Fluid warming system and technique for using the same
View Patent ↗A fluid warming device for warming medical fluids, such as intravenously administered blood or saline solutions, is provided. The fluid warming device includes a conduit at least partially formed from a material with positive temperature coefficient properties. A supply of blood or other fluids may pass through the device and be heated to temperatures appropriate for administration to a patient.
1. An apparatus comprising:
a flexible conduit for transferring a medical fluid, wherein the conduit comprises at least one portion configured to heat the medical fluid to approximately body temperature via a positive temperature coefficient material disposed in-line along the length of the conduit, wherein the positive temperature coefficient material comprises a temperature self-regulating polymer or a resin; and
at least one electrically conductive element disposed in or adjacent to the positive temperature coefficient material, wherein when the electrically conductive element conducts electricity, a temperature of the positive temperature coefficient material increases until body temperature is reached.
2. The apparatus of claim 1 , wherein the positive temperature coefficient material comprises polyethylene, polyvinyl chloride, polyester, polyurethane, polyimide, silicon or epoxy resins.
3. The apparatus of claim 2 , wherein the positive temperature coefficient material comprises a resin.
4. The apparatus of claim 1 , wherein the positive temperature coefficient material has a switching temperature from about 30° C. to about 45° C.
5. The apparatus of claim 1 , wherein the positive temperature coefficient material conducts substantially no current at temperatures greater than at least 50° C.
6. The apparatus of claim 1 , wherein the positive temperature coefficient material comprises electrically conductive particles, fibers, or a combination thereof.
7. The apparatus of claim 1 , wherein the positive temperature coefficient material comprises carbon, coated carbon, graphite, coated graphite, metal alloy, or ceramic.
8. The apparatus of claim 7 , wherein the carbon comprises carbon black.
9. The apparatus of claim 1 , wherein the conduit comprises an annulus diameter measured from the outermost wall ranging from 0.005 inches to 0.5 inches.
10. The apparatus of claim 1 , wherein the positive temperature coefficient material comprises electrically conductive bodies in the concentration of at least 0.5% by weight.
11. The apparatus of claim 1 , wherein the electrically conductive element comprises at least one electrically conductive bus wire, bus bar or bus wrap.
12. The apparatus of claim 11 , wherein the positive temperature coefficient material is extruded over the electrically conductive bus wire or bus bar.
13. The apparatus of claim 11 , wherein the bus wrap is disposed on the positive temperature coefficient material.
14. The apparatus of claim 1 , wherein the conduit is configured so that positive temperature coefficient material forms a lumen.
15. The apparatus of claim 1 , wherein the conduit is configured so that positive temperature coefficient material forms a substantially rod-shaped structure.
16. The apparatus of claim 1 , wherein the conduit is configured so that positive temperature coefficient material forms a planar structure.
17. The apparatus of claim 1 , comprising at least one insulating layer.
18. The apparatus of claim 17 , wherein the insulating layer is extruded over the positive temperature coefficient material.
19. The apparatus of claim 17 , wherein the insulating layer is co-extruded with the positive temperature coefficient material.
20. The apparatus of claim 1 , wherein the medical fluid comprises whole blood, serum, plasma, a blood substitute, electrolytes, or a therapeutic compound.
21. The apparatus of claim 1 , wherein the apparatus does not comprise a temperature sensor.
22. The apparatus of claim 1 , wherein the fluid is visible through at least a portion of the conduit.
23. The apparatus of claim 1 , wherein the positive temperature coefficient material divides the conduit into multiple passageways for the medical fluid.
24. The apparatus of claim 1 , wherein the positive temperature coefficient material is disposed along a center axis of the conduit.