US 3485245 A
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Description (OCR text may contain errors)
Dec. 23, 1969 R LAHR ETAL 3.485,245
PORTABLE FLUID HEATER Filed June 21, 1967 T 2 Sheets-Sheet 1 INVENTORS.
ROY J. LAHR ARTHUR L. NIX, JR. HERBERT I. TERWILLIGER ATTORNEY.
2 Sheets-Sheet 2 R. J. LAHR ETAI- PORTABLE FLUID HEATER In N Dec. 23, 1969 Filed June 21, 1967 United States Patent O 3,485,245 PORTABLE FLUID HEATER Roy J. Lahr, Penfield, N.Y., and Arthur L. Mix, Jr., and Herbert W. Terwilliger, Lexington, Ky., assignors to International Business Machines Corporation, Armonk, N.Y., a corporation of New York Filed June 21, 1967, Ser. No. 647,814 Int. Cl. A61j 1/00; F28f 7/00; A6lf 7/00 US. Cl. 128-272 Claims ABSTRACT OF THE DISCLOSURE An apparatus for heating fluids to the correct body temperature prior to their intravenous injection. The fluid flows from its cold storage container through tubing to a sterile, disposable, heat conductive, fluid impervious pouch, and from the pouch through tubing to the patient. The pouch is clamped within conduit defining heating platens which heat the fluid as it passes through the pouch in a defined path. Temperature sensing means located in the heating unit and an automatic control device insure the correct fluid temperature. When the injection is complete, the pouch is removed from the heating platens and a new pouch installed for subsequent operation.
BRIEF BACKGROUND OF THE INVENTION Field This invention relates to an improved fluid heater for heating fluid for intravenous injection, and more particularly to a fluid heater which can rapidly heat a fluid from its cold storage temperature to a temperature compatible with human injection and which can be thereafter utilized for another patient with a minimum of delay.
Description of prior art The present fluid heater is designed for use in field situations where blood transfusions are necessary on an unpredictable schedule and where the blood transfusion must be administered as quickly as possible.
Blood plasma is generally stored in cold storage at about 40 degrees Fahrenheit. In order to inject blood plasma into a human, it is necessary to heat the blood plasma from its cold storage temperature to 95 to 100 degrees Fahrenheit (the approximate body temperature of the human). The prior are fluid heaters fall into two general categories. One type of fluid heater heats the entire volume of fluid to be administered to the patient. In its most elemental form, this type of fluid heater comprises a kettle ofwater maintained at a fixed temperature in which is dropped a sealed container containing the fluid to be administered. The sealed container can be a bottle,'plastic bag, or other well known blood storage device. More sophisticated devices utilize electrical heating elements which are adapted to surround the fluid containing memher and temperature sensing devices to determine when the fluid has reached the cor-rect temperature. In either instance, it is necessary to heat the entire volume of fluid to be administered to the correct temperature prior to its administration. While such fluid warmers are satisfactory in non-emergency situations where it has been previously determined that the fluid will be required, they are not readily adaptable to emergencies or unpredictable situations where itis necessary to administer the fluid as quick- 1y as possible. v i
The second prior art approach is to heat the fluid as it is being utilized. Devices which accomplish this generally comprise elongated tubular members through which the fluid flows. Surrounding the tubular member are heating elements and temperature sensing devices which cause the fluid flowing through the tubular member to be heated 3,485,245 Patented Dec. 23, 1969 to the correct temperature at its exit point whereupon it is applied to the patient. While such devices prove satisfactory for emergency situations, they are not readily adaptable for reuse. In order to reuse such a device, it is necessary to insure that all of the fluid from a previous intravenous injection has been removed from the tubular member prior to introducing the fluid to be injected into a second patient. It is also necessary to insure that the tubing and containers are sterile. Thus, once such a device has been utilized, it may not again be reused until it has been thoroughly cleansed. Such devices are not practical where it is necessary to treat a plurality of patients within a short time period.
SUMMARY In order to overcome the above problems of prior art and to provide a portable fluid heater which can rapidly heat fluid from its cold storage condition to a temperature compatible with human injection and which can be reutilized for a plurality of patients without necessitating cleansing or sterilizing procedures, the fluid heater of the present invention is provided with a novel, sterile, disposable, fluid impervious heat conductive pouch which is clamped within a conduit defining heating member.
The fluid to be administered is introduced into the pouch from the cold storage container through a disposable sterile tube which is inserted into the pouch. The conduit defining heating member causes the fluid to pass through the pouch in a predetermined path to an exit point. As the fluid passes through the pouch, it is heated by the conduit defining heating member to be at the correct temperature when it exits from the pouch. Since it is necessary that the fluid be at the correct temperature only at the exit point, it is unnecessary to first heat the entire volume of fluid in the pouch to the correct temperature prior to injecting the fluid. A second disposable tube is inserted into the pouch at the exit point and serves to connect the pouch with the patient.
When the injection is complete, the pouch and the tubing are disposed of, a new pouch is inserted into the conduit defining heating member, and the portable fluid heater is then ready to be reused.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of the preferred embodiment of the invention as illustrated in-the accompanying drawings.
In the drawings:
FIGURE 1 is a top perspective view of the portable fluid heater.
FIGURE 2 is a cross-sectional side view of the fluid heater of FIGURE 1 showing a conduit forming heating platen.
FIGURE 3 is a side view of the disposable pouch and its associated tubing as it would appear when filled with fluid andlocated between the conduit forming members of the heater of FIGURE 1.
FIGURE 4 is an exaggerated partial cross-sectional viewof the disposable pouch of FIGURE 3.
FIGURE 5 is a schematic diagram of an electronic automatic control device which can be utilized to insure that the fluid reaches the correct temperature for injec tion.
The portable fluid heater of the present invention consists of two parts, a permanent heating unit and a disposable pouch. The pouch is adapted to fit within the heating unit and contain the fluid. The heating unit heats the fluid in the pouch and additionally, defines the path which the fluid takes through the pouch. Referring now to FIGURE 1, there is shown a top perspective view partially in section of the heating unit. The heating unit .11 is shown as a box-like structure having a front panel 13, side panels 15 and 17, a back panel (not shown), a bottom panel (not shown) and top panels 19 3 and 21. The panels are joined to one another by fasteners 23. Joined to the heating unit 11 is a structure 25 which contains the electrical circuits necessary to regulate the fluid heating.
Adjustable clamping screws 27 and 29 are threadably mounted through the front panel 13 and engage a movable wall 31. Rotation of the clamping screws causes the movable wall 31 to move in a direction perpendicular to the front panel 13. The movable wall 31 has four heating elements 32-33 mounted thereon. Spacing members 35 and 37 are fixedly attached to the two heating elements 32 and to a conduit forming member 39. Movement of the movable wall 31 thus results in corresponding movement of the heating elements 32 and 33, spacing the members 35 and 37, and the conduit forming member 39. In addition to forming a mechanical connection, the spacing members 35 and 37 cause the conduit forming member 39 to be spaced away from the heating elements 32 and 33 to insure an even distribution of heat in the conduit forming member which is made of a heat conducting material such as aluminum.
A complementary conduit forming member 41 is mounted in a similar manner to a spacing member 43 and to a spacing member not shown. The spacing members are mounted to heating elements 45 which along with heating elements 46 are fixedly mounted to a stationary wall47.
The conduit forming member 41 has located therein a continuous channel 51-53 which has been hollowed out of the solid member. The conduit forming member 39 has a complementary continuous channel 55-57 located therein. Referring now to FIGURE 2, a cross-sectional side elevation view along lines 2-2 of FIGURE 1 shows the conduit forming member 41 resting upon the bottom panel 60. As can be seen, the elongated channel 51-53 is continuous and winds throughout the conduit forming member. Channel 55-57 of the conduit forming member 39 shown in FIGURE 1 is the mirror image of the channel 51-53 and it complements the channel 51-53 to form a conduit which is oval or circular in cross section when the two conduit forming members are brought together.
Referring once again to FIGURE 1, the heating unit 11 is depicted as being of relatively rugged construction in order to facilitate a field use such as battlefield use. The outer panels 13, 15, 17, 19, 21, 60 (FIGURE 2) and the back panel (not shown) of the heating unit 11 can be made of a durable material, such as, for example, rolled steel. The movable wall 31 and the stationary wall 47 can also be made of the same material. The spacing members 35, 37, and 43 are preferably made of a heat resistant insulating material such as asbestos while the conduit forming members 39 and 41 are made of a heat conducting material such as aluminum. The heating elements are commercially available electrical resistance heating units.
In operation, the adjustable clamping screws 27 and 29 are rotated in a direction to cause their movement to be away from front panel .13. Since the clamping screws are attached to the movable wall 31, withdrawal of the clamping screws causes the movable wall 31 and the forming member 39 which is mechanically coupled thereto to move toward the front panel 13 and away from the conduit forming member 41.
The resulting separation of the conduit forming members 39 and 41 leaves a void in which a pouch filled with fluid (see FIGURES 3 and 4) is inserted. The top plates 19 and 21 are separated by a sufficient distance to allow the pouch to be inserted therebetween. Once the pouch is so located between the conduit forming members 39 and 41, the adjustable clamping screws 27 and 29 are tightened down causing the movable wall 31 and conduit forming member 39 to move toward the conduit forming member 41. Movement of the conduit forming member 39 traps, clamps, and embraces the pouch be- 4 tween the conduit forming members and causes the fluid located within the pouch to conform to the shape of the conduit thus formed.
Referring now to FIGURES 3 and 4, a pouch 61 is shown as it would appear when clamped between the two conduit forming members ofjFl GURE l. The pouch 61 is made of a thin (2 mils nominal) metal foil layer 63, the inner surface of which is coated with a thin plastic coating 65 which is compatible with the temporary storage of blood. The metal foil 63 utilized should have good heat transfer characteristics and be flexible while the plastic coating 65 must be thin enough so that the pouch has superior heat transfer characteristics, For example, the metal foil could be aluminum foil and the plastic coating could be polyethylene.
Two rubber-like plugs 67 and 69, similar to those utilized on medical vaccine bottles, are inserted into the uppermost surface 71 of the pouch 61 and serve as connector points which define the entrance and exit ports of the pouch. When ready for use, hollow needles 73 associated with sterile tubing 75, 77 may be inserted into the rubber-like plugs 67, 69. Thereafter, fluid can flow from a supply (not shown) through tubing 75 to the pouch 61, then through tubing 77 to the patient (not shown). The path that the fluid takes through the pouch is determined by the conduit forming members of FIG- URE 1 and is denoted as conduit 79-81 in FIGURE 3.
When manufactured, the interior plastic coating of the pouch is sterilized and all edges of the pouch except uppermost surface 71 are heat sealed. A measured quantity of sterile fluid 83 such as saline water, glucose water solution, or other human blood compatible fluid is inserted into the pouch through the opening in uppermost surface 71. The rubber-like plugs 67, 69 are then put in place and the uppermost surface 71 is sealed. The fluid 83 serves to hold the pouch 61 in shape and forces the pouch to conform with the channeled surfaces of the conduit forming members when placed in use. The fluid excludes air from the pouch and can also be utilized when the pouch is placed in use to remove air from the connector tubing 75, 77.
Referring once again to FIGURE 1, the heating elements 32, 33, 45 and 46 must be supplied with a suflicient amount of electrical energy to heat the fluid to its proper temperature. The amount of electrical energy supplied depends upon the rate of flow of the fluid, upon the efficiency and heat transfer characteristics of the device, and upon the cold storage temperature of the fluid. Assuming a flow rate of /2 pint of fluid per minute, a 50% heat transfer efficiency, a fluidinput temperature of 5 C. and a fluid exit temperature of 40 C., it has been found that a 1200 watt heating circuit will supply the requisite heat.
Of course, the cold storage temperature of the fluid and efiiciency of the device vary from situation to situation thereby necessitating an automatic control device to regulate the heat dissipated by the heating elements and to thereby insure that the fluid exits at the proper temperature, Many types of automatic control devices could be utilized. Structure 25 is shown for housing such a device.
In the embodiment illustrated, two temperature responsive elements 101, 103 are embedded in conduit forming member 41 (see FIGURE 2) with one preferably located near the conduit exit and the other located near the center of the conduit forming member.
Referring now to FIGURE 5, there is shown a schematic diagram of an electronic automatic control device utilized to regulate the amount of heat imparted to the fluid to be warmed. Alternating current is supplied to terminals 104 and 105. Switch 106 allows for ready operator control and fuse 107 prevents circuit overload. Load 109 represents the heating elements shown in FIGURE 1. The remaining circuitry shown in FIGURE 5 located within blocks 111 and 113 controls the amount of current available at terminals 104 and that will be utilized by the load 109. The circuitry located within block 111 is identical to that located within block 113, one block controlling the amount of current utilized during the positive half cycle of the alternating current input while the other controls the current utilized during the negative half cycle.
The circuitry in block 111, which is operative during positive half cycles to regulate the current delivered to the load 109 comprises a control transistor 115 which is turned on and off by positive and negative going pulses respectively. When the transistor 115 is on, the current flowing through its emitter gates a silicon control rectifier (SCR) 116. When the SCR 116 is on, a current path is provided through the SCR from terminal 104 through the load 109 to terminal 105 during positive half cycles. The point in time during the positive half cycle that the control transistor 115 turns on determines the length of time that current will flow through the load 109 during the positive half cycle. This in turn is determined by the voltage appearing on base electrode 117 of the transistor.
The voltage at the base electrode 117 of the transistor 115 is a function of the values of the resistor 119 and the variable resistor 121 which form a series connection from the fuse 107 to the base electrode 117 and the resistive value of the temperature responsive element 101 which is connected to the base electrode 117 to form a voltage divider network with the resistors 119 and 121.
The variable resistor 121 is set in accordance with the value of the input voltage appearing across terminals 104 and 105 and in accordance with the desired output temperature. Once this resistor is set, the voltage appearing at the base electrode 117 becomes a function of the resistive value of the temperature responsive element 101, The resistive value of the temperature responsive element decreases when its temperature increases and increases when its temperature decreases. This action causes the control transistor to conduct for a shorter time period when the temperature of the temperature responsive element 101 is relatively high and for a longer time period when the temperature is relatively low.
A thermal control 123 and a resistor 125 are connected in series and shunt the temperature responsive element 101. When the temperature of the device exceeds a predetermined maximum, the thermal control 123 closes and forms a low resistance shunt path to the temperature responsive element 101 thereby biasing the control transistor 115 out of conduction. This device thus forms a safety feature which prevents overheating in case there is a malfunction in the voltage divider network or in the temperature responsive element 101.
A capacitor 126 connected between resistor 119 and the load 109 forms an RC network with the resistor 119 to integrate the input sine wave to allow control of the SCR 116 through a high percentage of its half cycle. A diode 127 and resistors 129 and 131 connected to the collector electrode of the control transistor 115 provide a DC bias for the control transistor. A resistor 132 is connected between the emitter electrode of the transistor 115 and load 109.
The circuitry appearing in block 113 is a duplicate of that in block 111 and operates during the negative half cycles to control the amount of current supplied to the load 109. This circuitry includes temperature responsive element 103.
Typical operating values are shown in the following table:
Voltage at terminals 104, 105 117 volts AC. Resistor 119 K.
Resistor 121 10K.
Resistor 125 100 ohms. Capacitor 126 1 microfarad. Resistor 129 39 K.
Resistor 131 1K.
Resistor 132 1K. Temperature sensitive element 101 100 ohms to 1K.
It is of course recognized by those skilled in art that many such control devices could be utilized in accordance with the circumstances. In the particular embodiment shown, it has been assumed that an AC supply of approximately 117 volts is available. A control circuit responsive to DC voltages could also be utilized.
Further, the mechanical construction of the heating unit can be Widely varied. For example, the heating platens could be hingedly connected and operate in the manner that a waflle iron does. Also, the pouch could partially extend from the confines of the heating platens.
While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it should be understood by those skilled in the art thatthe foregoing and other changes in form and detail may be made therein without departing from the scope of 'the invention.
What is claimed is:
' 1. A fluid heater comprising:
a fluid impervious flexible pouch having an entrance port and an exit port, the interior of said pouch being compatible with the temporary storage of blood, the exterior of said pouch having good heat transfer characteristics;
a first conduit forming member having an elongated channel located Within one surface thereof;
a second conduit forming member for cooperatively embracing said fluid impervious pouch between said second conduit forming member and said first conduit forming member to effect the formation within said pouch of a continuous conduit leading from said entrance port to said exit port;
heating means for heating the pouch so embraced between said conduit forming members.
2. The portable fluid heater set forth in claim 1 wherein said first and second conduit forming members are made of heat conductive material and wherein said heating means heats said first and said second conduit forming members to thereby heat said pouch.
3. The fluid heater set forth in claim 1 further comprising:
temperature sensing means located closely adjacent to said pouch for indicating the temperature of said pouch;
control means responsive to said temperature sensing means to control the amount of heat supplied by said heating means.
4. The fluid heater set forth in claim 3 wherein said second conduit forming member having a second elongated channel located within one surface thereof adapted to cooperate with the elongated channel of said first conduit forming member to embrace said pouch and form a continuous channel within said pouch leading from said entrance port to said exit port.
5. The fluid heater set forth in claim 4 wherein said second conduit forming member is adapted to cooperatively embrace the entire pouch between the first conduit forming member and the second conduit forming member.
References Cited UNITED STATES PATENTS 1,995,302 3/1935 Goldstein 128254 XR 2,760,630 8/ 1956 Lakso.
3,042,086 7/ 1962 Winchell 128214 XR 3,140,716 7/1964 Harrison et al. 128214 XR 3,158,283 11/ 1964 Rinfret et a1 220-64 3,293,868 12/1966 Gonzalez 46 XR 3,370,153 2/1968 Du Fresne et al. 128214 XR 3,411,630 11/1968 Alwall et al. 210-321 RICHARD A. GAUDET, Primary Examiner M. F. MAJESTIC, Assistant Examiner US. Cl. X.R.