Abstract: A disposable outlet patient flow line for in-line blood/fluid warmer devices uses both passive insulation and active warming to deliver normothermic intravenous fluid to the patient connection site at very low flow rates. A co-extruded annular air space provides passive insulation which reduces heat loss to the cooler ambient air, but by itself this is inadequate for flow rates less than about 15 milliliters per minute. Temperature controlled heating elements located inside the annular air space replace heat lost to ambient air outside the flow line, maintaining the annular air space at about 42 degrees C., thus preventing heat loss from the central blood/fluid carrying lumen. Normothermic fluid is delivered to the patient at body temperature down to essentially zero flow-rate, using a low cost, convenient disposable outlet patient flow line.

Abstract: An improved dry heat method and apparatus for thawing frozen biological fluids utilizing electrically heated plates and oscillatory motion to enhance heat transfer by mixing as the fluid thaws. Bags of frozen fluid to be thawed are lightly squeezed between two heating plates, one of which is gently oscillated to facilitate mixing of the thawing fluid, increasing heat transfer and reducing time required for thawing. Direct contact of the heating plates against the bag surfaces increases heat transfer by eliminating insulative effects of another bag wall and a water boundary layer, compared to water bath units. Flat (or curved to conform to bag) heat pipes are preferred as heating plates compared to plain aluminum sheet. Flat heat pipes have the property of an isothermal heating surface, thus maximizing heat transfer to the coldest areas, preventing hot spots, and simplifying heating plate temperature control.

Abstract: An improved dry heat method and apparatus for thawing frozen biological fluids utilizing electrically heated plates and oscillatory motion to enhance heat transfer by mixing as the fluid thaws. Bags of frozen fluid to be thawed are lightly squeezed between two heating plates, one of which is gently oscillated to facilitate mixing of the thawing fluid, increasing heat transfer and reducing time required for thawing. Direct contact of the heating plates against the bag surfaces increases heat transfer by eliminating insulative effects of another bag wall and a water boundary layer, compared to water bath units. Flat (or curved to conform to bag) heat pipes are preferred as heating plates compared to plain aluminum sheet. Flat heat pipes have the property of an isothermal heating surface, thus maximizing heat transfer to the coldest areas, preventing hot spots, and simplifying heating plate temperature control.

Abstract: A very thin flat plate shaped sintered copper powder wick with a waffle pattern on one surface is sealed between two sheets of thin copper foil. The interior space within the sealed foil is evacuated and charged with sufficient water to saturate the wick through a copper tube which is then hermetically sealed, producing the working core of a flat plate heat pipe. Heat treated aluminum plates are bonded with thin, thermally conductive adhesive layers to both the evaporator and condenser surfaces of the copper foil heat pipe container. The resulting flat heat pipe is lighter in weight by about 40%, much more durable, and less expensive to fabricate than all-copper, machined container flat plate heat pipes, while high performance is maintained.

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.

Abstract: A very thin flat plate shaped sintered copper powder wick with a waffle pattern on one surface is sealed between two sheets of thin copper foil. The interior space within the sealed foil is evacuated and charged with sufficient water to saturate the wick through a copper tube which is then hermetically sealed, producing the working core of a flat plate heat pipe. Heat treated aluminum sheets are bonded with thin, thermally conductive adhesive layers to both the evaporator and condenser surfaces of the copper foil heat pipe container. The resulting flat heat pipe is lighter in weight by about 40%, much more durable, and less expensive to fabricate than all-copper, machined container flat plate heat pipes, while high performance is maintained.

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.

Abstract: A system for warming blood or other liquids to body temperature and maintaining the liquid at that temperature for infusion into a patient. The system is characterized by a cylindrical condensation liquid heating chamber having an inner tubular air heater. A cylindrical heat retaining shell surrounds and is spaced from the outer wall of the heating chamber. A flat flexible heat exchanging liquid warming envelope is held clamped between the outer wall of the heating chamber and the surrounding shell. An external outer elongated air hose is connected at one end to a warmed air outlet from the air heater and extends to the patient and surrounds an inner elongated warm liquid flow line to maintain the temperature of the liquid.

Abstract: A system for warming blood or other liquids to body temperature for infusion into a patient. The system includes a blood warmer apparatus having a pair of closely spaced apart heat transfer plates, each of which forms one face of a housing containing flat vapor condensation heating units. A flat disposable heat exchanging blood warming envelope is held clamped between the heat transfer plates. The envelope is provided with an air escape vent covered by a hydrophobic filter eliminating the need for a vent separate check valve. An air heating unit in one of the apparatus housings includes a cool air inlet, heat transfer fins on the walls of the vapor condensation heater unit, a fan and guides for conducting air past those fins and a warmed air outlet. An external elongated insulated air hose is connected at one end to the warmed air outlet and extends to the patient.

Abstract: An apparatus for warming refrigerated blood to physiologic temperature during transfusion at flow rates from zero to greater than 160 milliliters per minute. The apparatus consists primarily of two hollow metal rectangular box shaped heating units containing a water reservoir in equilibrium with a larger volume of water vapor. Heat is applied to the water reservoir, generating steam which condenses on one wall of each heating unit serving as a heating plate. Heat is then transferred by conduction to a thin metal cartridge or plastic pouch type conduit sandwiched between the two heating plates. Very high heat transfer coefficients maintain heating plates at constant temperature without the possibility of damage to blood by local overheating.

Abstract: An apparatus for warming blood from storage to physiologic temperatures at transfusion rates up to 160 milliliters per minute includes a flat metal cartridge formed by a pair of thin generally rectangular planar members spaced slightly apart in parallelism and sealed at their peripheral edges to define one or more thin constant-width and uniform thickness ribbon-like conduits through which blood flows from an inlet port to an outlet port at opposite ends of the cartridge. An inlet chamber and an outlet chamber, each defined by an elongated recess in one of the planar members, communicates the entire width of a corresponding end of each conduit with the inlet and outlet ports to establish uniform blood flow across each full conduit width.

Abstract: An apparatus for warming flowing blood from storage to physiologic temperatures at transfusion rates up to 160 milliliters per minute includes a flat metal cartridge formed by a pair of thin generally rectangular planar members spaced slightly apart in parallelism and sealed at their peripheral edges to define a thin unobstructed, constant-width and uniform thickness ribbon-like conduit through which the blood flows from an inlet port to an outlet port at opposite ends of the cartridge. An inlet chamber and an outlet chamber, each defined by an elongated recess in one of the planar members, communicates the entire width of a corresponding end of the conduit with the inlet and outlet ports to establish uniform blood flow across the full conduit width. The cartridge is clamped between a pair of thick metal buffer blocks which dampen fluctuations in the flow of heat to the planar members of the cartridge from electric resistance heaters located on the opposite side of each buffer block.