
Senile psychosis
Phlegmatic personality
Addison's disease
The route of administration of these drugs depends on the time avail-
able before start of anesthesia, since it is desirable that the peak of action
of the pr~~dicati~ be reached or just paswd at the tima anesthesia is begun,
When the medication is given h~od~~ically 90 mZnu%es is necessary far the de-
velopment of ~x~~ effect, when intr~us~u~rly, 45-60 minutes, while only 10
to 15 ~nutes are needed for the peak of action after intravenous pre~di~ati~.
The last is, therefore, the only efficacious route when the tlme between
sc~edul~~ an operation and the start; of a~sthesi~ is short. The mal and
rectal routes are both ~de~nda~le because of the maw variabla factors in ab-
sorpt i on.
The follwing ~e~~al~tie~ are s~~sted far ~dicat~~ before various
.
Nitrous oxide needs heavy premedication. Nitrous oxide is nat; a patent
agent, therefore the metabolfc rate and reflex irritabilfty mu& be brought to
It
Lbasaf conditions" by appropriate doses of morphine or by a  basal aneElfrhetiGff
(Avertin) in order to produce surgical anesthesia without sacrificing adequate
oxygenation, Reduction of reflex irritability and metabalio rate not on& Bsmn
t
the amount of nitrous oxide necemary, but also tend to reduce the oxygen re-
quirements of the tissues.
Cyclopropane is potent and rapid in effect, therefore need not be gm-
ceded by the de~res~ant type of ~~~icati~n, but because it is cholinergic atra.
pine OT aoopolamine should be administered to counteract this effect,
Ether, because of' 5ts slaw onset and unpleasant imitating qualltfels
should be preceded by moderate doses of the d~p~~sa~ drugs and sufficierrt
atropine or ~co~o~~~e to inhibit excess secretions.
XmaL, ~~ina1 or regiona3. technics am best preceded by B short acting
barbiturate, and 8 mall dose of morphine, but inbibition of sacretias is not
necessary unless the use of ~u~ple~~~a~ a~sthesia (ether, c~lopr~ane, i.v4
bar~~t~a~es~ is anticipated, ~opo~ine iB frequently used before local,
blaok or spinal anesthesia, but it is used for its counteracting of respiratory
depression and nausea from morphine, and for its production of amnesia, rather
than for its effect on secretions.
     Intravenous barbituratee, like cyclopropane are cholinergic, and are
frequently accompanied by increased secretione. Atropine or scopolamine should
therefore be given before their use. Small doses of morphine to reduce pain per-
ception are helpful since reeponses to pain stimuli are abolzshed only with re-
latively deep barbiturate anesthesia, Oral premedication with ems11 amounts of
other barbituratee is not contraindicated, but is ueually unnecessary and beat
omit ted.
Avertin is eseentially a depreeeant premedication, and eo should be
preceded by minimal doees of morphine (for reflex depression) but the neceeattry
amount of atropine or ecopolamhe should not be reduced.
Suggested dosea in healthy adults are
Magendie 0.3 C.C. (morphine .009 gm} + Scopolamine 0,0004 gm.
Demerol 0.075 gm + Scopolamine 0.0004 gm.
General princlplee of medication:
1.
A combination of two depressant drugs, i.e., nembutal and morphine is
more depressant than either one alone. Correct this by decreasing the dose of
each.
2.
Because the cambination of barbiturate, morphine and a general anesthe-
-
tic so often produces marked respiratory depreesion,  it is better to give the
barbiturate the night before operation, uslng; a medium or long acting one so
that its action will be present but waning on the morning of operation. For
case8 scheduled late in the morning a short-acting barbiturate (nembutal,
seconal) given "on awakening" will allay anxiety, yet be past it8 peak of action
when the pre-operative morphine le given,
3.
Beware of using depressant drugs in patients with preexisting
18
respiratory difficulty. Such patient '6 respiratory exchange may be just adequate
to keep them oxygenated without such drugs, but even slight respiratory depres-
sion caused by the drugs nay lead to mvere hypoxia. Patient8 with severe hemor-
rhage, anemia, asthma , cardiac decmpensation, substernal thyroids, marked e-
phosis, and marked abdominal distention, are in this group, as well as those
with pulmonary disease o
4.
Every time a depressant drug is used, the cough reflex is diminished.
me dosage of opiates necessary ta control cough is materially smaller than that
neceasary to relieve pain, An active cough reflex is the best prophylaxis
against respiratory complications. THINK TWICE before ordering depressant drugs.
INHALATION AGENTS
There are at least ten anesthetic gases and vapors. A omparison of im-
portant properties of the six most common is tabulated on page 19.
The anesthetic gases obey all the well-established physical gas laws,
but the one of particular importance to the physiology of aneatheeia is that the
direction of diffusion of a gas 18 from a region of high tension (partial pres-
sure) to regions of lower tensions. This is the machanim by which gases pass
from the alveoli to the blood stream and thence to the tissues when they are ad-
ministered, and pass in tie reverse direction to be excreted when administration
Is stopped,
An important difference between the voletile agents and the nun-vola-
tile one8 is that they are not changed in the body, and are quantitatively ex-.
areted by the lungs. A negligfble amount diffuses through the sMn and into the
sweat, urine, and other secretions, but the liver and kidneys are spared the $
metabolic work of inactivating the drugs. The significance of this mode of exom-
tion :E that should overdose occur, the drug can be removed from the body by
SCME PROPERTIES OF CCNMON INEALATION ANESTVE!l?IC AGElpflS
CHLOROI CYCLO- N-rrROUS
NAME ETHER FORM VINE!I'HENE PROPANE E'J3YIZI'?E OXIDE
STABam
~. .
FAIR FAIR
POOR GOOD GOOD GOOD
4.1
2.42 1.45
*97 1.52
FIRE 80 EXPLOSZON ++* 0 ++++ ++++ ++++ 0
HAZAiW
PCVEIICY WITHUJT
OfiGEll WANT
$ IN INSPIfiED AIR 4.C$
(2nd plane)
MPLDITY OF INDtfc-
TION - CONTROL &
IIECOVERY
4- ++
++ U++ ++++ ++++
MARGm OF SAW Depends on ability 05 anestbetist
IKR. SECRETIOHS ++++ +++ ++++ +' + 0
ADVERSE METAB.%tC
   CHANGES
+++ +U+ +++ ++ + 0
CAUSE OF
DEATH
liESP.    CARDIAC     RESP o     ma.
DEPrnSS.   mPmss,   rnPRESs*   DEPrnSS.
AFlJOX;LA    ANOXIA    ANOXIA    ANOXIA ANOXIA ANOXIA
Waxe prepdkations administered Intravenously can be used to produce
relaxation of striated muscle and is especially indicated with the lese potent
anesthetic agents. Some respiratory depression always accompanies its use and
some method of assisted ventilation should always be at hand to assure proper
exchange of eases.
20
artificial respiration provided that the circulation has not entirely ceased to
carry the drug from the tissues to the lungs. There is more safety in using a
drug which can be removed in the same way it is administered, than in using a
drug which must be metabolized by the patient before li&teniag of the anesthe-
sia can DCCLW.
Many theories (see Goodman and Gilman, p. 32) have been advanced to
explain the phenmenon of narcosis, but few are equally applicable to all types
of anesthetic drws. It is most likely that the ultimate mechanism of the pro-
duction of narcosis is an interference with the oxidative enzyme systems of
nervous tissue. The oil-water solubility ratio of the anesthetic drug, it8 ad-
sorptive properties, or its alteration of surfaoe tension may be of importance
only in intermediate stepe leading to the afteration of tissue  oxidation. This
assumption explains why several of the theories may have coneiderable corrobora-
tive evidence without being sufficientlx applicable to all drugs to permit their
acceptance. It is far from established at the pmsent time that enzyme  disturb-
ances are the explanation of reversible cell depression (narcosie), but a shift
in the relative importance of different enzyme systems is a tempting way of ex-
plaining haw nerve cell activity (energy production) can be ixhibited by anes-
thetic drugs without causing death of the cell.
IMlALATION TECHNICS
Inhalation methods as previously mentioned are the on$y ones in which
the anesthetic drug can be removed frm the patient at will, and thereby are the
- safest of all methods. They also allow the most accurate individualization of
dosage o
The follawing factors directly influence inhalation anesthesia:
21
Change in the inspired atmosphere
Minute volume exchange
Available alveolar surface
Pat lent 's respirat my tract
Efficiency of the cimulation
Blood supply to various tissues
Amount of adipose tissue in body
Composition of the blood
There are three fundamental types of inhalation technics, with nmr-
ous variation; open drop, carbon dioxide absorption, and insufflation technics.
The open drop method is characterized by the use of a wire mask
covered thinly with layers of gauze, on which the liquid anesthetic agent is
dropped and allowed to vaporize. The vapor being heavier than air, ooncentratea
under and close to the mask, and is inhaled by the patient, Exhalation through
the mask increases the rate of vaporization of the liquid.
The carbon dioxide absorption system involves the us0 of a machine
with yokes for attaching tanks of cmpressed gasee, valves to adjust the rate
at which the gases escape from the tanks, a fhmeter to indicate the flaw of
gas, a rubber bag to act 88 a reservoir for the gas mixture, and a canister of
absorbing material (sodalime, baralyme) to absorb the carbon dioxide made by the
patient .
     Ineufflation mthods are characterized by blowing an anesthetic mix-
ture into the patient 's respiratory tract (naso-pharynx, mouth or trachea) in
sufficient concentrations to maintain surgical anesthesia, after it has been
induced by one of the above methods. The anesthetic mixture may be oainposed of
gases delivemd frcan high presaure tanks at a mure rapid rate of flow than used
with the closed system, and nay be used as vehicle8 to carry the vapor of a liq-
uid drug from a reservoir to the mtient. (Exanplea: Insufflation of nitrous
oxide and oxygen, &her vapor earried by a atream of oxygen.) Cmpmsaed air
piped to the operatine; room from a central source, or delivered by a motor-
driven pump or foot bellme, may be used instead of oxygen as the vehicle for
the vapor of volatile agents.
All tbree systems can be considered a6 extensions of the respiratory
                                                             22
system of the patient. The gases under the mask, in the breathing bag,  or in the
insufflation stream come into equilibrium with the alveolar gas concentrations
after a short time. From this point, equilibrium is reached with the blood
stream, and finally with the tissues.
There are advantages and disadvantage of each method:
PRO
Open drop -
1. SSmple, portable
2. Inexpensive equipment
3. Minimal rebreathing C02
4. Minimal reaistance to
breathing
,Ab sorption
1. Good control respiration
2.   Re susc Itati on easy
3. Economical, anes. agent
4, Heat, water vapor preserved
5. Oxygen easily added, carbon
dioxide removed
Insufflation
1. Technically easy, head and
    neck surgery
2. Lowest rebreathing C%
3.
Easy route to add 02
1.
2.
3.
4.
5.
6.
7.
E;.
1.
2.
3.
4.
5.
5.
C ON
No control of respiration
Poor set-up for resuscitation
Very wasteful, anes. agent
Loss of heat, and water vapor
Irritating, cold vapor
Always lower oxygen than air
Fire hazard
Skin burns, liquid ether
-
Initial expense hi@
Less portable; tanks of gases
Can get out of order
Increased temperature inspired
Slight resistance to breathing
Explosion hazard
a ir
1,2,3,4,5, and 7 same a8 open
1 and 3 mnte as ab8~rptiOn
Re la t ive ly purtab le when f oat
Cif f ic ult to maintain deep
drap metbad
bellows type used
am s th e a ia
To each ayetern, an endotracheal airway, introduced througb the nose or
mouth, may be added. Its advantages and disadvantages are  listed below:
1.
2.
3.
4.
5.
5.
PRO
I_
Free airway, cc~nmon sites of
  ob struo t i on under c ontr ol
   (tongue , larynx 1
Dead apace diminished - quieter
respiration, lower C02
Prevention of material from
entering trachea (tube with
   cuff or packing)
Pathway for auction established
Control. of pressure in chest
Ideal aet-up for resuscita-
tion
1.
2.
3.
4.
C ON
Moderate obstruction to respf-
-
ration if tube too low or
Possible trauma to larynx and
pharynx by inexperienced
Possible injury to epithelium
of trachea or larm by
Anesthesia must be kept deep
enou& to abolish cough
narrow
ane sthet ist
pressure of tube or cuff
ref lex
Indications for endotracheal airwag
1.
2.
3.
4.
5.
5.
7.
8.
9.
Operations in areas of high reflex irritability: upper abdomen
Operatiom on patients with high reflex irritability: alcoholics
Head and neck surgery: anesthetist out of surgeon's way, but goad con-
Poor risk patients: if resuscitation may be necessary; eapecially
Thoracic surgery: control of pressure relations in chest; suction of
Insufflation technics, delivery of agent more efficient and effective
Long operations in unphysiological positions: Ex. : spinal fusion, in
prone positJon. Respirations often aided by anesthetist
Patients in whom an adequate airway cnanot be establi&ed and main-
tained by simpler means: receding jaw, short neck, intractable
In war sqery when one anesthetist must manage several general anes-
trol of airway
neurological patients
secretions frm trachea and branchi
laryngospasm
thesias at once
OmEER TECHNICS
Rectal, Intravenous, Regional Blocks
In these technics, d~ugs can be administered with comparative ease,
but cannot be recovered at will. The patient destroys and excretes the metabo-
lized drug at varying and wontrollable rates of speed.
PRO
-
Reotal route
Slmple, portable
Painless
No fire hazard
(except ether)
Intravenous
' Simpl.5, portable
Minimal pain
No fire hazard
Quick induction
Quick recovery
Inte'rmittent dosage
quite accurate
Good supplement
  for blocks
C ON
c_
Unpre dic tab le ab s orpt i on
Variation in rectal preparation
Sph inc t er re laxat i on
Needs cooperative patient
Rectal patholaigy
Long recovery period, requiring
constant nursing care
Narrow margin of safety
Overdose of drug easy
No control of respiration '
Only light anesthesia obtainable
May need help to keep free airway
(two people desirable)
24
Nerve Blocks
Excellent re laxation
No fire hazard
Portable Need cooperation (children
Minima 1 metabolic
Special knowledge and training
Limited duration of' block
dif f io ult )
disturbance because
    of anesthesia
POsSible damage to nerve
of limited area
Avertin overdose results in marked ciroulatory and respiratory depres-
sion (more of depth than rate). Treat with pressor drugs (ephedrine, neosyne-
phrine) and oxygen.
     Pentothal overdose results in apnea with variable degrees of circula-
tory depression. Treat with artificial respiration with oxygen. Analeptic drugs
(coramine, benzedrine, metrazol, picrotoxin) are advisable only when overdose is
known to be large since smaller doses of pentothal my be metabolized quickly
and the patient then may have an overdose of the analeptic.
Procaine "reaction" frm overdose or intravenous injection results in
one of two syndromes:
1.
Marked blood pressure drop, bradycardia, pallor, nausea and vcnniting.
Treat with pressor drugs (ephsdrine, neosynephrine ) and oxygen.
2. Increased C .N.S. stimulation: apprehension, reetle~~~ness, convuleions
afid hypoventilation from spasm of respiratory muscles. Treat with  intravenous
barbiturate and oxygen (artificial respiration if necessary) . Prevent by proper
premedication.
PRO
cc
Simple technic, portable
Non -explosive
Excellent re laxat ion
Minima 1 me tab olio changes
CON
-
Numerous uncontrollable factors
Drug cannot be recovered
C irc ula t or y de pre as ion f req uent
Pos8ible nerve root damage
Late recovery of active intercostale
Shwk more eevere after hemorrhage
25
LI
8
8
d
0
x
h
d
d
x
9
m
26
Factors concerned in the DURATION and  HE^^ of spinal anesthesia
Controllable Urn ontrollab le
Space of injection
Speed of injection
Volume of solution used
Dosage of drug
Specific gravity 601.
Posit ion of patient
Choice of drug
Diffusion
Circulation cf spinal fluid
Movemnt of fluid by respirations
Length of spine
Previous pathology or anmalies
Movement of patient
and pulsations
Change CSF pressure by straining
Breaking needles during
a dmini stra t i on
DRUGS used:
Procaine.. . . . .short acting, but least toxic
Monocaine . . . . .isomer of procaine
Metycaine.. . . .longer acting than procaine
Pontocaine. . . .long acting, 1OX more toxic 11 than procaine
II 11
Nupercaine . . . . I' I' , 20x
Glucose or alcohol may bo added to tbe ffrst four drugs to make the
solution hyper- or hypobaric. Nupercaine is slightly hyperbaric in the 1:200
solution, and may have glucose added; it is hypobaric in the 1:1500 solution.
Continuous or intermittent method of administration allows for much
more accurate dosage, and es8ures adequate anesthesia until end of operation.
Severe respiratory depression frmn too high a level oan be avoided entirely.
Circulatory depression, hawever, has not been avoided by the continuous method.
some of the Taotors in the production of circulatory depreseion by
spinal anesthesia during surgery, are listwa below:
1.
2.
3.
4.
5.
6.
7.
9.
10 .
a.
Relaxation of skeletal muscles, followed by poorer venous return.
Vasodilatation of blood vossels in the anesthetized regime.
Stagnation of blood in tAe peripfieral vaecolar bed.
Dbinished thoracic excursion frm partly paralyzed intercostal
muscles caueiw dieturbance of preseure relations and poor venoue
    return to heart.
Eypaxia of myocardium.
?Toxic'' effect of anesthetic drug itself.
Accentuated vagotonic response to traction, due to autonomic imbalance
Poor adjustment to change in position.
Poor canpensation to changes in blood volume (hemorrhage).
Decreased adrenalin output. (Adrenals functionally denervated.)
resulting frm anesthetized splanchnic nerves.
Treatment is best prophylactic, by use of a vasopressor drug, which
may act at one of three sites, the vaaanotor oantsr, the heart muscle,  or on the
blood veesels peripherally. The best vasopressor drug is ephedrine, because  of
its sustained action, and minimal toxic effects. Other drugs in use for this
purpose are neospephrine, benzedrine, cobefrin and paredrine .
After the drop in pressure has occurred, treatment should be directed
toward providing ample oxygenation for the brain and heart muscle.
1.
2,
3.
4.
5. Fluid therapy: blood, plasma or salipe, as indicated
Head down position (if hyperbaric drug has not been added to subarach-
Oxygen, bg insufflation or closed inhalation system
Restoration of normal ventilation by manual methods
Additional doses of pressor drug
noid space recently)
Retchin6 is a cmon and troublesome complication of spinal anesthesia.
It may be caused by:
1. Intraabdcaninal traction
2. Hypoxia due to:
a. Marked blood preasure fall
b . Respiratory paralysis
c. Overdose premedication
3. Reaction to premedication (morphine)
4. Psychic
          a. Inadvertent seeing of blood on drapes
    b. Odor of "prep" ether - odor of cautery
      C. Anxiety
Reaction to spinal drug (only with very laree doses)
5.
Treatment of retching .under spinal anesthesia depends on the cauee.
For 1:
Exert traction as slowly and gently as pos6ibb. Depress reflex
irritability with morphine or light general aneethesia.
For 2:
Sapply oxygen: artificial respiration with mask and bag if tidal
volume is too small or paralysis cmplete.
For 3:
Scopolamine or atropine may help. (1 part:25 parts morphine) add
treat as for $+.
For 4:
Any treatment that distracts patient will help: deep breathing,
ice water cmpress to forebead, aromatic apirita of ammonia,
etc o
For 5: As for procaine overdose.
28
POSTOPERATIVE PULMONARY COMPLICATIONS
Pulmonary complications f olluwing anesthesia and surgeryf om the most
frequent and most serious type of morbidity and mortality, Many factors cmtrib-
ute to their incidence, but most revolve around the ineffectual removal of 88-
cretions from the tracheobronchial tree. Under normal conditions,  secretions are
constantly produced in this tract, are in part dried by the air currents, and in
part removed by the action of the ciliated epithelium, as well as by the peri-
staltic action of the bronchial musculature. Both these actions are inhibited by
anesthetic agents, and by therapeutic doees of morphine. The defense of the pa-
tient against accumulated secretions is further weakened by the presence  of an
ineffective cou&. The f ollming circumstances contribute to its ineffectiveness.
1.
2.
3.
4.
Inability to inspire deeply
Splinting of abdominal musoles inhlbiting motion of diaphragm
Pam.1ysi.s or paresis of interoostals following spinal anesthesia
Fluid or air below diaphragm,  or in chest
Tight binders
Prone, or lateral position
IFhrenicect qr
Bronch ospaLm
Too much postoperative medication (morphine)
Irresponsive central nervous system
Weak, exhausted patient, senility
Inability to tighten abdominal lnuscles
Post- spinal paresis
Avitaminosis
Eefect in chest wall (thoracuplasty)
Open glottis (endotracheal tube) ; tracheotmy
Inadequate cough reflex
Ventral herniae, diastasis f
Inability to produce positive pressure  in chest
The ptient; most likely to develop postoperative pulmonary cmplica-
tims are those with :
1.
2. Chronic respiratory infection, with sputum: chronic bronchitis and
3 . Upper abdominal operations
4, Neurological operations
5.
Previous history of pulmonar=. camplication, especially postoperative
pne monia
emph yseme
Long period of irmnob$lity in imnediate postoperative period: plaster
mat, or poor nursing car0
1.
2.
3.
4.
5.
7.
/
3.
1.
2.
3.
4.
5-
6.
7.
8.
6. Alcabolic history
7.
8.
Operations of over three hours' duration
Presence of shock dur3.ng operation or in postoperative period
The two types of pathology which dovelop are:
1. Atelectasis: patchy or confined to one lobe, or one lung. The origin
of the atelectasis is most frequently obstruction by mucous plugs lodged in the
major bronchi, or in smaller divisions of the bronchi. The obstruction my ab0
be caused by reflex bronchospaam. The gases in the lung distal to the  obstruc-
tion are absorbed into the blood stream, %he alveoli becme airless,  and the
solid area of lung thus produced is a perfect field for the development of in,
fections, or
  2. Bronchopneumonia: the causative organisms of this complication may be
thoae present in the lower tract before operation, or ones aspirated during an-
esthesia. Aapiratian of vcanitus almost as6ures development of pnemonia, not so
much because of the bacteria present in this instance, but because the chemical
irritation fram the hydrochloric acid predisposes to infection.
Prophylactic treatment before operation consists of
Preventing secretions by use of belladonna group.
Minimal use of belladonna group if secretions already present.
Postural drainage to remove sputum; occasionally bronchoecopy.
Afternoon operations far thoracic surgery.
Choice of non-irritating anesthotfc agent .
Good ore1 hygiene,
Ernpty stomach before operation.
Prophylactic treatment at end of operation consists of
?rei%2nce of cough reflex before patient k3aVeS operating row-.
Removal of secretions by aspiration, and stimulation of cough reflex.
Mhbw1 postoperative medication for pain relief.
Byperventilation, by voluntary deep breathing, or by carbm dioxide
Frequent change in positiolr.
Head dwn position until patient conscious.
~tercoatal. block in upper abdcminal cases.
Use of non-diffusible gas at end of anesthesia (air or helium).
inhalations ( ~OO$ air) if patient uncooperative .
Treatment if atelectasis oocurs:
1.
2.
3.
4.
5.
6.
Change in position, with affected lung uppermost.
Hyperventilation in several positions.
Assistance with expiration by judioious pounding on chest.
Aspiration of trachea with catheter, and 8tUulation of cough reflex.
Bronchoscopy, if above are inadequate .
Pen; ci llin therapy .
The incidence of explosions with ethylene, cyclopropane and ether is
rou@ly between l:lOO,OOO and 1:500,000 cases. Statistically this is one of
the most unimportant anesthesia cmplications, but it should be zero.
The cantroversy between safety of a cmpletely grounded operating
room VB. room completely isolated fram ground still continues. Other questions
under investigation involve the use of conductive rubber, the  use of inert
gases with explosive gases to make them non-explosive, and the true nature of
statio electricity. Air conditioning, by raising the humidity in the operating
room, permits partiel distribution of statio cbargea so that sparks are less
apt to pas8 between points of different potentials. If the atmosphere has been
mebed free of C02 by the air conditioning, however, even very humid air will
not prevent sparks .
All the inhalation agents except nitrous oxide and chloroform are
exploaive in the ranges in which we use them. A few common sense principles ap-
ply to their we:
1.
If' the use of electrical equipment is imperative far the surgery,
ohoose a non-explosive agent : nitrous oxide, with ample premedication; in$ra-
venous barbiturate, spinal, nerve block or local infiltration, or coanbinations
of` these technics.
2.
If explosive agents are being used, avoid using electrical equipment;
i.e . , carbolic knife for severing appendix instead of cautery.
31
3.
The danger zone with these drugs,,is at ana near the face mask. It is
the mixture leaking at the face mask which is hazardous, not blood or tissues
contalnia the agent. If electrical equipment must be used at a distance frcnn
the face', partla1 protection may be afforded by  heping fit of the mask as
tight as possible, or enclosing the area in a wet towel.
4.
It is believed widely that dapger is minimized if the patient, machine
and ahesthetist are kept at the same electrical potential by using an inter-
coupler between these three - This proteats only against static electricity, and
is entirely useless for sparks from a cautery, coagulating machine, or X-ray
apparatus, and similar electrical equipment.
5.
Members of the operating rom staff, visitors and bystanders should
avoid brushing past the anesthesia machine or bumping it with metal obJects,
such as spotlights, and portable tables.
5.
Elncwn sources of static slectricity, such as wool blankets and wool,
@ilk or rayon outer garments should be prohibited frm the operating roan.
RESUSCITATION
A ew general prlnciples apply to any type of Pesusoltation done for
any Hason by any of a number of techpics.
I,
There must be a FIE3 AW4Y. Artificial respiration is futile unless
the airway is patent.
Explore mouth with finger, remove foreign bodies.
Remove fluids by gravity: head dawn position.
Elevate chin, turn In lateral or prone positim to keep tongue frm
obstructing airway.
Introduce pharyngeal or endotracheal airway if available .
Po tracheotomy, if above not avaihbb.
32
2.
The patient must be ventilated. There is no way to store oxygen. It
must be supplied bmedfately. Prone prensure method, or mouth to mouth respira-
tion are always available,
3. The patient is in shock. Warmth and head dawn position should be sup-
plied.
4.
Stimulating drugs are of NO USE unless the patient is well oxygenated.