US3282266A

US3282266A - Method and apparatus for humidifying inhalation mixtures

Info

Publication number: US3282266A
Application number: US214393A
Authority: US
Inventors: Jr John M Walker
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-08-02
Filing date: 1962-08-02
Publication date: 1966-11-01
Anticipated expiration: 1983-11-01

Description

Nov. 1, 1966 J M. WALKER, JR 3,282,266

METHQD AND APPARATUS FOR HUMIDIFYING INHALATION MIXTURES Filed Aug. 2; 1962 FIGI from 2! 20 Oxygen Supply 23 27 29 Hi 1 f. j 25 I0 IT24 32 Power 34 mpg I I I 35 W I 32 l (l H62 Q51 [Q :3 @Jo I! INVENTOR. JOHN M. WALKER,JR.

A TTORNE Y S United States Patent 3,282,266 METHOD AND APPARATUS FOR HUMIDIFYING INHALATION MIXTURES John M. Walker, Jr., Langhorne, Bucks County, Pa. Filed Aug. 2, 1962, Ser. No. 214,393 14 Claims. '(Cl. 128-209) The present invention relates to an improved method and apparatus for nebulizing a liquid and dispersing it Within a gaseous medium. More particularly, the present invention relates to improvements in inhalation therapy so that oxygen, anaesthetic gases and similar inhalation mixtures intended for human respiration may be humidified to a considerably greater extent than is possible with known nebulizers, aspirators and the like. Known apparatus can at best humidify an inhalation mixture to 100% relative humidity with perhaps a very small amount of water present in aerosol dispersion.

In normal human respiration air is inhaled at the temperature and relative humidity of the surroundings. It is exhaled at approximately body temperature and 100% relative humidity containing a larger amount of water vapor than that present in the inhaled air. There is thus a net loss of water from the body during respiration. The above will become more apparent from a consideration of the water content of air inhaled at room temperature of about 70 F. and exhaled at normal body temperature at 98.6 F. The inhaled air has been warmed to body temperature and then exhaled saturated with water vapor at body temperature. If it is assumed that the room air at 70 F. is at 50% relative humidity, the air contains 11 milligrams of water vapor per liter of air. The exhaled air at 98.6% and 100% relative humidity, i.e., saturated with water vapor, contains 44 milligrams per liter. It is thus apparent that for every liter of air inhaled and exhaled there is a net loss of 33 milligrams of water from the body. This is a 300% increase in water content in the exhaled air over that present in the entering air.

Similarly, if the room air at 70 F. were at 100% relative humidity, it would contain 22 milligrams of water vapor per liter. In this case, for every liter of air used in respiration, there would be a net loss of 44 minus 22 or 22 milligrams of water per liter of air. This is a 100% increase in the actual water content of the air.

The above noted water loss from the body cannot be stopped or decreased by supplying air or oxygen substantially at body temperature of 98.6 F. and saturated with water vapor since in the case of air such a mixture would be distressing to a healthy person, and especially distressing to a person having a respiratory disorder. A saturated oxygen-rich mixture inhaled at body temperature would be intolerable to all.

The water given up to the air during respiration comes from the lungs. The mucous membranes lining the lungs are provided with cilia, small hair like structures which are continuously in motion. There are hundreds of cilia per square micron of surface moving independently of one another in a whip-like forward motion with a somewhat slower return more than 100 times a minute. The motion of the cilia propels a film of liquid up and out of the lungs carrying airborne bacteria, dust and the like, and thus constitutes one of the protective mechanisms of the human body. When the liquid film thickens, as is the case when there is a substantial amount of water being lost to the air, the cilia have difiiculty in propelling the liquid film. As the film further thickens, the protective mechanism stops operating and many undesirable consequences can ensue, for example, postoperative pneumonia.

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One of the aims of the present invention is to control the fluidity of the liquid film within the lungs by stopping and/or decreasing the net water loss from the body during respiration. The present invention achieves the above by introducing a precisely controlled volume of steam into a high velocity stream of air or other inhalation mixture to be molecularly dispersed in the inhalation mixture. The quantity of steam introduced is sufiicient to raise the total amount of water present to about 44 milligrams of water per liter, which corresponds to the amount of water present in saturated air at body temperature. The mixture of steam in the inhalation mixture exists as a molecularly dispersed mixture for about 600 milliseconds and is a transient condition. Within this time, using a channel of small crosssection and low heat conductivity, the mixture can be supplied to the patient, and inhaled and warmed to body temperature already containing 44 milligrams of water vapor per liter of air. Starting with an inhalation mixture at initially approximately 0% relative humidity, the addition of a volume percent of steam of about 3% is sufiicient to raise the water content to the desired amount. The heat content of this small amount of superheated steam raises the temperature of the inhalation mixture only about 2 C.

One of the primary objects of the present invention is to provide an improved method of dispersing one fluid within another.

Another object of the present invention is to provide an improved method of humidifying an inhalation mixture.

Still another object of the present invention is to provide apparatus for humidifying an inhalation mixture to a considerably greater extent than that achieved with prior art apparatus.

A further object of the present invention is to supply an inhalation mixture for respiration at about normal room temperature, and containing as a transient mixture an amount of water vapor approximately corresponding to the amount of water vapor present in the mixture when subsequently exhaled at body temperature.

A still further object of the present invention is to provide apparatus for producing a transient molecular dispersion of water vapor within an inhalation mixture which is substantially in excess of relative humidity, relative to the ambient conditions.

These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the drawings, wherein:

FIGURE 1 is a schematic illustration of the embodiment for carrying out the present invention, and

FIGURE 2 is an end view of a self-contained unit including the elements schematically illustrated in FIG- URE 1.

Referring now to the drawing, and more particularly to FIGURE 1, there is shown a conduit 10 receiving an oxygen-rich inhalation mixture from a supply source schematically indicated by arrow 11, a flow meter 12, a flow control valve 13, an inhalation mixture supply conduit 14, a steam generator generally designated by reference numeral 15, a capillary tube 16 leading from steam generator 15 to conduit 14, and a point of respiration indicated by a face mask 17.

Steam generator 15 includes an outer casing 18 forming a liquid reservoir 19 in the interior thereof and provided with an atmospheric vent 20. Casing 18 is preferably made of glass or other transparent material so that the level of liquid reservoir 19 may be more readily checked. A removable cover 21 closes off the top of casing 18. A syphon tube 22 is mounted Within casing 18 by having its upper end secured to a depend- 3 ing flange portion 23 of cover 21 so that the lower end of syphon tube 22 extends down into reservoir 19 and terminates above the bottom of casing 18. A container 24 forming an enclosed vaporization space is mounted within syphon tube 22 by having portions thereof imbedded in flange portion 23, or by any other suitable means. Container 24 which is shown as a cylinder is preferably made of a microporous ceramic material such as that disclosed in my Patent No. 2,404,872, issued July 30, 1946, entitled, Method and Apparatus for Separating immiscible Fluids. The microporous ceramic material functions as a phase separator and permits water to flow through the micropores from syphon tube 22 into the interior of container 24 but prevents steam pressure generated within container 24 from being exerted back into the water within syphon tube 22.

The operation of syphon tube 22 and of cylinder 24 will become more apparent from the following. An electric heating element 25 is positioned within container 24 by any suitable means to vaporize water entering container 24 via the micropores of the ceramic material. The steam generated is vented from container 24 through the capillary tube 16. The steam pressure generated within container 24 may be of the order of 50 millimeters of mercury above atmospheric pressure, and yet due to the phase-separating characteristics of the microporous ceramic material this pressure would not be transmitted to the water within syphon tube 22. However, the steam pressure is effective to pass steam through capillary tube 16 wherein the pressure is of the order of 20 millimeters of mercury above atmospheric pressure into the oxygenrich stream in conduit 14 which is maintained at a slightly lower pressure, for example, millimeters above atmospheric pressure.

Due to the flow of water from syphon tube 22 into container 24 for vaporization therein, a suction is maintained in syphon tube 22 which maintains water in contact with the outside of the microporous ceramic container 24 so long as the liquid level within reservoir 19 is above the lower end of syphon tube 22.

Heating element 25 is supplied with electrical energy via

leads

26, 27 connected to a suitable power supply 28. Arheostat 29 regulates the current supplied to heater element 25 to provide a control over the amount of steam generated in cylinder 24 and supplied via capillary tube 16 for injection into supply conduit 14 to form a molecularly dispersed transient mixture substantially in excess of 100% relative humidity, relative to the ambient conditions. The amount of water vapor or steam generated is independent of the flow rate of the oxygen-rich, stream. Accordingly, the degree of humidification may be varied from nearly zero to about 200% relative humidity depending upon the setting of rheostat 29. A switch 30 enables an on and off control of heater element 25. A fuse 31, and a pilot light 32, which when lit signifies that the heater is in operation, are provided as safety features.

The above described steam generator is especially desirable since only a few cubic centimeters of water are being heated to boiling within cylinder 24 at any one time. This enables a fast start-up of the apparatus, and yet a constant supply of water through the micropores is assured. This is in contrast to a conventional steam boiler wherein a large volume of water would be initially brought to the boiling point before any steam would be generated. The steam generator of the present invention enables a more precise control of the output and requires only a small current supply for heater 25. The micropores of cylinder 24 in effect function as millions of boiler water feed pumps, without pulsation. While such a steam generator is preferred for the above noted reasons, it will be appreciated that any conventional steam generator might be utilized in lieu thereof, although, not as advantageously.

Since as stated above, the molecularly dispersed mixture exists for about 600 milliseconds, this is a critical lim- 4- itation since the steam and gas mixture must be supplied for respiration before there is any considerable condensation of the steam. One skilled in the art and appraised of the significance of this time period may so correlate the length of supply conduit 14 downstream of the capillary tube supplying the steam, the bore of conduit 14 and the gas velocities so that the transient mixture is inhaled before condensation occurs to any considerable extent. For example, it has been found experimentally that the velocity of a ten liter per'minute flow of gas is approximately 70 feet per second in a one-eighth inch diameter A tube. With a velocity of 70 feet per second, the flow would thus proceed through a five foot length of tube or pipe in second or about 70 milliseconds. As is known in the art, the rate of flow in a tube or pipevaries inversely as the square of the diameter thereof. Consequently, a one inch diameter tube would have a gas velocity which is approximately ,4 of 70 feet per second with a ten liter per minute flow. Thus, variations in the present invention may readily be made in order to achieve certain desired results by simple calculations.

The humidified inhalation mixture can be supplied to l the face mask 17 as shown, to a suifuser harness with plastic tubes entering the nostrils, to a nasal catheter, into a cap over a tracheotomy incision, directly into an incubator, or by other means.

FIGURE 2 illustrates that the above described elements may be all mounted within a small portable, selfcontained unit including a casing 33 provided with an inlet connection 34 for conduit 10, an outlet connection 35 for conduit 14, and with apertures enabling flow meter 12, control valve 13, rheostat 29, switch 30, fuse 31, and pilot light 32 to be accessible and visible from the outside.

The transient molecular dispersion of steam within an oxygen-rich atmosphere has been demonstrated by means of apparatus having two streams of dry oxygen each regulated by a flow meter and an associated valve. The flow meter of one stream is set to pass at 10 liters per minute through the humidifier of the present invention into a transparent enclosure containing a Serdex relative humidity indicator. The Serdex indicator initially records a reading of about 0% relative humidity. The humidifier is then started and the relative humidity of the stream is brought up to The second stream is now connected into the line downstream of the humidifier and its flow is also set at 10 liters per minute. A thermostat regulating the electric heater element of the humidifier of the present invention is adjusted to a higher setting so that more steam is evolved. All of the humidity for both streams is carried in the first stream from the humidifier to the point of admixture with the second stream. Eventually, the Serdex indicator reading is approximately 100% relative humidity for the two combined streams. Therefore, it is apparent that the first stream carried a water vapor content equivalent to 200% relative humidity since the second stream was entirely dry. The flow of the second stream is now stopped. Upon darkening the room and shining a light beam at right angles through the first stream it may be observed that the stream is optically empty, i.e., molecularly dispersed.

It will be appreciated that the present invention is susceptible to many changes and modifications within the scope of the instant disclosure. For example, medication may be added to the inhalation mixture, and the humidifier of the present invention may be utilized in conjunction with oxygen supplied to aviators or divers. Accordingly, I intend to encompass all such changes and modifications as are contained within the scope of the appended claims.

I claim:

1. Humidifier apparatus comprising a conduit supplying an oxygen-rich gas stream intended for human respiration, means for metering the flow of said gas stream through said conduit, a steam generator, a capillary tube leading from said steam generator to said conduit to inject a quantity of water vapor into said gas stream to form a transient molecularly dispersed mixture of said gas and water vapor, said mixture having a water vapor content corresponding approximately to the water content of said gas stream when saturated at body temperature, and means for delivering said mixture for respiration before any substantial condensation of the water vapor in said mixture occurs.

2. The humidifier apparatus as defined in claim 1, wherein said mixture has a water vapor content of approximately 44 milligrams of water per liter of gas.

3. Apparatus as defined in claim 1, wherein said steam generator comprises an outer casing forming a liquid reservoir, a syphon tube secured within said casing and having its lower end extending beneath the liquid level in said reservoir, a cylinder of a microporous ceramic material mounted within said syphon tube to permit water to flow into the interior of said cylinder, and an electric heating element Within said cylinder for vaporizing water therein.

4. Humidifier apparatus for humidifying an inhalation mixture comprising a supply source of a gas intended for human respiration, a conduit leading from said source, means for metering the flow of said gas stream through said conduit, a steam generator including heater means and control means for said heater means, a capillary tube leading from said stream generator to said conduit to inject a predetermined quantity of water vapor into said gas stream to form a transient molecularly dispersed mixture of said gas and water vapor, said mixture having a Water vapor content corresponding approximately to the Water content of said gas stream when saturated at body temperature, and means for delivering said mixture for respiration before any substantial condensation of the water vapor in said mixtureoccurs.

5. The humidifier apparatus as defined in claim 4 wherein said mixture has a water vapor content of approximately 44 milligrams of water per liter of gas.

6. A steam generator comprising an outer casing forming a liquid reservoir, a syphon tube secured within said casing and having its lower end extending beneath the liquid level in said reservoir, a cylinder of a microporous ceramic material mounted within said syphon tube to permit water to flow into the interior of said cylinder, an electric heating element within said cylinder for vaporizing water therein, and a steam discharge tube leading from said cylinder.

7. A steam generator comprising an outer casing forming a liquid reservoir, a cylinder having wall portions of a microporous material mounted within said reservoir to permit water to flow therethrough into the interior thereof, and to prevent steam pressure within said cylinder from being transmitted therethrough, a heating element within said cylinder for vaporizing water therein, and means for discharging steam from said cylinder.

8. A steam generator comprising an outer casing forming a liquidreservoir, a syphon tube secured within said casing and having its lower end positioned within said reservoir, a cylinder having wall portions of a microporous material mounted within said syphon tube to permit water to flow therethrough into the interior thereof and to prevent steam pressure within said cylinder from being transmitted therethrough, a heating element within said cylinder for vaporizing water therein, and means for discharging steam from said cylinder.

9. A method for humidifying a gas stream intended for human respiration which comprises regulating the quantity and velocity of said gas stream, injecting a predetermined small amount of steam into said gas stream to form a transient molecularly dispersed mixture of said gas and water vapor, said mixture having a water vapor content corresponding approximately to the water content of said gas stream when saturated at body temperature, and delivering said mixture for respiration prior to any substantial condensation of the water vapor in said mixture.

10. The method of claim 9, wherein said mixture has a water vapor content of approximately 44 milligrams of water per liter of gas.

.11. A method for humidifying a gas stream intended for human respiration which comprises regulating the quantity and velocity of said gas stream, injecting a predetermined small amount of steam into said gas stream to form a transient molecularly dispersed mixture of said gas and water vapor, said mixture having a water vapor content corresponding approximately to the water content of said gas stream when saturated at body temperature, and delivering said mixture for respiration within 600 milliseconds after its formation.

12. The method of claim 11, wherein said gas stream is an oxygen-rich gas stream.

13. A method for humidifying an oxygen-rich gas stream intended for human respiration which comprises regulating the quantity and velocity of said gas stream, injecting a predetermined small amount of super-heated steam into said gas stream to form a transient molecularly dispersed mixture of said gas and water vapor, said mixture having a water vapor content of approximately 44 milligrams of Water per liter of gas, and delivering said mixture for respiration prior to any substantial condensation of the water vapor in said mixture.

14. The method of claim 13, wherein said mixture is delivered for respiration within 600 milliseconds after its formation.

References Cited by the Examiner UNITED STATES PATENTS 680,122 8/1901 Camp 2l-1l7 2,023,324 12/1935 Johnson et al. 128-192 2,368,115 1/1945 Chapple 128192 2,547,865 4/1951 Hanks.

2,709,577 5/1955 Pohndorf et a1. 128-185 2,778,617 1/1957 Gibbon 128191 I 2,806,932 9/1957 Conlin et al.,

2,812,762 '11/l957 Jordan et al. 128l9l 2,847,548 8/ 1958 Gordon et a1.

RICHARD A. GAUDET, Primary Examiner. JORDAN FRANKLIN, Examiner.

R. D. TEGTMEYER, D. S. BURKS, W. E. KAMM, Assistant Examiners.

Claims

1. HUMIDIFIER APPARATUS COMPRISING A CONDUIT SUPPLYING AN OXYGEN-RICH GAS STREAM INTENDED FOR HUMAN RESPIRATION MEANS FOR METERING THE FLOW OF SAID GAS STREAM THROUGH SAID CONDUIT, A STREAM GENERATOR, A CAPILLARY TUBE LEADING FROM SAID STREAM GENERATOR TO SAID CONDUIT TO INJECT A QUANTITY OF WATER VAPOR INTO SAID GAS STREAM TO FORM A TRANSIENT MOLLECULARLY DISPERSED MIXTURE OF SAID GAS AND WATER VAPOR SAID MIXTURE HAVING A WATER VAPOR