Frogs, when placed for several hours in air devoid of O, give off just as much
C02 as in air containing 0, and they do this without any obvious disturbance
(Pfluger, Aubert). Hence, it appears that the formation of C0 2 is independent of
the absorption of 0, and the COg must be formed from the decomposition of other
compounds. Ultimately, however, complete motor paralysis occurs, whilst the
circulation remains undisturbed (Aubert).
134. Dyspnoea and Asphyxia.
[The causes of dyspnoea have already been referred to ( 111), and
those of asphyxia are referred to in detail in vol. ii. under Nervous
Mechanism of Respiration. If from any cause, an animal be not supplied
with a due amount of air, normal respiration becomes greatly altered,
passing through the phases of hyperpnoea, or increased respiration,
dyspnoea or difficulty of breathing, to the final condition of suffocation
or asphyxia. The phenomena of asphyxia may be developed in an
animal by closing its trachea by means of a clamp, and in fact by any
means which prevent the entrance of air or blood into the lungs.
The phenomena of asphyxia are usually divided into several stages.
1. During the first stage there is hyperpncea, the respirations being
deeper, more frequent, and laboured. The extraordinary muscles of
respiration both those of inspiration and expiration referred to in
1 1 8, are called into action, the condition of dyspnoea being rapidly
produced, and the struggle for air becomes more and more severe.
During this time the oxygen of the blood is being used up, the blood
PHENOMENA OF ASPHYXIA. 269
itself is becoming more and more venous. This venous blood circulat-
ing in the medulla oblongata, and spinal cord stimulates the respiratory
centres, thus causing these violent respirations. This stage usually
lasts about a minute and gradually gives place to
2. The second stage, when the inspiratory muscles become less active,
while those concerned in laboured expiration contract energetically,
and indeed almost every muscle in the body may contract ; so that
this stage of violent expiratory efforts ends in general convulsions.
The convulsions are due to stimulation of the respiratory centres by
the venous blood. The convulsive stage is short, and is usually reached
in a little over one minute. This storm is succeeded by
3. The third stage, or stage of exhaustion, the transition being usually
somewhat sudden. This condition is brought about by the venous
blood acting on and paralysing the respiratory centres. The pupils are
widely dilated, consciousness is abolished, and the activity of the reflex
centres is so depressed that it is impossible to discharge a reflex act,
even from the cornea. The animal lies almost motionless, with flaccid
muscles, and to all appearance dead, but every now and again, at long
intervals, it makes a few deep inspiratory efforts, showing that the
respiratory centres are not quite, but almost paralysed. Gradually, the
pauses become longer and the inspirations feebler and of a gasping
character. As the venous blood circulates in the spinal cord it causes
a large number of muscles to contract, so that the animal
extends its trunk and limbs. It makes one great inspiratory
spasm, the mouth being widely open and the nostrils dilated, and
ceases to breathe. After this stage, which is the longest and
most variable, the heart becomes paralysed, partly from being
over-distended with venous blood, and partly, perhaps, from the
action of the venous blood on the cardiac tissues, so that the pulse
can hardly be felt. To this pulseless condition the term " asphyxia "
ought properly to be applied. In connection with the resuscitation of
asphyxiated persons, it is important to note that the heart continues to
beat for a few seconds after the respiratory movements have ceased.
The whole series of phenomena occupies from 3 to 5 minutes, according
to the animal operated on, and depending also upon the suddenness
with which the trachea was closed. If the causes of suffocation act more
slowly, the phenomena are the same, only they are developed more slowly.
The Circulation. The post-mortem appearances in man or in an
animal are generally well marked. The right side of the heart, the
pulmonary artery, the vense cava3, and the veins of the neck are
engorged with dark venous blood. The left side is comparatively
empty, because the rigor mortis of the left side of the heart, and the
elastic recoil of the systemic arteries, force the blood towards the
270 THE CHANGES OF THE CIRCULATION DURING ASPHYXIA.
systemic veins. The blood itself is almost black, and is deprived of almost
all its oxygen, while its haemoglobin is nearly all in the condition of
reduced haemoglobin, while ordinary venous blood contains a considerable
amount of reduced and oxyhsemoglobin. The blood of an asphyxiated
animal practically contains none of the latter, and much of the former.
It is important to study the changes in the circulation in connection
with the outward phenomena exhibited by an animal during suffocation.
We may measure the blood-pressure in any artery of an animal while
it is being asphyxiated, or we may open its chest, maintain artificial respi-
ration, and place a manometer in a systemic artery, e.g., the carotid,
and another in a branch of the pulmonary artery. In the latter case,
we can watch the order of events in the heart itself, when the artificial
respiration is interrupted. It is well to study the events in both cases.
If the blood-pressure be measured in a systemic artery, e.g., the
carotid, it is found that the blood-pressure rises very rapidly and to a
great extent during the first and second stages ; the pulse-beats at first
are quicker, but soon become slower and more vigorous. During the
third stage it falls rapidly to zero. The great rise of the blood-pressure
during the first and second stages is chiefly due to the action of the
venous blood on the general vaso-motor centre, causing constriction of
the small systemic arteries. The peripheral resistance is thus greatly
increased, and it tends to cause the heart to contract more vigorously,
but the slower and more vigorous beats of the heart are also partly
due to the action of the venous blood on the cardio-inhibitory centre in
If the second method be adopted, viz., to open the chest, keep up
artificial respiration, and measure the blood-pressure in a branch of the
pulmonary artery, as well as in a systemic artery, e.g., the carotid we
find that when the artificial respiration is stopped, in addition to the
rise of the blood-pressure indicated in the carotid manometer, the
cavities of the heart and the large veins near it are engorged with
venous blood. There is, however, but a slight comparative rise in the
blood-pressure in the pulmonary artery. This may be accounted for,
either by the pulmonary artery not being influenced to the same extent
as other arteries, by the vaso-motor centre, or by its greater distensibility
(Lichtheim compare 88). But, as the heart itself is supplied through
the coronary arteries with venous blood, its action soon becomes
weakened, each beat becomes feebler, so that soon the left ventricle
ceases to contract, and is unable to overcome the great peripheral
resistance in the systemic arteries, although the right ventricle may
still be contracting. As the blood becomes more venous, the vaso-
motor centre becomes paralysed, the small systemic arteries relax, and
the blood flows from them into the veins, while the blood-pressure in
RESPIRATION OF FOREIGN GASES. 271
the carotid manometer rapidly falls. The left ventricle, now relieved
from the great internal pressure, may execute a few feeble beats, but
they can only be feeble, as its tissues have been subjected to the action
of the very impure blood. More and more blood accumulates in the
right side from the causes already mentioned.
The violent inspiratory efforts in the early stages aspirate blood
from the veins towards the right side of the heart, but of course this
factor is absent when the chest is opened.]
[Recovery from the condition of asphyxia. If the trachea of a dog be
closed suddenly and completely, the average duration of the respiratory move-
ments is 4 minutes 5 seconds, while the heart continues to beat for about 7 minutes.
Recovery may be obtained if proper means be adopted before the heart ceases to
beat; but after this, never.
If a dog be drowned, the result is different. After complete submersion for 14
minutes, recovery did not take place. In the case of drowning, air passes out of
the chest, and water is inspired into and fills the air-vesicles. It is rare for
recovery to take place in a person deprived of air for more than five minutes. If
the statements of sponge-divers are to be trusted, a person may become accustomed
to the deprival of air for a longer time than usual. In cases where recovery takes
place after a much longer period of submersion, it has been suggested that, in these
cases, syncope occurs, the heart beats but feebly or not at all, so that the
oxygen in the blood is not used up with the same rapidity. It is a well-known
fact that newly-born and young puppies can be submerged for a long time before
they are suffocated.]
Artificial Respiration. The methods of performing artificial respira-
tion in persons apparently suffocated are fully given in vol. ii., under
Nervous Mechanism of Respiration.
135. Respiration of Foreign Gases.
No gas without a sufficient admixture of O can support life. Even with com-
pletely innocuous and indifferent gases, if no O be mixed with them, they cause
suffocation in 2 to 3 minutes.
I. Completely indifferent gases are N, H, CELi. The living blood of an
animal breathing these gases yields no O to them (Pfluger).
II. Poisonous gases- () Those that displace O, and form a permanent
stable compound with the hsemoglobin (1.) CO ( 16 and 17). (2.) CNH
(Hydrocyanic acid) displaces (?) O from haemoglobin, with which it forms a
more stable compound and kills exceedingly rapidly. It prevents O being changed
into ozone in the blood. Blood-corpuscles charged with hydrocyanic acid lose the
property of decomposing hydric peroxide into water and O ( 17, 5).
(b.) Narcotic gases. (1.) C0 2 v. Pettenkofer characterises air containing O
with '1 p.c. C0 2 as "bad air ; " still, air in a room containing this amount of C0 2
produces a disagreeable feeling rather from the impurities mixed with it than from
the actual amount of COa itself. Air containing 1 p.c. C0 2 produces decided
discomfort, and with 10 p.c. it endangers life, while larger amounts cause death
with symptoms of coma. (2.) N 2 (nitrous oxide) respired, mixed with volume
O, causes, after 1 to 2 minutes, a short temporary stage of excitement ("Laughing
gas" of H. Davy), which is succeeded by unconsciousness, and afterwards an
increased excretion of C0 2 - (3.) Ozonised air causes similar effects (Binz).
272 ACCIDENTAL IMPURITIES IN THE AIR.
(c.) Reducing gases. (1.) H 2 S (sulphuretted hydrogen) rapidly robs blood-
corpuscles of O : S and HgO being formed, and death occurs rapidly before the
gas can decompose the haemoglobin (Hoppe-Seyler).
(2.) PHa Phosphuretted hydrogen is oxidised in the blood to form phosphoric
acid and water with decomposition of the haemoglobin (Dybkowski, KoschlakofF,
(3.) AsH 3 , arseniuretted hydrogen and SbH 3 , antimoniuretted hydrogen, act
like PHs, but in addition, the haemoglobin passes out of the stroma and appears in
(4.) C 2 N 2 , cyanogen absorbs 0, and decomposes the blood (Rosenthal and
Laschke witsch ) .
HI. Irrespirable gases, i.e., gases which, on entering the larynx, cause reflex
spasm of the glottis. When introduced into the trachea they cause inflammation
and death. Under this category come hydrochloric, hydrofluoric, sulphurous,
nitrous, and nitric acids, ammonia, chlorine, fluorine, and ozone.
136. Accidental Impurities of the Air.
Bust Particles. Amongst these are dust particles which occur in enormous
amount suspended in the air, and thereby act injuriously upon the respiratory
organs. The ciliated epithelium of the respiratory passages eliminates a large
number of them. Some of them, however, reach the air-vesicles of the lung,
where they penetrate the epithelium, reach the interstitial lung-tissue and lym-
phatics and so pass with the lymph-stream into the bronchial glands. Particles
of coal or charcoal are found in the lungs of all elderly individuals, and blacken
the alveoli. In moderate amount these black particles do not seem to do any
harm in the tissues, but when there are large accumulations they give rise to lung
affections, which lead to disintegration of these organs. [In coal-miners, for
example, the lung-tissues along the track of the lymphatics and in the bronchial
glands are quite black, constituting " coal-miners' lung."] In many trades various
particles occur in the air; miners, grinders, stone-masons, file-makers, weavers,
spinners, tobacco manufacturers, millers, and bakers, suffer from lung affections
caused by the introduction of particles of various kinds inhaled during the time
they are at work.
There seems no doubt that the seeds of some contagious diseases may be inhaled.
Diphtheritic bacteria become localised in the pharynx and in the larynx
glanders in the nose measles in the bronchi hay-monads in the nose. Many
seeds of disease pass into the mouth along with air, are swallowed, and undergo
development in the intestinal tract, as is probably the case in cholera and typhoid
137. Ventilation of Rooms.
Fresh air is as necessary for the healthy as for the sick. Every healthy person
ought to have a cubic space of 800 cubic feet, and every sick person 1000 cubic
feet of space. [The space allowed per individual varies greatly, but 1000 cubic
feet is a fair average. If the air in this space is to be kept sweet, so that the C0 2
does not exceed '06 p.c., 2000 cubic feet of air per hour must be supplied.] In
France only 42 cubic feet per head are allowed in barracks, 60 cubic feet in
hospitals. In Prussia in barracks 420-500 cubic feet are allowed for every
soldier, for hospital 600-720; in England 600 cubic feet per head. When there
is overcrowding in a room the amount of C0 2 increases, v. Pettenkofer found
the normal amount of CO 2 ( '04 to '05 per 1000) increased in comfortable rooms to
FORMATION OF MUCUS IN THE RESPIRATORY PASSAGES. 273
0'54-07 per 1000; in badly ventilated sick chambers = 2 '4; in overcrowded
auditoriums, 3 *2 ; in pits = 4'9 ; in school-rooms, 7 '2 per 1000. Although it is not the
quantity of C0 2 which makes the air of an overcrowded room injurious, but the
excretions from the outer and inner surfaces of the body, which give a distinct
odour to the air, quite recognisable by the sense of smell, still, the amount of C0 2
is taken as an index of the presence and amount of these other deleterious sub-
stances. The question as to whether the ventilation of a room or ward occupied
by persons is sufficient, is ascertained by estimating the amount of C0 2 . A room
which does not give a disagreeable, somewhat stuffy, odour has less than 07 per
1000 of C0 2 , while the ventilation is certainly insufficient if the C0 2 = 1 per 1000.
As the air contains only 0'0005 cubic meter C0 2 in 1 cubic meter of air, and as
an adult produces hourly 0'0226 cubic meters C0 2 , calculation shows that every
person requires 113 cubic meters of fresh air per hour, if the C0 2 is not to exceed
0-7 per 1000 : for 0'7 : 1000 = (0'0226 + x x 0*0005) :x, i.e., x = 113.
In ordinary rooms, where every person is allowed the necessary space (1000 cubic
feet) the air is sufficiently renewed by means of the pores in the walls of the room,
by the opening and shutting of doors, and by the fireplace, provided the damper
is kept open.
It is most important to notice that the natural ventilation be not interfered with
by dampness of the walls, for this influences the pores very greatly. At the same
time, damp walls are injurious to health by conducting away heat, and in them the
germs of infectious diseases may develop (Lindwurm).
138, Formation of Mucus in the Respiratory
The respiratory mucous membrane is covered normally with a thin
layer of mucus (Fig. 97). By its presence this substance so far inhibits
the formation of new mucus by protecting the mucous glands from the
action of cold or other irritative agents. New mucus is secreted as that
already formed is removed. An increased secretion accompanies con-
gestion of the respiratory mucous membrane. Division of the nerves
on one side of the trachea (cat) causes redness of the tracheal mucous
membrane and increased secretion (Kossbach).
Effects of reagents on the mucous secretion. If ice be placed on the belly
of an animal so as to cause the animal to " take a cold" the respiratory mucous
membrane first becomes pale, and afterwards there is a copious mucous secretion,
the membrane becoming deeply congested. The injection of sodium carbonate
and ammonium chloride limits the secretion. The local application of alum,
silver nitrate, or tannic acid makes the mucous membrane dry, and the epithelium
is shed. The secretion is excited by apomorphin, emetin, pilocarpin, and
ipecacuanha, while it is limited by atropin and morphia (Rossbach).
Normal Sputum. Under normal circumstances some mucus mixed
with a little saliva may be coughed up from the back of the throat.
In catarrhal conditions of the respiratory mucous membrane, the sputum
is greatly increased in amount, and is often mixed with other character-
istic products. Microscopically, sputum contains :
1. Epithelial cells chiefly squames from the mouth and pharynx
(Fig. 115), more rarely alveolar epithelium and ciliated epithelium (7)
from the respiratory passages, The epithelial cells are often altered,
having undergone maceration or other changes. Thus some cells may
have lost their cilia (6).
The epithelium of the alveoli (2) is squamous epithelium, the cells being 2 to 4
times the breadth of a colourless blood-corpuscle. These cells occur chiefly in the
morning sputum in individuals over 30 years of age. In younger persons their
presence indicates a pathological condition of the pulmonary parenchyma
(Guttman, H. Schmidt, and Bizzozero). They often undergo fatty degeneration,
and they may contain pigment granules (3); or, they may present the appearance
of what Buhl has called "myelin degenerated cells;" i.e., cells filled with clear
refractive drops of various sizes, some colourless, others coloured particles, the
latter having been absorbed (4). Mucin in the form of myelin drops (5) is
always present in sputum.
2. Lymphoid cells (9) are to be regarded as colourless blood- corpuscles
which have wandered out of the blood-vessels; they are most numerous
in yellow sputum, and less numerous in the clear, mucus-like excretion.
The lymph-cells often present alterations in their characters ; they may
be shrivelled up, fatty, or present a granular appearance.
Various objects found in sputum 1, Detritus and particles of dust ; 2, alveolar
epithelium with pigment; 3, fatty and partly pigmented alveolar epithelium;
4, alveolar epithelium containing myelin-f orms ; 5, free myelin-forms ; 6, 7,
ciliated epithelium, some changed, others without cilia; 8, squamous epithelium
from the mouth; 9, leucocytes; 10, elastic fibres; 11, fibrin-cast of a small
bronchus; 12, leptothrix buccalis with cocci, bacteria, and spirochseti; a,
fatty acid crystals and free fatty granules; b, hsematoidin; c, Charcot's
crystals; d, Cholesterin.
ACTION OF THE ATMOSPHERIC PRESSURE. 275
The fluid substance of the sputum contains much mucus arising from
the mucous glands and goblet cells ; together with nuclein, and lecithin,
and the constituents of saliva according to the amount of the latter
mixed with the secretion. Albumin occurs only during inflammation of
the respiratory passages, and its amount increases with the degree of
inflammation. Urea has been found in cases of nephritis.
Pathological. In cases of catarrh, the sputum is at first usually sticky and
clear (sputa cruda), but later it becomes more firm and yellow (sputa cocta).
Under pathological conditions there may be found in the sputum (a.) Red blood-
corpuscles from rupture of a blood-vessel. (b.) Elastic-fibres (10) from disintegration
of the alveoli of the lung; usually the bundles are fine, curved, and the fibres
branched. [In certain cases it is well to add a solution of caustic potash, which
dissolves the other elements and leaves the elastic fibres untouched.] Their pre-
sence always indicates destruction of the lung-tissue, (c.) Colourless plugs of
fibrin (11), casts of the smaller or larger bronchi, occur in some cases of fibrinous
exudation into the finer air-passages, (d.) Crystals of various kinds Crystals of
fatty acids (Fig. 1 15, a) in bundles of fine needles. They indicate great decomposition
of the stagnant secretion colourless, sharp-pointed, octagonal, or rhombic plates
(c) (Charcofs crystals) of unknown nature (perhaps tyrosin), Hsematoidin (b)
and cholesterin crystals (d) occur much more rarely. (/. ) Fungi and other lower
organisms frequently occur. The threads of leptothrix buccalis (12) ; Oidium
albicans in the mouth of sucklings, rod-shaped bacilli and bacteria. In phthisis,
the tubercle-bacillus of Koch.
Abnormal coloration of the sputum red from blood when the blood remains
long in the lung it undergoes a regular series of changes and tinges the sputum
dark red, bluish brown, brownish yellow, deep yellow, yellowish green, or grass
green. The sputum is sometimes yellow in jaundice. The sputum may be tinged
by what is inspired [as in the case of the "black-spit" of miners.]
The odour of the sputum is more or less unpleasant. It becomes very disagree-
able when it has remained long in pathological lung cavities, and it is stinking in
gangrene of the lung.
139. Action of the Atmospheric Pressure.
At the normal pressure of the atmosphere (height of the barometer,
760 millimetres Hg.), pressure is exerted upon the entire surface of the
body =15,000 to 20,000 kilos., according to the extent of the superficial
area (Galileo). This pressure acts equally on all sides upon the body,
and occurs also in all internal cavities containing air, both those that are
constantly filled with air (the respiratory passages and the spaces in the
superior maxillary, frontal, and ethmoid bones), and those that are
temporarily in direct communication with the outer air (the digestive
tract and tympanum ). As the fluids of the body (blood, lymph, secre-
tions, parenchymatous juices) are practically incompressible, their volume
remains practically unchanged under the pressure ; but they will absorb
gases from the air corresponding to the prevailing pressure (i.e., the
partial pressure of the individual gases), and according to their tempera-
ture (compare 33).
276 ACTION OF DIMINISHED ATMOSPHERIC PRESSURE.
The solids consist of elementary parts (cells and fibres), each of which
presents only a microscopic surface to the pressure, so that for each cell
the prevailing pressure of the air can only be calculated at a few
millimetres a pressure under which the most delicate histological
tissues undergo development. As an example of the action of the
pressure of the atmospheric pressure upon large masses, take that
brought about by the adhesion of the smooth, sticky, moist articular
surfaces of the shoulder and hip joints. In these cases, the arm and
the leg are supported without the action of muscles. The thigh-
bone remains in its socket after section of all the muscles and its
capsule (Brothers' Weber). Even when the colytoid cavity is perforated,
the limb does not fall out of its socket. The ordinary barometric
variations affect the respiration a rise of the barometric pressure
excites, while a fall diminishes, the respirations. The absolute amount
of C0 2 remains the same (127, 8).
A Great Diminution of the Atmospheric Pressure, such as occurs in
ballooning (highest ascent, 8,600 meters), or in ascending mountains, causes a series
of characteristic phenomena : (1.) In consequence of the diminution of the pressure
upon the parts directly in contact with the air, they become greatly congested,
hence, there is redness and swelling of the skin and free mucous membranes; there
may be haemorrhage from the nose, lungs, gums, turgidity of the cutaneous
veins ; copious secretion of sweat, great secretion of mucus. (2.) A feeling of