Adjustable heating infusion apparatus

March 26, 1935. h. goldstein 1,995,302

ADJUSTABLE HEATING INFUSION APPARATUS

Filed Nov. 24, 1933

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ATTORNEYS.

Patented Mar. 26, 1935

1,995,302

UNITED STATES PATENT OFFICE

1,995,302 ADJUSTABLE HEATING INFUSION APPARATUS

Harold Goldstein, New York, N. Y.

Application November 24, 1933, Serial No. 699,552 4 Claims. (Cl. 128—254)

The present invention relates to a construction for elevating and accurately maintaining the temperature of fluids prescribed by physicians for injection into the human system.

₅ Many physicians are extensively using this form of therapy at the present time for treating human ailments. Because of the many purposes that this form of therapy can serve, it manifestly has great practical possibilities. It may, for in10 stance, be used for the intravenous injection of fluids such as saline solutions or blood into the blood stream via the veins. Required fluids may by it be inducted into the body by hypodermoclysis, that is by injections through the skin. It 15 can also be directed to the washing of body cavities with suitable detergents and cleansing fluids. Likewise it comprehends the supplying of nourishment to the body by the installation of rectal feedings. There is therefore little wonder 20 that many eminent medical men are employing it more and more in their daily practice.

The widespread adoption of this form of therapy however, has been greatly retarded by the means now in general use for regulating and 25 controlling the temperature of the injected fluids. It is perfectly apparent that unless the fluids incorporated into the body are at or substantially at the temperature of the body, the introduction may lead to grave injury to the 30 patient. Thus, if the fluid is too cold there is danger of a chill resulting from the injection. On the other hand, the patient’s system is liable to overheating, and possible blood coagulation if the temperature of the fluids is immoderately 35 high. Any benefits that may accrue from this mode of treatment can, therefore, only be obtained if care is taken to adjust and retain the temperature of 'the fluids to the necessary degree.

The means now in vogue for controlling the 40 temperature of the fluids is an exceedingly crude one involving the encasing or enclosing of the fluid containing flask in hot water bags. Due to the rate of change of temperature of the bags under atmospheric or normal conditions, one 45 can readily perceive, that it is almost an impossibility to effect an accurate control of the temperature in this way. For instance, due to the fall in temperature of the bags, it necessarily follows that if the bags initially have a tempera50 ture sufficient to provide the desired amount of heat to the fluids to be injected, the first fraction injected will be at the optimum temperature while the last will be far too cold. Chilling of the system, as previously pointed out, may 55 therefore ensue. On the other hand, if the temperature imparted by the bags to the fluid is such that the end fraction of the fluid is at the temperature required, the primary fraction will be at an inordinately high temperature. Nothing 60 but ill effects can result in this case. When it is realized that these injections often last a period of twelve hours or more, one can readily appreciate the great variance that may exist between the temperatures of the initially and finally injected fractions of the fluid. 5

Attempts have been made to overcome this hazard to the utilization of this form of therapy by employing flasks narrower than standard to contain the fluid, the thought back of these attempts, of course, being to decrease the effective 10 heat radiating and conducting surface by use of the smaller flasks. While this does permit a trifle better heat control, it has the drawback that the flasks must be refilled during the process of injection. This, of course, increases the 45 amount of attention that must be paid to the operation and in addition, increases the danger of injecting bubbles of air with the fluid. It suffices to say that this suggestion has not met with any great success. ₂(j

It must also be remembered that these injections are seldom carried to completion by the medicos in charge of the injections. Generally the operation is begun by the physician and the completion thereof left to a nurse. It is, there- 25 fore, fundamental that the operation should omit any details which must be handled at the discretion of the nurse, for the members of this profession are of varying degrees of intelligence and consequently the safest course to pursue in ₃₀leaving matters of prime importance in their hands is to reduce the chance of error to a minimum.

It can be appreciated from this that this particular art is in crying need of some simple struc- 35 ture which will permit of a substantially automatic temperature regulation of the fluid to be inducted into the body and which is at the same time inexpensive and practically fool-proof. The device according to this invention has for its object the attainment of these ends.

An embodiment of this device is disclosed in the accompanying drawing according to which:—

Fig. 1 is a front elevation of my construction.

Fig. 2 is a cross-section on line 2—2 of Fig. 1, ₄₅and

Fig. 3 is a detail view of another modification of my temperature measuring device.

On the drawing:

My device, as depicted in Fig. 1, comprises the ₅₀usual standard fluid containing flask 1, an injection nozzle shown on the drawing as a conventional infusion needle 2, and a tube construction indicated generally at 6 for transporting the fluid from flask 1 to the infusion needle 2 at the tem- 55 perature desired for the injection.

The tube construction 6, as shown more clearly in Fig. 2, comprises an inner flexible tube 7 of rubber which serves to convey the fluid to the infusion needle 2. Said tube 7 is heated by means 60

1,995,302 of an insulated electric resistance wire 9 spirallywound about the outer surface of the tube. Current is supplied to the resistance wire by means of leads 14.

Injections such as, are contemplated according to this invention are rarely effected by the conduction to the patient of a uniform quantity of fluid per unit of time. On the contrary, it is the general practice to considerably vary the rate of 10 flow of the fluid during the injection. Now I have found that if the fluid in question be heated by passing it through a tube heated, by a resistance wire uniformly wound about the tube throughout its length, it is a practical impossi15 bility to obtain a satisfactory control of the temperature. of the fluid: at the point of injection, throughout the operation. This is due to the fact that in such an arrangement the initial current must be correlated with the initial rate of 20 flow of the fluid so that sufficient heat is imparted to. the fluid in its progress through, the tube to give, the fluid at its outlet from the tube the temperature desired. Now as previously explained, operations of this kind are not as a gen25 era! thing carried out with the same rate of flow of. the fluid during the entire course of the operation. Consequently as soon as the rate of flow of the fluid is modified, either too little or too much heat is supplied to the fluid. To compen30 sate for the altered rate of flow it is therefore necessary to co-ordinate the current supply with the new rate of. flow. This action must be taken each time the rate of flow is altered making it practically impossible to secure any careful reg35, ulation of the final temperature of the fluid.

This objection is overcome in my device by winding the resistance wire 9 about the conducting, tube 7 so that the spirals of the wire.are more concentrated at the upper end than at the lower 40j end. of the tube. A greater amount of heat is therefore supplied to the upper end of the tube, which, acts to raise the incoming fluid to substantially the temperature required. The winding at the lower end of the tube then functions to main45. tain the desired temperature or to supply the small amount of heat required to give the desired temperature.

With tubes bearing heating coils wound in this way, instead of uniformly over the length of the 50 tube, the high differential of temperature between the incoming fluid and the. upper part of the coil results in a material elevation of the temperature of the fluid. This action obviously takes place regardless of any alteration in the rate of 55 flow of. the fluid. Passage of the initially heated fluid through the cooler part of the tube then results in an adjustment of the temperature of the fluid to that desired. There is therefore no need with this arrangement to- continuously vary 60 the current to compensate for variations in the rate of flow of the fluid.

The tube 7 and its encircling resistance wire 9 is housed in. a close fitting sheathing 8 of a pliable heat insulation, such as asbestos or the like.

Due to the fact that rubber is to some extent a heat insulator, if the coil 9 were not surrounded by a medium of high heat insulation, the bulk of the heat from the coil would be radiated and conducted to the outer air instead of to the fluid 70 in the tube 7. This objectionable action is obviated by the sheathing 8 which prevents loss of heat to the surrounding air by concentrating it about the conducting tube.

The insulation 8 is, in turn, housed in a pro75 tecting flexible, tube 8α, preferably of pure rubber. In order to obviate any access of a foreign medium, such as water, to the resistance wire 9, the joints between the outer tube 8α and the inner tube 7 at the ends of tube 8α are formed by sealing the ends of said: tube 8α to the inner 5 tube. No water can therefore seep into the interior of the tube construction 6 through the union of the inner and outer tubes during the sterilization of the tube construction 6.

The upper end of tube 7 is secured to the flask 10 1: through a short piece of rubber tubing 15 and a conventional sight or Murphy glass 4. The rate of flow of the fluid from the flask 1 to the tube 7 is regulated by a pinch cock 3 of conventional construction applied to the tubing 15. 15 This method of uniting the tube 7 with flask 1 is conventional in the art. Hence the elements involved may be replaced by others of similar construction.

It is of course imperative, as previously pointed 20 out, when using a device like the present, to be absolutely sure that the fluid injected by. virtue of the needle. 2 into a human system is at a proper predetermined temperature. In order to ascertain the temperature of the fluid as it enters the 25 needle 2 and thereby provide a positive check upon the. temperature of the. fluid, I find it preferable to insert between the end of the tube 7 and the inlet of the needle 2 a temperature measuring element 10c. This element comprises a metallic 30 casing 10 having an enlarged central portion 10α defining a fluid chamber 12. Tapering connecting members 11 and 12α are formed on the ends of said central portion, said connecting members being provided with inlet and outlet 35; ports 16 and. 17. The walls of said, ports are flared toward the central chamber 12 to facilitate the ingress of fluid to and egress of fluid from said chamber.

The upper or top wall 13α of the casing is pro- 40 vided with a vertical tubular element 13, the walls of. which are extended inwardly and downwardly through the chamber 12 to a point adjacent the bottom wall 13b of said casing to form a socket 30. Said, socket constitutes a well for the recep- 45. tion of a thermometer (not shown).

It will be. apparent that with this construction the fluid entering the chamber 12 via inlet port 16. circulates about said well 30. Inasmuch as the casing 10 is formed of a metal of very high 50; heat conductivity, such as, aluminum, the temperature of the fluid in the chamber 12 is almost immediately imparted to the walls of. the thermometer well. A reading of the thermometer in the thermometer well 30 thus gives an accu- 55 rate indication of. the temperature of the. fluid just prior to its passage into the needle 2.

The temperature measuring device just described: permits a rather careful determination of the temperature of the fluid just before it 60 progresses, to the needle 2. I find it expedient, however, in order to render my device absolutely fool-proof to provide, in conjunction with the temperature measuring element 10c a thermostatic current control 5. Said.current control s 65 comprises a. heat insulated casing 20 having a passage 21 therethrough adjacent the lower end thereof for. the reception, of the tube construction 6 upon which the casing 20 is located, within the casing 20 is a switch member indicated gen- 70 erally by the reference numeral 22; one-half of, which is composed of a spring controlled arm 23, bearing an electrical contact 24. The other half of the switch member 22 is made up of a thermostatic element 25. bearing a contact point 26α 75

1,996,302 which is moved into and out of contact with element 24 in response to the heat developed by the current supplied to the switch element 22 by the leads 25. Said switch element 22 is, of course, 5 included in the main circuit carrying the current leads 14 and the resistance wire 9. The operation of the switch thereby regulates the current supplied to said resistance wire 9.

The switch is adjusted to a certain predeter10 mined temperature by means of a screw 26 which operates against one end of the lever 23 in such a way that by inward movement of the screw 26 said end of the lever is depressed while outward movement of the screw 24 permits elevation of 15 said end of the lever. The screw 26 carries a headed member 27, the base of which is provided with an indicating marker not shown. The base of the headed member 27 moves over a temperature graduated disc 28. By rotating the headed 20 member 27 so that the marker thereon corresponds to a certain temperature on the graduated disc, the switch member 22 is adjusted to permit current flow while the temperature does not exceed that indicated on the disc and to break 25 the circuit as soon as the temperature exceeds the indicated temperature.

A careful regulation of the temperature of the fluid is made possible with this thermostat arrangement even though the thermostat is posi30 tioned outside of and about the tube arrangement 6. This is due to the housing of the thermostat in the heat insulated space defined by casing 20. Manifestly after the device has been operating for a short time the temperature of said space 35 will be substantially that of the fluid traversing the conducting tube 7. Consequently making the thermostat responsive to the temperature of said space is in effect the same as making the thermostat responsive to the temperature of the 40 ^fluid·

Fig. 3 discloses a slightly modified form of temperature regulating device 10c. The end 40 of the casing 10, adjacent the needle 2, is according to this modification, constructed to resemble 45 the conventional Luer adapter by making said end cylindrical in shape and providing it with a slight taper. Said end 40 may then be inserted directly into the hub 41 of an ordinary Luer needle 2 and upon being rotated in said hub, may 50 be, by virtue of the taper given thereto frictionally engaged with said hub. This modification does away with the adapter 31 and tubing 30 of Fig. 1. The heat which is ordinarily dissipated by the passage of the fluid through said tubing 55 and adapter is thereby conserved.

It can be appreciated that my device, though exceedingly simple in construction, absolutely ensures the transmission of the desired fluid to the needle 2 at the necessary temperature for 60 the operation. The device is therefore manifestly a decided improvement upon the apparatus now employed for this purpose.

It is to be understood that while I have described a preferred modification of my inven65 tion, I do not intend to be limited to this exact construction since various modifications of my device will make themselves manifest to persons skilled in this particular art.