US 1995302 A
Description (OCR text may contain errors)
March 26, 1935. H, GOLDSTElN 1,995,302
ADJUSTABLE HEATING INFUSION APPARATUS Filed Nov. 24, 195s iwf A TTORNE YS.
Patented Mar. 26, 1935 ADJUSTABLE HEATING INFUSION APPARATUS Harold Goldstein, New York, N. Y.
Application November 24, 1933, Serial No. 699,552
'Ihe present invention relates to a construction for elevating and accurately maintaining the temperature of fluids prescribed by physicians for injection into the human system.
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 instance, 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 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 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 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 patient. Thus, if the fluid is too cold there is danger of a chill resulting from the injection. On the other hand, the patients system is liable to overheating, and possible blood coagulation if the temperature of the fluids is immoderately 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 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 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 temperal 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 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 aninordinately high temperature. Nothing but ill effects can result in this case. When it (Cl. 12S-254) 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.
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 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 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.
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, therefore, 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 leaving 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 structure 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, and
Fig. 3 is a detail view of another modification of my temperature measuring device.
On the drawing:
My device, as depicted in Fig. l, comprises the usual 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 temperature 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 of an insulated electric resistance wire 9 spirally wound about the outer surface of the tube. Current is supplied to the resistance wire by meansV of leads 14.
Injections such asare 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 isV the general practice to considerably vary the rate of flow of the fluid during the injection. Now I have found that if the fluid in questionbe heated by passing it through a tube heated by a resiste ance Wire uniformly wound Yabout the tube throughout its length, it is a practical impossibility 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 b e correlated with the initial rate of flow of the fluid so that sufficient heat is imparted tothe fluid in its progress through the tube to give the fluid at its outlet from the tube thetemperature desired. Now as previously eX- plained, operations of this kind are not as a general 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 ilow of; the fluid is modied, either too little or too much heat is supplied to the. fluid. To compensate for thealtered 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 regulation 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 ofthe wireare more concentrated at the upper endthan at the lower end of the tube. A greater amount of heat is therefore supplied to the upper endV of the tube, whichA acts toraisethe incoming fluid to substantially the temperature required. The winding at the lower end of the tube then functions to mainl 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 tube, the high Vdifferential, oftemperature between the incoming fluid and theupper part of the coilA results in a material elevation ofthe temperatureof the fluid. This action obviously takes place regardless of any alteration in therate of ilow ofthe 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 the current to compensate for variationsV in the rate of flow of the fluid.
The Vtube 7 and its. encircling resistance wire 9 is housed ina close fitting. sheathing 8 of a pliable heat insulation, such as asbestos or the like. Due to the factA 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 tol the fluidV Y progressesA to the needle 2.
ber. In order to obviate any access of a foreign medium, such as water, to the resistance wire 9, the joints between the outer tube 8c', and the inner tube 'l at the ends of tube 8dv are formed by sealing the ends of said tube 8c to the inner 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 1` through a'short piece of rubber tubing l5 and arconventional sight or Murphy glass 4. The rate of flow ofY the fluid from the flask 1 to the tube '7 is regulated by a pinch cock 3 of conven- Vtional construction applied to the tubing 15.
This method ofuniting the tube '7I with flask 1 is A conventional in the art. Hence the elements involved may be replaced by others of similar construction. V
It is of course imperative, as previously pointed out, when using a device like the present, to. be absolutely sure that the fluid injected by. virtue of the needle2 into a human system is at a proper predetermined temperature. In order to ascertain the temperature of the fluid as it enters the needle 2 and thereby provide a positive check upon thetemperature of thefluid, I nd it preferable to insert between the end of the tube 'Iv and the inlet of the needle 2 a temperature measuring element 10c. This element comprises a metallic casing 10 having an enlarged central lportion 10a defining a fluid chamber 12. Tapering connecting members 11 and 12a are formed on the ends of Vsaid central portion, said connecting members being provided with inlet and outlet ports 16 and. 17. The walls of said. ports are flared toward the central chamber 12 to facilitate the ingress of uid to and egress of` fluid from said chamber.
The upper or top wall13a of the casing is provided with a vertical tubular element 13, thewalls 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. SaidY socket constitutes a well for the recepitionfof 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 heat conductivity, such as, aluminum, the temperature of the fluid in the chamber 12 is almost immediately imparted to the walls ofv the thermometer well. A reading of the thermometer inthe thermometer Well 30 thus gives an accurate indication ofthe 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 temperatureVv of the fluid just. before it I nd 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, VSaidrcurrent control 5 comprises' aV heat insulated casing 20 having a 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, 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 predetermined 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 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 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 fiow while the temperature does not exceed that indicated on the disc and to break 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 positioned 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 will be substantially that of the fiuid 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 fluid.
Fig. 3 discloses a slightly modified form of temperature regulating device 10c. The end 40 of the casing l0, adjacent the needle 2, is according to this modification, constructed to resemble 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 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 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 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 modication of my invention, 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.
1. An intravenous infusion heating tube for providing and maintaining a desired temperature of fluids to be injected into the human body comprising an inner fluid conducting tube of flexible material, an insulated resistance wire spirally wound about said conducting tube, a sheath of asbestos encasing said conducting tube, a protective housing of soft rubber covering said asbestos sheathing, the ends of said protective housing being sealed to said conducting tube, a casing of a high heat conducting metal having a fluid chamber, secured to the outlet of said vconducting tube, a thermometer' well formed on said casing and projecting into said fluid chamber thereof whereby the fluids entering said chamber circulate about said well in intimate contact therewith.
2. A device as defined in claim l wherein the spirals of said resistance wire are more concentrated at the upper end of said conducting tube than at the lower end thereof, whereby the spirals at the upper end of the tube serve to elevate the temperature of the fluid in the conducting tube to substantially that desired and the spirals at the lower end of said tube serve to maintain said desired temperature.
3. An intravenous infusion heating tube for providing and maintaining a desired temperature of fluids to be injected into the human body comprising an inner flexible fluid conducting tube, an insulated resistance wire spirally wound around said conducting tube, a fiexible sheath of asbestos encasing said inner conducting tube and an outer protecting tube of soft rubber housing said asbestos sheath, the ends of said outer tube being sealed to said inner tube and a temperature device comprising a casing having an enlarged hollow central portion defining a fiuid chamber and carrying at its ends connecting members for joining said casing to thc conducting tube and to an infusion needle, said connecting members having inlet and outlet ports leading to and from said fluid chamber, the top of said casing carrying a socket defining a thermometer well extending through said fluid chamber, said casing being formed of a high heat conducting metal, whereby the heat of the fluid passing through said fluid chamber is immediately taken up by said thermometer well.
4. An intravenous infusion heating tube for providing and maintaining a desired temperature of fluids to be injected into the human body comprising an inner uid conducting tube of iiexible material, an insulated resistance Wire spirally wound about said conducting tube, the spirals of said resistance wire being more concentrated at the upper end of said conducting tube than at the lower end thereof, a sheath of asbestos encasing said conducting tube, a protective housing of soft rubber covering said asbestos sheathing, the ends of said protective housing being sealed to said conducting tube, a casing of a high heat conducting metal secured to the outlet of said conducting tube, an enlargement in said casing to hold a temperature measuring device, means mounted on said conducting tube for visually indicating the temperature desired and means for automatically controlling the desired temperature of the fluid in the tube.