Technical Field

The present invention relates to a disposable active humidifier, particularly for inspiratory lines of respiratory circuits for intensive care. Background Art

It is known that in intensive-care wards, where the patient is ventilated artificially with a respirator, heated humidifiers are usually used which are placed along the inspiratory line and are capable of providing a level of humidity and heat that the upper air passages of the patient, having been bypassed, cannot ensure, in order to maintain ordinary mucociliary functions.

Currently commercially available humidifiers heat the gases supplied by the ventilator and load them with humidity; in order to ensure the sterility of the inspiration gases, the water that is ventilated for humidification is necessarily sterile.

However, despite the use of sterile water, sterility conditions are not maintained, since in conventional active humidifiers the gas becomes loaded with humidity by flowing over the water surface. With this arrangement, the aerobic bacterial loads present in the incoming gases necessarily contaminate the heating bath.

The particular environmental condition, with the presence of humidity and heat, is the ideal medium for the proliferation of bacterial loads. Furthermore, in addition to this type of contamination, the bath is also contaminated by means of

the condensation that forms along the line that connects the humidifier to the patient; this condensation acts as a vehicle for the bacterial loads that are present in the air expired by the patient. Accordingly, after a period of approximately two or three hours of operation, a very high concentration of bacterial loads forms inside the humidification chamber; these loads constitute a severe risk of cross-infections for the patient. With the conventional solutions, therefore, humidifiers are used which require the use of sterile water for their operation but do not allow to maintain sterility conditions. Disclosure of the Invention

A principal aim of the present invention is to eliminate the drawbacks described above by providing a disposable active humidifier for inspiratory lines of respiratory circuits for intensive care that allows to heat and humidify the gas without having to necessarily use a sterile bath but at the same time with the assurance that any bacteria that may be present in the humidification and temperature-control water are not transmitted to the flow of gas that is inspired.

Within the scope of the above aim, a particular object of the invention is to provide a disposable active humidifier which, by modifying the conventional criteria for humidifying the flow of gas, allows to reduce the bacterial level that is present in the inspired gas, at the same time simplifying all the control and checking operations.

Another object of the present invention is to provide a disposable active humidifier that allows more efficient and immediate temperature regulation, by virtue of the fact that the amount of water to be heated is reduced significantly with respect to the amounts of water used in conventional humidifiers.

Another object of the present invention is to provide a disposable active humidifier that does not require connection to the external supply but is provided as a unit which is already preset for the amount of water that is sufficient for its use even for a prolonged time.

This aim, these objects, and others which will become apparent hereinafter are achieved by a disposable active humidifier particularly for inspiratory lines of respiratory circuits for intensive care, which comprises a body provided with an inlet and an outlet for its connection along the inspiratory line and internally forming a chamber for the flow of the gases for the inspiratory line, characterized in that it comprises a hydrophobic membrane that forms at least one portion of the surface of said chamber; in that said body can be introduced by immersion in a water containment chamber at least at the region affected by said membrane, said membrane being adapted to allow the passage of water in molecular form in said gas flow chamber. Brief Description of the Drawings

Further characteristics and advantages will become apparent from the following detailed description of a preferred but not exclusive embodiment of a disposable active humidifier particularly for inspiratory lines of

respiratory circuits for intensive care, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is a schematic view of the active humidifier according to the invention; figure 2 is a perspective view of a first embodiment of the interchangeable cartridge that constitutes the gas flow body; figure 3 is a sectional view, of the cartridge of figure 2 taken along an axial plane; figure 4 is a sectional view, taken along a plane that lies at right angles to the sectional plane of figure 3; figure 5 is a view of a different embodiment of the cartridge, with the inlet and the outlet for the gases arranged so that they are mutually aligned and opposite; figure 6 is a sectional view of a cartridge, taken along the plane VI-VI of figure 5; figure 7 is a sectional view, taken along the plane VII-VII of figure 6; and figure 8 is a view of a different embodiment of the cartridge. Ways of carrying out the Invention

With reference to the above figures, the disposable active humidifier particularly for inspiratory lines of respiratory circuits for intensive care, according to the invention, comprises a cartridge, generally designated by the reference numeral 1, constituted by a cylindrical body 2 provided with an axially arranged inlet 3 and with a radially arranged outlet 4; said inlet and said outlet allow to connect the cartridge along an inspiratory line,

which is constituted for example by a gas inlet tube 5 and by an outlet tube 6 that is connected to the patient.

The body 2 internally forms a chamber 10 for the flow of the gases of the inspiratory line. An important particularity is constituted by the fact that the chamber 10 is formed by means of a hydrophobic membrane 11 that affects the lateral surface and is in practice supported by a cage-like grille 12 made of plastics that holds said membrane. A closed bottom plate, designated by the reference numeral 15, is provided at the bottom.

In a similar manner, as shown in figures 5 to 7, a cartridge is provided, designated by the reference numeral 1' , wherein the body 2' has a gas inlet 3' and a gas outlet 4 ¹ that are mutually aligned and opposite.

The body 2 or 2' , as shown in figure 1, is inserted in a water containment chamber 21 so that the membrane 11 is fully immersed in the liquid.

The chamber 21 is provided, in an upward region, with sealing gaskets 22 for engagement with the body 2 or 2' , as well as with an upper branching duct 23, where the container 24 for introducing the water is arranged.

This arrangement causes new water to be introduced in the chamber 20 when the liquid of the chamber drops below the level at which the branching duct 23 is arranged.

The container 21 is preferably made of heat-conducting material and it can be applied above a heater, generally designated by the reference numeral 30, to heat the water.

The hydrophobic membrane 11, of a commercially available type, is constituted by a membrane having

microscopic holes below a preset level and in practice allows the passage of water at the molecular level while preventing the passage of bacterial loads.

The membrane is arranged so as to affect the lateral surface of the gas flow chamber and is fully immersed in the liquid.

With this arrangement, the water containment chamber contains a very small volume of water, despite having a considerable surface of water in contact with the membrane, thus obtaining a considerable exchange surface with a limited volume of water that can accordingly be brought in a very short time to the temperature set by the thermostat- controlled heater.

In order to increase the exchange between the gases flowing into the inspiratory line and the membrane inside the gas flow chamber, there are flow channeling paths that can be provided, as shown in figures 1 to 4, by an axial air injection channel 40 that opens proximate to the bottom, so as to create a return channel 41 arranged coaxially and so as to flow over the membrane more easily.

It is important to point out the fact that in order to prevent accidental obstructions of the gas flow, which might occur if water forms in the gas flow chamber, longitudinal slits, designated by the reference numeral 42, are provided on the inlet channel and in any case form a passage for the flow of gases even in the presence of water.

According to a different embodiment, illustrated in figure 5, the channeling paths are obtained by means of a diametrical dividing wall 50 forming a descending channel

51 and an ascending channel 52 arranged side by side, each one affecting a portion of the membrane; said channels are connected at the bottom region of the cartridge, proximate to the bottom plate 15. In this case, too, to prevent obstruction of the gas flow if water is present inside the chamber 10, the dividing wall 50 is narrower than the diameter of the chamber, so that longitudinal slits 55 form which in any case allow the passage of the gas flow. The gas outlet duct 6 is advantageously provided with a heating system and is provided with a double-walled tube, in which the resistor is inserted in the interspace between the two walls, according to an embodiment disclosed in a copending patent application by the same Applicant. Therefore, with the above described arrangement, a single-use disposable cartridge is provided in which hu idification is performed by means of water that need not be sterile, since the membrane 11 constitutes a diaphragm for the passage of the bacterial loads, which accordingly cannot pass from the liquid to the gas. Furthermore, the wide available surface, in relation to a limited volume of water, allows to significantly reduce thermal inertia, thus achieving a more rapid response to temperature regulation and allowing to significantly increase the surface for contact between the air and the membrane, said surface allowing both to humidify the air and to heat it.

The invention thus conceived is susceptible of numerous modifications or variations, all of which are within the scope of the inventive concept. All the details may furthermore be replaced with other

technically equivalent elements.

Thus, for example, as shown in figure 8, the cartridge, now designated by the reference numeral 60, can have a body 2 with connectors 3 and 4 to which a bag-shaped hydrophobic membrane 61 is connected.

In practice, the materials employed, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements.