WO2022078671A1

WO2022078671A1 - System for respiratory medical devices

Info

Publication number: WO2022078671A1
Application number: PCT/EP2021/074309
Authority: WO
Inventors: Joan Gavaldà Santapau; Marta Palau Gauthier; Javier Gomis Rodríguez
Original assignee: Fundació Hospital Universitari Vall D'hebron - Institut De Recerca
Priority date: 2020-10-15
Filing date: 2021-09-02
Publication date: 2022-04-21
Also published as: ES1274434Y; ES1274434U

Abstract

The present invention refers in general to biofilm preventive techniques. More specifically, an object of the invention is to provide a device that prevent biofilm formation in respiratory medical devices, like endotracheal tubes or respiratory facial masks. An additional object of the invention is to provide a biofilm preventing system, that is simple to use and have no side-effects.

Description

SYSTEM FOR RESPIRATORY MEDICAL DEVICES

D E S C R I P T I O N

Field and object of the invention

The present invention refers in general to biofilm preventive techniques.

More specifically, an object of the invention is to provide a device that prevent biofilm formation in respiratory medical devices, like endotracheal tubes or respiratory facial masks.

An additional object of the invention is to provide a biofilm preventing system, that is simple to use and have no side-effects.

Background of the invention

Access to effective antibiotics is essential in all health systems. Their use has reduced childhood mortality and increased life expectancy, and they are crucial for invasive surgery and treatments such as cancer chemotherapy and solid organ transplantation. Antimicrobial Resistance (AMR) is a concept rather than a disease like in itself and despite its dramatic rising, is not given the same attention as acute infectious threats like Severe Acute Respiratory Syndrome (SARS), Pandemic flu or Ebola or as the three major infectious diseases: Acquired Immunodeficiency Syndrome (AIDS), Tuberculosis and Malaria. AMR is a serious global menace, affecting global economical, social and public health. The most recent World Economic Forum Global Risks reports have listed AMR as one of the greatest societal risks’ threats to human health.

AMR is not only costly in terms of human suffering but also in economic terms. AMR currently claim at least 50,000 lives each year across Europe and the United States alone and about 700,000 lives worldwide, with an estimated cost of more than 1.5 billion EUR or 35$ billion annually.

Among the most important AMR bacteria in terms of causing infections in hospitalized patients are the so-called 'ESKAPE' pathogens. These microorganisms are Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. The most prominent threat of AMR is the rapidly rising of resistance among 'ESKAPE' bacteria that have caused hospital-acquired infections in the last years. In addition to the ESKAPE pathogens, AMR Escherichia coli remains the main cause of mortality by severe septicemia in hospitalized patients limited. In countries with high levels of multidrug-resistance (MDR), including resistance to carbapenemases, only a few therapeutic options are available against infections caused by carbapanem resistant P. aeruginosa (MDR/extensively-drug (XDR) P. aeruginosa incidence 25-50%), among these are polymyxins. In these countries and in the case of MDR/XDR P. aeruginosa, the presence of resistance to polymyxins or aminoglycosides is an important warning because options for the treatment of infected patients are becoming limited, in the sense that few antibiotics are deemed as an effective therapeutic option for these bacteriae and the antibiotics that still work, frequently have side effects, are less effective or are very expensive, such as tigecycicline.

Furthermore, some ESKAPE pathogens are able to grow as a community of microorganisms surrounded by a self-produced extracellular polymeric matrix attached to a surface. This community is known as a biofilm and has the ability to develop resistant mechanisms against the antimicrobial agents and the immune system cells. According to an announcement done by the United States National Institutes of Health, biofilm-producing microorganisms are medically crucial because they cause 80% of the infections in our body. Among nosocomial infections, which represent an important health care problem due to its high associated mortality, medical device-related infections mean almost one fourth of nosocomial infections. Ventilator-associated pneumonia (VAP) is considered the most severe form of nosocomial pneumonia and it contributes to a higher risk for the patient. VAP prevalence varies between 9-65% and has a mortality rate of 15-76%. It has been reported that endotracheal tubes (ETT) acts as reservoir of microbial pathogens, being a perfect environment for the colonization and adhesion of the microorganisms on the distal end of the endotracheal the tube, forming the biofilm. This biofilm can be developed rapidly after intubation, forming detectable antibiotic-tolerant structures within 24 h, or even they can be dislodged and reintroduced into the lung, causing critical infections. Although it has been reported some ETT biofilm preventive measures, they have not been implemented as they have not significantly demonstrated reducing VAP. Therefore, new preventive or treatment strategies need to be developed in order to decrease the high risk of ETT-related infections in critically ill patients.

In addition to increased resistance to existing agents, there is a lack of new antibiotics in development. For many years, the pharmaceutical industry has been successfully churning out new antibacterial drugs. However, it is becoming more difficult to find novel antibiotics and many large drug companies have withdrawn from antibiotic development programs because the process is extremely costly, and often produces fruitless drugs. Moreover, existing antibiotics are losing their potency due to the spread of resistance at an alarming rate while few new antibiotics are being developed. Therefore, we are facing a paradoxical situation, as a perfect storm, with increased levels of resistant bacteria along with a descending trend in antibiotic development.

The spread of AMR bacteria could dramatically set back modern medicine; achievements in modern medicine, such as decrease in the safety of childbirth, caesarean sections, treatment of preterm babies and major or even minor surgery, treatment of pneumonia, sexual transmitted diseases, organ transplantation and cancer chemotherapy, which we today take for granted would not be possible without access to effective treatments for bacterial infections.

It is now acknowledged the urgent need for funding research relevant to developing new antibiotics and alternatives for treating AMR and biofilm-producing strains. Therefore, it is primordial to increase economic incentives for developing urgently needed antibiotic or antimicrobial strategies, both in the human and animal health sector to preserve antibiotic effectiveness.

Moreover, since the removal the ETT from patients and the reintubation significantly contributes as a risk factor for pneumonia, there is a demand to inhibit the formation of biofilms inside the ETT in a simple manner, without side effects, and without relying in antibiotics.

Summary of the invention

The present invention is defined in the attached independent claim, and satisfactorily solves the demands of the prior art, by providing a technique that preferably prevents biofilm formation by homogeneously heating the air flowing through a respiratory device at a suitable temperature.

The system of the present invention incorporates a heater device that can be coupled upstream a respiratory medical device, such as endotracheal tubes or respiratory facial masks, and that it can also be coupled with an air ventilation equipment, in order to homogeneously raise the temperature of a flow of air entering a respiratory device, as to efficiently prevent or partially or completely remove the biofilm formation inside the respiratory device.

Preferably, the temperature of the air flowing through a respiratory device, such as endotracheal tubes or respiratory facial masks, is kept within the range of 37° to 50°, and preferably around 42°C.

In a preferred embodiment of the invention, the system is specially adapted to be coupled upstream an endotracheal tube, and to a forced ventilation medical equipment.

Therefore, an aspect of the invention refers to a system suitable for preventing or partially or completely removing bacterial biofilm, or biofilm-producing microorganisms, that comprises a heat radiator adapted to be fluidly coupled with a respiratory medical device, such as endotracheal tubes or respiratory facial masks, so as to raise the temperature of air flow entering the respiratory medical device. The heat radiator is a metallic elongated body having first and second ends, which incorporates a plurality of channels longitudinally extending along the body interior, and fluidly communicating the first and second ends for the passage of ventilation air therethrough.

In a preferred embodiment, the system is adapted to be used in conjunction with endotracheal tubes, such that, one end of the heat radiator is adapted to be coupled with an endotracheal tube of standard dimensions, and a second end adapted to be coupled with a source of ventilation air.

Preferably, one end of the radiator is configured as a male connection tube, and another end is configured as a female connection tube.

The system further comprises at least one electric resistor implemented as a heating wire coiled around the heat radiator to heat the same, and to heat air flowing through the channels. The heating wire is coiled on the external surface of the heat radiator, such that heating wire extends around the channels. Preferably, the whole length of the channels is covered by hearing wire.

Preferably, the heating wire includes a first and second filaments, wherein the first and second filaments are obtained from different metals or metals alloys. In a preferred implementation, the first filament is a nickel-chromium alloy, and the second filament is a nickel-aluminium alloy. These two filaments that form the resistor are connected in parallel, and significantly reduce manufacturing cost compared with the use of a single filament of more electric nominal power.

Preferably, the system includes a thermal insulation cover, such the heat radiator and the wire are enclosed inside the insulation cover.

In a preferred embodiment, the radiator has a central channel arranged axially, and a set of channels circumferentially arranged around the central channel, and also extending longitudinally inside the radiator, such that the circumferentially arranged channels are parallel to the central channel. This arrangement of the channels inside the heat radiator, allows the homogenization and uniformity of the air temperature at the exit of the radiator. The electric resistor has enough power to compensate any temperature lost, when the air enters into the heat radiator. Preferably, the radiator has a cylindrical configuration.

The system further comprises at least one temperature sensor, thermally coupled with the heat radiator to measure its temperature. In addition, the system comprises a temperature controller operatively communicated with the temperature sensor and with the heating wire and adapted to maintain radiator temperature within the above-mentioned temperature range of 37° to 50°

The temperature controller includes a timer device, adapted to activate the heating wire during predefined time periods at predefined time intervals. Preferably, the time period is within the range 10 to 20 minutes and preferably about 15 minutes, and the time interval is within the range 20 to 40, and preferably 30 minutes.

Brief description of the drawings

Preferred embodiments of the invention are henceforth described with reference to the accompanying drawings, wherein:

Figure 1 shows a perspective view of the heat radiator and the thermal insulation cover. Figure 2.- shows in Figure A, a longitudinal cross-sectional view of the heat radiator; in Figure 2B, a longitudinal cross-sectional view of the sleeve, and in Figure 2C, a transversal cross-sectional view of the heat radiator.

Figure 3.- shows a longitudinal cross-sectional view of the heat radiator and the insulation cover coupled together.

Figure 4.- shows in a perspective view the heating system in use, connected to a ventilation equipment and to an endotracheal tube.

Figure 5.- shows an electric diagram of the temperature controller.

Figure 6.- shows in graphs A and B, the efficacy of the heating system of the invention against one P. aeruginosa strain (Pa1016) and one K. pneumoniae strain (Kp16) growing in silicone discs determined by quantitative culture

Figure 7.- shows in graphs A and B, the efficacy of the of the heating system of the invention against a Pa1016 strain growing in silicone discs by applying 1 , 2 or 3 shots of 45°C during 15 min.

Figure 8.- shows in graphs A to H, the efficacy of the of the heating system of the invention against different strains growing in PVC discs by applying 1 , 2 or 3 shots of 42°C during 15min.

Figure 9.- shows in graphs A to C, the efficacy of the of the heating system of the invention against two P. aeruginosa (Pa1016 and Pa46) and one K. pneumoniae (Kp16) strains growing in silicone discs determined by quantitative culture.

Figure 10.- shows in graphs A to L, the efficacy of the heating system of the invention against different strains growing on PVC discs by applying 1 , 2 or 3 shots of 42°C during 15min. The treatment was applied after 30 min of the adhesion step of the biofilm formation. Cells were stained with the LIVE/DEAD® viability kit and visualized using confocal laser scanning microscopy (magnification of 60x). Imaged was used to calculate the number of green pixels (viable cells). The results were expressed as the percentage of viable cells after the shot compared to the control group. Figure 11.- shows in graphs A to L, the efficacy of the HeatShot against different strains growing on PVC discs by applying 1 , 2 or 3 shots of 42°C during 15 min. The treatment was applied after 90 min of the adhesion step of the biofilm formation. Cells were stained with the LIVE/DEAD® viability kit and visualized using confocal laser scanning microscopy (magnification of 60x). Imaged was used to calculate the number of green pixels (viable cells). The results were expressed as the percentage of viable cells after the shot compared to the control group.

Figure 12.- shows, respectively, in graphs A to B, the in vivo efficacy of the system of the invention against one K. pneumoniae (Kp6) and one P. aeruginosa (Pa1016) strains growing in endotracheal tubes in a rabbit intubation model. The treatment consisted in applying 3 shots of 42°C during 15 min after the adhesion step of the biofilm formation.

Detailed description of the invention

In a first aspect of the invention, the present invention is directed to a system for respiratory medical devices, such as endotracheal tubes or respiratory facial masks, more preferably an endotracheal tube, the system comprising: a heat radiator (2) adapted to be fluidly coupled with a respiratory medical device, so as to raise the temperature of flow of air entering the respiratory medical device, wherein the heat radiator (2) is a metallic elongated body having first and second ends (2a, 2b), and a plurality of channels (4', 4) longitudinally extending along the body interior, and fluidly communicating the first and second ends (2a, 2b) for the passage of ventilation air from one end to the other end, the system further comprising at least one heating wire (21) coiled around the heat radiator (2) to heat air flowing through the channels (4).

In a preferred embodiment of the first aspect of the invention, one end (2a) of the heat radiator (2) is configured as a male connection tube, and the other end (2b) is configured as a female connection tube.

In another preferred embodiment of the first aspect of the invention or of any of its preferred embodiments, one end (2a) is configured to be coupled with a source of ventilation air, and the other end (2b) is configured to be fluidly coupled with the respiratory medical devices, preferably with an endotracheal tube.

In another preferred embodiment of the first aspect of the invention or of any of its preferred embodiments, the heating wire (21) includes a first and second filaments connected in parallel, wherein the first and second filaments are obtained from suitable metals or metals alloys. Preferably, the first filaments are obtained from an alloy such as a nickel-chromium alloy, and the second filaments are obtained from the same or a different alloy such as a nickel-aluminum alloy. More preferably, the first filaments are obtained from an 80120 nickelchromium alloy.

In another preferred embodiment of the first aspect of the invention or of any of its preferred embodiments, the system further comprises at least one temperature sensor (10) thermally coupled with the heat radiator (2). Preferably, the system still further comprises a temperature controller (11) operatively communicated with the temperature sensor (10) and with the heating wire (21) and adapted to maintain radiator (2) temperature within a desired temperature range, wherein, preferably, the temperate is within the range of 80 - 90 °C, and, more preferably, the temperature controller (11) is adapted to maintain a temperature inside a respiratory medical device, preferably an endotracheal tube, connected to the radiator (2), within the range of 37 - 50 °C, and preferably about 42 °C, in order to prevent biofilm formation inside the device. Preferably, the temperature controller (11) includes a timer device adapted to activate the heating wire (21) during one or more predefined time periods, preferably between 1 and 5 time periods, and at predefined time intervals, wherein, preferably each time period is within the range 10 to 20 minutes and preferably about 15 minutes, and wherein the time interval are within the range 20 to 40 minutes, and preferably 30 minutes.

In another preferred embodiment of the first aspect of the invention or of any of its preferred embodiments, the heat radiator (2) has a central channel arranged axially, and a set of channels circumferentially arranged around the central channel, and also extending longitudinally inside the radiator, such that the circumferentially arranged channels are parallel to the central channel. Preferably, the heat radiator (2) has a cylindrical configuration.

In another preferred embodiment of the first aspect of the invention or of any of its preferred embodiments, the system further comprises a thermal insulation cover (3), such the heat radiator (2) and the heating wire (21) are enclosed inside the insulation cover (3). In another preferred embodiment of the first aspect of the invention or of any of its preferred embodiments, the system further comprises electrically insulating sleeves, electrically isolating respectively the first and second filaments of the heating wire (21).

In yet another preferred embodiment of the first aspect of the invention or of any of its preferred embodiments, the inlet and outlet (9a, 9b) of the channels (4', 4) have concave shape, preferably a cone shape.

A second aspect of the invention, refers to a method for preventing, or partially or completely removing, bacterial biofilm or biofilm-producing microorganisms, in a respiratory medical device, such as endotracheal tubes or respiratory facial masks, more preferably an endotracheal tube, in a patient; the method comprising coupling the system comprising a heat radiator (2), adapted to be fluidly coupled with a respiratory medical device, as defined in the first aspect of the invention or in any of its preferred embodiments, with a source of ventilation air, on one end (2a), and on the other end (2b) fluidly coupling the system with the respiratory medical device, preferably an endotracheal tube, in the patient in need thereof, and maintaining a temperature inside the respiratory medical device, preferably an endotracheal tube, connected to the radiator (2), within the range of 37°C - 50 °C, and preferably about 42 °C, during one or more predefined time periods, and at predefined time intervals, in order to prevent biofilm formation inside the tube and/or in order to partially or completely removing bacterial biofilm or biofilm-producing microorganisms.

In a preferred embodiment of the second aspect of the invention, the bacterial biofilm is produced by 'ESKAPE¹ biofilm-producing microorganisms selected from any one of the list consisting of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.

In another preferred embodiment of the second aspect of the invention, the biofilmproducing microorganisms are 'ESKAPE' biofilm-producing microorganisms selected from any one of the list consisting of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.

In yet another preferred embodiment of the second aspect of the invention or of any of its preferred embodiments, the system comprises at least one temperature sensor (10) thermally coupled with the heat radiator (2), and further comprising a temperature controller (11) operatively communicated with the temperature sensor (10) and with the heating wire (21), wherein in the method the system is adapted to maintain radiator (2) temperature within the range of 37 - 50 °C, and preferably about 42 °C, during the one or more predefined time periods, and at the predefined time intervals.

In yet another preferred embodiment of the second aspect of the invention or of any of its preferred embodiments, the temperature controller (11) comprises a timer device adapted to activate the heating wire (21) during the predefined time periods, and at the predefined time intervals, wherein the time period is within the range 10 to 20 minutes and preferably about 15 minutes, and wherein the time intervals are within the range of every 20 to 40 minutes, and preferably every 30 minutes.

A third aspect of the invention, refers to a method for maintaining, regulating or increasing the core body temperature of a patient in need thereof connected or intubated with a respiratory medical device, preferably an endotracheal tube; the method comprising coupling the system comprising a heat radiator (2) adapted to be fluidly coupled with a respiratory medical device as defined in any of claims 1 to 17 with a source of ventilation air, on one end (2a), and on the other end (2b) fluidly coupling the system with the respiratory medical device, preferably an endotracheal tube, in the patient in need thereof, and maintaining a temperature inside the respiratory medical device, preferably an endotracheal tube, connected to the radiator (2), within the range of 37 - 50 °C, and preferably about 42 °C, during one or more predefined time periods, and at predefined time intervals, in order to maintain, regulate or increase the core body temperature of a patient in need thereof

In a preferred embodiment of the third aspect of the invention, the system comprises at least one temperature sensor (10) thermally coupled with the heat radiator (2), and further comprising a temperature controller (11) operatively communicated with the temperature sensor (10) and with the heating wire (21), wherein in the method the system is adapted to maintain radiator (2) temperature within the range of 37 - 50 °C, and preferably about 42 °C, during the one or more predefined time periods, and at the predefined time intervals.

In another preferred embodiment of the third aspect of the invention or its preferred embodiment, the temperature controller (11) comprises a timer device adapted to activate the heating wire (21) during the predefined time periods, and at the predefined time intervals, wherein the time period is within the range 10 to 20 minutes and preferably about 15 minutes, and wherein the time intervals are within the range of every 20 to 40 minutes, and preferably every 30 minutes. In order to provide a complete understanding of the system of the present invention, the system shall be further explained in virtue of the illustration shown in the figures. It is noted that all of the specific elements specifically indicated in the explanations below, are understood to be incorporated as potential preferred embodiments of the system as defined in the first aspect or in any of its preferred embodiments.

Figure 1 shows a perspective view of the biofilm preventing system (1) for respiratory medical devices according to a preferred implementation of the invention, wherein the system comprises a heat radiator (2) and a thermal insulation cover (3). The heat radiator (2) is a metallic elongated body having first and second ends (2a, 2b) and a plurality of channels (4), longitudinally extending along the heat radiator, and fluidly communicating the first and second ends (2a, 2b) for the passage and heating of ventilation air through them.

In this preferred example, there are nine channels (4) each one with a diameter of 3 mm, so that the total cross-sectional area of the holes is 63.617 mm², which matches the area of a conventional endotracheal tube, thus, the heat radiator guarantees air flow homogeneity through an endotracheal tube.

The heat radiator (2) can be manufactured as a unitary body, made for example of stainless steel or other suitable metal or metal alloy.

The heat radiator (2) of this embodiment, is specially configured to be coupled to an endotracheal tube and to a forced ventilation equipment. For that, a first end (2a) of the radiator has a male configuration, and a second end (2b) has a female configuration.

The heat radiator (2) could be coupled likewise, to other respiratory medical devices such as a respiration mask.

The system further includes an electric resistor consisting of a heating wire (21) that is coiled around the heat radiator (2), to heat the same when an electric current flows through it. The resistor is isolated by a layer of Kapton.

The whole extension of the channels (4) is surrounded by the heating wire (21), such that the heating wire (21) provides a uniform and proper transmission of heat to the radiator (2), which in turn raise the temperature of air flow entering the respiratory medical device. As shown in Figure 2C, the heat radiator (2) in this example is a cylindrical body, and a central channel (4') is arranged along the axis (x) of the heat radiator, whereas the other channels (4) are distributed circumferentially around that central channel (4'). Preferably, the channels (4) are parallel to the axis (x). With this distribution of channels, a major part of the flow of air circulates close to the external surface (5) where the heating wire (6) is coiled, that is, closer the source of heat.

As shown in Figure 2A, the inlet and outlet (9a, 9b) of the channels (4', 4) have concave shape, preferably a cone shape, that serves for the air to enter and exit from the radiator (2) in a more homogenous way.

The thermal insulation cover (3) is a cylindrical body, dimensioned such the heat radiator (2) with the heating wire (21), can be received inside the cover (3) as shown in Figure 3. In this way, the radiator and the wire are thermally insulated from the exterior, and temperature is kept continuous inside the cover, and at the same time accidental burning to users are avoided. The insulation cover (3) can be obtained for example from polyoxymethylene (POM).

Furthermore, the thermal insulation cover (3) has several annular grooves (6), that allow a better insulation and ventilation of the radiator.

Respectively at each end (2a, 2b), the heat radiator (2) has annular extensions (8a, 8b), that serve as contact areas between the radiator (2) and an internal surface of the cover (3), and to prevent contact between the wire (21) and the cover (3).

The heating wire (21) is formed by two filaments connected in parallel; one of them is made of nickel-chromium (preferably an 801 20 nickel-chromium alloy), and the other one of nickel-aluminium. The heating wire (21) has a resistance of 10 Q, so by applying 12 V, it gives a power of 14.4 W.

The heating system operates preferably with alternating current, but it could also work with direct current. Each filament is covered with Teflon sleeve, and both of them are covered with a Teflon tube of 0.8 mm in order to confer isolation.

The system incorporates a temperature sensor (10) thermally coupled with the heat radiator (2) to measure its temperature while it is being heated. The temperature sensor (10) is thermally coupled with an outer surface of the heat radiator (2), and it has a high precision (Class A) with a 0.3 °C of tolerance and allows blocking the heating system in case of damage or accidental crossing. Preferably, the temperature sensor (10) is implemented as a Pt100 sensor.

The system further comprises a temperature controller (11), such that the heat radiator (2) is connectable with the controller (11) by means of a cord (7) that includes four wires, namely: two wires for connecting the heating wire (21) and two wires for connecting the temperature sensor (10) with the controller (11). For that purpose, the cord (7) has a four- poles connector (20), that can be plugged to a complementary connector provided at the controller (11).

In this way, the temperature controller (11) can be operatively communicated with the temperature sensor (10) and with the heating wire (21), which is adapted to maintain radiator (2) temperature within a desired temperature range. Preferably, temperature is maintained within the range 37 - 50 °C, and more preferably around 42 °C.

Figure 4 shows in a perspective view the heating system (1) in use, wherein the heat radiator (2) is shown connected to a ventilation equipment (22) and also connected to an endotracheal tube (24). In particular, the first end (2a) of the radiator (2) with male configuration is connected to the ventilation equipment (22) by means of respiratory hoses

(23), and the second end (2b) with female configuration is connected to an endotracheal tube

(24). As illustrated in the figure, the radiator (2) can be easily coupled simply by inserting the radiator ends (2a, 2b) respectively in the endotracheal tube and ventilation equipment.

Figure 5 shows the electrical diagram of the temperature controller (11), which comprises: a digital temperature regulator (12) with a Proportional-lntegral-Derivative (PID) control system, that allows stopping the thermal inertia when necessary. Moreover, this control is improved by a FlIZZI process based on an artificial intelligence program. It has one release to activate the heating and another one to deactivate when the temperature is exceeded. If a second control system was required, it could be incorporated as a second lock on the system.

The controller (11) further includes a cyclic timer (13) communicated with the temperature regulator (12). The cyclic timer (13) allows activation of the system for a determinate period of time and stops working automatically when the temperature increases above a predefined value. The controller (11) also includes a solid state relay (14) operated by the cyclic timer (13), and a transformer (15) connected to the output of the relay (14), such that the AC input (16) is applied to the primary side of the transformer. The heating wire (21) is connected to the output of the transformer (15) by means of the cord (7), which in the case provides 12 Volts output.

The digital temperature regulator (12) is connected with the temperature sensor (10) attached to the radiator (2), in order to regulate temperature based on the temperature of the radiator (2).

The temperature controller (11), is fed from the low voltage AC source (16) through a fuse (17) and a selector (18) of three positions (central, disabled; position D, direct action and position C, cyclic interval). The controller further includes a security relay (19) operated by the digital temperature regulator (12), and connected to cut off the solid state relay (14), to stop heating in case of reaching a higher temperature than the one determined by the temperature regulator.

1. In vitro efficacy studies

1.1 Strains

For the biofilm formation, eight XDR gram-negative isolates were studied. Three strains of Acinetobacter baumannii (Abl1 ; isolate harbouring a NDM-2 and an OXA-51 , only susceptible to colistin and tigecycline (sequence typing (ST)- 103), Abl4; isolate harbouring an OXA-51 , only susceptible to colistin, amikacin and tigecycline (ST-2) and Ab60; isolate harbouring an OXA-51 and an hiperproduction AmpC, resistant to gentamycin (ST-38)), two strains of Klebsiella pneumoniae (Kp6; harbouring an extended-spectrum beta-lactamase (ESBL) only susceptible to colistin, fosfomycin and imipenem and Kp16; hiperproduction of cephalosporinase, only susceptible to colistin, clavulanic and gentamycin) and three strains of Pseudomonas aeruginosa (Pa3; harbouring a VIM-2 carbapenemase, only susceptible to colistin and isolate disseminated worldwide (ST-235), Pa46; harbouring a VIM-2 carbapenemase, only sensible to colistin and amikacin (ST-111) and Pa1016; harbouring an hiperproduction AmpC, OprD inactivation (Q142X), only susceptible to colistin and amikacin and isolate disseminated in Spanish hospitals (ST-175)) were tested. One strain of methicillin- resistant Staphylococcus aureus was also studied (MRSA15). All of them were isolated from patients of Vail d’Hebron Universitary Hospital (VHLIH). All strains were stored in skim milk at -80°C in cryovial storage containers. Prior to each experiment, strains were plated in Trypticase Soy Agar (TSA, BioMerieux® SA, Marcy I’Etoile, France) and incubated at 37°C during 24 h.

1 .2 Substrates used in the biofilm formation

Two types of substrates were used for the biofilm formation: silicone discs (15 mm of diameter and 0.5 mm of thickness, Merefsa, Barcelona, Spain) and polyvinyl chloride discs (PVC; 15 mm of diameter and 0.5 mm of thickness; Servicio Estacion S.A, Barcelona, Spain). In order to improve the formation of the biofilm, K. pneumoniae strains were grown in thicker PVC discs (15 mm diameter and 1 mm of thickness; Servicio Estacion S.A, Barcelona, Spain).

1.3 Biofilm formation on silicone or PVC discs

For the biofilm formation on the surface of the discs, the protocol described by Chandra et a/.²⁸ was followed, with some modifications. Firstly, the biofilm-producing strains were grown overnight in Tryptic Soy Broth (TSB; Becton Dickinson and Company, Le Pont de Claix, France) at 37°C and 60 rpm. After centrifuging and washing the cell suspension three times with sterile Phosphate buffer saline pH 7.2 (PBS; Merck, Germany), an inoculum of T 10⁷ colony-forming units (CFU)/mL was prepared with PBS pH 7.2. Secondly, 4 mL of the inoculum and silicone or PVC discs were added in each well of a 12-well plate (Sarstedt AG & Co, Numbrecht, Germany). The plate was incubated for 30 or 90 min at 37°C (adhesion step) and then was placed in a new plate containing 4 mL of fresh TSB. Then, the plate was incubated for 24 h at 37°C under stirring at 60 rpm (growth step).

1 .4 Application of the System of the invention treatment

1.4.1 Post-adhesion treatment

After the adhesion step of the biofilm formation on the surface of the discs, the discs were placed in a new 12-well plate. Three of them were incubated at 37°C (control group) while the other three were placed in a heating plate (Sanara, Barcelona, Spain). 1 , 2 and 3 shots of 42°C, 45°C or 50°C during 15 min were applied. Between shots, the discs were incubated at 37°C during 30 min. A thermometer (Omega Instruments, Manchester, United Kingdom) and a probe (Sanara, Barcelona, Spain) were used to verify the temperature in a control disc during all the experiment.

After every shot, the discs were placed in a new plate containing 4 mL of TSB to follow the growth step. The plate was incubated at 37°C during 24 h under stirring at 60 rpm. Then, the efficacy of the System of the invention was evaluated. 1 .4.2 Post-growth treatment

The protocol used was similar to the post-adhesion treatment, with some modifications.

After the growth step of the biofilm formation on the surface of the discs, the discs were placed in a new plate. Three of them were incubated at 37°C (control group) while the other three were placed in a heating plate (Sanara, Barcelona, Spain). 1 , 2, 3, 4 and 5 shots of 50°C during 15 min were applied. Between shots, the discs were incubated at 37°C during 30 min. A thermometer (Omega Instruments, Manchester, United Kingdom) and a probe (Sanara, Barcelona, Spain) were used to verify the temperature in a control disc during all the experiment.

1 .5 Evaluation of the System of the invention efficacy

1.5.1 Quantitative culture

The discs were placed in a new 12-well plate containing 1 mL of TSB in each well. The biofilm was scrapped (Cell scrapper, Sarstedt. AG & Co, Numbrecht, Germany), plated in TSA and incubated at 37°C during 24 h. Then, cells were quantified and expressed as Log CFU/mL.

1.5.2 Confocal Laser Scanning Microscopy

The efficacy of the System of the invention was visualized using Confocal Laser Scanning Microscopy (CLSM) with an Olympus FV1000 with excitation wavelengths of 488 and 568 nm and a magnification of 60x. Biofilms were stained using a LIVE/DEAD® BacLight™ viability kit (Molecular Probes, Invitrogen, Leiden, The Netherlands) following the manufacturer’s instructions, which consisted of staining with a mixture of SYTO 9 (3.34 mM solution in DMSO) and propidium iodide (20 mM solution in DMSO) and incubating at room temperature in the dark for 30 min. Three areas of the biofilm of each silicone disc were scanned with a 2-pm step size. Simultaneous dual-channel imaging was used to display the green (live cells) and red (dead cells) fluorescence. IMARIS 8 Software (Bitplane, Belfast, UK) was used to create a projection view of the formed biofilms, and the Imaged 1.45s software package was used to calculate the value of live (green) pixels.

The results were expressed as the percentage of cell viability of the shots vs the control group.

2. In vivo safety studies

2.1 Endotracheal intubation model

2.1.1 Animals For the study, male New Zealand rabbits weighing between 2 kg-2.3 kg (Granja Cunicola San Bernardo, Navarra, Spain) were housed individually in regulation cages, provided with water and food ad libitum throughout the experiments and housed under a reversed 12h/12h light/dark cycle.

2.1.2 Ethics

This study was carried out in strict accordance with the recommendations of the Guide for the Care and Use of Laboratory Animals and the Animal Research Reporting of In Vivo Experiments (ARRIVE) guidelines. All experimental procedures were done in accordance with Catalan, Spanish and European laws and regulations on the protection of animals used for experimental and other scientific purposes.

The experimental protocol was approved by the Animal Experimentation Ethics Committee of our Institution (registration number 69/16 CEEA).

2.1.3 Anesthesia

Animals were firstly anaesthetized by an intramuscular (IM) injection of 100 mg/kg Ketamine (Pfizer, Madrid, Spain) plus 20 mg/kg Xylacene (Laboratorios Calier S.A., Barcelona, Spain). When the animal had no corneal reflex, we placed a line in the peripheral vein of the ear for anesthetic maintenance with a continuous infusion of 1 pg/kg/h fentanyl and 0.1 mg/kg/h midazolam at an infusion rate of 1 mL/h. If we noticed that during the experiment the animal was awake, a bolus injection of 0.5 mL of 0.1 mg/kg/h vecuronium was also administered. It was also maintained with a fluid therapy of Ringer Lactate (B. Braun, Barcelona, Spain) at a rate of 1-2 mL/kg/h.

2.1 .3.1 Endotracheal intubation

For the endotracheal intubation, the protocol described by Thompson et al ²⁹ was followed, with some modifications.

When the rabbit reached the anesthetic plane, it was placed on the preparation table with its head slightly extended over the edge of the table and in straight aligning with the spine column. After checking the completely jaw relaxation, by lifting the head up, a gauze was used to pull the rabbit’s tongue to the right lower incisors, taking care to avoid trauma from the incisors. 2% Lidocaine (Inibsa, Barcelona, Spain) was sprayed into the larynx of the rabbit to locally anesthetize the vocal cords and to avoid the risk of laryngospasm. Then, while extending the rabbit's head back and the neck forward to maintain an open airway and view the larynx, the endotracheal tube (3.5 mm of internal diameter, Covidien, Mansfield, USA) was slowly introduced from the rabbit's left side until we noticed some resistance (confirmation that we were in the larynx). To prevent oxygen desaturation, it was important to keep the neck extended as described to maintain an open airway during intubation. The successful introduction of the tube was done by observing the fogging of a glass/mirror at the end of the tube and listening for airflow. Consequently, the tube was gradually introduced to the desired position. To secure the endotracheal tube, the rabbit was placed on its side and an umbilical tape around the tube was used.

2.1.4 Ventilation parameters

Animals were ventilated using a mechanical ventilator and a humidifier (Serve Ventilator 300, Siemens, Germany). The mechanical ventilator was used in neonatal mode and in pressure-control, with an airway pressure peak of 15 cmFW and a PEEP of 5, a breathing rate of 44 breathes/min, an inspiration period of 0.35 sec, a tidal volume of inspiration of 40 mL and a concentration of O2 of 50%. Inspiratory gases were conditioned through the heated humidifier.

2.1.5 Application of the System of the invention treatment

After the intubation of the animal, an electric resistance (Forbac 100 CE, Sanara, Barcelona, Spain) was placed between the endotracheal tube and the ventilator tube and plugged to a control box (Gavalbac 100, Sanara, Barcelona, Spain). The temperature of the control box was varied in order to keep the temperature inside the endotracheal tube at 42°C. 3 shots of 42°C during 15 min were applied leaving 30 minutes without heat between shots. The temperature inside the endotracheal tube was verified during all the experiment using a thermometer (Omega Instruments, Manchester, United Kingdom) and a probe (Sanara, Barcelona, Spain).

2.1.6 Evaluation of the System of the invention safety

Immediately after the application of the System of the invention or 24 h later, animals were euthanized by an intraperitonal injection of 200 mg/kg pentobarbital. Then, the lungs were aseptically removed and kept in 10% neutral buffered formalin (Diapath S.p.A, Martinengo, Italy). The System of the invention safety was evaluated by analyzing the lungs microscopically and macroscopically by a Pathological Anatomy Laboratory from the VHUH.

RESULTS

1. In vitro susceptibility studies

1.1 Efficacy of the System of the invention applied after the adhesion step a) In silicone discs By applying the system of the invention after the adhesion step, 1 shot of 50°C during 15 min was needed to prevent the formation of the biofilm of Pa1016 and Kp16 strains on the surface of the silicone discs (see Figure 6).

Moreover, it was also tested the effect of bringing the temperature down to 45°C. In this case, after 90 and 30 min of adhesion, the eradication of the Pa1016 growing in silicone discs was achieved by applying 3 shots of 45°C during 15 min (see Figure 7).

Figure 6. Efficacy of the system of the invention against one P. aeruginosa strain (Pa1016) and one K. pneumoniae strain (Kp16) growing in silicone discs determined by quantitative culture. The treatment consisted in applying from 1 to 5 shots of 50°C during 15 min and it was applied after 90 min of adhesion of the biofilm

Figure 7. Efficacy of the system of the invention against a Pa1016 strain growing in silicone discs by applying 1 , 2 or 3 shots of 45°C during 15 min. The treatment was applied after 90 min (A) or 30 min (B) of the adhesion step of the biofilm formation. Cells were stained with the LIVE/DEAD® viability kit and visualized using confocal laser scanning microscopy (magnification of 60x). Imaged was used to calculate the number of green pixels (viable cells). The results were expressed as the percentage of viable cells after the shot compared to the control group. b) In PVC discs

The results of the system of the invention efficacy applied after 30 minutes of adhesion in PVC discs are shown in Figure 8. The application of system of the invention successfully prevented the biofilm formation in PVC discs in 100% (8 out of 8) of the tested strains: 2 shots of 42°C during 15 min were necessary to prevent the biofilm formation of 2 out of 8 tested strains (Abl 1 and MRSA15). Furthermore, the application of 3 shots of 42°C during 15 min was required to avoid biofilm formation of the rest of the tested strains: two P. aeruginosa (Pa1016 and Pa3), two A. baumannii (Abl4 and Ab60) and two K. pneumoniae (Kp6 and Kp16) strains.

Figure 8. Efficacy of the system of the invention against different strains growing in PVC discs by applying 1 , 2 or 3 shots of 42°C during 15min. The treatment was applied after 30 min of the adhesion step of the biofilm formation. Cells were stained with the LIVE/DEAD® viability kit and visualized using confocal laser scanning microscopy (magnification of 60x). Imaged was used to calculate the number of green pixels (viable cells). The results were expressed as the percentage of viable cells after the shot compared to the control group. In addition, further results of the system of the invention efficacy applied after 30 minutes of adhesion in PVC discs, were performed and further shown in Figure 10. The application of the system of the invention successfully prevented the biofilm formation on PVC discs in 100% (12 out of 12) of the tested strains: 1 shot of 42°C during 15 min was necessary to prevent the biofilm formation of 33% of the studied strains (Kp26, Kp27, Pa46 and Pa1016). With only 2 shots of 42°C during 15 min, we prevented the biofilm formation of 50% of the studied strains (Abl1 , Abl4, Kp6, Pa3, Ba9 and SARM61). Finally, 3 shots of 42°C during 15 min were required to avoid biofilm formation of the remaining 17% of the studied strains.

Moreover, still further results of the system of the invention efficacy applied after 90 minutes of adhesion in PVC discs are shown in Figure 11. The application of system of the invention successfully prevented the biofilm formation on PVC discs in 100% (12 out of 12) of the tested strains: 1 or 2 shots of 42°C during 15 min were necessary to prevent the biofilm formation of 50% of the tested strains (Abl4, Ab60, Kp6, Kp26, Kp27 and Pa46). Furthermore, the application of 3 shots of 42°C during 15 min was required to avoid biofilm formation of the rest of the tested strains (Abl1 , Pa6, Pa1016, MRSA9, MRSA14 and MRSA61).

1 .2 Efficacy of the System of the invention applied after the growth step a) In silicone discs

The results of the system of the invention efficacy applied after the biofilm formation in the surface of the silicone discs are shown in Figure 9. The application of 4 shots of 50°C during 15 min against two P. aeruginosa (Pa1016 and Pa46) and one K. pneumoniae (Kp16) strains allowed the complete eradication of a biofilm of 8 log CFU/mL. However, in the case of Kp16, with only 1 shot of 50°C during 15 min the reduction was 50%.

Finally, the reduction of more than 70% of the Pa46 bioflim was achieved by applying 2 shots of 50°C during 15 min, whereas the total eradication of this strain was obtained by only applying 2 shots of 50°C during 15 min.

Figure 9. Efficacy of the system of the invention against two P. aeruginosa (Pa1016 and Pa46) and one K. pneumoniae (Kp16) strains growing in silicone discs determined by quantitative culture. The treatment consisted in applying from 1 to 5 shots of 50°C during 15 min and it was applied after the growth step of the biofilm formation.

2. In vivo safety studies

Microscopic and macroscopic analyses of the animals' lungs showed that the application of System of the invention did not damage the anatomical structures. 3. In vivo efficacy studies

The in vivo results of the efficacy of the system of the invention applied after the biofilm formation inside the endotracheal tube are shown in Figure 12.

The application of 3 shots of 42°C during 15 min against one P. aeruginosa (Pa1016 and Pa46) and one K. pneumoniae (Kp6) strains caused a decrease of the cell viability of more than 96%.

Claims

C L A I M S

1 A system for respiratory medical devices, the system comprising: a heat radiator (2) adapted to be fluidly coupled with a respiratory medical device, so as to raise the temperature of flow of air entering the respiratory medical device, wherein the heat radiator (2) is a metallic elongated body having first and second ends (2a, 2b), and a plurality of channels (4', 4) longitudinally extending along the body interior, and fluidly communicating the first and second ends (2a, 2b) for the passage of ventilation air from one end to the other end, the system further comprising at least one heating wire (21) coiled around the heat radiator (2) to heat air flowing through the channels (4).

2.- The system according to claim 1 , wherein one end (2a) of the heat radiator (2) is configured as a male connection tube, and the other end (2b) is configured as a female connection tube.

3.- The system according to claim 1 or 2, wherein one end (2a) is configured to be coupled with a source of ventilation air, and the other end (2b) is configured to be fluidly coupled with a respiratory medical device, preferably an endotracheal tube.

4.- System according to any of the preceding claims, wherein the heating wire (21) includes a first and second filaments connected in parallel, and wherein the first and second filaments are obtained from different metals or metals alloys.

5.- System according to claim 4, wherein the first filaments are obtained from an alloy such as a nickel-chromium alloy, and the second filaments are obtained from an alloy such as a nickel-aluminum alloy.

6.- System according to claim 5, wherein the first filaments are obtained from an 80120 nickel-chromium alloy.

7.- A system according to any of the preceding claims, further comprising at least one temperature sensor (10) thermally coupled with the heat radiator (2).

8.- A system according to any of the preceding claims, further comprising a temperature controller (11) operatively communicated with the temperature sensor (10) and with the heating wire (21) and adapted to maintain radiator (2) temperature within a desired temperature range.

9.- A system according to claim 8, wherein the temperate is within the range of 80 - 90 °C.

10.- A system according to claim 8 or 9, wherein the temperature controller (11) is adapted to maintain a temperature inside an endotracheal tube connected to the radiator (2), within the range of 37 - 50 °C, and preferably about 42 °C, in order to prevent biofilm formation inside the tube.

11 .- A system according to claim 8 or 9, wherein the temperature controller (11) includes a timer device adapted to activate the heating wire (21) during predefined time periods, and at predefined time intervals.

12.- A system according to claim 11 , wherein the time period is within the range 10 to 20 minutes and preferably about 15 minutes, and wherein the time interval is within the range 20 to 40 minutes, and preferably 30 minutes.

13.- A system according to any of the preceding claims, wherein the heat radiator (2) has a central channel arranged axially, and a set of channels circumferentially arranged around the central channel, and also extending longitudinally inside the radiator, such that the circumferentially arranged channels are parallel to the central channel.

14.- A system according to any of the preceding claims, wherein the heat radiator (2) has a cylindrical configuration.

15.- A system according to any of the preceding claims, further comprising a thermal insulation cover (3), such the heat radiator (2) and the heating wire (21) are enclosed inside the insulation cover (3).

16.- A system according to any of the preceding claims, further comprising electrically insulating sleeves, electrically isolating respectively the first and second filaments of the heating wire (21).

17.- A system according to any of the preceding claims, wherein the inlet and outlet (9a, 9b) of the channels (4', 4) have concave shape, preferably a cone shape.

18.- A method for preventing, or partially or completely removing, bacterial biofilm or biofilm-producing microorganisms, in a respiratory medical device, preferably an endotracheal tube, in a patient; the method comprising coupling the system comprising a heat radiator (2) adapted to be fluidly coupled with a respiratory medical device as defined in any of the preceding claims, with a source of ventilation air, on one end (2a), and on the other end (2b) fluidly coupling the system with the respiratory medical device, preferably an endotracheal tube, in the patient in need thereof, and maintaining a temperature inside the respiratory medical device, preferably an endotracheal tube, connected to the radiator (2), within the range of 37 - 50 °C, and preferably about 42 °C, during one or more predefined time periods, and at predefined time intervals, in order to prevent biofilm formation inside the tube and/or in order to partially or completely removing bacterial biofilm or biofilm-producing microorganisms.

19. The method of claim 18, wherein the bacterial biofilm is produced by 'ESKAPE¹ biofilm-producing microorganisms selected from any one of the list consisting of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.

20. The method of claim 18, wherein the biofilm-producing microorganisms are 'ESKAPE' biofilm-producing microorganisms selected from any one of the list consisting of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.

21. The method of any of claims 18 to 20, wherein the system comprises at least one temperature sensor (10) thermally coupled with the heat radiator (2), and further comprising a temperature controller (11) operatively communicated with the temperature sensor (10) and with the heating wire (21), wherein in the method the system is adapted to maintain radiator (2) temperature within the range of 37 - 50 °C, and preferably about 42 °C, during the one or more predefined time periods, and at the predefined time intervals.

22. The method of any of claims 18 to 21 , wherein the temperature controller (11) comprises a timer device adapted to activate the heating wire (21) during the predefined time periods, and at the predefined time intervals, wherein the time period is within the range 10 to 20 minutes and preferably about 15 minutes, and wherein the time intervals are within the range of every 20 to 40 minutes, and preferably every 30 minutes.

23.- A method for maintaining, regulating or increasing the core body temperature of a patient in need thereof connected or intubated with a respiratory medical device, preferably an endotracheal tube; the method comprising coupling the system comprising a heat radiator (2) adapted to be fluidly coupled with a respiratory medical device as defined in any of claims 1 to 17 with a source of ventilation air, on one end (2a), and on the other end (2b) fluidly coupling the system with the respiratory medical device, preferably an endotracheal tube, in the patient in need thereof, and maintaining a temperature inside the respiratory medical device, preferably an endotracheal tube, connected to the radiator (2), within the range of 37 - 50 °C, and preferably about 42 °C, during one or more predefined time periods, and at predefined time intervals, in order to maintain, regulate or increase the core body temperature of a patient in need thereof

24. The method of claim 23, wherein the system comprises at least one temperature sensor (10) thermally coupled with the heat radiator (2), and further comprising a temperature controller (11) operatively communicated with the temperature sensor (10) and with the heating wire (21), wherein in the method the system is adapted to maintain radiator (2) temperature within the range of 37 - 50 °C, and preferably about 42 °C, during the one or more predefined time periods, and at the predefined time intervals.

25. The method of any of claims 23 or 24, wherein the temperature controller (11) comprises a timer device adapted to activate the heating wire (21) during the predefined time periods, and at the predefined time intervals, wherein the time period is within the range 10 to 20 minutes and preferably about 15 minutes, and wherein the time intervals are within the range of every 20 to 40 minutes, and preferably every 30 minutes.