CONVECTION BLOOD WARMING SYSTEM WITH DISPOSABLE FLATTENED TUBE ENVELOPE INCORPORATING PAPERBOARD “NEEDLE” FOR INSERTING ENVELOPE BETWEEN HEATING PLATES AND EMPLOYING ACTIVE AND PASSIVE INSULATION OF OUTLET FLOW PATH TO PROVIDE NORMOTHERMIC FLUID AT ZERO TO 600 MILLILITERS PER MINUTE

• US 6,608,968 B2
• Filed: 11/12/2002
• Issued: 08/19/2003
• Est. Priority Date: 11/23/2001
• Status: Active Grant

• Current Assignee: Allan P. Bakke
• Original Assignee: Allan P. Bakke
• Inventors: Bakke, Allan P
• Primary Examiner(s): CAMPBELL, THOR S
• Application Number:
  US10/292,749
• Publication Number:
  US 20030099469A1
• Time in Patent Office: 280 Days
• Field of Search: 392/470, 392/471, 604/6.13, 604/6.11, 604/6.14, 604/6.15, 604/903, 604/113, 604/153
• US Class Current: 392/470
• CPC Class Codes: A61M 2205/3633 thermally insulated
• CPC Class Codes: A61M 2205/3653 by Joule effect, i.e. electric resistance
• CPC Class Codes: A61M 5/44 having means for cooling or heating the devices or media
• CPC Class Codes: A61M 5/445 the media being heated in the reservoir, e.g. warming bloodbags
• CPC Class Codes: H05B 3/58 Heating hoses; Heating collars

Abstract

A thin, flat paperboard inserter or “needle” which is longer than the blood warmer heating plates is attached to the edge of the flattened tube envelope to enter the very narrow gap between the heating plates. The inserter is fed between the heating plates and advanced to emerge from the other end of the blood warmer where it is grasped and used to pull the envelope into operational position. A high air flow hydrophobic vent with check valve to prevent reverse flow is incorporated into the drip chamber to allow automatic priming and venting of air bubbles. A conductively heated and externally insulated drip chamber holder and a patient intravenous line that is passively insulated by a small annular air space extruded as part of the tube preserve heat in the warmed fluid, improving low flow rate performance. A reusable external heater may optionally be applied to the distal portion of the patient line to provide normothermic fluid to the patient down to essentially zero flow rate.

Claims

1. A system for warming blood or other liquids to body temperature for infusion into a patient comprising:

A.) a blood warmer apparatus having a pair of fixedly closely spaced apart heat transfer plates adapted to receive a flat heat exchanging blood warming envelope between said fixedly closely spaced apart heat transfer plates, wherein the gap between said fixedly closely spaced apart heat transfer plates is exposed at two opposite ends forming a wide slot,

B.) an inserter for positioning said flat heat exchanging blood warming envelope between said fixedly closely spaced apart heat transfer plates including,

1.) a sheet of semi-rigid material slightly thinner and narrower and longer than said wide slot formed by the gap between said fixedly closely spaced apart heat transfer plates,

2.) means for attaching said sheet of semi-rigid material to said flat heat exchanging envelope along its insertion edge,

3.) means such as perforations for tearing off or otherwise removing all but about 2 inches of said sheet of semi-rigid material after it has been used to insert and position said blood warming envelope,

4.) means such as a hole about 0.25 to 0.38 inch in diameter in the remaining approximately 2 inches of said semi-rigid material for attaching it to a post or other attaching means fixedly mounted appropriately on rear case of said blood warmer apparatus after said semi-rigid material has been used to insert and position said blood warming envelope,

whereby a person can easily insert and correctly position said flat heat exchanging blood warming envelope in said blood warming apparatus.

2. A system for warming blood or other liquids to body temperature for infusion into a patient comprising:

A.) a blood warmer apparatus having a pair of fixedly closely spaced a heat transfer plates adapted to receive a flat heat exchanging blood warming envelope between said fixedly closely spaced apart heat transfer plates, wherein the gap between said fixedly closely spaced apart heat transfer plates is exposed at two opposite ends forming a wide slot,

B.) said flat heat exchanging blood warming envelope having a blood inlet tube adapted to be connected to a source of blood to be warmed and a blood outlet tube adapted to be connected to a blood drip chamber adapted to be connected to a flow line to the patient, said drip chamber adapted to be supported inside a warmed drip chamber holder,

C.) said flow line to the patient being a flexible tube made of polyvinyl chloride or other resinous plastic material,

D.) said drip chamber holder being made of aluminum or other highly heat conductive material about 0.06 inch thick and having a flat sheet of said material about 2 to 4 inches wide and 3 to 6 inches long welded or otherwise heat conductively attached to said holder, said flat sheet being heat conductively attached by epoxy adhesive or other attaching means to the outside of one of said heat transfer plates,

E.) said drip chamber holder being coated on its outer surfaces with a layer of heat insulating material about 0.06 inch thick,

whereby blood passing slowly through said drip chamber is maintained near the temperature of said heat transfer plates and heat from blood being warmed is not lost to the ambient air by convection.

3. A system according to claim 2 wherein said drip chamber and said warmed drip chamber holder are approximately cylindrical in shape with diameters about 1 to 3 inches and heights about 2 to 5 inches.

4. A system according to claim 2 wherein the distal portion of said flexible tube flow line is removably inserted into an external heater,

A.) said external heater being comprised of an elongated flexible plastic or silicone rubber tube having a cross-section in the form of a “ C”

, with a wall thickness of approximately 0.12 inch, closely fitting around said flexible tube flow line,

B.) said external heater being heated electrically by an electrical resistance heater embedded in the wall or in an extruded elongated cavity in the wall of said external heater, extending for the full length of said heater,

C.) said electrical resistance heater being maintained at a controlled temperature of about 42C by a controller mounted inside said blood warmer apparatus,

whereby in synergistic and complementary effect with said drip chamber holder heat is preserved in the blood as it flows slowly to the patient by reducing heat loss by convection to the ambient cooler air.

5. A system according to claim 2 wherein said flexible tube flow line has a central blood-carrying tube about 0.12 inch inside diameter and a wall thickness of about 0.04 inch, and is supported inside a larger tube which is co-extruded with said central tube and has an outside diameter of about 0.37 inch and a wall thickness of about 0.04 inch, said central and outer tubes being interconnected by co-extruded webs about 0.04 inch thick which appear in cross section as a planar diametrical web across the entire cross section with the exception of said central tube'"'"'s lumen, wherein an annular space between said central and outer tubes is filled with heat insulative still air,

whereby in synergistic and complementary effect with said drip chamber holder heat is preserved in the blood as it flows slowly to the patient by reducing heat loss by convection to the ambient cooler air.

6. A system according to claim 5 wherein the distal portion of said flexible tube flow line is removably inserted into an external heater,

A.) said external heater being comprised of an elongated flexible plastic or silicone rubber tube having a cross-section in the form of a “

C”

, with a wall thickness of approximately 0.12 inch, closely fitting around said flexible tube flow line,

B.) said external heater being heated electrically by an electrical resistance heater embedded in the wall or in an extruded elongated cavity in the wall of said external heater, extending for the full length of said heater,

C.) said electrical resistance heater being maintained at a controlled temperature of about 42C by a controller mounted inside said blood warmer apparatus,

whereby in synergistic and complementary effect with said drip chamber holder and said flexible tube flow line heat is preserved in the blood as it flows slowly to the patient by reducing heat loss by convection to the ambient cooler air.