Catheter, System for Target Temperature Management and Method for Target Body Temperature Management
20210361476 · 2021-11-25
Inventors
Cpc classification
A61F2007/126
HUMAN NECESSITIES
A61F7/12
HUMAN NECESSITIES
A61F2007/0092
HUMAN NECESSITIES
A61F7/123
HUMAN NECESSITIES
International classification
A61F7/12
HUMAN NECESSITIES
A61F7/00
HUMAN NECESSITIES
Abstract
A catheter provides temperature management for a target body. A system provides for target temperature management and a method allows for target body temperature management. The target body temperature management may be performed in cavities, such as the nasopharynx route, of a body.
Claims
1. A catheter comprising for insertion into a nasopharyngeal cavity of a body, the catheter comprising: at least one expandable section comprising: at least one first opening connected to at least one first non-expandable tubular section, and a second opening connected to at least one second non-expandable tubular section; and at least one guidance member cooperating with the at least one expandable section for facilitating the insertion of the catheter into the nasopharyngeal cavity of the body through nasal and oral cavities, wherein a wall of the at least one expandable section is adaptable to conform with the nasopharyngeal cavity of the body by means of pressure of a fluid; wherein the at least one first opening is structured to receive at least one fluid inlet and to allow said at least one fluid inlet to pass through the at least one first opening and at least one second opening; and wherein the fluid passes through the at least one first non-expandable tubular section, the at least one expandable section, and the at least one second non-expandable section; wherein the guidance member comprises a guidance wire which passes through the at least one first non-expandable tubular section and is connected to the at least one second non-expandable tubular section.
2. The catheter according to claim 1, wherein at least a respective one of the at least one first opening and the second opening is continuously connected by means of fusion, screwing, or interference connection to a respective one of the at least one first non-expandable tubular section and the at least one second non-expandable tubular section.
3. The catheter according to claim 1, wherein the at least one expandable section has a length with a proximal end and a longitudinally opposite distal end, the at least one expandable section is connected to the first non-expandable tubular section etween a distal end of the first non-expandable tubular section and the proximal end of the at least one expandable section, the at least one expandable section is connected to the second non-expandable tubular section between the distal end of the expandable section and a proximal end of the at least one second non-expandable tubular section.
4. The catheter according to claim 3, further comprising at least one tubular port which is located inside or adjacent to any section of a wall of the catheter.
5. A system for target body temperature management of a target body, the system comprising: at least one catheter comprising at least one expandable section comprising a first opening connected to at least one first non-expandable tubular section, and a second opening connected to at least one second non-expandable tubular section; wherein a wall of the at least one expandable section is adaptable to a conformation of a nasopharyngeal cavity of the target body by means of pressure of a fluid; and wherein the first opening is structured to receive fluid inlet and to allow said fluid inlet to pass through the first opening into the at least one expandable section, through the second opening and into the at least one second non-expandable tubular section; at least one guidance member cooperating with the at least one expandable section for facilitating the insertion of the catheter into a nasal cavity of the target body; at least one means for counteracting the cooling or heating of the rest of the target body; and at least one fluid provider connected to the catheter; wherein the at least one catheter is inserted through the nasal cavity and exits through an oral cavity, such that the at least one expandable section is in contact with the nasopharyngeal cavity of the target body to manage temperature of the target body; wherein the guidance member comprises a guidance wire which passes through the at least one first non-expandable tubular section and is connected to the at least one second non-expandable tubular section.
6. The system according to claim 5, further comprising at least one means for temperature management.
7. A method for temperature management of a target body by means of a catheter, wherein the catheter comprises at least one expandable section and at least one guidance member, the at least one expandable section comprises a length with at least one first opening arranged at an end of the at least one expandable section and at least one second opening arranged at a longitudinally opposite end of the at least one expandable section, the at least one first opening connected to at least one first non-expandable tubular section, and the at least one second opening connected to at least one second non-expandable tubular section; and the at least one guidance member cooperates with the at least one expandable section for facilitating the insertion of the catheter into the nasopharyngeal cavity of the target body, wherein a wall of the at least one expandable section is adaptable to conformed with the nasopharyngeal cavity of the target body by means of pressure of a fluid, wherein the at least one first opening is structured to receive at least one fluid inlet and to allow said at least one fluid inlet to pass through the at least one first opening into the at least one expandable section and into the at least one second opening, and wherein the fluid passes through the at least one first non-expandable tubular section, the at least one expandable section, and the at least one second non-expandable section, the method comprising the steps of: inserting the catheter through a nasal cavity of the target body and exiting the catheter out through an oral cavity of the target body; positioning the at least one expandable section of the catheter in contact with or inside of the nasopharyngeal cavity of the target body; and infusing a fluid through the catheter by means of a system for target body temperature management of the target body; wherein a wall of the at least one expandable section is adaptable to be conformed with the nasopharyngeal cavity of the target body by means of pressure of the fluid; wherein the at least one first opening is structured to receive at least one fluid inlet from the at least one first non-expandable tubular section, and to allow the fluid inlet to return through the at least one second opening into the at least one second non-expandable tubular section; wherein said temperature management is done by cooling or heating by means of infusing the fluid through the at least one expandable section; wherein the expandable section is expanded by the pressure or volume of the fluid enough to enable contact of the wall of the at least one expandable section of the catheter with the nasopharyngeal cavity of the target body.
8. The method according to claim 7, wherein the method prevents or reduces secondary lesions to a nervous system.
9. A catheter for insertion into an oropharyngeal cavity of a body, the catheter comprising: an expandable section comprising a length with a first opening arranged at an end of the expandable section and a second opening arranged at a longitudinally opposite end of the expandable section, the first opening connected to a first non-expandable tubular section, and the second opening connected to a second non-expandable tubular section; and at least one guidance member cooperating with the expandable section for facilitating the insertion of the catheter into the oropharyngeal cavity of a body through nasal and oral cavities, wherein a wall of the expandable section is adaptable to be conformed with an oropharyngeal cavity of a body by means of pressure of a fluid, wherein the first opening is structured to receive a fluid inlet from the first non-expandable tubular section and to allow said fluid inlet to pass through the first opening into the expandable section, and the second opening is structured to receive the fluid inlet from the expandable section and to allow said fluid inlet to pass through the second opening into the second non-expandable tubular section; and wherein the fluid passes through the first non-expandable tubular section, the expandable section, and the second non-expandable section.
10. The catheter according to claim 9, wherein at least a respective one of the first opening and the second opening is continuously connected by means of fusion, screwing, or interference connection to a respective one of the first non-expandable tubular section and the second non-expandable tubular section.
11. The catheter according to claim 9, wherein: the expandable section is connected to the first non-expandable tubular section, said connection being between a distal end of the first non-expandable tubular section and a proximal end of the expandable section.
12. The catheter according to claim 11, wherein the expandable section is connected to the second non-expandable tubular section, said connection being between a proximal end of the second non-expandable tubular section and a distal end of the expandable section.
13. The catheter according to claim 12, further comprising: at least one tubular port which is located inside or adjacent to any section of a wall of the catheter.
14. The catheter according to claim 1, wherein the catheter is inserted through a nasal cavity of the body and exits through an oral cavity of the body, said at least one expandable section being adapted to take the form of the nasopharyngeal cavity of the body.
15. The catheter according to claim 9, wherein the catheter is inserted through a nasal cavity of the body and exits through an oral cavity of the body, said at least one expandable section being adapted to take the form of the oropharyngeal cavity of the body.
16. The catheter method according to claim 7, wherein the guidance member comprises a guidance wire which passes through at least one of the at least one first non-expandable tubular section and is connected to the at least one second non-expandable tubular section.
17. The catheter according to claim 9, wherein the guidance means member comprises a guidance wire which passes through at least one of the first non-expandable tubular section and is connected to the second non-expandable tubular section.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] In order to clearly define the content of the present application, the following drawings are presented:
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DETAILED DESCRIPTION OF THE INVENTION
[0089] The term/expressions below are defined in the context of the present invention:
[0090] Catheter: are medical devices made of flexible or rigid hollow tube inserted through body channels or natural cavities in order to allow the passage of fluids or to dilate the pathway.
[0091] Expandable: means something able to increase in size in any dimension, for example in length or in diameter.
[0092] Non-expandable: means something not able to increase in size in any dimension, for example in length or in diameter.
[0093] Heat exchange/transfer is defined as the exchange of thermal energy between physical systems, depending on the temperature and pressure, by dissipating heat. The fundamental modes of heat transfer are conduction or diffusion, convection and radiation. Heat energy transferred between a surface and a moving fluid at different temperatures is known as convection.
[0094] Convective heat transfer may take the form of either forced or natural convection, wherein forced convection occurs when a fluid flow is induced by an external force, such as a pump, fan or a mixer, and natural convection is caused by buoyancy forces due to density differences caused by temperature variations in the fluid.
[0095] Typical convective heat transfer coefficient for some common fluids: [0096] Forced Convection [0097] Air and gases: 10-1000 (W/(m.sup.2K)) [0098] Water and liquids: 50-10000 (W/(m.sup.2K)) [0099] Liquid metals: 5000-40000 (W/(m.sup.2K)) [0100] Natural Convection [0101] Air and gases: 0.5-1000 (W/(m.sup.2K)) [0102] water and liquids: 50-3000 (W/(m.sup.2K))
[0103] Newton's Law of cooling succinctly describes conductive heat transfer:
Q=h.Math.AT.Math.A Equation 1.
In which:
Q=total conductive heat transfer
h=Convective Heat Transfer Coefficient
AT=temperature difference between the fluid and the surfaces involved in the transfer
A=Area of surfaces over which transfer is taking place
[0104] Temperature difference (AT) and area (A) are the most important influencers of heat transfer. Convective Heat Transfer Coefficient (h) is another key influencer in heat transfer of fluids. Convective Heat Transfer Coefficient (h) is dependent on the flow properties such as velocity, viscosity and type of media (gas or liquid), and other flow and temperature dependent properties. Velocity has the greatest affect with a direct relationship in convective heat transfer. Geometric shape of the surface and surface condition are other major influencers of heat transfer. Therefore, the more contact exists in between the surface and the fluid, the higher will be the heat exchange. Orientation to the flow may play a role as well.
[0105] Good heat exchange capacity: means a combination of features which will lead to fast and efficient heat exchange from the fluid to the surface.
[0106] Little heat exchange capacity: means a combination of features which will lead to slower and less efficient heat exchange from the fluid to the surface.
[0107] Matter: is defined as any substance or object which has a physical body. E.g. a cavity or a body part.
[0108] Protective means: refers to substances employed to protect the surface of the part that will be in contact with the catheter during heat transfer
[0109] Temperature management: targeted temperature management (TTM) is defined as an active treatment that tries to achieve and maintain a specific body temperature in a person for a specific duration of time in an effort to improve health outcomes'.
Catheter
[0110] In a first aspect of the present invention, the catheter comprises at least one expandable section comprising one opening, wherein the expandable section of the catheter is expanded by the pressure or volume of the fluid enough to enable contact of its wall with the conformation the body part.
[0111] The expandable section of the catheter was made with a thin wall with good heat exchange capacity. This section was responsible for the wide contact with the outside structure. This allows the catheter to provide an extensive surface area for heat exchange.
[0112] The expandable section of the catheter expanded inside the structure by the pressure generated by the circulating fluid.
[0113] Non-expandable sections, when present, were made with a wall presenting lower heat exchange capacity than the expandable section. This characteristic was implemented with the intention to avoid lesions of the outside structure caused by the temperatures of the fluids circulating inside the catheter.
[0114] On
[0115] On
System for Target Temperature Management
[0116] In a second aspect, the present invention defines a system for target temperature management comprising at least one said catheter and means to provide a fluid to the catheter.
[0117] In an embodiment of the system, it comprises a heat exchanger, a circulating pump and connectors.
[0118] The heat exchanger can be a cooling or heater generator, wherein it may be coupled with a thermometer which allows an improved temperature management.
[0119] The pump generates a high flow of the fluid, which improves the heat exchange, and applies pressure inside the walls of the expandable section of the catheter. Said expandable section of the catheter is expanded by the pressure or volume of the fluid enough to enable contact of its wall with the conformation of the body part.
[0120] In one embodiment, the connectors consist of hoses which are coupled to the system using fast connectors.
[0121] In one embodiment, the system for target temperature management also comprises at least one means to counteract the influence of the system throughout the remaining non-target structure. In one embodiment, the target structure is being cooled and the means for counteract are blankets, thermal blankets, thermal mattress, vascular catheters, thermal bags and combinations thereof.
Method for Target Body Temperature Management
[0122] In a third aspect, the present invention defines a method for target body temperature management comprising the steps of:
[0123] positioning the expandable section of the catheter as defined above in contact with or inside at least one body part; and [0124] infusing fluid through the system as defined above;
[0125] wherein said temperature management is done by cooling or heating by means of infusing the fluid through the expandable section of the catheter;
[0126] wherein the expandable section of the catheter is expanded by the pressure or volume of the fluid enough to enable contact of its wall with the conformation of the body part.
[0127] In an embodiment, the target body part for temperature management is the brain. In a further embodiment, the target body part is preferably one brain hemisphere.
[0128] In an embodiment, the method consists of the insertion of said catheter through a structure, wherein the catheter is connected to a heat exchange system of circulating fluid, using a continuous high flow pump which allows temperature management.
[0129] In one embodiment, the guidance means of the catheter presents a covered tip with rounded section which facilitates the insertion of the catheter through the body part.
[0130] In one embodiment, the method also comprises a continuous temperature measurement of the fluid through the whole system. In one embodiment, the measured temperature is a body part targeted by the system. Said continuous measurement allows tight control of the temperature based on the treatment strategies. In one embodiment, the temperature measurement of the body part targeted is done by using a thermometer, near infrared spectroscopy (NIRS), magnetic resonance imaging (MRI), radiometry or combinations thereof.
[0131] In one embodiment the temperatures measured consist of brain.
[0132] The present invention defines the following clauses:
[0133] Clause 1. Catheter (1) comprising: [0134] at least one expandable section (2) comprising at least one opening (3);
[0135] wherein the wall of the expandable section (2) is capable of adapting to the conformation of an outside structure by means of pressure of a fluid;
[0136] wherein the at least one opening (3) is capable of receiving at least one fluid inlet means and capable of allowing said fluid inlet to return through the same opening (3).
[0137] Clause 2. Catheter (1) according to clause 1 wherein opening (3) contains a segmentation (3.1) in its area capable of directing the fluid inlet inwards and outwards.
[0138] Clause 3. Catheter (1) according to clause 2 wherein said segmentation (3.1) is directed towards the inside section of the expandable section (2).
[0139] Clause 4. Catheter according to clause 2 wherein said at least one opening (3) is continuously connected by means of fusion, screwing or interference connection to at least one non-expandable section (4).
[0140] Clause 5. Catheter (1) according to any one of clauses 1 to 4 comprising: [0141] at least one first non-expandable tubular section (4); and [0142] at least one expandable section (2);
[0143] wherein the expandable section (2) is connected to the non-expandable tubular section (4), said connection by the distal end (4.1) of the first non-expandable tubular section (4) to the proximal end (2.1) of the expandable section (2);
[0144] wherein the wall of the expandable section (2) is capable of adapting to the conformation of an outside structure by means of pressure of a fluid.
[0145] Clause 6. Catheter (1) according to any one of clauses 1 to 5 further comprising: [0146] at least one second non-expandable section (5) connected to the expandable section.
[0147] Clause 7. Catheter (1) according to any one of clauses 1 to 6, further comprising at least one guidance means (6).
[0148] Clause 8. Catheter (1) according to any one of clauses 1 to 7, wherein the expandable section (2) is made of a material which has good heat exchange capacity.
[0149] Clause 9. Catheter (1) according to clause 7, wherein said guidance means (6) is a guidance wire which passes through at least one of the sections.
[0150] Clause 10. Catheter (1) according to clause 9 wherein the guidance wire (6.1) presents at least one covered tip (6.2).
[0151] Clause 11. Catheter (1) according to clause 10 wherein the covered tip (6.2) presents a rounded section.
[0152] Clause 12. Catheter (1) according to clause 1 wherein the material of the expandable section (2) has good heat exchange capacity.
[0153] Clause 13. Catheter (1) according to clause 12 wherein the material is a plastic polyurethane-based compound.
[0154] Clause 14. Catheter (1) according to clause 13 wherein the plastic polyurethane-based compound of the expandable section (2) is made of Neusoft 40A.
[0155] Clause 15. Catheter (1) according to clause 4 or 5 wherein the material of the non-expandable section (4) has little heat exchange capacity.
[0156] Clause 16. Catheter (1) according to clause 15 wherein the material is a plastic polyurethane-based compound.
[0157] Clause 17. Catheter (1) according clause 16 wherein the plastic polyurethane-based compound is Texin 50D.
[0158] Clause 18. Catheter (1) according to clause 9 wherein the guidance wire (6.1) is made of a material which is selected from the group consisting of SS pebax.
[0159] Clause 19. Catheter (1) according any one of clauses 1 to 18 further comprising: [0160] at least one tubular port (7) which is located inside or adjacent to any section of the catheter (1) wall.
[0161] Clause 20. Catheter (1) according to clause 19 wherein the at least one tubular port (7) is infused with a protective means.
[0162] Clause 21. Catheter (1) according to clause 20 wherein said protective means is selected from the group consisting of an oil, gas, gel or combinations thereof.
[0163] Clause 22. System for target temperature management comprising: [0164] at least one catheter (1) as defined in any one of clauses 1 to 21; and [0165] at least one fluid provider (8) connected to the catheter (1);
[0166] wherein the expandable section (2) of the catheter (1) is in contact with or inside at least one matter to manage temperature of the matter.
[0167] Clause 23. System according to clause 22 wherein said matter is a body part including internal cavities, external cavities and solid organs.
[0168] Clause 24. System according to clause 23 wherein the body part is nasal cavities, nasopharynx, oropharynx, oral cavity, esophagus, stomach, small intestine, large intestine, rectus.
[0169] Clause 25. System according to clause 22 further comprising at least one mean for temperature management.
[0170] Clause 26. System according to clause 22 further comprising at least one means for counteracting (9) the cooling or heating of the rest of the body.
[0171] Clause 27. System according to clause 26 wherein said means for counteracting (9) the cooling or heating of the rest of the body is selected from the group consisting of blankets, thermal blankets, thermal mattress, vascular catheters, thermal bags and combinations thereof.
[0172] Clause 28. Method for target body temperature management comprising the steps of: [0173] positioning the expandable section (2) of the catheter (1) as defined in any one of clauses 1 to 21 in contact with or inside at least one body part; and [0174] infusing fluid through the system as defined in any one of clauses 22 to 27;
[0175] wherein said temperature management is done by cooling or heating by means of infusing the fluid through the expandable section (2) of the catheter (1);
[0176] wherein the expandable section (2) of the catheter (1) is expanded by the pressure or volume of the fluid enough to enable contact of its wall with the conformation the body part.
[0177] Clause 29. Method according to clause 28 wherein said contact is a substantial contact.
[0178] Clause 30. Method according to clause 28 further comprising: [0179] when said temperature management is done by cooling to at least one body part, a heating means (9) for counteracting the cooling to the rest of the body will be applied; or
[0180] when said temperature management is done by heating to at least one body part, a cooling means (9) for counteracting the heating to the rest of the body will be applied.
[0181] Clause 31. Method according to any one of clauses 28 to 30 wherein it is for preventing or reducing secondary lesions to the nervous system.
[0182] Clause 32. Method according to any one of clauses 28 to 30 wherein it is for preventing or reducing primary lesions to the nervous system caused by surgical or clinical interventions in which the nervous system is brought to risk.
[0183] Clause 33. Method according to any one of clauses 28 to 30 wherein it is for preventing, reducing or treating spontaneous bleeding or bleeding caused by surgeries.
[0184] Clause 34. Method according to any one of clauses 28 to 30 wherein it is for preventing, reducing or treating lesions of body parts.
[0185] Clause 35. Method according to any one of clauses 28 to 30 wherein it is for treating body parts with thermal cauterization.
[0186] Clause 36. Method according to any one of clauses 28 to 35 wherein said catheter (1) is inserted to the target body part by: [0187] inserting at least one catheter (1) through at least one of the openings of the body; [0188] passing through the cavity intended for temperature management; [0189] coming out from the same opening or another opening of the body.
[0190] Clause 37. Method according to clause 36 wherein the catheter (1) is inserted through the nasal cavity and comes out through the oral cavity.
[0191] Clause 38. Method according to clause 28 wherein said body part is the nasopharynx.
[0192] The present invention shows many advantages such as: its easiness to access the target body part, its possibility of performing a selective fast temperature management, between further technical and economic advantages.
[0193] In one embodiment, the induction of exclusive brain hypothermia is feasible by means of a novel nasopharyngeal cooling device associated with body temperature preservation mechanisms. In one embodiment the brain temperature was lowered by 4.5° C., whereas the systemic temperatures remained stable (
[0194] The method implemented in our invention provides a substantial reduction of temperature of a target body part, in one embodiment the induction of exclusive brain hypothermia is feasible by the use of a nasopharyngeal cooling device associated with mechanisms of systemic temperature preservation. This exclusive brain cooling does not influence systemic and brain hemodynamics.
[0195] In one embodiment, the catheter is a nasopharynx cooling catheter that is used to decrease the temperature of encephalic tissue adjacent to the nasopharynx route. The components of the system facilitate catheter positioning. Inside the catheter, there will be continuous flow of liquid cooled by an external system connected to the catheter. The nasopharynx cooling catheter can be used on subjects with severe brain injuries which receive therapeutic brain cooling indication as method for neuroprotection. In one embodiment the system comprising the nasopharynx cooling catheter provides wider heat exchange surface between the catheter and the nasopharynx region which provide better results without complications as compared to the prior art.
[0196] In a preferred embodiment, the catheter of the present invention is associated with means for preserving systemic temperature such as blankets, thermal blankets, thermal mattress, vascular catheters, thermal bags and combinations thereof.
[0197] Earlier treatment with hypothermia induction was proven crucial to reduce motor and/or cognitive sequels for the patients and, in one embodiment, the catheter of the present invention allows to reduce the cerebral temperature in a fast and selective way, avoiding complication presented by other devices presented in the art. Preserving the systemic temperature and preserving the systemic and encephalic hemodynamics is also crucial to avoid further complications to patients undergoing hypothermia treatment.
EXAMPLES—EMBODIMENTS
Example 1
[0198] Examples presented herein only illustrate one way of performing the invention, however, without restricting the scope of the same.
Catheter Positioning
[0199] One example of the expandable section of the catheter positioning can be found in
Catheter Construction
[0200] One example of embodiment of the catheter presents a catheter comprising:—at least one expandable section (2) comprising at least one opening (3);
[0201] wherein the wall of the expandable section (2) is capable of adapting to the conformation of an outside structure by means of pressure of a fluid;
[0202] wherein the at least one opening (3) is capable of receiving at least one fluid inlet means and capable of allowing said fluid inlet to return through the same opening (3).
[0203] Further catheter examples are indicated in
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[0216] The fluid provider (8) connected to the catheter by the proximal end of the first non-expandable tubular section provides fluid (in an embodiment said fluid is water) which passes through the first non-expandable tubular section (4), the expandable section (2) and the second non-expandable tubular section (5). Said expandable section (2) expands to the conformation of an external structure by the pressure of the fluid.
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Effectiveness Tests
Selective Encephalic Hypothermia Induction
[0238] Nasopharyngeal cooling device implemented on the effectiveness test:
a. The nasopharyngeal cooling device was composed by a catheter, a heat exchanger, a circulating pump, its connectors and a thermometer. All components worked together in order to delivering controlled cooling to the nasopharynx using water for this purpose. [0239] i. Catheter was composed by one expandable section and two non-expandable sections. [0240] The expandable section was made with a thin wall with good heat exchange capacity. This section was responsible for the wide contact with the nasopharyngeal irregular conformation. This allowed the catheter to provide an extensive surface area for heat exchange. [0241] The two non-expandable sections were made with a thick wall which had lower heat exchange capacity than the expandable section. This characteristic was implemented with the intention to avoid nasal or nasopharyngeal thermal lesions caused by the low temperatures of the fluids circulating inside the catheter. [0242] ii. The catheter was inserted through the left nostril of all animals and visualized in the oral cavity using direct laryngoscopy. The catheter was connected to the heat exchange system of circulating cold water, between 0° C. and 2° C. using a continuous high flow generated by a water pump. [0243] iii. The expandable section of the catheter expanded inside the nasopharyngeal cavity due to the pressure generated by the circulating fluid pumped by the water pump.
b. The system consisted of a cooling (or heater) generator and a water pump. [0244] i. The cooling (or heater) generator was coupled to the parenchymal brain thermometer which allowed a continuous feedback to the temperature control during the experiment. [0245] ii. The water pump generated a high flow of the fluid in a closed loop layout.
c. The connectors consisted of hoses which were coupled to the system using fast connectors
[0246] Animals were subjected to anesthesia procedures, systemic and brain physiological monitoring, selective brain hypothermia via nasopharyngeal cooling, rewarming and euthanasia.
[0247] For the experiment, 10 (ten) healthy crossbred pigs (Landrace, Duroc and Pietrain), males and females, weighing 18 to 25 kg (mean, 20.6 kg±1.8) were used. They were purchased from breeders near Sao Paulo, within the legal procedures of the Department of Agriculture and Supply and Agricultural Defense and subsequently, were delivered at the School of Veterinary Medicine and Animal Science at the Universidade de Sao Paulo (USP), in a way that they could be sent to the School of Medicine at USP, on the morning of the trial.
[0248] Cooling was initiated 30 minutes after stabilization of respiratory and systemic hemodynamic variables. The cooling process lasted 60 minutes. After turning off the cooling system, brain rewarming occurred passively over 15 minutes.
[0249] During the experiment, body temperature of the animals was maintained by means of thermal mattresses and blankets. Body heating and nasopharyngeal cooling systems were turned on together and the first was maintained until the end of the rewarming phase.
[0250] The temperatures of both cerebral hemispheres were measured catheters inserted through cranial holes performed 0.5 cm lateral to the midline and 1 cm above the coronal suture bilaterally. Its extremities were positioned 1.5 cm from the cortical surface; the positioning of the distal end of the catheter was confirmed by intraoperative ultrasonography.
[0251] Systemic temperatures were measured by a thermometer placed in the lumen of the rectum (RT), another in the lumen of the esophagus (ET) and a third at the tip of a catheter (93A-131H-7F, Baxter Edwards Critical Care, Irvine, Calif., USA) placed in the lumen of the pulmonary artery (AT). These measurements were transmitted and stored on a multiparametric monitor (DX 2020, Philips/Dixtal, Manaus, AM, Brazil).
[0252] Systemic hemodynamic monitoring consisted in the measurement of the following physiological parameters: heart rate (HR), blood pressure (BP) and cardiac output (CO). HR was measured by three electrodes placed in the chest area, mean arterial pressure (MAP) via a polyethylene catheter (PE240) implanted in the lumen of the femoral artery and CO with a catheter (7F93A131H, Baxter Edwards Critical Care of Irvine, Calif., USA) positioned in the lumen of the pulmonary artery, using the intermittent thermo dilution technique 191.192. The catheter used for the measurement of CO was also used to measure the AT. Systemic hemodynamic data were captured and stored in a multiparameter monitor (DX 2020, Philips/Dixtal, Manaus, Brazil).
[0253] Through a system of multi-frequency ultrasound transducer coupled to a 4 to 8 MHz (MicroMaxx® SonoSite, Bothell, Wash., USA), cerebral blood flow velocity (CBFv) was measured in a porcine cerebral artery. Mean velocities, peak systolic velocity (SV), the end-diastolic velocities (EDV) and resistance index (RI) were recorded every five minutes.
[0254] Results obtained at the study performed with the present invention. Baseline temperatures
[0255] Baseline temperatures of the right and left cerebral hemispheres, had no significant differences (TCeO: 38.78±1.16° C.; TCdO: 38.82±1.12° C., p=0.7). Baseline esophageal (ET), rectal (RT:) and pulmonary artery temperatures (AT), also had no significant differences (ET: 39.74±0.86° C.; RT: 39.9±0, 86° C., AT: 39.82±0.86° C., for relations between ET: RT, p=0.164; ET: AT, p=0.45; RT: AT, p=0.62).
Temperature Measurement During Hypothermia
Brain Temperature
[0256] In the nasopharyngeal cooling phase, there was a significant decrease in the temperature of both brain hemispheres (
[0257] The temperature of the left hemisphere was reduced by 1.47±0.86° C. (95% Cl: −2.09 to −0.85, p=0.0004) after 5 minutes and 2.45±1 02° C. (95% Cl: −3.19 to −1.71, p<0.0001) after 10 minutes, reaching 4.45±1.36° C. (95% Cl: −5, 43 to −3.47, p<0.0001) after 60 minutes (
[0258] The temperature of the right hemisphere (RbT) was also reduced, but to a lesser extent. After 60 minutes, the observed reduction was 3.52±0.94° C. (95% Cl: 4.19 to −2.85, p<0.0001).
[0259] The temperature difference between the hemispheres was significant after twenty minutes of cooling (LbT: 35.24±1.49° C.; RbT: 36.06° C.±0.98, p=0.014) and was maintained until the end of that phase.
[0260] There was a rate of temperature decrease in the left brain of 0.3° C./min in the first 5 minutes, and 0.16° C./min until 15 minutes. After this period, the rate was slower: 0.06 to 0.02° C./min until the end of the experiment.
TABLE-US-00001 TABLE 1 Variation of left brain temperature (LbT) compared to baseline temperature. The LbT reduction became significant within the first 5 minutes (p < 0.0004). Values expressed as mean. Left brain Temperature (LbT) Time Difference (compared (min) to baseline) CI 95% p 5 −1.47 −2.09 a −0.85 0.0004 10 −2.45 −3.19 a −1.71 <0.0001 15 −3.21 −4.14 a −2.28 <0.0001 20 −3.40 −4.45 a −2.63 <0.0001 25 −3.65 −4.51 a −2.79 <0.0001 30 −3.80 −4.75 a −2.84 <0.0001 35 −3.93 −4.86 a −2.30 <0.0001 40 −4.08 −5.01 a −3.15 <0.0001 45 −4.13 −5.06 a −3.20 <0.0001 50 −4.23 −5.17 a −3.29 <0.0001 55 −4.25 −5.17 a −3.33 <0.0001 60 −4.45 −5.43 a −3.47 <0.0001
Core Temperature
[0261] Core temperatures showed no significant variation during the experiment as compared to baseline temperatures. The maximum reduction of the rectal temperature (RT) ° C. was 0.23±1.16 (p=0.55), pulmonary artery (AT) was 0.62±0.95° C. (p=0.07) and esophageal temperature (ET) 0.84±1.93° C. (p=0.20).
Difference Between Brain and Core Temperatures
[0262] There was a significant difference between the brain and core temperatures since the first 5 minutes of nasopharyngeal cooling and remained until the end of the procedure.
Hemodynamic Monitoring
Systemic Hemodynamic Measurements
[0263] The systemic hemodynamic parameters (HR, MAP, and CO) remained stable throughout the nasopharyngeal cooling phase. The HR remained at 117±23 bpm, and a MAP of 79.1±13.9 mmHg. There was a non-significant reduction of CO during the first 10 minutes (from 3.7±0.6 to 3.3±0.5 ml/min), which then stabilized. Tachycardia was observed during the rewarming phase.
Brain Hemodynamic Measurements
[0264] There was no significant variation in CBF velocities during the nasopharyngeal cooling phase. After 60 minutes of cooling, a slight reduction of CBF velocities was noticed, along with increased resistance index.
[0265]
[0266] The temperature of left cerebral hemisphere reduced 1.47±0.86° C. after five minutes treatment, 2.45±1.02° C. after ten minutes treatment and 4.45±1.36° C. after sixty minutes treatment
[0267] There was significant difference between cerebral and systemic temperature since the first five minutes of nasopharynx cooling and the significant difference remained until the end of the hypothermia treatment as can be seen in
Systemic Hemodynamics
[0268] Systemic hemodynamic variables (FC—cardiac frequency, PAM—Mean Arterial Pressure and DC—Cardiac debt) remained stable during the hypothermia treatment. FC remained 117±23 bpm, PAM remained 79.1±13.9 mmHg and DC ranging from 3.3±0.5 mL/min to 3.7±0.6 mL/min during the first 10 minutes as can be seen in
Encephalic Hemodynamics
[0269] As can be seen in
[0270] So far, we have not found studies concerning the effects on systemic and brain physiological mechanisms resulting from isolated brain cooling. Similarly, the brain hemodynamics evaluated by Doppler ultrasonography had presented stable without significant changes in response to the exclusive hypothermia. The reduction of the CBF associated with systemic TH was previously demonstrated (33) and can be justified by the systemic hemodynamic variations secondary to whole body cooling.
[0271] The person skilled in the art will appreciate the knowledge presented herein and will be able to reproduce the embodiments of the invention and other variants, which are encompassed by annexed claims.
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