Monthly Archives: February 2015

1960s, Spirometer

Spirometer using a Pitot-style mechanism, 1963

Leave a comment

Spirometer_Pitot_1963

From Patent number 3,081, 766 granted March 19, 1963 to B. Dubsky et al.  A combination of mechanical and electrical components.  It was likely never manufactured.

“..it is an object of this invention to provide an open circuit spirometer for measuring both the quantities of air that are inhaled and exhaled by the subject or patient and the rates at which the air is inhaled and exhaled, without requiring the use of an air or oxygen container.

“Another object is to provide an open circuit spirometer that is constructed and arranged so that those parts with which the patient or subject comes into contactmay be conveniently and effectively sterilized.

“A further object is to provide an open circuit spirometer of relatively small size and weight so that it is conveniently portable and therefore may be used in laboratories and health centers, as well as at the bedsides of patients in a hospital.

“Still another object is to provide an open circuit spirometer in which the moving parts thereof have a negligible inertia, thereby to provide measurements of the respiration of a patient or subject with an increased accuracy.

“In accordance with an aspect of this invention, the foregoing objects are achieved by providing a spirometer comprising an open-ended conduit with a mouthpiece at one end through which the patient or subject inhales and exhales, two Pitot tubes disposed in the conduit and respectively opening axially toward the opposite ends or” the latter, a substantially closed chamber having a movable torsional body, a source of alternating current connected with the exciting winding so that torsional stressing of the body causes a signal voltage to be induced in the pick-up winding, and indicating or recording means connected to the pick-up winding so as to be actuated by the signal voltage.

“In a preferred embodiment of the invention, the signal voltage from the pick-up winding or coil is fed to an amplifier having a feed-back circuit and a non-linear resistor arranged so that the output from the amplifier is proportional to the square root of the input or signal voltage from the pick-up coil, and therefore proportional to the square root of the difference between the pressures sensed by both Pitot tubes which corresponds to the speed of movement of air through the conduit during inhalation or exhalation by the patient. Further, the output from the amplifier is fed to the control winding of a two-phase asynchronous servo-motor which suitably drives a carriage or movable support carrying a pencil or stylus engaging a strip or web of recording paper that is suitably displaced in the direction at right angles to the direction of movement of the carriage so that the position of the carriage, and hence of the stylus on the recording paper, is proportional to the quantity of air flowing through the conduit.”

1890s, Spirometer

Spirometer, Lacey’s, 1892

Leave a comment

Spirometer_Lacey_1892_Patent

From Patent application number 471,289 dated March 22, 1892.

“The operation of my invention is as follows: The mouth-piece a is placed in the mouth and air slowly inhaled until the lungs are completely filled. The opening S in the side of the main tube is closed by a finger of the person using the instrument and the air which has been taken into the lungs is forced out.  This outward passage of air operates the valve B to close the outlet b, and the column of air, acting on the piston or plunger G, causes the same to move longitudinally in the tube E. A person can thus by repeated tests inform himself as to the increase in the capacity of the lungs by the distance the plunger is moved at each exhalation.  When the instrument is removed from the mouth, the air withing the tube is forced out through the mouth-piece and the opening S by reason of the spring K drawing the plunger or piston back to its normal position.”

1880s, Spirometer

Spirometer, Barton, 1888

Leave a comment

Spirometer_Barton_1888

Patent number 392,711 by W.H.H. Barton.

“The instrument consists, essentially, of a flexible, collapsible, non-elastic reservoir or bag, preferably elongated or substantially cylindrical in shape, proved with a scale that indicates the cubic contents of the different portions of said bag when distended or filled.

“The bag or reservoir is provided at one end with a spindle or roll upon which the unfilled portion may be wound, so that the scale will indicate the cubic contents of the part of the reservoir that is filled.  The said spindle or roll preferably forms the inlet to the reservoir and is provided with a suitable mouthpiece. One important advantage to this kind of spirometer arises from the fact that their is no back-pressure of the atmosphere, and the instrument is very light, compact and inexpensive.”

1900s, Spirometer

Spirometer, Marcet, modified Hutchinson, 1909

Leave a comment

Spirometer_Marcet_Modification_1909_Cam_Counterpoise

From Artificial Respiration in Man, by Prof. E. A. Schafer, The Harvey Lectures, Volume 3, Academic Press, 1909, page 226.

“Hutchinson’s spirometer is defective on one point, viz., that the inner cylinder is not equally balanced at all points of its immersion in the water which is contained in the outer cylinder.  This defect was made good by Marcet, by the introduction of a secondary counterpoise.  This works from a cam-like projection attached to the pulley over which the cord carrying the main counterpoise passes. This cam is so arranged that the secondary counterpoise exerts more leverage the more the inner cylinder of the spirometer becomes lifted out of the water as air passes into it; and in this manner the increased weight of the cylinder is, more or less exactly, compensated.”

1880s, Basal metabolism, CO2 Production

Respiration Apparatus, Voit’s, 1887

Leave a comment

Respiration_Apparatus_Voit_1887

From Treatise on human physiology by Henry Cadwalader Chapman, Published by Lea Brothers & Co, 1887, page 446.

“We therefore, usually determine at the same time the amount of carbonic acid and water exhaled by the system, and for this purpose we make use of Voit’s respiration apparatus.  This consists, as constructed by C. Stollventner and Sohn of Munich (Fig. 252), of a chamber (H) in which the subject of the experiment, a large dog, for example, is placed; of a large drum, and pumps worked by a waterwheel for the production of a constant draught of fresh air through the apparatus; of bottles and tubes containing appropriate materials for the absorption of water and carbonic acid of the air surrounding the chamber, as well as that from within it; and of meters for registering the total amount of air that has passed through the chamber analyzed for comparison.”

1880s, Basal metabolism, CO2 Production, Oxygen Consumption

Respiration Apparatus, Ludwig’s, 1887

Leave a comment

Respiration_Apparatus_Ludwig_1887

From Treatise on human physiology by Henry Cadwalader Chapman, Published by Lea Brothers & Co, 1887, page 446.

“A more modern apparatus used by Ludwig and his pupils, differs from that of Regnualt and Reiset just described, not so much in principle as in certain mechanical details. The most noticeable of these is the ingenious contrivance by means of which the oxygen expired passes from g (Fig. 251) into the respiratory tube d, communicating through an air-tight covering with the nostrils of the animal at e, alternately with the passage of the carbonic acid expired into the bulbs f, and which is accomplished through the alternate expansion and contraction of valve c. For with the rarefaction of the air through inspiration the valve c is drawn from the end of the tube b, the effect of which is that the air entering the tube b drives the water out of a, which in turn drives the oxygen out of g into the tube d.  On the other hand, with the condensation of the air through expiration, the valve c is forced back close to the end of tube b, the flow of oxygen from the tube d ceases, the carbonic acid exhaled passing into the bulbs f.”

1870s, Basal metabolism, CO2 Production, Oxygen Consumption

Respiration Apparatus, Regnault and Reiset, 1887

Leave a comment

Respiration_Apparatus_Regnault_Reiset_1887

From Treatise on human physiology by Henry Cadwalader Chapman, Published by Lea Brothers & Co, 1887, page 443.

“Within the tabulated bell-jar A, immersed in the cylinder of water B, is placed a little animal, a dog, for example, the subject of the experiment.  The animal having been introduced from below, and the opening hermetically closed, the large pipettes G G, filled with a solution of potash or soda of known strength and quantity, and communicating with each other by a caoutchouc tube, absorb and measure the CO2 exhaled unto the air of the jar A, the air being drawn alternately into the pipettes G G through their elevation and depression by hand of some simple mechanical arrangement.  According as the oxygen is absorbed by the animal, the gas pressure falls in A, and consequently the oxygen of the balloon N, under the pressure of the calcium chloride solution in P, flows through M, replacing that lost in A.”

1880s, Basal metabolism, CO2 Production, Oxygen Consumption

Respiraton Apparatus, Valentin and Brunner, 1887

Leave a comment

Respiration_Apparatus_Valentin_&_Brunner_1887

From Treatise on human physiology by Henry Cadwalader Chapman, Published by Lea Brothers & Co, 1887, page 438.

“Let us endeavor to determine the amount of oxygen absorbed, and that of carbonic acid, etc., exhaled in a given time.  This can be done is several ways the simplest of which consists in comparing the composition of the ordinary atmospheric air with that which has been breathed, with the object of determining the amount of oxygen absorbed during one inspiration, and multiplying this by the minutes, hours, etc. in order to obtain, approximately at least, the amount of oxygen absorbed in the twenty-four hours. The apparatus of Valentin and Brunner, as used by the author for this object, consists (Fig. 249) of a Woulff’s bottle A having a capacity of about a liter (61 cubic in.). One of the openings communicates with the mouth-piece B, into which the person expires, the air first passing through pumice-stone and sulphuric acid C so as to dry it. The middle opening communicates with the set of tubes G H I K.  H and I contain phosphorus and baryta for the absorption of the oxygen and carbonic acid of the expired air, G and K pumice stone, etc., that of G for the absorption of watery vapors that may have escaped, the pumice-stone, etc., in C K for retaining that taken up by the dry air passing through the baryta solution, and which, if lost, would cause an error in the estimate of the carbonic acid exhaled, the tubes being weighed before and after the experiment. Through the middle opening of the Woulff’s bottle a funnel (D) provided with a stopcock is introduced, the opening then being hermetically closed.  The funnel is filled with a know quantity of mercury. The manner of using the apparatus is as follows: having breathed for say fifteen minutes through the mouthpiece until the air of the Woulff’s bottle has been entirely displaced by the expired air, the mouth-piece is entirely closed, any external air being further prevented from passing into the Woulff’s bottle by the mercury in E acting as a valve, the air-tightness of the apparatus being assured by the rise of the mercury in the tube F, through the contraction of expired air in A, consequent upon its cooling and the closure of the tube funnel. The stopcock of the funnel being then turned, the mercury passes into the Woulff’s bottle, displacing a know quantity of expired, the latter passing into the set of tubes G H I K, previously adjusted to the middle opening.  The weight of the tubes H and I having been previously determined, their increase in weight will give, respectively, the amount of cabonic acid and oxygen absorbed.”