Patent Description:
In normal breathing, the upper airways contribute to heat and humidify the inspired air and to retain the heat and the humidity contained in the expired air, then to release them again during the subsequent inspiration.

During inspiration, environmental air is normally heated until reaching, at the level of the branching between the trachea and the bronchi, the "carina", <NUM> and fully saturated at <NUM>% until it contains <NUM> of water per litre of ventilated air.

In invasive mechanical ventilation, the upper airways of the patient are bypassed by the introduction of the tracheal tube. Consequently, the patient's lungs are reached by colder and drier inspired gases with respect to normal breathing without bypass. The normal exchange process (absorption and transfer of heat and humidity by the airways during breathing) is thus missed.

Prolonged exposure of the delicate pulmonary tissues and of the mucociliary epithelium to improperly conditioned ventilation gases can cause numerous problems, such as localised inflammation of the trachea, reduction of the cilia function, retention and thickening of secretions, lowering of the patient's body temperature, reduction of the cardiopulmonary function, increased risks of occlusion of the tracheal tube.

This drawbacks are remedied by preventively humidifying and heating the gases inspired by the patient.

Existing heating systems, traditionally used to condition the inspiratory gases, known as active humidifiers, all consists of a reusable electrical appliance containing all electric power systems and electronic temperature control systems and user interface and of a disposable system for channelling and conditioning the respiratory gases, consisting of a circuit of tubes and of a usually disposable chamber for containing the water to be heated, the so-called cartridge, in turn formed by a body made of plastic material having at least one metallic surface, usually made of aluminium.

A permanent electrical resistor contained in the reusable body of the active humidifier heats a temperature conducting metal element, usually made of steel, which is placed in contact with the metal surface of the disposable cartridge, positioned to rest thereon. The water contained in the disposable cartridge is then heated through the metal surface with which it is in direct contact.

The water heats and humidifies the residual volume of air contained in the disposable cartridge so that the inspiratory gases that traverse the disposable cartridge, which can be both alternating and constant, are channelled by the circuit, heated and humidified drawing the volume of residual gas already present in the cartridge itself and sent to the patient.

A series of temperature sensors positioned at the output of the disposable cartridge and at the end of the inspiratory tube, control the value of the temperature of the inspiratory gases and, consequently, regulate the value of energy which the electrical resistor immersed in the heating element supplies to the surface of the disposable cartridge to heat the water contained therein, which in turn transfers heat and humidity to the gases that traverse it, trying to maintain the value of temperature of the aforesaid gases at the value pre-set by the operator on the active humidifier.

In practice, the operator sets the desired temperature of the inspiratory gases on the active humidifier; the reusable electrical resistor contained in the active humidifier heats the reusable metallic element with which it is in contact; the metallic element of the active humidifier transfers by conduction the thermal energy to the metallic surface of the disposable cartridge; the metallic surface of the disposable cartridge is heated by the metallic element of the active humidifier; the heated metallic surface of the disposable cartridge in turn transfers, also by conduction, the thermal energy to the water contained in the cartridge; the hot water contained in the disposable cartridge transfers temperature and humidity to the residual volume of gas present in the cartridge itself; the tubes that channel the respiratory gases carry the cool, dry air coming from a source positioned upstream of the cartridge inside the cartridge itself; the water heated in the cartridge transfers temperature and humidity to the inspiratory gases that traverse it; the inspiratory gases, traversing the heated disposable cartridge, are then loaded with temperature and humidity, being conditioned to the value pre-set on the active humidifier; exiting from the disposable heating cartridge, the inspiratory gases are channelled to the patient; the temperature sensors positioned at the output of the disposable heating cartridge and in proximity to the respiratory tract of the patient, control the temperature values of the gases in order to reach and maintain the values set on the active humidifier.

Therefore, known active humidifiers are based on six heat conduction steps, in particular between the reusable electrical resistor and the reusable metallic element; between the metallic surface of the disposable cartridge and the water contained in the disposable cartridge; between the volume of residual gas in the disposable cartridge and the inspiratory gases that traverse the disposable cartridge.

Therefore, in known systems, the presence of multiple steps of transmissions-conductions of thermal energy, presents a series of problems, including the time required for the inspiratory gases to reach the set value of temperature and humidity; latency and the thermal flywheel once the set temperature value is reached; the "pendulum" effect of the various temperatures both to maintain the pre-set value and with changes in respiratory flows, which can be both alternating and constant, with different characteristics and performances of the active humidifier and related controls; the high quantity of electricity necessary to heat the entire system.

Moreover, in known active humidifiers, the expiratory gases coming from the patient can be subject to condensation during their exit path during which they are cooled. Therefore, it is necessary to manage this condensation because it could be contaminated by pathogenic microorganisms and create contamination.

conditions that are dangerous for the patient itself. <CIT> and <CIT> disclose an air humidifier according to the preamble of claim <NUM>. A further example of an air humidifier provided with a heating element comprised in the air chamber is disclosed in <CIT>.

The aim of the present invention is to provide an active humidifier and a thermoregulated circuit integrating said active humidifier that solve the technical problems indicated above.

Another aim of the present invention is to provide an active humidifier and a thermoregulated circuit integrating said active humidifier in which the electrical connections are made in a rapid and simple manner for the operators.

An additional aim of the present invention is to provide an active humidifier and a thermoregulated circuit integrating said active humidifier that can be directly interfaced at the input with a probe for measuring the patient's body temperature.

Another aim of the present invention is to provide an active humidifier and a thermoregulated circuit integrating said active humidifier that are particularly simple and functional, with low costs.

These aims according to the present invention are achieved by making an active humidifier as set forth in claim <NUM>.

Further features of the active humidifier and of the thermoregulated circuit integrating said active humidifier are set forth in the dependent claims.

The features and advantages of an active humidifier and of a thermoregulated circuit integrating said active humidifier according to the present invention will be more readily apparent from the following exemplifying and non-limiting description, referred to the schematic accompanying drawings, wherein:.

With reference to the figures, an active humidifier is shown, indicated in its entirety by the numeral <NUM>, along with a thermoregulated circuit indicated in its entirety by the numeral <NUM>, integrating said active humidifier <NUM>.

The active humidifier <NUM> comprises a disposable cartridge <NUM> comprising a humidification chamber <NUM> able to contain water to be heated for the humidification of the air, an inlet mouth <NUM> for air introduced by a ventilation device <NUM> and with an outlet mouth <NUM> for conditioned air to a patient.

The cartridge <NUM> comprises a disposable heating element <NUM> directly inserted inside the chamber <NUM> close to the bottom, immersed in the water contained in the cartridge itself and lapped on all sides. The disposable heating element <NUM> is, according to the invention, positioned on a plurality of support pegs <NUM>, which keep it distanced from the bottom.

The disposable heating element <NUM> is positioned on the plurality of support pegs <NUM>, which keep it distanced from the bottom for the purpose of facilitating the convective motion of the water molecules positioned on the bottom of the chamber <NUM> and in contact with the lower heating surface which, being hotter because:.

rise to the surface passing beyond the disposable heating element <NUM> mixing itself to the volume of water present in the upper part, raising its temperature and allowing better conditioning (heating and humidification) of the gas flow.

The disposable heating element <NUM> consists of a disposable electrical resistor <NUM>, preferably having planar development substantially equal to the diameter of chamber <NUM>.

The electrical resistor <NUM>, shown schematically in the section of <FIG> as a planar element, preferably consists of a metallic wire wound in a spiral covered by a thin layer of plastic material, such as silicone, not shown in the figures.

Two electrical contacts <NUM>' are provided, schematically shown in <FIG> and <FIG>, which put the electrical resistor <NUM> in contact with an electrical connector <NUM>.

According to a preferred embodiment of the invention, the electrical resistor <NUM> bears an integrated thermistor <NUM> able to keep monitoring its internal temperature, which must not exceed a predefined value to avoid the degradation of the coating made of medical silicone, and to verify any malfunctions.

The electrical connector <NUM> for the electrical connection of the resistor <NUM> contained in the disposable cartridge <NUM> projects in part from the wall of the chamber <NUM>.

The electrical resistor <NUM>, of appropriate power, assures the attainment of the temperature of the water necessary to supply adequate temperature and humidity to the gases inspired by the patient, also if high constant flows are used.

According to an embodiment of the invention, shown schematically in <FIG>, the electrical resistor <NUM> is overprinted with a film of medical grade silicone <NUM>, which provides a sealed external coating, to avoid the entry of water and to isolate the two electrical contacts <NUM>'.

According to an additional embodiment of the invention, shown schematically in <FIG>, the electrical resistor <NUM>, comprising the metallic wire coated with the thin layer of silicone, is coupled with aluminium foils <NUM>', preferably with thickness between <NUM> and <NUM>.

The aluminium foils <NUM>' are preferably fixed on the thin layer of silicone coating the metallic wire of the electrical resistor <NUM> for example by vulcanisation, so as to avoid the presence of layers of air between the resistor <NUM> and the aluminium foils <NUM>', which would disadvantageously act as a heat insulator.

The aluminium foils <NUM>', in the example shown, are two foils, substantially planar and with circular shape, respectively positioned above and below the electrical resistor <NUM>. The lower aluminium foil <NUM>' is planar and circular and the upper aluminium foil <NUM>' is shaped in the plane in a manner adapted to house the connector <NUM>; for example, it is cut around the connector <NUM>, which may integrate the thermistor <NUM>.

Alternatively, according to an embodiment not shown, the upper aluminium foil <NUM>' can be, similarly to the lower aluminium foil <NUM>', circular and so shaped as to form a seat able to house and cover the connector <NUM> which may integrate the thermistor <NUM>.

On the entire perimetric edge of the resistor <NUM> and on the two electrical contacts <NUM>' on the connector <NUM> a layer of sealing material <NUM>' is provided, for example medical silicone, to seal the resistor <NUM> and avoid the entry of water and to isolate the two electrical contacts.

In another example, shown in <FIG>, the aluminium in foils <NUM>' could configure a single pocket, obtained by drawing, to house the electrical resistor <NUM>, the inner part of the connector <NUM> and the thermistor <NUM>. In this configuration it is advantageously superfluous to apply an outer silicone seal, except possibly limited to the inlet portion to the chamber <NUM>.

According to an additional example, not shown, the thermistor <NUM> and possibly a portion of the connector <NUM> are embedded inside the electrical resistor <NUM> itself, i.e. in direct contact with the metallic wire under the thin layer of silicone coating the metallic wire.

The positioning of the thermistor <NUM> internal to the inner resistor <NUM>, i.e. internal to the thin layer of silicone that coats the metallic wire, allows an even more precise reading of the temperature of the heating element <NUM> and therefore it makes the heating element <NUM> more reliable.

The use of aluminium sheets <NUM>' as a coating of the disposable heating element <NUM> allows a sharply higher heat conduction than the coating with the medical-grade silicone film <NUM>.

In fact, the heat conduction of aluminium is <NUM>-W m-<NUM>·K-<NUM> versus approximately <NUM> W·m-<NUM>·K-<NUM> of the silicone used previously.

This allows a better heat conduction between the electrical resistor <NUM> and the water to be heated, considerably improving the effectiveness of the system, allowing the water to reach higher temperature with lower consumption of electrical power.

This obviously is due to the fact that the water is in direct contact, through the aluminium, with the heating element.

The humidification chamber <NUM> is a sealed case entirely made of plastic material. In fact, the disposable cartridge <NUM> according to the invention does not have a metallic outer contact surface.

The level of the water inside the humidification chamber <NUM> is controlled through a known float, not shown, which effects a hydraulic closure/opening on an inlet hole for the entry of the water <NUM>.

The active humidifier <NUM> further comprises two capacitive sensors to signal with an audible warning device any attainment of a minimum level and a maximum level of the water present inside the humidification chamber <NUM> and to signal any alarm in case of erroneous level.

The water contained in the cartridge <NUM> and in direct contact with the heating element <NUM> is rapidly heated. The residual volume contained in the disposable cartridge <NUM> is in turn rapidly heated by the water contained in the cartridge <NUM>. The inspiratory gases that traverse the residual volume of the cartridge <NUM> are rapidly heated and humidified.

From the above description it is evident that the entire system is based on only four heat conduction steps: disposable electrical resistor - water contained in the disposable cartridge - residual volume of gas in the disposable cartridge - inspiratory gases that traverse the disposable cartridge.

The active humidifier <NUM> according to an embodiment of the invention comprises a control and power supply unit <NUM> of the cartridge <NUM>, preferably provided with a user interface panel <NUM>, for displaying and setting the operating parameters of the active humidifier <NUM>.

The control and power supply unit <NUM> of the cartridge <NUM> further comprises a housing seat <NUM> of the cartridge <NUM>, provided with an electrical connector <NUM> for the electrical connection of the electrical resistor <NUM>, able to house the electrical connector <NUM> of the cartridge <NUM>.

The control and power supply unit <NUM> of the cartridge <NUM> further comprises, according to what is shown, an on/off switch <NUM>, a connector for connection with the electrical grid <NUM>, an additional electrical connector <NUM> able to house other electrical connectors, for example those for supplying power to the circuit <NUM>, as well as a USB plug <NUM> for example to update the firmware containing the control programmes of the active humidifier <NUM> and the download of the operating data.

In the active humidifier <NUM> according to said embodiment of the invention, the control and power supply unit <NUM> of the cartridge <NUM> lacks heating elements, such as a reusable heating electrical resistor or a reusable heating metallic element.

The function of the control and power supply unit <NUM> of the cartridge <NUM> is only to regulate the electrical energy necessary to heat the water contained in the disposable cartridge <NUM>. This function, according to an alternative form of the active humidifier <NUM> of the invention, can be carried out by a system external to the humidifier itself.

The control and power supply unit <NUM> of the cartridge <NUM> also has the function of positioning of the disposable cartridge <NUM>. This function, according to an alternative form of the active humidifier <NUM> of the invention, can be carried out by a dedicated system external to the humidifier itself.

The control and power supply unit <NUM> of the cartridge <NUM> also has the function of electrically connecting the reusable electrical resistor <NUM> positioned inside the disposable cartridge <NUM>. This function, according to an alternative form of the active humidifier <NUM> of the invention, can be carried out by a dedicated normal separate electrical connection.

According to the present invention, the active humidifier <NUM> is integrated in a thermoregulated circuit <NUM> for the ventilation of a patient.

The thermoregulated circuit <NUM> comprises a first tube <NUM> for the introduction of air from the ventilation device <NUM>, connected to the air inlet mouth <NUM> of the cartridge <NUM>. The air that transits through this tube, not conditioned, generally has an ambient temperature between <NUM> and <NUM>.

The thermoregulated circuit <NUM> also comprises an inspiration tube <NUM> connected at a first end thereof to the conditioned air outlet mouth <NUM> of the cartridge <NUM> by means of a first fitting <NUM> and connected at an opposite end thereof to a respiratory patient interface Y-fitting <NUM>.

The inspiration tube <NUM> is provided with a wire electrical resistor <NUM> arranged along its entire longitudinal development and with a first thermistor <NUM>, positioned in proximity to the outlet of the cartridge <NUM>, and a second thermistor <NUM>, positioned in proximity to the connection with the patient, respectively arranged at opposite ends of the inspiration tube <NUM>. The power delivered to the wire resistor <NUM> is managed by the thermistor <NUM> positioned in proximity to the connection with the patient.

The thermoregulated circuit <NUM> further comprises an expiration tube <NUM>, connected at a first end to the respiratory interface Y-fitting <NUM> and provided with a wire electrical resistor <NUM> arranged along its entire longitudinal development. The opposite end of the expiration tube <NUM> is connected to the ventilation device <NUM>. The air expired by the patient into the expiration tube <NUM> through the Y fitting <NUM> has a temperature of approximately <NUM> while at the output from the expiration tube <NUM> it was heated to maintain an equal or higher temperature value.

According to the invention, the respiratory interface Y fitting <NUM> comprises a connector <NUM> for the connection and acquisition of a patient temperature probe <NUM> of a known, standardised type, shown schematically in <FIG>.

Such temperature probes, which have long been on the market and used daily in critical areas of hospital wards, constantly measure the patient's body temperature. Such probes can be positioned in the oesophagus, in the pulmonary artery, in the bladder or in the eardrum and they are provided with a standardised connector.

The continuous acquisition by the active humidifier <NUM> of the patient's body temperature through direct connection with a patient temperature probe <NUM> is used to perform an automatic control of the operation of the active humidifier <NUM>, automatically adapting it to changes in the patient's body temperature, providing ideal inspiratory gases, proportionate to aforesaid temperature changes, improving the patient's respiratory comfort.

Into the first fitting <NUM> merge, according to the invention, a pair of wires of the electrical resistor <NUM>, a pair of wires for each of the two thermistors <NUM> and <NUM> and a pair of wires, not shown in <FIG>, of the connector <NUM> of the patient temperature probe <NUM>. A printed circuit board (PCB) connector <NUM>, integrated in the first fitting <NUM> of the inspiration tube <NUM>, provides for the electrical power supply of the resistor <NUM>, the acquisition of the thermistors <NUM>, <NUM> and the acquisition of the patient temperature probe <NUM> associated with the inspiration tube <NUM>.

In particular, the thermistor <NUM> is placed at the centre of the flow of the inspiratory gases, in the outlet fitting <NUM> for the outflow of the gases from the cartridge <NUM>.

The welding of the thermistor <NUM> and of its pair of wires on the PCB connector <NUM> assures the same positioning of the temperature sensor on each individual thermoregulated circuit <NUM> produced.

The reading carried out by said thermistor <NUM> assures the perfect regulation of the power supplied and to be supplied to the electrical resistor <NUM> positioned inside the humidification chamber <NUM>, in order to maintain constant the value of temperature of the water as the flow of gas that traverses it changes, and consequently the value of temperature of the gases supplied to the patient.

The function of the second thermistor <NUM> positioned in proximity to the patient connection is to control and modulate the power supplied to the resistor <NUM> positioned inside the inspiration tube <NUM>. The aim of said resistor <NUM> is to keep constant and/or to regulate the temperature of the air flowing out of the cartridge <NUM> and therefore to prevent the formation of condensation inside the inspiration tube <NUM> which is caused by the temperature drop during the travel from the cartridge <NUM> to the patient.

The expiration tube <NUM> is connected at the opposite end to a second fitting <NUM> connectable to the ventilation device <NUM>.

Into the second fitting <NUM> merges a pair of wires of the electrical resistor <NUM>, which are supplied with electrical power through a printed circuit board (PCB) connector <NUM>, integrated in the second fitting <NUM> of the expiration tube <NUM>.

The function of the electrical resistor <NUM> positioned inside the expiration tube <NUM> is to prevent the formation of condensation inside this part of the circuit as well. Considering that the temperature of the gases expired by the patient is approximately <NUM>, practically constant, it is possible to avoid control on the power of said resistor <NUM>, also considering that heating the air inside the expiration tube <NUM> at higher values than those inspired does not entail any problem, since the tube is downstream of the patient.

The active humidifier <NUM> and the related thermoregulated circuit <NUM> is intended for adult, pediatric and neonatal patients.

The active humidifier <NUM> and the related thermoregulated circuit <NUM>, according to the invention, is used to assure the humidification of inspiratory gases in intubated patients or in NIV (Non-invasive Ventilation), with both alternating and constant flows through the use of interfaces such as helmets, masks or high flow cannulas and it is advantageously designed to be used in intensive care units and in all hospital and non-hospital environments, including homes.

The active humidifier and the thermoregulated circuit integrating said active humidifier of the present invention has the following advantages:.

Another advantage of the active humidifier and of the thermoregulated circuit according to the invention is the possibility of executing an automatic feedback on the basis of the body temperature of the patient acquired by the system.

In fact, it is well known that the body temperature of a patient can change several times within the same day. To changes in the body temperature of the patient corresponds a different quantity of temperature and humidity released in the expired gases by the patient itself. Therefore, to a change in the body temperature of the patient, corresponds a change in the temperature and humidity expired and hence relinquished/lost.

The ability to condition the inspiratory gases in a manner that is automatic and dependent on the value of the patient's body temperature and of its changes with immediacy offers advantages, for example for the comfort of the patient him/herself and greater practicality for health care operators who are forced to make small temperature changes of the active humidifier as body temperature changes.

Claim 1:
Active humidifier comprising a disposable cartridge (<NUM>) provided with a humidification chamber (<NUM>) adapted to contain a volume of water and a residual volume of gas to be heated for air humidification of the inspiratory gases traversing the disposable cartridge (<NUM>), with an inlet mouth (<NUM>) for air to be introduced in the chamber (<NUM>) by a ventilation device and with an outlet mouth (<NUM>) for conditioned air exiting the chamber (<NUM>) to a patient, the humidification chamber (<NUM>) being a sealed casing entirely made of plastic material, the humidification chamber comprising a bottom with a plurality of support pegs,
wherein said cartridge (<NUM>) comprises a disposable heating element (<NUM>) comprising an electrical resistor (<NUM>), said cartridge (<NUM>) comprising also an electrical connector (<NUM>) for the electrical connection of the disposable heating element (<NUM>), characterised in that the disposable heating element (<NUM>) is positioned on the plurality of support pegs (<NUM>), such that the plurality of support pegs keep it distanced from the bottom inside the humidification chamber (<NUM>), immersed in the water and lapped on all sides by water.