Patent Application
20210361476
The present invention describes a catheter for target body temperature management. Furthermore, it also presents a system for target temperature management and a method thereof. The present invention is in the technical fields of Medicine and Engineering.
Brain injury are serious causes of motor and/or cognitive sequels for the subject and, many times, leads the subject to death. The initial brain injuries may become worse in the first 120 hours, mainly in the first 48 hours. In order to avoid progression of brain injuries, some means may be employed in order to reduce cell metabolism aiming cell protection and regeneration.
Therapeutic hypothermia (TH) is considered, at the present, the most effective neuroprotective measure. The application of TH is indicated by the guidelines of the American Heart Association (AHA)1 and by the systematic reviews of The Cochrane Collaboration2 for patients who remain comatose after the reversal of cardiopulmonary arrest (CPA).
Medical conditions such as stroke3 and traumatic brain injury (TBI)4 may also benefit from this therapy. The most promising data comes from two recent TBI systematic reviews which pose TH as a suitable treatment for this severe group of neurological patients4,5.
TH was initially induced by methods which decreased the temperature of the entire body, the so called systemic cooling methods. The reduction of body temperature may lead to brain protection, but can produce severe systemic complications such as systemic hemodynamic disturbances, infections and blood clotting disorders6-9; therefore, the therapeutic cooling should ideally occur strictly to the brain (exclusive brain cooling).
To avoid the deleterious effects of whole body cooling, techniques to selectively cool the brain have previously been investigated10-13. Among the most promising for using in humans, those that induce cooling of nasopharyngeal surface enable effective brain hypothermia10-12,14 and are considered as non-invasive because they are minimally invasive, easy to apply and promote fast brain cooling. To date, none of the nasopharyngeal methods was able to achieve the exclusive brain cooling. Despite its effectiveness in promoting reduction of brain temperature, some decrease in body temperature of up to 2.5 degrees Celsius15 are still observed, which can still cause deleterious systemic side effects. The known intranasal devices have not been designed for prolonged use and novel devices should address this gap.
By preventing the reduction of systemic temperatures, severe and undesirable complications could be avoided16. It is known that slight body temperature reductions, as little as 1-3° C., are sufficient to produce side effects6-9. Hemodynamic complications are extremely common17 and are related to disturbances of baroreceptors 18,19 myocardial contractility20-22 or secondary to electrolytes changes23,24. Infections and coagulation disorders can occur through several mechanisms6-9 and worsen the condition of patients.
So far, we have not found studies concerning the effects on systemic and brain physiological mechanisms resulting from selective brain cooling16. Yet, human studies with nasopharyngeal cooling using evaporation of perfluorocarbon gas presented damage to the nasopharyngeal mucosa resulting from cooling. Adverse events occurred in 16% of cases, such as nasal discoloration (11%), epistaxis (2%) and cold-induced tissue injury (1%)26,26. The extremely low and uncontrolled temperature of the evaporated gas was probably the cause for the adverse events.
Search in the state of the art in patent and non-patent literature revealed the following documents:
Covaciu et al. 200810 discloses selectively cooling of the brain with cold saline circulating inside thin walled balloon catheters presenting an inlet and an outlet port configuration (William Cook Europe, Bjaeverskov, Denmark) introduced into the nasal cavity of pigs. Catheters were coupled to a circuit in which cold saline was circulated by means of a roller pump and cooled with a heat-exchanger machine. Subsequently it was connected to a circuit including a Stockert twin pump and a heat exchanger machine Stockert HCU (heat-cooling unit). Said document presents a balloon device which is restrictedly positioned at the nasal cavity, thereby resulting in a reduced contact of the balloon which limits heat exchange purposes. The inlet and outlet port are adjacently configured which reduces the potential flow to the device limited by the radius of nostrils. For heat exchange purposes, the lower the flow the worse will be the heat exchange.
Busch et al. 201025 is a safety and feasibility study regarding an evaporative method for nasopharyngeal cooling. The method comprises cooling assemblies with elongate tubular members, a reservoir containing pressurized gas and a manifold connecting the reservoir and the elongate tubular members. The elongate tubular members were inserted only into the patient's nostrils and a pressurized gas was directly delivered onto the surface of the nasal cavity through ports. The method described in said document has no control of the gas temperature vaporized onto the nasal cavities nor continuous feedback control from the brain temperature. Also, the method described in said document promotes direct contact of the evaporated gas with nasal mucosae which may cause adverse events such as periorbital gas emphysema, coolant in facial sinus, epistaxis and tissue damage, as described by the authors. Additionally, the gas may be absorbed by lung circulation.
Doll et al. 201027 discloses one approach of pharyngeal selective brain cooling (pSBC) in rats. Said document presents a method which includes a roller pump (1.) circulating ice water (2.) through a cooling tube (3.), which is placed in the pharynx of the animal. The inlet and outlet port are adjacently configured which reduces the potential flow to the device limited by the radius of nostrils. For heat exchange purposes, the lower the flow the worse will be the heat exchange. Furthermore, the cooling tube is not expandable, thereby resulting in a reduced contact of the tube with the conformation of the body part which limits heat exchange as well.
US2010217361A1 discloses esophageal heat transfer device which has input port connected with external supply tube and receiving coolant from chiller, output port connected with external return tube, and end cap affixed with coolant supply tube. US2012265172A1 discloses esophageal heat transfer device for inducing hypothermia during surgical procedures to treat cardiac arrest which has proximal end including input port and output port, and distal end configured for insertion into esophagus of patient. US2013006336A1 discloses esophageal heat transfer device, useful e.g. for controlling core body temperature, comprises lumens, distal end for insertion into pharyngeal opening, heat transfer region, heat transfer medium input and output port, and gastric tube. US2014155965A1 discloses a system for controlling core body temperature of patient, which has microprocessor which is coupled to external source and is provided to regulate flow of heat transfer means to the esophagus. All above related devices failed to provide a selective and mainly exclusive body part cooling which leads to known severe adverse events. Furthermore, the methods and systems stated above are restricted to cooling techniques. Depending on the therapeutic purpose, heating can be a suitable treatment choice. Another restriction of the methods and systems stated above is that it is restricted to esophageal cooling. Another restriction of the methods and systems stated above is that the inlet and outlet ports are positioned through the same orifice which reduces the potential flow to the device limited by the radius of the catheter. For heat exchange purposes, the lower the flow the worse will be the heat exchange. Furthermore, the cooling tube used in the systems stated above is not expandable, thereby resulting in a reduced contact of the tube with the conformation of the body part which limits heat exchange as well.
Document US2014343641 discloses methods for brain cooling. Such methods comprise cooling assemblies including elongate tubular members, a reservoir containing pressurized gas and a manifold connecting the reservoir and the elongate tubular members. The elongate tubular members are inserted only into the patient's nostrils and a pressurized gas is directly delivered onto the surface of the patient's nasal cavity through a plurality of ports passing only through the nasal cavity in the elongate tubular members. The pressurized gas is vaporized in one or two nasal cavities only and it is vented through the same pathway. The gas is inserted in a temperature of −20° C. The method described in said document has neither control of the gas temperature vaporized onto the nasal cavities nor continuous feedback control from the brain temperature. Also, the method described in said document promotes direct contact of the evaporated gas with nasal mucosae which may cause adverse events such as periorbital gas emphysema, coolant in facial sinus, epistaxis and tissue damage, as described by the authors. Additionally, the gas may be absorbed by lung circulation.
As described in US2014343641, the delivery of fluid causes cooling by direct heat transfer. Said direct heat transfer and the contact of the fluid to the nasal cavity can cause damage to the patient's nasal cavity.
Recent published review manuscripts28-30 have disclosed some possible modalities of therapeutic hypothermia, however, none had suggested any similar catheter as disclosed in the present invention.
Therefore, based on the searches, documents anticipating or suggesting the teaching of the present invention were not found, therefore, the solution herein proposed presents novelty and inventive activity in view of the state of the art.
Thus, the present invention presents a solution for the problem of temperature management without causing further problems to the patient which undergoes treatment.
To date, none of the nasopharyngeal methods was able to achieve the exclusive brain cooling. Despite its effectiveness in promoting reduction of brain temperature, some decrease in body temperature of up to 2.5 degrees Celsius15 are still observed, which can still cause deleterious systemic side effects. The known intranasal devices have not been designed for prolonged use and novel devices should address this gap.
The present invention aims to solve the problem presented in the state of the art with a new device, system and method which solves the problem of:
The present invention promotes heat transfer using a catheter which enables wide contact of an expansible section with the outer conformation.
The present invention
a. promotes heat transfer using any kind of fluid.
b. promotes heat transfer using a catheter which may be inserted through one cavity and exteriorized through another cavity or inserted through one cavity and exteriorized through the same cavity.
c. promotes heat transfer using fluid in steady or moving state.
d. enables heat transfer to organs or cavities with therapeutic purposes also enabling exclusive brain cooling
e. promotes heat transfer instead of using effective counteracting measures to promote whole body temperature normalization
f. enables implementation of mucosal protection means during heat transfer, minimizing mucosal damage caused by the intervention.
g. provides improvement to the status quo of the present temperature management medical devices due to:
The above advantages being able to be provided with a selective body part temperature control method, an increase in the temperature gradient between the target body part and the rest of the body part and the lessening of surgical complications by means of the non-invasive device of the present invention.
In a first aspect, the present invention defines a catheter comprising:—at least
one expandable section comprising at least one opening;
wherein the wall of the expandable section is capable of adapting to the conformation of an outside structure by means of pressure of a fluid;
wherein the at least one opening is capable of receiving at least one fluid inlet means and capable of allowing said fluid inlet to return through the same opening.
In a second aspect, the present invention defines a system for target temperature management comprising:
wherein the expandable section of the catheter is in contact with or inside at least one matter to manage temperature of the matter.
In a third aspect, the present invention defines a method for target body temperature management comprising the steps of:
wherein said temperature management is done by cooling or heating by means of infusing the fluid through the expandable section of the catheter;
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.
These and further objects of the invention would be immediately appreciated by the person skilled in the art and by firms of the same segment, and will be described with enough details so as to allow its reproduction as follows.
In order to clearly define the content of the present application, the following drawings are presented:
The term/expressions below are defined in the context of the present invention:
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.
Expandable: means something able to increase in size in any dimension, for example in length or in diameter.
Non-expandable: means something not able to increase in size in any dimension, for example in length or in diameter.
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.
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.
Typical convective heat transfer coefficient for some common fluids:
Newton's Law of cooling succinctly describes conductive heat transfer:
Q=h·AT·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
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.
Good heat exchange capacity: means a combination of features which will lead to fast and efficient heat exchange from the fluid to the surface.
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.
Matter: is defined as any substance or object which has a physical body. E.g. a cavity or a body part.
Protective means: refers to substances employed to protect the surface of the part that will be in contact with the catheter during heat transfer
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'.
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.
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.
The expandable section of the catheter expanded inside the structure by the pressure generated by the circulating fluid.
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.
On
On
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.
In an embodiment of the system, it comprises a heat exchanger, a circulating pump and connectors.
The heat exchanger can be a cooling or heater generator, wherein it may be coupled with a thermometer which allows an improved temperature management.
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.
In one embodiment, the connectors consist of hoses which are coupled to the system using fast connectors.
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.
In a third aspect, the present invention defines a method for target body temperature management comprising the steps of:
positioning the expandable section of the catheter as defined above in contact with or inside at least one body part; and
wherein said temperature management is done by cooling or heating by means of infusing the fluid through the expandable section of the catheter;
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.
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.
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.
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.
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.
In one embodiment the temperatures measured consist of brain.
The present invention defines the following clauses:
Clause 1. Catheter (1) comprising:
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;
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).
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.
Clause 3. Catheter (1) according to clause 2 wherein said segmentation (3.1) is directed towards the inside section of the expandable section (2).
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).
Clause 5. Catheter (1) according to any one of clauses 1 to 4 comprising:
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);
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.
Clause 6. Catheter (1) according to any one of clauses 1 to 5 further comprising:
Clause 7. Catheter (1) according to any one of clauses 1 to 6, further comprising at least one guidance means (6).
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.
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.
Clause 10. Catheter (1) according to clause 9 wherein the guidance wire (6.1) presents at least one covered tip (6.2).
Clause 11. Catheter (1) according to clause 10 wherein the covered tip (6.2) presents a rounded section.
Clause 12. Catheter (1) according to clause 1 wherein the material of the expandable section (2) has good heat exchange capacity.
Clause 13. Catheter (1) according to clause 12 wherein the material is a plastic polyurethane-based compound.
Clause 14. Catheter (1) according to clause 13 wherein the plastic polyurethane-based compound of the expandable section (2) is made of Neusoft 40A.
Clause 15. Catheter (1) according to clause 4 or 5 wherein the material of the non-expandable section (4) has little heat exchange capacity.
Clause 16. Catheter (1) according to clause 15 wherein the material is a plastic polyurethane-based compound.
Clause 17. Catheter (1) according clause 16 wherein the plastic polyurethane-based compound is Texin 50D.
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.
Clause 19. Catheter (1) according any one of clauses 1 to 18 further comprising:
Clause 20. Catheter (1) according to clause 19 wherein the at least one tubular port (7) is infused with a protective means.
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.
Clause 22. System for target temperature management comprising:
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.
Clause 23. System according to clause 22 wherein said matter is a body part including internal cavities, external cavities and solid organs.
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.
Clause 25. System according to clause 22 further comprising at least one mean for temperature management.
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.
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.
Clause 28. Method for target body temperature management comprising the steps of:
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);
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.
Clause 29. Method according to clause 28 wherein said contact is a substantial contact.
Clause 30. Method according to clause 28 further comprising:
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.
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.
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.
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.
Clause 34. Method according to any one of clauses 28 to 30 wherein it is for preventing, reducing or treating lesions of body parts.
Clause 35. Method according to any one of clauses 28 to 30 wherein it is for treating body parts with thermal cauterization.
Clause 36. Method according to any one of clauses 28 to 35 wherein said catheter (1) is inserted to the target body part by:
Clause 37. Method according to clause 36 wherein the catheter (1) is inserted through the nasal cavity and comes out through the oral cavity.
Clause 38. Method according to clause 28 wherein said body part is the nasopharynx.
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.
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 (
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.
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.
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.
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 presented herein only illustrate one way of performing the invention, however, without restricting the scope of the same.
One example of the expandable section of the catheter positioning can be found in
One example of embodiment of the catheter presents a catheter comprising:—at least one expandable section (2) comprising at least one opening (3);
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;
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).
Further catheter examples are indicated in
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.
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.
Animals were subjected to anesthesia procedures, systemic and brain physiological monitoring, selective brain hypothermia via nasopharyngeal cooling, rewarming and euthanasia.
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.
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.
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.
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.
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).
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).
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.
Results obtained at the study performed with the present invention. Baseline temperatures
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).
In the nasopharyngeal cooling phase, there was a significant decrease in the temperature of both brain hemispheres (
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 (
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).
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.
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.
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).
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.
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.
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.
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
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 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
As can be seen in
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102015002008-2 | Jan 2015 | BR | national |
This application is a continuation of Ser. No. 15/546,161, filed Jul. 25, 2017, currently pending, which is a national stage of PCT/BR2016/050014, filed Jan. 27, 2016, which claims priority to BR102015002008-2, filed Jan. 28, 2015, the disclosures of which are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15546161 | Jul 2017 | US |
| Child | 17370089 | US |
