METHOD OF SEQUENTIAL INTRAVENOUS INFUSION OF MULTIPLE FLUIDS

Abstract: A method for sequential intravenous administration of fluid solutions. The method provides for administering a first fluid solution (12) through a catheter tube (20) followed by the contiguous administration of a predetermined amount of spacer solution (10). The spacer solution (10) is then contiguously followed by a second solution (14). The amount of spacer solution (10) used between fluid solutions (12, 14) should be large enough to substantially prevent the first and second fluid solutions (12, 14) from mixing.

Description: METHOD OF SEQUENTIAL INTRAVENOUS INFUSION OF MULTIPLE FLUIDS Background of the Invention This invention relates to the intravenous administration of multiple fluids. There are many medical applications for which an intravenous infusion for a multiplicity of fluid solutions can be beneficial. One such application is chemotherapy infusions used in cancer treatment. This was recognized in the recent 13th Annual Cancer Course, given March 1-3, 1984, by the Harvard Medical School and New England Deaconess Hospital. In the syllabus article entitled "Multi-Drug Infusion Chemotherapy: the Delivery of Two or More Drugs Simultaneously", Dr. Jacob J. Lokich described techniques for mixing drug solutions to form a combination which can be delivered to a patient by continuous intravenous infusion. The use of combination multi-drug chemotherapy has been developing in medicine since the 1960's. It has been used for such diseases as acute leukemia, Hodgkins disease, lung cancer, breast cancer and ovarian cancer. Unfortunately, there are only a limited number of drug combinations which have been found to be compatible and stable and which can produce a synergistic effect when administered. There are many drugs which may not be used simultaneously because of reactions between the drugs which make infusion impracticable or undesirable. Some drugs react and thereby neutralize one another. Other drugs react to form precipitates which may clog the catheter tubing or even worse cause an embolism in the patient. Thus, according to present multi-drug combination treatments, physicians are limited in their choice of drug solutions. Summary of the Invention This invention is directed to a method for sequential intravenous administration of fluid solutions. The method provides for administering a first fluid solution through a catheter tube followed by the contiguous administration of a predetermined amount of spacer solution. The spacer solution is then contiguously followed by a second fluid solution. The amount of spacer solution which would be used between fluid solutions would be prescribed by the physician and should be large enough to prevent the first and second fluid solutions from substantially mixing. The method of the present invention enormously increases the number of variations available to physicians for treating cancer and other diseases with multiple drug infusions. Since the intravenous spacer solution prevents the drug solutions from substantially mixing with one another before entering the body, drug solutions which were formerly incompatible because of deleterious reactions may now be tried as potentially beneficial treatments. Once a drug solution is infused into the patient the blood stream carries :' the drug away so quickly that it is usually safe to follow the drug solution with another solution after the spacer. By sequentially alternating between drug solutions and spacer solutions many new multiple drug treatments may be developed. Other objects and advantages of the invention will become apparent during the following description of the presently preferred embodiments of the invention taken in conjunction with the drawings. Brief Description of the Drawings FIG. 1 is an elevational view of an apparatus for performing the method of the present invention. FIG. 2 is a sectional view of the catheter tube of FIG. 1 demonstrating the method of the present invention. FIG. 3 is a cross-sectional view of the catheter tube of FIG. 1 after the spacer solution has been pumped through a length of catheter tubing. FIG. 4 is an elevational view of a peristaltic pump for use in the method of the present invention. FIG. 5 is an elevational view of a syringe-type cartridge pump for use in the method of the present invention. Detailed Description of the Preferred Embodiments Turning now to the drawings, FIG. 1 illustrates an apparatus for performing the method of the present invention. The apparatus is described in the inventors 1 copending application U.S. Serial No. 619,847, entitled "Apparatus and Method for Administering Multiple Fluid Infusions", sharing the same filing date and assignee as the present invention. The inventors' copending application is hereby incorporated by reference herein. Their apparatus enables one to switch between different fluid solutions being intravenously administered through a catheter tube without allowing any air bubbles to enter into the line. A valve receives inputs from a plurality of fluid solution sources and has a primary input for a spacer solution 10 source. The valve switches between sources to alternately provide one of the fluid solutions and the ./ ■ *-/ -w spacer solution 10. According to the method of the present invention, the spacer solution 10 is provided for substantially isolating the different fluid solutions during intravenous administration. FIG. 2 shows a first solution 12 and a second solution 14 separated by the spacer solution 10. The solutions are carried by a catheter tube 20 through a needle and into a patient. Pump P keeps the fluids moving through the catheter tube 20 at a predetermined rate. The spacer solution 10 must be a solution which is suitable for intravenous infusion into a patient. The spacer 10 must also be neutral with respect to each of the fluid solutions on either side of it. In other words, the spacer solution 10 must not substantially react with either the first fluid solution 12 or the second fluid solution 14 while it is traveling through the catheter tube 20 into the patient. Some solutions may react with one another over a long period of time, however, it is only necessary that there be no adverse reactions prior to the infusion. There are a number of intravenous solutions which may be selected as the neutral spacer 10, including but not limited to saline solutions, dextrose solutions and intravenous lipid solutions. The appropriate spacer solution 10 should be selected according to a patient's needs. For example, a patient requiring nutritional supplement may receive a high concentration dextrose solution as the spacer, whereas a patient merely requiring liquids may receive a saline solution or a low concentration dextrose solution. The volume of the spacer solution 10 affects the rate of mixing between the fluid solutions on adjoining sides of the spacer. A spacer with a low volume would have a tendency to allow the adjoining fluids to diffuse more quickly into each other. On the other hand, a spacer with a larger volume would decelerate the rate of diffusion of adjoining drug solutions into each other. The volume of the spacer solution must be selected so as to avoid substantial mixing between the fluid solutions on either side of the spacer solution 10 in the time that the solutions are in transit within the catheter tube 20. If the diffusion rate between a fluid solution and the spacer solution 10 is rapid, the spacer solution 10 must have a greater volume to avoid mixing of the two isolated fluid solutions. Some insubstantial mixing may be allowed where the first drug solution 12 and the second drug solution 14 are relatively compatible with one another and will not react when in contact to a small extent. For more highly reactive fluid solutions, any amount of mixing would be substantial and must be prevented. Thus, the appropriate volume of spacer 10 depends on a variety of factors. Because of laminar flow which occurs during the movement of fluids through the catheter tube 20, the type of pump being used will also be determinative of the minimum volume of spacer solution 10 required to separate the first and second fluid solutions. Referring now to FIG. 3, the affects of laminar flow of fluids as they travel through the catheter tube 20 is shown. There is friction between the walls of the catheter tube 20 and the fluids which are flowing through it. This friction slows the outer layers of fluid. Thus, the fastest flowing fluid is found along the center axis of the catheter tube 20. Over a period of travel through the tube the spacer solution 10 develops a convex pointed front sided and a concave indented rear side. The volume of spacer solution 10 must be prescribed to be large enough so that the rear edge of the first fluid solution 12 does not substantially overlap the leading front point of fluid solution 14. A cross-section showing such an overlap is illustrated in FIG. 3 at cross-section 16. A peristaltic pump 30, illustrated in FIG. 4, operates by squeezing the catheter tube 20. If there is a cross-section 16 including the first and second fluid solutions as they reach the peristaltic pump 30, upon being squeezed by pump 30 the two solutions would be in direct contact as a result of the pump action. Therefore, it is important that when using a peristaltic pump 30 that there be a cross-section 17 maximally filled with spacer solution 10 as the spacer solution reaches the peristaltic pump 30. A syringe-type cartridge pump 40, also known as volumetric pump, illustrated in FIG. 5 works in a different manner. The cartridge pump 40 operates by filling and emptying a chamber 42. A valve 44 rotates to switch between a filling and an emptying position. To prevent substantial mixing between fluid solution 12 and second fluid solution 14, it is again necessary to prescribe a sufficient volume of spacer solution 10 to substantially isolate the two fluid solutions. To " accomplish this, the spacer solution 10 should encompass a volume which fills a cylindrical cross-section 19 of the tube which is equal to or greater than the volume of the chamber 42. Thus, the pump chamber 42 will be prevented from substantially filling with more than one of the fluid solutions separated by the spacer 10. The treatment variations made possible by the method of the present invention are numerous. Various drugs, nutrients, electrolytes or other items capable of being delivered in fluid solutions may be sequentially infused into a patient according to the present invention. The number of fluid solutions which may be sequentially infused into a patient are only limited by the ability to connect the solutions by valves to a catheter tube in a manner which continuously administers fluids without allowing any air bubbles into the line. The compatibility and stability of the various fluid solutions with one another are now of less importance. Almost any drug solution which can produce synergistic effects when used in combination, may be infused according to the method of the present invention. By frequently alternating between fluid solutions and spacer, several drug solutions can be administered to a patient in sequence over and over again without the problem of substantial mixing prior to infusion. The patient is thus able to obtain many benefits which may derive from the combination of a plurality of drug solutions. Many new drug solution combinations will be made possible through the use of the present invention. Of course, it should be understood that various changes and modifications to the preferred embodiments described above will be apparent to those skilled in the art. Any intravenous solution which does not react with adjoining fluid solutions may be substituted for the saline, dextrose and lipid solutions of the present invention. These and other changes can be made without departing from the spirit and the scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be covered by the following claims.

Claims: WE CLAIM: 1. A method for sequential intravenous administration of a first and second fluid solution, said method comprising: providing a catheter tube connected to a needle for intravenous administration of fluid solutions; administering a first fluid solution intravenously through said catheter tube; contiguously following said first solution with a predetermined amount of intravenous spacer solution through said catheter tube; and contiguously following said neutral spacer solution with a second fluid solution said predetermined amount of said intravenous spacer solution being large enough to prevent said first fluid solution and said second fluid solution from substantially mixing. 2. The method of Claim 1 further comprising a peristaltic pump coupled to said catheter tube for pumping fluids through said tube, said predetermined amount of said spacer solution being large enough so that said spacer solution substantially fills a cross-section of said catheter tube between said first fluid solution and said second fluid solution at said peristaltic pump. 3. The method of Claim 1 further comprising a syringe-type cartridge pump, having a pumping chamber, coupled to said catheter tube for pumping fluids through said tube, said predetermined amount of spacer solution being large enough so that when said spacer solution reaches said pumping chamber, said spacer solution fills a cylindrical cross-section of said tube having a volume which exceeds the volume held by said pumping chamber. 4. The method of Claim 1 wherein said spacer solution does not substantially react with said first or said second solution while they are travelling through said catheter tube. 5. The method of Claim 4 wherein said spacer solution comprises saline solution. 6. The method of Claim 4 wherein said spacer solution comprises a dextrose solution. 7. The method of Claim 4 wherein said spacer solution comprises an intravenous lipid solution. 8. A method for sequential intravenous administration of a plurality of fluid solutions, said method comprising: providing a catheter tube connected to a needle for intravenous administration of a plurality of fluid solutions; and alternately administering one of said fluid solutions and a neutral spacer solution through said catheter tube, the amount of said neutral spacer solution administered between each fluid solution being large enough to prevent the fluid solutions on opposite sides of said neutral spacer solution from substantially mixing with one another. 9. The method of Claim 8 further comprising a peristaltic pump coupled to said catheter tube for pumping fluids through said tube, said amount of neutral spacer solution being such that said spacer solution maximally fills a cross-section of said tube between the fluid solutions on opposite sides of said neutral spacer solution at said peristaltic pump. 10. The method of Claim 8 further comprising an infusion syringe-type cartridge pump, having a pumping chamber, coupled to said catheter tube for pumping fluids through said tube, said amount of neutral spacer solution being such that when said neutral spacer solution reaches said cartridge pump, the volume of said tube filled in total cross-section by said neutral solution exceeds the volume of said pumping chamber. 11. The method of Claim 8 wherein said neutral spacer solution comprises a saline solution. 12. The method of Claim 8 wherein said neutral spacer solution comprises a dextrose solution. 13. The method of Claim 8 wherein said neutral spacer solution comprises an intravenous solution.

Inventors: BROWN ERIC W, TAI HENRY T, BROWN, ERIC, W., TAI, HENRY, T.
Applicants: I FLOW CORP, I-FLOW CORPORATION
Application year: 1985
Main classification: A61M5
IPC codes: A61M5