WO2008113424A1 - Respirator - Google Patents

Abstract

The invention relates to a respirator having a feed device (2, 4) for feeding inspiration air to a patient, a removal device (3, 5) for removing expiration air from patients, and at least one moisture meter (1) for determining the moisture of the inspiration air fed to the patient and/or the expiration air removed from the patient, wherein the moisture meter comprises a condensation surface, means are provided for adjusting the temperature of the condensation surface, and an optical verification device is provided for determining the condensation state of the condensation surface.

Description

 Beatmunqsqerät

The invention relates to a ventilator with the features of the preamble of claim 1. Such a ventilator is designed with a supply device for supplying inspiratory air to a patient, a discharge device for discharging expired air from the patient and at least one moisture measuring device for determining the moisture supplied to the patient Inspiratory air and / or patient exhaled air.

Mechanical ventilation plays an important life-sustaining role in intensive care, anaesthesiology and emergency medicine. For mechanical ventilation mechanical ventilators with a supply line and a discharge line for breathing gas are known, which open into a tube, a mask or a cannula, in particular an endotracheal tube.

For mechanical ventilation, especially over a longer period of time, the humidity regime must be observed. During normal breathing, the mucous membrane of the respiratory tract on the way to the lung periphery releases so much water and heat to the inspiratory air that the air in the alveoli arrives body-warm and saturated with water vapor and, in particular, an isothermal saturation state prevails. This air conditioning of the respiratory air takes place predominantly in the upper airways, ie in the nose and in the naso-acrary. In contrast, the absolute humidification or warming capacity of the lower airways is rather low.

During expiration water and heat exchange are in the opposite direction. Since the mucous membranes have cooled due to evaporation during inspiration, moisture is now condensed on the mucous membrane, recovering some of the moisture and heat inspiratory to the breath. The breath-induced water and heat losses are thereby reduced. Due to the comparatively high temperature This process is most effective in the area of the nasal cavity. On average, an adult at rest loses approximately 250 ml of water per day during normal breathing of room air, which can increase the loss of water during exercise and high volumes of breathing.

Mechanical ventilation by means of a breathing tube usually involves bridging the upper respiratory tract, in which the respiratory air is moistened, heated and cleaned. Due to the bridging of the upper airways associated with intubation, their respiratory air conditioning function is at least partially switched off. The warming and moistening of the respiratory gases shifts in the direction of the lung periphery and thus into areas which are only limitedly suitable for the heat and moisture exchange. This may be associated with an increase in the loss of water due to evaporation from the lower airways compared to the conditions of nasal breathing.

If the increased water loss were not counteracted, the mucous membranes could become dehydrated and disorders of the mucociliary clearance function could occur. Prolonged exposure to dry and cold respiratory gases can lead to detectable morphological damage to the ciliary, mucous and epithelial cells, as well as profound changes in the basement membrane. Bacterial colonization is facilitated under these conditions, with patients with prominent pulmonary diseases being particularly at risk. Damaged epithelium can only contribute to humidification and warming to a limited extent, so that the isothermal saturation limit would be shifted ever further towards the small airways.

This may be accompanied by measurable changes in pulmonary parameters, such as decreased functional residual capacity and compliance, increased resistance, and pulmonary gas exchange limitations. The severity of these changes is time-dependent and the greater the lower the water content of the inspiratory air. In addition to the formation of dystelectasis and atelectasis by secretion retention in the airways Tubusokklusionen are particularly feared by tough secretions, as they can threaten the patient vital.

It is therefore necessary to take measures for the air conditioning of the respiratory gases immediately after the intubation, especially since medical gases from compressed gas cylinders or central As a rule, gas supply systems only have a very low moisture content. The Atemgasklimatisierung suitably takes place both by heating and by moistening the supplied gas. The Atemgasklimatisierung allows to avoid disturbances of the mucociliary clearance function.

In order to monitor the breathing gas air conditioning, the temperature of the exhaust gas is generally measured. In any case, humidity measurements in the supply air or exhaust air flow were also carried out on a laboratory scale.

For moisture measurement, for example in the respiratory air flow, capacitive humidity sensors are known. Such capacitive humidity sensors usually work passively and measure the relative humidity. Although capacitive humidity sensors can be manufactured at reasonable prices, their reliability can be limited in the saturation range. Since the air-conditioned breathing air used for ventilation is usually almost saturated, the usefulness of capacitive humidity sensors in breathing air measurement may be associated with limitations. There have therefore been attempts to heat a capacitive sensor, thus leaving the saturation region. A corresponding sensor is described in EP 0 778 941 B1.

In addition, the long-term stability of capacitive humidity sensors, even in the non-saturation region, may be limited, requiring frequent recalibration, which is undesirable in routine clinical use. In addition, capacitive humidity sensors can be comparatively sensitive to soiling and can no longer be used for a prolonged period of time when condensation starts, so that under certain circumstances unwanted incorrect measurements can occur.

A humidity sensor for medical ventilators, which is based on the measurement of infrared absorption in the gas, is known from EP 0 762 107 A1.

It is an object of the invention to specify a ventilator with which a reliable and accurate monitoring of the moisture content of the respiratory air can be realized with a particularly low cost.

The object is achieved by a ventilator with the features of claim 1. Preferred embodiments are given in the dependent claims. , ,

The ventilator according to the invention is characterized in that the moisture measuring device has a condensation surface, means for adjusting the temperature of the condensation surface and an optical detection device for determining the condensation state of the condensation surface.

A basic idea of the invention can be seen in the optical determination of the determination of the humidity in the respiratory air of the ventilator. For this purpose, the moisture measuring device on a condensation surface, which is in contact with the air flow to be measured. The temperature of the condensation surface is selectively varied and this changes the Betauungszustandes, in particular the onset of condensation or the evaporation of condensate, brought about. These changes in the state of condensation are detected optically, for example as a change in the reflectivity of the condensation surface. From the temperature at which the Betauungszustand changes, can be deduced the dew point temperature, from which in turn the humidity, in particular the absolute humidity and / or the relative humidity can be determined. It has been found that with such an optical moisture measuring device at low cost, a particularly high accuracy, a particularly high long-term stability and a particularly high reproducibility with low hysteresis or memory effect can be obtained. Moreover, a particularly large measuring range can be achieved with an optical moisture measuring device, which is particularly suitable for measuring in the saturation-near humidity range and / or at low dew point temperatures. Condensation is systemic in a moisture measuring device according to the invention and leads, in contrast to capacitive moisture measurement, no negative effects. Also, no adjustment under moisture is usually required and a simple visual function test is possible. The moisture measuring device according to the invention allows the implementation of a primary measurement method in which the absolute humidity is determined. This measure is independent of the gas composition and the ambient pressure.

According to the invention, it is particularly preferred that the supply device has a humidifying device for the supplied inspiration air. This can be counteracted unwanted loss of water during ventilation. The moistening device can be designed, for example, as an active moistening device, in particular as a nebulizer, evaporator and / or bubbler. The invention - -

A proper humidity measuring device can be provided for monitoring the function of the moistening device.

A particularly high degree of reliability in humidification is provided according to the invention in that the humidifying device is a passive humidifying device, with which humidity from the expired air can be stored and the stored humidity of the subsequently supplied inspiratory air can be supplied. A passive moistening device may, in particular, be understood as meaning a moistening device which is independent of external energy sources and / or water reservoirs. Such a passive humidifier may also be referred to as a Heat and Moisture Exchanger (HME). Such a Heat and Moisture Ex changer removes heat and moisture from the exhaled air of the patient, stores them reversibly in the inner material and feeds them into the respiratory air during the subsequent inspiration process. A moisture measuring device according to the invention makes it possible to check the performance of the passive humidifying device in a particularly simple and accurate manner. In particular, the moisture measuring device for determining the residual moisture of the expiratory air dehumidified by the passive humidifying device can be provided for this purpose. For this purpose, the moisture measuring device is suitably arranged downstream of the passive moistening device. A low moisture content of the expired air can be seen as an indication of a satisfactory Atemgasklimatisierung.

In principle, it is possible to irradiate the condensation surface with light through the measurement gas and, for determining the condensation state, to detect the light intensity reflected back into the measurement gas. However, such a so-called Tauspiegelanordnung may be relatively susceptible to Meßgasverunreinigungen, such as dust and aerosols, because these impurities can get into the beam path and thus can influence the used to detect the condensation, reflected back light intensity. It is therefore particularly preferred for the condensation surface to be arranged on an optical waveguide, and for the optical detection device to have a light source for emitting light through the optical waveguide onto the condensation surface and a light receiver for determining the light reflected back from the condensation surface into the optical waveguide. In this embodiment, the measuring beam path runs in the interior of the optical waveguide and the internal reflection, in particular , ,

Total reflection, of the light on the condensation surface used to demonstrate the condensation. This embodiment is based on the finding that, as the condensation surface changes, the proportion of light radiated internally onto the condensation surface, which is coupled out of the waveguide into the environment, changes. Correspondingly, the light intensity reflected back into the optical waveguide changes, so that this intensity represents a measure of the condensation.

Since, in the case of a moisture measuring device based on the principle of internal reflection, the reflected measuring beam path does not run through the measuring gas but through the optical waveguide on the side of the condensation surface facing away from the gas, this arrangement is comparatively insensitive to contamination in the measuring gas. Moreover, such an arrangement allows a particularly compact design, since the light source and the light receiver in the immediate vicinity of the condensation surface, in particular directly on the optical waveguide, can be attached without a passage for the sample gas must be given between them. The compact, in particular modular design in turn allows a particularly simple arrangement on the supply line or discharge line of the feeder or the discharge device of the ventilator. Moreover, in the detection device based on the principle of internal reflection, only the condensation surface must be in communication with the measurement gas, while the light source and the light receiver can be arranged at a distance from the measurement gas on the rear side of the optical waveguide facing away from the condensation surface. This makes it possible to seal the components of the moisture measuring device, in particular the light source and the light receiver, in a particularly simple manner with respect to the sample gas, so that a particularly high corrosion resistance is achieved.

In particular, all electronic and optical components can be arranged in a particularly simple manner in a housing. Since only the condensation surface must be open, a particularly simple cleaning of the moisture meter is given.

For a particularly simple design, the condensation surface is suitably flat. The optical waveguide is preferably at least approximately plate-like. shaped and / or cuboid shaped. Preferably, the optical waveguide is made of glass. The optical waveguide may be coated on the condensation surface. For example, a passivation layer of silicon dioxide may be provided on the condensation surface.

Especially with regard to the signal evaluation, it is particularly advantageous that the light source, a light beam in the optical waveguide is generated whose angle of incidence on the condensation surface between the critical angle of the transition optical fiber / air and the critical angle of the transition optical fiber / water. In such an arrangement, when the condensation surface is dry, total internal reflection of the light irradiated internally to the condensation surface occurs. On the other hand, as soon as condensate settles on the condensation surface, part of the incident light is coupled out of the optical waveguide and the light intensity reflected back to the light receiver decreases.

For a particularly high measuring accuracy, the condensation surface is suitably semi-hydrophobic, semi-hydrophobicity being understood in particular in the sense of the publications WO2006 / 015734A1 and / or DE102004038397B.

With regard to the measurement accuracy, it is also advantageous that the light source and the light receiver are arranged so that the light emitted by the light source reaches the light receiver after multiple internal reflection in the optical waveguide. For this purpose, for example, the distance between the light source and the light receiver significantly larger, in particular by at least an order of magnitude greater than the thickness of the optical waveguide are selected perpendicular to the condensation surface.

The cost of the humidity measuring device can be further reduced with particularly high reliability, characterized in that the means for adjusting the temperature of the condensation surface are formed as a Peltier element. Suitably, this Peltier element is arranged centrally between the light source and the light receiver.

Preferably, the Peltier element is arranged on the one hand on the light guide and on the other hand on a housing of the moisture measurement device. In this case, the heat dissipation from the Peltier element can be done through the housing. With regard to the heat , ,

It is particularly advantageous that at least the housing parts in contact with the Peltier element are made metallic. For example, copper, in particular nickel-plated copper, and / or aluminum, in particular cast aluminum, may be used as the metal material.

During operation of the ventilator according to the invention, the inspiratory air temperature is typically set at about 3 ° C below body temperature, that is about 34 ° C. The moisture content of the inspiratory air must not be less than 33 mg / l according to ISO 8185, which corresponds to a dew point temperature of at least 32 ° C. This means that in normal operation, the dew point distance must not exceed -2 °. The maximum temperature for the inspiratory air is typically 42 °. The metrologically relevant temperature range thus extends from 32 ⁰ C to 42 ° C. The cooling / heating power, which must be provided by the means for adjusting the temperature, in particular by the Peltier element, is thus generally about +/- 5 ° C. The cooling surface required for heat dissipation of the Peltier element can thus be made comparatively small.

For particularly accurate dew point and thus moisture determination, it is advantageous that the moisture measuring device has a surface temperature sensor for determining the temperature of the condensation surface. This sensor is suitably arranged on the condensation surface and in particular has a temperature-dependent conductor. By way of example, the surface temperature sensor may have a temperature-dependent conductor layer which is applied to the condensation surface, for example vapor-deposited.

A particularly reliable moisture determination is provided by the fact that the moisture measuring device has a controller which is adapted to vary the temperature of the condensation surface by means of the means for adjusting the temperature of the condensation surface to detect a change in the condensation state of the condensation surface by means of the optical detection means, the temperature to determine the condensation surface at which the change in the Betauungszustandes has occurred, and to determine the moisture from this temperature. In order to determine the moisture, in particular the relative moisture content, from the stated temperature, further measured variables, such as, for example, the sample gas temperature, can be used. , ,

For a particularly meaningful monitoring of the ventilation and / or for a particularly high precision in the determination of the humidity, in particular the relative humidity, it is advantageous for the humidity measuring device to have a gas temperature sensor for determining the temperature of the air flowing past the humidity measuring device. The gas temperature sensor and the optical waveguide preferably form a unit and / or are arranged on a common housing. In particular, the gas temperature sensor can be arranged on the optical waveguide, for example, next to the condensation surface. However, the temperature sensor may also be formed protruding with respect to the condensation surface, so that it projects into the respiratory gas flow. The gas temperature sensor may, for example, have a temperature-dependent conductor. In particular, a temperature-dependent conductor layer can be provided, which is arranged on the optical waveguide. In this case, the gas temperature sensor may also be referred to as a layer sensor. The temperature-dependent conductor may, for example, comprise platinum.

A structurally particularly simple arrangement is provided in that at least part of the moisture measuring device is arranged on a line of the feed device or the discharge device. The pipe may be, for example, a pipe or a hose. In particular, if the line is designed as a disposable part which is intended for single use, it is advantageous that the moisture measuring device is arranged detachably on the line. For a detachable connection, the moisture measuring device may be arranged, for example, positively and / or flush on the line. In particular, the moisture measuring device can be arranged by means of a sliding closure and / or by means of a snap closure on the line. Suitably, the moisture measuring device is designed so that it can be snapped and / or pushed directly from outside on the line. A detachable arrangement allows the reuse of the moisture meter.

For a particularly simple structural design, it is also advantageous that the line for a gas connection of the condensation surface with the interior of the conduit in its jacket has a passage opening.

In addition to a respirator, the invention also encompasses the use of the moisture measuring device described here for determining the humidity of a patient. _ _

th by means of a ventilator supplied inspiratory air and / or exhaled by the patient exhaled air. The invention further comprises the described humidity measuring device for use in a ventilator.

The invention will be explained in more detail below with reference to preferred embodiments, which are shown schematically in the accompanying drawings. In the drawings show schematically:

1 shows an inventive ventilator with a moisture measuring device.

FIG. 2 is a sectional view of the humidity measuring device of FIG. 1; FIG.

FIG. 3 is a sectional detail view of the moisture measuring device of FIG. 2; FIG.

4 is a side view of the housing of the moisture measuring device of FIG.

2;

Fig. 5 is an end view of the moisture measuring device of Fig. 2;

6 shows a side view of the moisture measuring device from FIG. 2 for the representation of holding elements for holding the moisture measuring device on a line;

FIGS. 7 and 8 are front views of two differently mounted moisture measuring devices;

FIG. 9 shows a plan view of the moisture measuring device from FIG. 2 from below; FIG. and

10 is a plan view of a further embodiment of a moisture measuring device according to the invention from below.

Like-acting elements are identified by the same reference numerals in the figures.

An embodiment of a ventilator according to the invention is shown schematically in FIG. The ventilator has a delivery device 2 with a line 4 for supplying breathing air to a patient and a discharge device 3 with a line 5 for discharging breathing air from the patient. The lines 4 and 5 _, _

open into a tube 6, which is intended for insertion into the trachea of the patient.

The lines 4, 5 are arranged on a ventilator 7, which supplies breathing air to the line 4 and removes breathing air from the line 5.

On the line 4 of the feeder 2, a humidifying device 8 is provided for enriching the incoming air from the fan 7 with moisture. In the illustrated embodiment, a humidifier 1 is further provided on the line 4 downstream of the humidifier 8, to control the moisture content of the incoming air following the humidification.

The moisture measuring device 1 is shown in Fig. 2 and in particular in Figures 3 and 9 in detail. It has an optical waveguide 11 in the form of a planar glass plate, on which a condensation surface 10 is formed. This condensation surface 10 is in fluid communication with the measuring gas flowing in the interior of the conduit 4 via a passage opening 20, which is formed in the jacket of the conduit 4. In order to prove the condensation state of the condensation surface 10, an optical detection device 16 is provided which has a light source 17 configured as a light-emitting diode and a light receiver 18 designed as a photodiode. Light source 17 and light receiver 18 are arranged on the side of the optical waveguide 11 facing away from the line inside and thus away from the measurement gas. By means of the light source 17, a light beam can be generated which falls through the optical waveguide 11 on the condensation surface 10, depending on the Betauungszustand the condensation surface 10 is reflected back into the optical waveguide 11 and finally detected by the light receiver 18.

Centered between the light source 17 and the light receiver 18 are formed as a Peltier element means 13 for adjusting the temperature of the condensation surface 10 is provided. The formed as a Peltier element means 13 lie on the condensation surface 10 facing away from the back of the optical waveguide 11 on the optical waveguide 11, so that via the optical waveguide 11, a thermal coupling between the condensation surface 10 and the means 13 is given.

The light source 17 and the light receiver 18 are arranged on a common printed circuit board 31, on which further electronic components 34, in addition _ _

For example, for signal processing, are provided. On the circuit board 31, a cable 32 is connected to the measured value output.

The condensation surface 10 is semi-hydrophobic and has a silicon dioxide passivation coating. The condensation surface 10 is suitably smooth, that is, in particular, its roughness is less than the wavelength of the light.

On the circuit board 31 of the humidity measuring device 1, a gas temperature sensor 25 is further provided, which protrudes from the humidity measuring device 1 and extends into the interior of the conduit 4. By means of this gas temperature sensor 25, the temperature of the flowing past the condensation surface 10 gas can be determined.

As shown particularly in FIG. 9, a surface temperature sensor 21 is provided on the surface of the optical waveguide 11 in the vicinity of the condensing surface 10. This surface temperature sensor 21 is formed by a temperature-dependent conductor, which is applied as a layer on the surface of the optical waveguide 11 and surrounds the condensation surface 10 in a U-shape. By means of this surface temperature sensor 21, the temperature of the condensation surface 10 can be determined.

The circuit board 31 together with the light source 17, light receiver 18 and electronic components 34 and the means 13 for adjusting the temperature of the condensation surface 10 are housed in a housing 40. This housing 40 has a first housing part 41, which closes off the moisture measuring device 1 on the rear side facing away from the condensation surface 10. This first housing part 41 is metallic. It has a projection 45 which projects into the interior of the housing and adjoins the means 13 configured as a Peltier element for adjusting the temperature of the condensation surface 10. As a result, a thermal coupling between the metallic first housing part 41 and the means 13 formed as a Peltier element is provided, so that the first housing part 41 can serve as a temperature sink.

The housing 40 further has a ring-like, second housing part 42, in which the first housing part 41 is embedded and which is adjacent to the underside of the optical waveguide 11. The second housing part 42 is made of plastic. _ _

An attachment of the moisture measuring device 1 to the line 4 is shown in Figures 4 to 6. For fastening, therefore, grooves 47, 47 'running parallel to the line 4 are provided on the second housing part 42 of the housing 40 of the moisture measuring device 1. On the line 4, two snap elements 48, 48 'are arranged, which protrude transversely to the line path from the line 4. These flexible snap elements 48, 48 'each have a nose 49, 49', which in each case in one of the grooves 47, 47 'can engage and secure the housing 40 on the pipe 4 formed as a pipe.

Other different mounting options are shown in Figures 7 and 8. In the embodiment of Fig. 7, the housing 40 is secured by means of a sliding connection to a base member 53 which projects from the conduit 5, in the present embodiment, the discharge device 3. In the embodiment of FIG. 8, the housing 40 has a concave, cylinder-segment-shaped recess, so that the housing 40 can cling to the jacket of the line 5.

Fig. 10 shows another embodiment of a humidity measuring device 1. Compared with the embodiment of Fig. 9, in which a protruding gas temperature sensor 25 is provided, which projects into the interior of the conduit 4, the gas temperature sensor 26 is in the embodiment of FIG Given temperature-dependent conductor, which is provided as a vapor-deposited layer on the optical waveguide 11.

The humidity measuring devices 1 shown in the figures can be arranged both on the line 4 of the feed device 2 and on the line 5 of the discharge device 3. The specified lines are therefore only to be regarded as examples.

The ventilator according to the invention is preferably provided for the active, external ventilation of the patient and for this purpose suitably comprises a pumping device for the air. In principle, however, the ventilation device can also be designed as a pure measuring device for the air humidity, in particular the expired air, in which the air flow is caused by the natural breathing activity of the patient.

Claims

claims 1. Ventilator with a delivery device (2) for supplying inspiratory air to a patient, - An expelling means (3) for discharging expired air from the patient and at least one moisture measuring device (1) for determining the humidity of the inspiratory air supplied to the patient and / or the expired air discharged by the patient, characterized - that the moisture measuring device (1) has a condensation surface (10), - That means (13) for adjusting the temperature of the condensation surface (10) are provided and - That an optical detection device (16) for determining the Betau- ungszustandes the condensation surface (10) is present. 2. The ventilator according to claim 1, characterized in that the supply device (2) has a humidifying device (8) for the supplied inspiration air. 3. The ventilator according to claim 2, characterized in that the moistening device (8) is a passive moistening device, with which humidity from the expired air storable and the stored moisture of the subsequently supplied inspiration air can be fed. , , 4. The ventilator according to claim 3, characterized in that the humidity measuring device (1) is provided for determining the residual moisture of the expiration air dehumidified by the passive humidifying device. 5. The ventilator according to one of the preceding claims, characterized in that: - That the, preferably flat, condensation surface (10) on an optical waveguide (11) is arranged, and - That the optical detection means (16) comprises a light source (17) for emitting light through the optical waveguide (11) on the condensation surface (10) and a light receiver (18) for detecting the from the condensation surface (10) in the optical waveguide (11 ) having reflected light back. 6. The ventilator according to claim 5, characterized in that the light source (17) is a light beam in the optical waveguide (11) can be generated whose angle of incidence on the condensation surface (10) between the critical angle of the transition optical fiber / air and the critical angle of the transition fiber optic / Water is lying. 7. The ventilator according to one of claims 5 or 6, characterized in that the light source (17) and the light receiver (18) are arranged so that the outgoing light from the light source (17) the light receiver (18) after multiple internal reflection in Fiber optic cable (11) reached. 8. The ventilator according to one of the preceding claims, characterized in that the means (13) for adjusting the temperature of the condensation surface (10) are formed as Peltier element, which in particular between the light source (17) and the light receiver (18) is arranged. _ _ 9. The ventilator according to claim 1, characterized in that the moisture measuring device (1) has a surface temperature sensor (21) for determining the temperature of the condensation surface (10). 10. The ventilator according to claim 1, characterized in that the humidity measuring device (1) has a controller which is set up for this purpose: to vary the temperature of the condensation surface (10) by means of the means (13) for adjusting the temperature of the condensation surface (10), to detect a change in the condensation state of the condensation surface (10) by means of the optical detection device (16), to determine the temperature of the condensation surface (10) at which the change of the dewing condition has occurred, and - Determine the moisture from this temperature. 11. The ventilator according to one of the preceding claims, characterized in that the humidity measuring device (1) has a gas temperature sensor (25, 26) for determining the temperature of the humidity measuring device (1) passing air, wherein the gas temperature sensor (26) in particular on the Optical waveguide (11) is arranged. 12. A respirator according to one of the preceding claims, characterized in that at least a part of the moisture measuring device (1), in particular detachably, on a line (4, 5) of the feed device (2) or the discharge device (3) is arranged. 13. The ventilator according to claim 12, characterized in that the moisture measuring device (1) is arranged in a form-fitting manner, by means of a sliding closure and / or by means of a snap closure on the line (4, 5). _ _ 14. Breathing apparatus according to one of claims 12 or 13, characterized in that the line (4, 5) for a gas connection of the condensation surface (10) with the interior of the conduit (4, 5) in its jacket has a passage opening (20).