CHOICE OF ANÆSTHETIC.
In considering this matter, some repetition of points to which
reference has already been made, is inevitable. Indeed, this chapter
may be regarded as a revision of the whole subject.
Before deciding upon drug and method suitable for the individual case,
we must consider the age and sex, the physical type and temperament,
the possible presence of some definite pathological condition, and the
nature and duration of the operation.
In relation to this last point, we must remember that an anæsthesia
must be adequate to the purpose of the surgeon, but that it is improper
to incur more risk to life than is necessary. For instance, an
abdominal section case must be fully relaxed, and if in an individual
case, chloroform is the only drug which will give that effect, there
need be no hesitation in using it. On the other hand, many other
methods with a far smaller mortality rate are available if all that is
required is the extraction of a tooth or the incision of an abscess,
and in that group of cases, unfamiliarity with such anæsthetics as
nitrous oxide or “ethyl chloride and ether” will not be held as a
sufficient defence if chloroform has been given with a fatal effect.
Normal Subjects.
Let us take first the case of the healthy adult about to undergo a
_major_ operation. For this, we unhesitatingly choose what we may term
the “stock” method--open-ether preceded by morphia and atropine.
If the operation be _brief_, we have a choice of methods. For the
extraction of teeth, where access to the mouth is essential, the
following table will help:--
+------------------------+---------------------------+-------------------------+
| |Duration of Available | |
|ANÆSTHETIC DRUG AND | Anæsthesia, when | REMARKS. |
|METHOD. | given as “Single | |
| | Dose.” | |
+------------------------+---------------------------+-------------------------+
|Nitrous oxide |30 to 40 seconds | |
|Nitrous oxide and |40 to 50 seconds | |
| oxygen | | |
|Ethyl chloride |70 to 90 seconds |Only to be recommended |
| | | in special cases (_see_|
| | | page 127). |
|Gas and ethyl chloride |70 to 90 seconds | |
|Gas-oxygen and ethyl |70 to 90 seconds | |
| chloride | | |
|Gas and ether |Anything up to 2 to 5 |May cause after vomiting.|
| | minutes according to | |
| | duration of inhalation | |
|Ethyl chloride and ether|Anything up to 2 to 5 |May cause after vomiting.|
| | minutes according to | More portable. |
| | duration of inhalation | |
|Nasal gas |5 to 10 minutes (not a |Requires considerable |
| | “single dose” anæsthetic)| practice to give well. |
|Nasal gas and oxygen |No limit |Easier to give than |
| | | above but apparatus |
| | | rather importable. |
+------------------------+---------------------------+-------------------------+
In cases where access to the mouth is not required, and where it is
therefore unnecessary to “charge up” the patient with anæsthetic, we
have also a choice which may be expressed tabularly:--
+------------------------+-----------------------------------------------------+
| ANÆSTHETIC. | REMARKS. |
+------------------------+-----------------------------------------------------+
|Nitrous oxide |Apparatus simple: short administration can be |
| | mastered easily. A little more practice required |
| | for cases prolonged by admitting air. Muscles |
| | not relaxed, and patient may move when cut. |
| | |
|Nitrous oxide and |Apparatus more complicated, but short administrations|
| oxygen | present no great difficulty to the beginner. |
| | Muscles not completely relaxed unless a little |
| | ether added. |
| | |
|Gas and ether |Quick and safe anæsthetic. Deep anæsthesia |
| | may be obtained if ether is “pushed.” |
| | |
|Ethyl chloride and ether|The same. More portable than above. |
+------------------------+-----------------------------------------------------+
In this group of short operations, special reference must be made to
the _reduction of dislocations_. Here two important features
require notice. The whole object of the proceeding is to relax muscles,
and therefore nitrous oxide or gas-oxygen are unsuitable. Secondly,
the tendency to reflex syncope just at the moment of reduction is very
great. For this reason, chloroform has here a painfully high mortality
rate; closed-ether, preceded by gas or ethyl chloride, is undoubtedly
the method of choice.
The Extremes of Age.
Children up to the age of ten years take ether badly, salivation
and bronchial secretion being sometimes very troublesome. Atropine
mitigates this nuisance to a limited degree only. Chloroform is the
best drug up to five or six years; from five to ten, mixture; after
that, open ether.
In children of any age, suffering from acute sepsis, the immediate
annoyances and possible respiratory sequelæ of ether must be faced
(_see_ page 156), owing to the probability of acidosis.
As regards short anæsthetics in children, nitrous oxide, if given at
all, should be freely diluted with oxygen, otherwise most undesirable
cyanosis will occur. To children under three or four, even gas-oxygen
is of doubtful safety. Short anæsthesias in such cases may be induced
by open ethyl chloride, with a few drops of ether added.
Old people are, unless very feeble, best anæsthetised by a mixture of
chloroform and ether. Whatever anæsthetic be chosen, the utmost care
must be taken to avoid cyanosis. A cylinder of oxygen should be at hand
from which to enrich the atmosphere breathed, by trickling the gas into
the mouth through a rubber tube, and is a great safeguard in dealing
with the old.
Sex.
On the average, women take anæsthetics much better than men, being far
less liable to jaw clenching and other forms of mechanical asphyxia,
and showing less excitement during the induction stage. In the female
subject induction by open-ether requires very little assistance from
C.E. mixture.
Physical Type and Temperament, and Habits of Life.
Heavily built muscular men are troublesome subjects. Induction requires
a rather strong vapour of ether: if the open method is used, there may
be to the beginner much temptation to make use during the induction
stage of C.E. mixture to an extent not contemplated in the description
given of that method in chapter IX.: it is therefore wise to induce
either with closed-ether or with C.E. mixture as described in chapter
XV., and to change to the perhalation method only when full anæsthesia
is attained.
As regards alcoholics and excessive smokers, these are well dealt with
by the C.E. open-ether sequence. Recourse may be made to the Ormsby
inhaler as already explained on page 137. The reader is warned not to
be deceived by the stout, rosy face of the typical alcoholic. He often
looks a great deal stronger than he really is. Many such are really
feeble subjects: although they shout and struggle no great addition
to the usual vapour strength of anæsthetic is safe or required: what
_is_ required, is a little extra time. Once fully under, the robust
appearance of the patient disappears, and the fact that one is dealing
with a rather broken constitution and a poor circulation is obvious.
Reference has already been made to the fact that persons with defective
nervous systems, neurotics, and especially epileptics, show persistence
of some muscular movements for some time, and therefore require very
careful watching.
Special Operations and Pathological Conditions in the Patient.
These are of the utmost importance, but to consider each fully from
the anæsthetic point of view, would lead us into great detail. The
anæsthetist must acquaint himself with any abnormality present, and
consider it carefully in the light of the general principles already
explained. The following very brief hints for selected cases and
operations may, however, be found useful.
UPPER AIR PASSAGES.
_Artificial teeth._ Must be removed before inducing.
_Tongue and jaw cases._--Intratracheal ether the best--failing that,
rectal oil ether, or Junker’s inhaler.
_Nasal operations._--If adrenalin is to be used, it must precede,
not follow, chloroform--many fatalities have occurred from injecting
or even packing with adrenalin in light chloroform narcosis. Some
surgeons object to ether because of the bleeding, but this can be
largely remedied by raising the head and shoulders, and by packing with
adrenalin. Many surgeons prefer local to general anæsthesia.
_Nasal insufficiency._--Don’t allow a patient to continue to make
ineffectual attempts to breathe through a narrow nose. Establish mouth
breathing, or use Silk’s tubes (_see_ Fig. 9).
_Tonsils and adenoids._--Give ethyl chloride by the vapour method.
_Tumours and inflammatory swellings obstructing respiration._--
Don’t use closed methods. Have tracheotomy instruments at hand, and a
cylinder of oxygen.
_Gôitres, especially exophthalmic gôitre._--Don’t use chloroform: it
has caused many fatalities; morph-atropine, followed by open-ether is
the safest. In bad cases, use rectal oil ether if intratracheal is not
available. The “sitting up posture” is a great help (_see_ page 168).
Use anoci-association if surgeon is willing.
CHEST.
_Bronchitis and pneumonia_ (_see_ remarks in chapter XVII).
_Emphysema and rigid chest wall._--Patients take anæsthetics badly;
they cyanose quickly, the abdominal wall cannot be made either lax or
quiet, since the patient’s natural method of respiration is abdominal
rather than thoracic. Lastly, there is frequently a dilated heart with
degenerate cardiac muscle, giving an abnormal tendency to secondary
syncope. Give a trickle of oxygen through a tube from a cylinder: don’t
be tempted to overdose with anæsthetic in the vain hope of securing
ideal relaxation of the abdominal wall.
_Empyæma._--Be careful: a good many accidents have happened. Use
chloroform with added oxygen: aim at an anæsthesia just deep enough
to prevent straining which might rupture the empyæma into the lung
and drown him in his own pus. Withdraw the anæsthetic as soon as the
abscess is opened.
_Phthisis._--Don’t use closed-ether: it may start
hæmorrhage--open-ether rarely does any harm unless the condition is
very acute.
CIRCULATORY SYSTEM.
_High tension, arterio-sclerosis, and aneurysm._--Avoid pure
nitrous oxide: in severe cases, C.E. mixture and oxygen is the safest.
_Heart._--Well compensated cases of _valvular disease_
take chloroform or open-ether well, provided a free air-way is
maintained. Closed methods should be avoided. Cases of _myocardial
disease_ with dilated cavities present special dangers. Open-ether
with added oxygen meets the case better than any other anæsthetic.
_Pericarditis_, both acute and chronic, has been found as the
determining factor in many anæsthetic fatalities.
ACUTE INFECTIOUS DISEASE.
_Febrile patients_ absorb anæsthetics very rapidly and therefore
go under very quickly. Acute septic cases must not have chloroform
or ethyl chloride (_see_ page 155): nitrous oxide and oxygen is
ideal, ether the next best. Patients who have suffered from acute
infectious disease, especially diphtheria and influenza, may present
some weakness of heart muscle for many months after the attack.
EXHAUSTED AND SHOCKED CASES.
Give nitrous oxide and oxygen if possible--failing that, ether.
Closed-ether sometimes does very well for the induction stage.
DIABETES.
Chloroform is wholly inadmissible.
GENITO-URINARY SYSTEM.
_Kidneys._--Avoid ether in acute or sub-acute nephritis: give it,
however, for nephrectomy when the other kidney is sound.
_Bladder._--Distending the bladder with lotion often causes reflex
inhibition of respiration: if that happens, stop the anæsthetic, give
artificial respiration, and ask the surgeon to get on with opening the
bladder. _Morphia_ usually arrests temporarily the secretion of urine:
it should therefore not be given if chromocystoscopy or catheterisation
of the ureters is contemplated.
_Prostatectomy cases_ are often rather broken subjects: give a fairly
deep anæsthesia until the shelling out of the prostate is begun: then
be careful--the patient is breathing deeply as a rule, and can readily
get an overdose. He will inevitably suffer a fair amount of shock:
be ready to lower the table at the head end if any serious collapse
occurs. Don’t be shy of starting a little artificial respiration even
though the natural function is not entirely abolished.
_Circumcision_ usually causes a good deal of laryngeal spasm,
especially in children. Don’t try to abolish this by deepening the
anæsthesia. You won’t succeed unless you nearly kill the patient. Rub
the lips, and if very severe ask the surgeon to stop a minute until the
crowing becomes less.
_Castration._--Always give ether, or gas-oxygen. Castration and
reduction of dislocation are the two commonest causes of reflex syncope
under chloroform.
MENSTRUATION, PREGNANCY, AND LABOUR.
It is usual to avoid anæsthetics during the menstrual period if
possible, the nervous system being unlikely to be at its best at that
time.
Pregnant patients take no harm from an anæsthetic properly given,
but undue cyanosis must be avoided or abortion may occur. The pains
of labour may be alleviated by chloroform given to an early second
stage only, or by “twilight sleep” (_see_ page 44). For the major
operations of obstetrics, however, ether has its usual advantages,
provided no bronchitis be present. The shock of such operations as a
difficult version is considerable, and quite sufficient to call for
ether rather than chloroform.
_Indication for Local and Spinal Anæsthesia._--The foregoing has
been written in reference to inhalational anæsthesia solely. Mr
Wood has indicated in chapters XX. and XXI. the class of case in
which the methods he describes are to be preferred.