Patent ID: 12194212

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the description hereinafter, spatial orientation terms, if used, shall relate to the referenced embodiment as it is oriented in the accompanying drawing figures or otherwise described in the following detailed description. However, it is to be understood that the embodiments described hereinafter may assume many alternative variations and embodiments. It is also to be understood that the specific devices illustrated in the accompanying drawing figures and described herein are simply exemplary and should not be considered limiting.

Referring to the drawings in which like reference characters refer to like parts throughout the several views thereof, several embodiments of an apparatus and method for rapidly cooling or heating the body temperature of a patient are presented. With reference toFIG.1, an extracorporeal blood cooling or heating circuit10in accordance with one embodiment is shown. The extracorporeal blood cooling or heating circuit10includes an intravenous catheter20inserted into a patient30for withdrawing the patient's blood into the extracorporeal blood cooling or heating circuit10. The catheter20is desirably inserted to a suitable point inside patient's vascular system to unload the patient's heart during extracorporeal blood cooling or heating and return the blood to the patient after it has been heated or cooled. Catheter20may be, for example, a central venous catheter placed into a patient's neck (internal jugular vein or external jugular vein), chest (subclavian vein), or groin (femoral vein). In some embodiments, catheter20may be inserted, for example, into the left atrium of the patient's heart to withdraw blood into the circuit10. Optionally, catheter20may have a dual-lumen design, such that catheter20may be placed into a vessel to withdraw blood and return it to a nearby location, desirably downstream, after the blood has been heated or cooled. In other embodiments, two independent catheters may be used, wherein one catheter is used for blood withdrawal and the other catheter is used for blood return.

With continuing reference toFIG.1, the catheter20is coupled to a combined pump/heat exchanger device40which can selectively cool or heat the patient's blood. One or more sensors50may be provided upstream and/or downstream of the pump/heat exchanger device40. The one or more sensors50are operative for measuring, for example, pressure, temperature, fluid flow, blood oxygenation, and other essential parameters. The circuit10may further include one or more modules60for optional blood treatment. The one or more modules60may be provided upstream or downstream of the pump/heat exchanger device40, or they may be combined therewith. Additionally, the one or more modules60may contain one or more sensors50. The one or more modules60may be operative for blood oxygenation or dialysis. For example, module60may be a blood oxygenator to regulate the oxygen content in the patient's blood.

The extracorporeal blood cooling or heating circuit10further includes a controller70operatively coupled to the pump/heat exchanger device40, one or more sensors50, and/or one or more modules60. The controller70receives power from a power supply (not shown) and controls the operation of the circuit10. For instance, the controller70controls the speed of the pump inside the pump/heat exchanger device40to regulate the blood withdrawal rate. Additionally, the controller70monitors blood temperature provided by the one or more sensors50and, controls the operation of the heat exchanger in response to the temperature values. In some embodiments, the controller70may be provided with an interface80to provide an indication of the operating status of the circuit10. The controller70may further regulate the operation of the one or more modules60for further blood processing.

With reference toFIG.2, venous blood is withdrawn by a pump90of a combined pump/heat exchanger device40. As will be described herein, the pump90may be a conventional arterial blood pump, including, for example, a centrifugal pump or a roller pump. The pump90may be mechanically driven or powered by an electric motor. In some embodiments, the pump90has an electromagnetic drive. The pump90is directly integrated with a heat exchanger100such that the pump90and the heat exchanger100share a common housing110. Housing110is shown inFIG.2as having a generally cylindrical shape, however other housing shapes may be used and the cylindrical shape is for exemplary purposes.

With continuing reference toFIG.2, the combined pump/heat exchanger device40includes a plurality of fluid inlet ports and fluid outlet ports disposed on the housing110. A blood inlet120is provided for receiving blood from the patient30into the pump/heat exchanger device40. Similarly, a blood outlet130expels the blood once it passes through the pump/heat exchanger device40. A fluid inlet140receives heat exchange fluid coming into the pump/heat exchanger device40, while a fluid outlet150expels the heat exchange fluid after it passes through the pump/heat exchanger device40. Fittings160may be provided on each of the fluid inlet ports and fluid outlet ports140,150for attaching conventional devices for carrying perfused blood, such as the catheter20. The fittings160may include a barbed connection, or an otherwise known connection arrangement used in the medical field, to facilitate the coupling of tubing to the housing110of the pump/heat exchanger device40.

Referring toFIG.3, one embodiment of the combined pump/heat exchanger40is shown. Venous blood is received inside a first chamber170after passing through the blood inlet120. The chamber170is in direct fluid communication with the pump90via a blood conduit180extending substantially along the longitudinal centerline of the housing110. As previously noted, the pump90desirably has the construction of a conventional blood pump. In one embodiment, the pump90includes a pump housing190in direct fluid communication with the blood conduit180. The pump housing190includes an impeller200driven by an electromagnetic drive device210. It will be apparent that several other embodiments of the pump90may be utilized with the pump/heat exchanger device40in accordance with this disclosure, including a roller pump. Blood is received into the pump housing190(or tubing, if pump90is a roller pump) from the blood conduit180parallel to the spinning axis220of impeller200. Blood is circulated inside the pump housing190and expelled through an outlet230into a second chamber240. The second chamber240is contained directly inside the heat exchanger100such that heat exchange between blood and the heat exchanger100takes place directly inside second chamber240. After passing through the heat exchanger100, cooled or heated blood is returned to the patient's body through the blood outlet130.

With continuing reference toFIG.3, the heat exchange fluid, such as water or saline solution, enters the heat exchanger100through the fluid inlet140into the first cavity250. The first cavity250surrounds the first chamber170in the upper part of the housing110. A bottom part of the first cavity250includes a first perforated plate260having a plurality of fluid openings270in direct fluid communication with a plurality of heat exchange tubes280. The perforated plate260separates the first cavity250of the heat exchanger100from the second chamber240. The heat exchange tubes280extend through the longitudinal length of housing110between the first perforated plate260located at a top portion of housing110and a second perforated plate290located at a bottom portion of housing110. The heat exchange tubes280connect to a second cavity300provided below the second perforated plate290and provide direct fluid communication between the first cavity250and second cavity300. Heat exchange fluid flows from the first cavity250to second cavity300through the plurality of heat exchange tubes280. Fluid outlet150is in fluid communication with second cavity280to expel the heat exchange fluid once it passes through heat exchanger100.

Components of the combined pump/heat exchanger device40are desirably manufactured from a material having thermal characteristics which facilitate heat transfer. For example, the housing110and internal components of the pump/heat exchanger device40may be manufactured from a metallic or polymeric material having high thermal conductivity. In some embodiments, the pump/heat exchanger device40is made from a glass, acrylic, or aluminum materials. Heat can be added or removed from blood flowing through the pump/heat exchanger device40depending on the temperature of heat transfer fluid as well as the flow rate through the pump90. For example, blood can be cooled by circulating a heat exchange fluid through heat exchanger100that is cooler than the blood entering the pump/heat exchanger device40. The temperature of the blood can be lowered further by reducing the flow rate of pump90such that blood spends more time inside the heat exchanger100when heat exchange fluid has a lower temperature than the blood. Alternatively, blood can be heated by circulating a heat exchange fluid through the heat exchanger100that is warmer than the blood entering the pump/heat exchanger. The temperature of the blood can be raised further by reducing the flow rate of the pump90such that blood spends more time inside the heat exchanger100when heat exchange fluid has a higher temperature than the blood.

With reference toFIG.4, a second embodiment of the pump/heat exchanger device40is shown. In this embodiment, the heat exchange tubes280are oriented in a horizontal direction which is perpendicular to the longitudinal axis of the pump/heat exchanger device40. Venous blood enters the pump/heat exchanger device40through the blood inlet120. Blood is then received inside a blood chamber310in direct fluid communication with a blood inlet320on the pump90. After passing through the blood chamber310, blood is received inside the pump housing190parallel to the spinning axis220of the impeller200. Blood is circulated inside the pump housing190and expelled through the blood outlet130.

With continuing reference toFIG.4, a heat exchanger cavity330is located concentric to chamber310. A plurality of heat exchange tubes280extend through the chamber310between opposing ends of the heat exchanger cavity330. Heat exchange fluid is received inside the heat exchanger cavity330. Heat exchange fluid passes through the plurality of heat exchange tubes280and also flows inside the heat exchanger cavity330around the chamber310. The fluid is expelled from the heat exchanger100through the fluid outlet140. The heat exchangers100shown inFIGS.3-4have the form of a tube-in-tube heat exchanger, where fluid to be cooled or heated flows through a separate conduit from the cooling or heating fluid.

In another embodiment shown inFIG.5, the heat exchanger100may utilize a thermoelectric device350to add or remove heat from the patient's blood. A thermoelectric device350may be a Peltier cell360having one or more thermoelectric modules370in direct thermal contact with a blood conduit380. The Peltier cell360operates on a Peltier effect principle, whereby a temperature differential is created in different portions of the Peltier cell360by applying voltage to semiconductor materials of the thermoelectric modules370contained between ceramic substrates390. Thermal insulation (not shown) may be provided around the heat exchanger100to minimize thermal loss and maximize heat transfer efficiency.

As shown inFIG.5, blood is passed through the pump90and is received inside a blood conduit380through the blood inlet120. The blood conduit380desirably has a channel400defining a tortuous path to increase the amount of time blood spends inside the blood conduit380. Blood is expelled through the blood outlet130located opposite the blood inlet120. Preferably, the blood conduit380is made from a material having high thermal conductivity, such as aluminum, in order to ensure efficient transfer of heat from the blood conduit380and Peltier cell360. The Peltier cell360may further include a heat sink410for dissipating heat from thermoelectric device350. A fan420is provided to increase the efficiency of heat removal from the heat sink410. More than one Peltier cell360may be provided. The controller70desirably controls the operation of the thermoelectric device350and the fan420.

With the basic structure of the extracorporeal blood cooling and heating circuit10according to several embodiments now described, a method for rapidly cooling or heating the body temperature will now be generally described. Such a method for rapidly cooling or heating the body temperature of a patient may begin by inserting an intravenous catheter20into a patient30to withdraw blood into the extracorporeal blood cooling or heating circuit10. Next step, the controller70may be activated to regulate the operation of the pump/heat exchanger device40, one or more sensors50, and one or more modules60to control the temperature, pressure, and flow rate of blood flowing through the circuit10. Prior to activating the controller70, the user may be prompted to initialize and configure the system via an interface80. Venous blood from the patient30is withdrawn into the combined pump/heat exchanger device40to be cooled or heated to a desired temperature. Blood is cooled or heated inside the heat exchanger100depending on whether the heat exchange fluid that flows through the heat exchanger100is cooler or warmer than the blood entering the pump/heat exchanger device40. Optionally, the blood may be passed through one or more modules60to further process the blood. For example, one or more modules60may be a blood oxygenating module, a hemodialysis module, etc. After passing through the circuit10, the blood is returned to the patient30in a cooler or warmer state compared to the blood withdrawn from the patient's body.

While embodiments of an apparatus and method for rapidly cooling or heating the body temperature of a patient are shown in the accompanying figures and described in the foregoing in detail, other embodiments will be clear to, and readily made by those skilled in the art, without departing from the scope and spirit of the invention. For example, while the present disclosure generally discusses a centrifugal-type pump90and tube-in-tube heat exchanger100, it is contemplated that various other embodiments of pump90and heat exchanger100may be equally applicable to the present apparatus and method. The scope of the invention will be measured by the appended claims and their equivalents.