Frank Pierce Foster.

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portance. Paradoxical as it may seem, it is the
condensed-air bath (or absolute positive pres-
sure) that, intermittently used at low levels,
best imitates the therapeutic eflEects of altitude ;
and it was in fact through studies of the efiects
of condensed air upon vegetable and animal life,
together with observations of the results upon
men of descent in diving bells and into deep
mines, that this important, but as yet imper-
fectly appreciated, addition to the resources of
medicine was made.*

Tabarie made a communication upon the
subject to the Parisian Academy of Sciences
in 1833, f and in 1853 Junod reported to the
same body the results of his own experiments
upon man. The first practical applications of
the method in the treatment of disease seem to
have been made in 1838, under the direction of
Tabarie, by Pravaz and others. Tabarie's ap-
paratus, upon the principle of which most sub-
sequent ones have been modelled, consisted of a
wrought-iron spheroidal chamber, large enough
to accommodate a dozen persons, into which
the external air was forced by a steam pump,
and from which the air respired by patients
was removed, the rate of efflux being made
sufficiently less than the rate of afflux to se-
cure any desired elevation of pressure within
, the chamber. Pneumatic chambers of variously
modified construction have been erected and
are in operation at many resorts on the Conti-
nent of Europe.^ There is one at the Bromp-
ton Hospital, London, but the writer knows of
none in America. At each medical centre,
however, there should be such a chamber (or a
number of such chambers), under the care of
an experienced physician, for the use of pa-
tients referred by their medical attendants, the
latter retaining proper control or oversight of
the details of treatment in consultation with
the specially expert physician in charge. *

Absolute-Pressure Method. || — Without
entering into mechanical details, the general
features of a pneumatic chamber may be de-
scribed. The purpose of the apparatus is to
immerse the patient for a certain time in air
of greater (or less) density than that to the ac-
tion of which he is ordinarily exposed. The
change of pressure must be brought about
gradually, after the patient has entered the
chamber ; and after a certain length of expo-
sure to the modified atmosphere the ordinary
pressure must be gradually restored before the
patient emerges. The apparatus consists,



* Tide J. Solis-Cohen : Inhalation ; its Therapeutics
and Practice, 3d ed., Philadelphia, 1876, p. 37.

t Comptes, rendus t. vi, p. 896.

i For a description of the different forms of pneu-
matic chambers, see Oertel, Handbuch der respira-
torischen Therapie, Leipzig, 1883 ; English transla-
tion, by Yeo, London, 1885.

* There is at Brussels such an establishment, which
owes its existence to the gratitude of a wealthy resi-
dent of ^hat city who recovered his health under
pneumatic treatment at Montpellier.

1 With this the writer has had no detailed personal
experience, and he relies principally upon the writ-
ings of von Vivenot, Oertel, and Hovent.



therefore, of two essential parts : an air-tight
chamber (usually of iron — m one instance, at
least, of stone), and a pump or other mechan-
ism by which air is forced into, or removed
from, the chamber. The chamber consists of
a properly lighted and tastefully furnished
room in which a patient or several patients
may be seated, and a vestibule, or antecham-
ber, in which changes of pressure may be ef-
fected independently of the pressure in the
main or respiration chamber. The object of
this latter provision is to afford a means of
exit or entrance to the physician or attendant
without disturbing the pressure in the respira-
tion chamber, and without subjecting the per-
son entering or leaving to too sudden a change.
Some chambers have a sort of double window
by means of which books and other small ar-
ticles may be passed in or out without disturb-
ing the pressure. Electric bells and other
means of calling instant attention are likewise
provided. In addition there must be suitable
devices for the removal of carbon dioxide and
other products of respiration, and for the regu-
lation of the temperature and the humidity of
the air of the chamber. Provision can also be
made for modifying the proportions of oxy-
gen, nitrogen, or carbon dioxide, or for the
impregnation of the incoming air or of the air
of the chamber in any proportion desired with
any gas, vapour, or volatile medicament, or any
drug susceptible of nebulization. The various
desiderata have been well accomplished by the
chamber erected at Beichenhall by G. von Lie-
big. It is figured in Yeo's translation of Oer-
tel's Mespiratory Therapeutics : London, Smith
Elder & Co., 1885.

It consists of three rooms of sheet iron, ar-
ranged somewhat on the plan of a trefoil and
communicating by means of an antechamber,
the whole being inclosed by an outer iron wall
with a door through which entrance is gained
into the antechamber. The three other walls
of the antechamber are formed by the walls of
the three respiration chambers. Each room con-
tains three windows of thick glass, and is 3'33
metres high and 3'04 metres in diameter. Its
base is thus 3-267 square metres, and its capac-
ity 7'613 cubic metres. Three persons can sit
around a table in each of the chambers, and
altogether nine persons can be accommodated
in the apparatus. The antechamber has an
average width of 1 metre and a depth of 1'3
metre, and is a little lower than the respiration
chambers. Air is forced in by a pump which
stands in another room and is operated by a
steam engine. The air enters the antechamber
on each side of the door, through two iron
tubes, each 7 centimetres in diameter and 39
metres in length. To these tubes regulating
cocks are attached. The wooden floor of the
antechamber and the carpeted floors of two
of the main chambers are perforated, and there
is an orifice in the floor under the wall sepa-
rating each of these main chambers from the
antecJiamber. The air from the antechamber
entering the chambers through these perfora-
tions, the patient does not feel the shock of
the pumping and the elevation is regulated
more equably. Air escapes from the chambers



AIR, CONDENSED OR RAREFIED



20



through orifices in the walls near the ceiling,
closed by gratings, to which outlet pipes fur-
nished with regulating cocks are attached. A
mercury manometer with millimetre divisions
for determining the air pressure in the chamber
is placed outside near the door in communi-
cation with the antechamber, while within,
near the window of the respiration chamber,
an August's psyohrometer shows the tempera-
ture and amount of moisture. The double-
action air pump yields with every lift 27-3
metres of air and the piston makes about 140
excursions in the minute. An overplus of air,
therefore, constantly streams into the cham-
bers, and a uniform regulation is brought
about by an assistant who stands in the ante-
chamber and observes the manometer and the
psychrometeru

The pressure is increased not by arresting
the efUux, but by increasing the aiflux of air,
in this way giving satisfactory ventilation.
The pressure in the third chamber may be
made lower than that of the other chambers by
means of a stopcock cutting off a part of the
air from entrance by way of a pipe leading
from the antechamber. The temperature is
regulated by cooling or warming the instream-
ing air as it passes through the feeding pipes.

At Brussels a different plan is adopted. By
means of a specially constructed pump the
same air is kept circulating through the res-
piration chamber and a series of pipes com-
municating with immense wash bottles, some
containing alkaline solutions and others con-
taining pure water, in order to remove the
carbonic acid and other products of respira-
tion. A gas engine furnishes the power.

Other forms of apparatus have been devised
not materially differing in essential principles
from those described. In some, rarefaction of
the air of the chamber can be effected by re-
versing the action of the pump. The doors
must be specially adjusted.

Management of the Apparatus. — An experi-
enced attendant familiaf with the construction
and the physical principles of the apparatus
must always be at hand to observe and to
regulate, according to the directions of the phy-
sician, the conditions of pressure, temperature,
moisture, etc. The physician in charge of the
institution should always be within easy call.
The preferable pressure varies with the indi-
vidual case and with the nature of the disease
for which the patient comes under treatment.*
As a rule, an excess pressure of f to f of an at-
mosphere (equal to 30 to 32'5 centimetres — 13
to 12J inches — mercury) gives the best results.
With weak patients, however, it is not safe to
exceed ^ of an atmosphere (15-2 centimetres — 6
inches — of mercury) — at all events until the pa-
tient has become habituated to the treatment
and has shown signs of marked improvement.



* Pressures are usually described In fractions of an
atmosphere, and it must be remembered that the fig-
ures given are to be added to or subtracted from the
standard atmospheric pressure. Thus, when an ex-
cess pressure of i atmosphere is mentioned, it means
an absolute pressure of H atmosphere, or 22'5 pounds
to the square inch ; a negative pressure of § atmos-
phere means an absolute pressure of J atmosphere,
i. e., 12 pounds to the square Inch.



Very weak persons, especially those with febrile
temperatures and much depressed in general
condition by chronic exhausting disease, should
not be subjected to pneumatic treatment. It
could only hasten the end. Symptoms of fever
in young and strong persons suffering with
acute catarrhal inflammations of the respira-
tory tract are not, however, considered to
contra-indicate pneumatic treatment. The
transition from ordinary pressure to an excess
pressure previously determined should occupy,
as a rule, about thirty minutes. When the
excess pressure has reached the intended limit,
it must be maintained unchanged for about an
hour (or, in exceptional cases, two hours), and
half an hour should again be consumed in
gradual transition to the barometric figure.
It has been given as a general rule that each
transition period should occupy one minute
for every centimetre of mercury measuring the
increase of pressure, and that the period of
unchanged pressure should be two minutes for
each centimetre of mercury of excess pressure.

Acute forms of disease, hypersemias, and
catarrhal infiammations usually require a
shorter period of treatment than chronic oases.
In the beginning of treatment the sittings
should occur daily. After some weeks every
two or three days may be sufficient. Some
physicians make more or less prolonged inter-
missions between successive series of daily sit-
tings. Apart from recovery or improvement,
the indications for ceasing pneumatic treat-
ment or for intermitting it for a long time are
the signs of excessive organic combustion — that
is, fever, emaciation, excessive hunger (some-
times followed by complete loss of appetite),
marked lassitude, and muscular weakness.

The physiological and therapeutical effects of
the methods of the pneumatic chambers can be
best studied after we have considered those of
the

Differential Pressure Method. — The cost
of pneumatic chambers, their restriction to cer-
tain resorts, and their inapplicability or ineffi-
ciency in certain particulars have led to many
endeavours to construct portable apparatus for
pneumotherapy. The first practical appara-
tus for inhalation of condensed air was made
by Hauke, of Vienna, in 1870 ; and the same"
observer likewise devised a pneumatic cuirass
and a pneumatic tub, by which the air about
the chest or that about the entire body of the
patient could be rarefied while the ordinary
atmosphere was breathed. Hauke's apparatus
has, however, only an historical interest, hav-
ing been superseded by that of Waldenburg
and others. Waldenburg's apparatus is simply
a gasometer in which air is compressed or rare-
fied by means of weights, and from which or
into which the patient breathes. There are va-
rious scales, gauges, and other attachments for
p\irposes of exact observation. The air, taken
from a proper source and filtered on its way
to the gasometer, is conveyed to the patient by
means of a rubber tube, and prevented from
escaping by means of a mask of spun metal or
of rubber edged with pneumatic rubber cush-
ions, which is placed over the nose and mouth
and correctly adjusted to the face. A two-way



31



AIR, CONDENSED OR RAREFIED



stopcock of hard rubber, or a metallic arrange-
ment modelled on the cornet-piston placed be-
tween the supply tube and the mask, regulates
the ingress and egress of air. The same ap-
paratus may be used for both inspiration from
and expiration into condensed or rarefied air,
but it is best to have two cylinders for expira-
tion, so that the air inhaled may run no risk of
contamination. Weil and others have com-
bined the two cylinders in one apparatus, and
variously modified the details of construction.
(See Oertel, op. cit.). Fraenkel has constructed
an apparatus like an accordion, Biedert a large
reversible bellows, Geigel and Mayr a water-
engine bellows, Mathieu and others various
forms of apparatus utilizing hydrostatic prin-
ciples. Tne writer's apparatus (Pig. 1), de-



ervoir and pump with steam or electric mo-
tor, is substituted. See N. Y. Med. Jour.,
Feb. 33, 1889.) Filtered air from out of
doors is conveyed to the bellows through a
tube attached to a window board, and pres-
sure is made by weights placed upon the air
chamber. A second cylinder with suspended
weights may be used for rarefied air, and a
second bellows may be so combined with the
first that one stroke of the foot operates both.
(For details see N. Y. Med. Jour., Nov. 23,
1889). A further improvement contemplates
a great reduction in size by surrounding one
air chamber by another, instead of using two
gasometers. In the physician's oflBce and in
hospitals the double apparatus is desirable;
in the patient's residence the single cylinder




Fio. 1.— The author's apparatus for inspiration of condensed air and expiration into rarefied air.



scribed in 1884, is designed to furnish an in-
strument as simple, but more cleanly, manage-
able, and reliable than Praenkel's or Biedert's,
and at the same time less cumbersome and
expensive than Waldenburg's or Geigel and
Mayr's, and thus capable of being used by the
patient at home. A further advantage that it
offers over all instruments except that of Geigel
and Mayr is its continuous action. As now im-
proved, it eonsLSts of a small gasometer of zinc,
the air chamber of which is 8 inches in diame-
ter and 24 inches high, and a foot bellows such
as is used by dentists. (For office use a pump,
and for hospital work a special form of res- j



for condensed air is usually sufBcient. With
all these forms of apparatus various attach-
ments for medicating, warming, cooling, mois-
tening, or drying the air can be utilized.

Williams and Ketcham have devised an ap-
paratus termed a " pneumatic cabinet." It is
an air-tight metal chamber, just large enough
to allow one patient to be comfortably seated
therein ; containing a glass window, through
which the patient can be observed, and having
an hermetically closing door. By means of a
bellows attached to the instrument the air
within it can be slightly condensed or rarefied,
and a tube leading to the outer air is furnished



AIR, CONDENSED OR RAREFIED



22



with a mouthpiece through which the patient
inhales and exhales. The inspired air can be
medicated or otherwise modified. The degree
of pressure is shown by a mercury manometer.
While theoretically this instrument may be used
in various ways, in practice the air about the



pocket instruments haTe been described. Do-
bell has devised an apparatus called a residual
air pump. It consists of a mouthpiece with a
valvular arrangement which allows freedom of
expiration, but partially impedes inspiration,
the nostrils being closed or unused during the




Fig. 8.— Explanation of figure. The parts are numbered in order of attachment, and in the direction of atr-
current ; from the window to the mask through the compressed-air gasometer ; and from the mask to
the discharge pipe of the rarefying bellows through the rarefled-air gasometer. The discharge-pipe may
also be connected with window if desired. The direction of air-current is indicated by the arrows.



patient is usually rarefied by about ^ atmos-
phere, and he thus inspires from and expires
into relatively condensed air. Its effects will
therefore be considered under the head of Con-
tinuous respiration of condensed air (see page
25). It is at once much more expensive and
considerably inferior in range of usefulness to
the other forms of apparatus described.
For special purposes a number of handy or



process. It is intended for use in the treat-
ment of emphysema.

The writer has devised an apparatus which
he has termed " the pneumatic resistance
valves." It consists of a pair of small hollow,
bipartite, metal cylinders (1 in. x3 in.), each
containing an ebonite valve, the movement of
which is resisted by a spiral spring, the ten-
sion of the spring being regulated by turning



23



AIR, CONDENSED OR RAREFIED



the perforated cap of the cylinder. Beneath
the cylinders, and communicating with them
through the valve seats, runs a metallic tube
open at both extremities and attached at one
extremity to a rubber tube, terminating in a
hard-rubber mouthpiece. The patient inhales
and exhales through the apparatus, occluding
the anterior opening of the air tube during
the phase of respiration to be afiEected. The
respiratory current is then forced to pass
through the cylinder. One valve is so ar-
ranged as to impede the inspiratory current,
the other to impede the expiratory current.
Thus are obtained the effects of inspiration
from rarefied air, and of expiration into con-
densed air. The instrument is intended to be
used as a means of regulated pulmonary gym-
nastics. A scale of fractions of an atmosphere
engraved upon the cylinder shows the degree
of positive or negative pressure needed to over-
come the resistance of the valve. In place of
a spring, weights may be used to regulate the
pressure. In such a case, a square opening of
J-inch side will be most convenient. A sponge
or cotton wad, on which a few drops of a vol-
atile medicament are placed, may be inserted
in the path of the incoming air.

The cylinders can be used separately or to-
gether, or either may be used in connection
with a gasometer apparatus by inserting it
into the proper part of the stopcock.

Changes of intrathoracic air pressure can
of course be obtained without any apparatus
whatever. Thus if, while nostrils and mouth
are closed, forced expansion of the chest is
made (Muller's experiment), the air within the
lungs will be rarefied ; or if after a full inspira-
tion the glottis or the mouth and nostrils are
closed and an effort is made to contract the
chest (Valsalva's experiment), assisted perhaps
by manual compression of the chest (Weber's
experiment), or of the chest and abdomen
(Gerhardt's experiment), the .intrapulmonary
air will be condensed. A less degree of con-
densation may be caused by exhaling through
but partially closed lips or by interrupting
the expiration following a prolonged inspira-
tion by slowly counting aloud (phonic expira-
tion). It is obvious, however, that the effect
of rarefaction can thiis be produced only dur-
ing a prolongation of the inspiratory phase of
the respiratory act, while compression can be
brought about only by a baffied or impeded
expiration. The respiratory rhythm is com-
pletely deranged, the mechanical force devel-
oped and employed remains an unknown and
variable quantity, and the disturbance of cir-
culation IS usually out of all proportion to the
therapeutic value of the expedients.

Method of employing the Portable Appa-
ratus. — Atmospheric pressure upon the exteri-
or surface of the body remaining unchanged,-
increase of pressure upon the surface of the
air passages (pulmonary surface) may be ob-
tained, first, by inspiration of condensed air ;
second, by expiration into condensed air. De-
crease of pressure upon the pulmonary surface
may be obtained, first, by inspiration of rare-
fied air; second, by expiration into rarefied
air. These procedures may be so combined as



to maintain the increase or decrease during
both phases of the respiratory act, or to allow
of increase during one phase and decrease
during the other. There are thus eight meth-
ods of respiratory differentiation, which may be
tabulated as follows :





Inspiration of


With expiration into


1.


Condensed air


Atmosphere.


3.


Condensed air


Condensed air.


3.


Condensed air


Rarefied air.


4.


Rarefied air


Atmosphere.


5.


Rarefied air


Rarefied air.


6.


Rarefied air


Condensed air.


7.


Atmosphere


Condensed air.


8.


Atmosphere


Rarefied air.



To carry out all these eight methods, two of
Waldenburg's gasometers, or the writer's double
gasometer and a pair of resistance valves, will
suffice.

The procedures numbered 1 and 3 are the
most generally applicable. Eor the former a
single gasometer of Waldenburg's or the
writer's apparatus, for the latter a double
gasometer is required. That numbered 2 is
physically the equivalent of the method of the
pneumatic cabinet of Williams. It is, in the
writer's experience, of but limited applicability
and inferior to the other methods. It requires
two of Waldenburg's gasometers or one of the
writer's gasometers and an expiration resistance
valve. The procedures numbered respectively
4, 6, and 7 can be carried out with no other ap-
paratus than the resistance valves. The proced-
ure numbered 5 would require two cylinders
of Waldenburg's or the writer's expiration gas-
ometer, and an inspiration valve. It is of only
theoretical importance. Procedure No. 8 re-
quires a single cylinder of Waldenburg's or the
writer's expiration gasometer.

The excess or negative pressures employed
in the differential methods are much smaller
than in the pneumatic chambers, varying from
tV to ^ of an atmosphere. In negative pres-
sure (rai'ef action) ^ atmosphere is rarely to be
exceeded. In expiration into condensed air
or against the resistance valve ^ atmosphere
should not be exceeded except with great
caution. It is always wise to begin with the
minimum pressure and increase as the patient's
susceptibility is learned and his progress indi-
cates. Patients use the apparatus at first for
five minutes, later for thirty minutes at a time,
and from one to four times a day. If weak
they may be seated, but it is better to stand.
All constricting garments should be loosened.
Inspiration should be as slow, expiration as
prolonged as possible, the patient being en-
couraged to increase the volume of air inhaled
or exhaled at each respiration, as shown by the
scale of cubic contents upon the air cylinder.
The treatment should not be pushed to the
point of fatigue. A rest of ten minutes before
and after treatment, and sometimes an inter-
ruption and rest of five or ten minutes during
treatment, are advisable. The time thus con-
sumed is a great drawback when the treatment
must be carried out at the physician's office.
For this reason it is preferable in cases of
chronic disease, like pulmonary tuberculosis or



AIR, CONDENSED OR RAREFIED



24



asthma, to have the patient purchase (or rent
from the instrument maker) some form of ap-
paratus that can be used at home after due in-
struction has been given. The home apparatus
has also the advantages of cheapness and of ap-

Elicability to cases of patients confined to the
ouse or prevented by bad weather, distance, or
other causes from visiting the physician's office.
The physical effects of respiratory differen-
tiation must be considered with reference,
first, to respiration; second, to circulation.
Motion of air and of blood takes place from
the point of high pressure toward the point
of low pressure. Increased pressure upon the
pulmonary surface, therefore, favors the en-
trance of air into the chest and the expansion
of the lungs, and opposes the exit of air from