IMPROVEMENTS IN APPARATUS FOR TESTING THE CAPACITY OF THE LUNGS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Edmund Edwards at the Office of
the Commissioners of Patents on the 7th June 1882. A communication to
him from abroad by Maurice Dupont, of Paris, in the Republic of France
EDMUND EDWARDS, of the firm of Edwards and Co:-Patent Agents and
Engineers, of 40, Southampton Buildings, Chancery Lane, in the County of
Middlesex "IMPROVEMENTS IN APPARATUS FOR TESTING THE CAPACITY OF THE
LUNGS [A communication to him from abroad by Maurice Dupont, of Paris, in
the Republic of France]
"
This invention relates to Spirometers or apparatus for testing the capacity of the
human lungs, and has for its object improvements in such apparatus so that the
patient, the capacity of whose lungs is to be tested has to make no effort whilst
using it.
The apparatus consists of two vessels preferably of glass, each having two
openings at their upper ends. One of these openings in each vessel is closed by an
india rubber stopper, through which passes a glass tube descending nearly to the
bottom of the vessels, the two tubes being bent at right angles above the stoppers
and connected together by an india rubber tube of sufficient length, the two glass
tubes and the india rubber tube constituting a syphon connecting the two vessels.
The second opening in the first vessel remains open, whilst that in the second
vessel is closed by an india rubber stopper through which passes a small glass tube
to the outer end of which is connected an india rubber tube of sufficient length,
terminating in a mouthpiece within which is a cock by which the tube can be
opened or closed.
The second vessel is graduated from the top downward from zero to 5000 cubic
centimêtres, allowance being made for the volume of the syphon itself, by degrees
of 25 cubic centimêtres, the lower end of the small glass tube corresponding with
the mark at zero.
In order to use the apparatus, the first vessel is filled with water, and the cock
at the mouthpiece being opened, the water is made to pass from the first to the
second vessel, by means of the syphon pipes described, until the water rises in the
second vessel to the mark zero, when the cock is closed.
A sufficient quantity of water is then poured into the first vessel to keep the
lower end of the tube in the latter always covered, and the vessel is then placed at

page_text: a level lower than that of the second vessel,-
-on a chair for instance whilst the
second vessel remains upon a table.
The syphon being charged, the water in the second vessel may be easily made to
flow into the first one, by opening the cock and placing the first at a lower level
than the second vessel; and the flow can be stopped at any time by closing the
cock.
In order to test the pulmonary capacity of a patient, he takes a deep inspiration,
and then, before commencing an expiration applies the mouthpiece to his mouth,
the cock being at the same time opened.
He then makes as complete an expiration as possible, shutting the cock quickly
directly it ends. The breath from his lungs has during this time driven the water
back from the second vessel into the first, and the figure at which its level then
stands in the former indicates the volume of the expired air.
By the action of the syphon, the expiration is made without effort, and solely
under the influences of the atmosphere pressing upon the walls of the thorax; and
the air contained in the lungs escaping as the water flows through the syphon is
really drawn into the second vessel, the lungs being thus more completely emptied
than by the most powerful expiration.
The apparatus described may be used to determine the capacity of the lungs for
air at different periods of pulmonary tuberculosis.
A diagram in the form of a curve may thus be drawn showing daily the extent
of hematosis and the variations of this curve will point out the greater or less
progress of the disease.
The apparatus may be used for the diagnosis of pulmonary emphysema, by
measuring the extent of lung rendered useless and incapable of utilizing the air
breathed.
It also enables the extent of pleuretic effusions to be determined, and the
variations which they shew after blisters or vesicatory treatment, the administration
of purgatives and diuretics, or operations on the thorax.
The apparatus as described possesses also the advantage, that by its use the air
expired can be readily collected and analysed.
To prevent the carbonic acid from being dissolved in the water, a very thin film
of oil is placed upon the surface of the latter.
The apparatus may also be used to measure the capacity of the lungs, and from
such measurement to establish or confirm the diagnosis of tubercular disease and.
to observe its progress, also to obtain forced respiration in rarified air as a means
of treatment in diseases of the chest, and more especially as a means for preventive
treatment.
When used as a measure, the length of the india rubber tube which forms the
syphon should be such that one vessel may be placed its own height above the
other, one being upon a table the other upon a stool. When used medically,
the difference of level should be greater in proportion to the energy of the expiration
which it is desired to produce, the length of the india rubber tube being pro-
portioned to the extent of such force, one of the vessels for instance being upon a
table and the other upon the floor.