Respirator
Disclosed is a respirator comprising at least one flow path. Said respirator is composed of several interconnected components which ar disposed one behind another in the flow path and through which the flow path extends. The fluid resistance of each individual component is optimized so as to obtain a low total fluid resistance of all components.
The invention concerns a ventilator, which has at least one flow path and comprises several interconnected components, which are successively arranged along the flow path, which runs through these components.
In previously known ventilators, the air path is characterized by several components with different functions. In particular, these components are air-intake filters, air lines in the ventilator, sound absorbers, fans, air line to the patient, hose, and patient interface (mask, tube, nasal pillow).
The invention can be used, for example, in the following types of medical apparatuses: CPAP devices, APAP devices, bilevel ventilation devices, titration devices, home ventilators, emergency ventilators, hospital ventilators, suction devices, and other types of medical apparatuses.
In the previously known devices, the individual elements of the air path are optimized for their specific function and are not necessarily designed for optimum flow guidance. For example, the sound absorber is designed primarily to minimize sound and not to allow ideal flow of the respiratory gas. However, the competing goals can result especially in flow effects that increase the sound and the power consumption and adversely affect the quality of the therapy.
The large number of parameters makes it very difficult to objectify individual elements. Nevertheless, the use of fluid-mechanical experiments and numerical control systems makes it possible to isolate individual parameters and make them accessible to objective evaluation. Naturally, the optimization of individual elements will have different effects elsewhere, so that it is necessary to coordinate the optimization of the individual elements.
The objective of the present invention is to lower power consumption by reducing the total resistance coefficient and to reduce sound generated by turbulence.
In accordance with the invention, this objective is achieved by optimizing the flow resistance of each individual component to achieve a low resultant total flow resistance of all components.
To this end, components that are coordinated with one another are produced, which do not necessarily have optimized characteristics with respect to their individual functions, but rather produce optimized characteristics for a ventilator by the interaction of all of the components.
In particular, the following measures serve this purpose:
creation of flow-optimized surfaces in the total air path, for example, similar to a shark's skin,
coordination of the transitions/interfaces to achieve idealized flow guidance (no corners and edges), and
consideration of physical principles to reduce the flow resistance.
These measures can be carried out, for example, on the following components: air-intake filters, air line in the ventilator, sound absorbers, fans (optimization of blade geometry, air baffles), air line to the patient, hose, patient interface, and interfaces between the individual components.
In a ventilated patient, two systems are connected with each other—the ventilation system and the lung. The connecting piece between these two systems is the hose and/or the patient interface (PI). As a rule, this connecting piece has a smaller diameter than the part of the system before it and the part after it.
This diameter dimensioning results in considerable flow resistance, which manifests itself as a pressure drop and can be quantified. It is defined as the pressure difference between the outer, proximal end of the hose and the inner, distal end of the hose.
To quantify this resistance, the pressure can be measured at each end, and then the resistance (ΔPPI; PI=patient interface) can be computed from the measured values. Pprox is the pressure at the proximal end, and Pdis is the pressure at the distal end. This indicates that a difference is involved. The formula is:
ΔPPI=Pprox=Pdis.
During inspiration, the pressure before the tube is greater than the pressure after the tube. This results in a positive ΔPPI. During expiration, the pressure in the trachea is greater, and this results in a negative ΔPPI. This difference depends on both the inside diameter (ID) of the PI and the flow (gas flow, F [L/s]).
The measurements of the pressure drop of different PI's at different flows yield PI-specific pressure-flow characteristic curves. The PI-produced pressure loss means additional, ineffective respiratory work. This additional respiratory work must be performed by the:
(a) patient
(b) ventilator
(c) ventilator and patient.
If the patient must take over the work, there is a risk of early respiratory exhaustion.
If the ventilator takes over the work, it must perform additional work during an inspiration, which can result in increased power consumption, increased sound generation, and diminished automatic control precision.
During expiration, the pressure in the PI must be reduced in such a way that expiration is not hindered and effective elimination of CO2 is possible.
The flow resistance can be reduced by providing the component with a surface profile.
In particular, it is proposed that the surface profile have a lotus structure.
In another embodiment, the surface profile has a sharkskin structure.
If the surface profile has longitudinal grooves, this contributes to the development of laminar flow.
To adapt to specifically prevailing flow velocities and volume flows, it is provided that the longitudinal grooves have different widths relative to one another.
In accordance with another design variant, it is also proposed that the longitudinal grooves be separated from one another by different distances.
In one embodiment, the longitudinal grooves are formed as sawtooth grooves.
In another embodiment of the invention, the longitudinal grooves are formed as trapezoidal grooves.
In another embodiment, the longitudinal grooves are formed as L-shaped grooves.
If at least two components have flow paths with a continuous transition into each other, this helps prevent the development of turbulence.
Sound emission can be reduced if the flow path has a porous trailing edge in the vicinity of at least one cross-sectional constriction.
To avoid turbulence, it is also useful if the flow path is provided-with a flow guide element in the vicinity of at least one cross-sectional change.
In a preferred embodiment, the flow guide element is designed as a brush-shaped edge.
In accordance with another embodiment, it is also proposed that the flow guide element be formed as a soft lamella.
Different advantageous material properties can be combined by using a porous flow guide element.
A further objective of the invention is to design a medical apparatus in such a way that its functionality is improved.
In accordance with the invention, this objective is achieved by providing at least one of the components of the apparatus with a surface coating and/or by providing the surface with functional properties that include at least optimized flow.
Another objective of the present invention is to improve a method of the aforementioned type in such a way that an embodiment is realized which is functional and at the same time inexpensive and capable of operating for extended periods of time.
In accordance with the invention, this objective is achieved by producing the molded body by plastic injection molding and then coating at least certain sections of the molded body.
The use of surface-coated components in medical apparatuses basically allows much greater design latitude. The functional properties desired in a given situation can be provided by the surface coating, independently of the material of the substrate. The functional properties can be related, for example, to antifriction properties, friction properties, surface shaping, or surface hardening.
The surface coating of the substrate is selected according to the predetermined functional property, and the base material of the substrate can be determined independently of the desired functional property of the surface and the mechanical or static boundary conditions. For example, it is possible, when high mechanical stresses are present, to provide a hard substrate with a softer surface coating or to furnish a soft and elastic substrate with an antiseptic functional surface. If necessary, the desired surface coatings are applied to the substrates with the use of suitable intermediate layers that serve as adhesion promoters.
In a preferred embodiment, the molded body is basically formed as an apparatus part, apparatus cover, apparatus internal part, apparatus accessory part, apparatus component, air humidifier, nebulizer, medication atomizer, ventilator, air-intake filter, sound absorber, air path in the apparatus, filter, ventilator mask, ventilator hose, emergency ventilator, suction device, suction hose, collecting container of a suction device, or housing part.
A molded body of this type for a medical apparatus is produced at least partly and/or in certain sections from plastic. In this regard, different plastics are often used. The plastics perform various functions and must be suited in the best possible way for the given function to be performed. The plastics used to make, for example, a ventilator are thus optimized for the specific purposes of the individual components, i.e., intake filter—ventilator—output filter—patient hose—filter—patient contact point.
All known plastics can be used as the plastics, e.g., polyethylenes, polypropylenes, polyvinyl chlorides, polystyrenes, polycarbonates, cellophanes, cellulose acetates, polyolefins, fluorocarbon resins (Teflon), polyhydroxyethyl methacrylates (PHEMA) (Hydron), polymethyl methacrylates (PMMA), polysiloxanes, polyethers, polyesters, polyacetals, polyvinyls, polyether silicones, polyurethanes, natural and synthetic rubber, silicone, latex, ABS resin, acrylic resins, triacetates, vinylides, and rayon.
In addition, it is possible to use all polymers that are suitable for the injection molding of injection-molded parts. Materials to be used for injection molding are preferably polymers or polymer blends that contain a polymer based on polycarbonates, polyoxymethylenes, poly(meth)acrylates, polyamides, polyvinyl chloride, polyethylenes, polypropylenes, linear or branched aliphatic polyalkenes, cyclic polyalkenes, polystyrenes, polyesters, polyethersulfones, polyacrylonitrile or polyalkylene terephthalates, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoropropylene oxide, polyfluoroalkyl acrylate, polyfluoroalkyl methacrylate, polyvinylperfluoroalkyl ether or other polymers of perfluoroalkoxy compounds, polyisobutene, poly(4-methylpentene-1), polynorbornenes as homopolymers or copolymers or their mixtures. Especially preferred materials to be used for injection molding are polymers or polymer blends that contain a polymer based on polyethylene, polypropylene, polymethyl methacrylates, polystyrenes, polyesters, acrylonitrile-butadiene-styrene terpolymers (ABS), or polyvinylidene fluoride, such that the plastics can be used in pure form and/or as a mixture. Polycarbonates, polyoxymethylenes, poly(meth)acrylates, polyamides, polyvinyl chloride, polyethylenes, polypropylenes, linear or branched aliphatic polyalkenes, cyclic polyalkenes, polystyrenes, polyesters, polyacrylonitrile or polyalkylene terephthalates, polyvinylidene fluoride, or other polymers of polyisobutene, poly(4-methylpentene-1), polynorbornenes as homopolymers or copolymers, a polymer based on polycarbonates, polyoxymethylenes, poly(meth)acrylates, polyamides, polyvinyl chloride, polyethylenes, polypropylenes, linear or branched aliphatic polyalkenes, cyclic polyalkenes, polystyrenes, polyesters, polyacrylonitrile or polyalkylene terephthalates, polyvinylidene fluoride, or other polymers of polyisobutene, poly(4-methylpentene-1), polynorbornenes as homopolymers or copolymers and their mixtures, and their mixtures.
In addition to plastics, it is also possible to use metals and/or ceramic and/or glass, or any desired combinations of these materials, including combinations with the plastics listed above.
In this regard, the surface can be completely or partially covered with the polymers.
It is possible merely to melt the polymer on and/or to apply only such a small amount to the surface that, if desired, a granular structure of the polymer is maintained. Surface texturing is achieved in this way.
In accordance with the invention, it is proposed that the surfaces be designed to be rough and hydrophobic. In this regard, it can be a surface with an artificial surface structure consisting of elevations and depressions and, in addition, with self-cleaning properties. The surface structures are preferably on the nm to um scale. It is especially preferred for the surface structures to be spaced more or less evenly apart.
In addition, the surface can contain particles that are fixed on the surface by means of a matrix system.
In this regard, at least one surface of the molded body is made of a material which has flow-optimized properties and is selected from among polymers, such as polyamides, polyurethanes, polyether block amides, polyester amides, polyvinyl chloride, polyolefins, polysilicones, polysiloxanes, polymethyl methacrylates or polyterephthalates, metals, fibers, fabrics, glasses, or ceramics.
To this end, the surface structure is produced by applying and fixing particles on the surface.
In this connection, it is provided that the particles have a mean particle diameter of 0.05 to 2,000 nm.
These particles form an irregular fine structure in the nanometer range on the surface.
In a preferred modification of the invention, the molded bodies have a textured surface with regular and/or irregular elevations and/or depressions on the nm and/or um scale.
In this regard, the surface has at least one firmly anchored layer of microparticles that form elevations. The elevations have a mean height of 20 nm to 25 μm and are spaced apart a mean distance of 20 nm to 25 μm. However, a mean height of 50 nm to 4 um and/or a mean spacing distance of 50 nm to 4 μm is preferred.
Furthermore, the surface has self-cleaning properties and elevations formed by microparticles. It is produced by pressing hydrophobic microparticles into the surface of the surface extrudate. The microparticles that are used have a mean particle diameter of 0.02 to 100 μm.
Textured surfaces with a low surface energy are also part of the invention.
Therefore, an object of the present invention is textured surfaces which have elevations with a mean height of 10 nm to 200 μm and a mean spacing distance of 10 nm to 200 μm and whose outer shape is described by a mathematical curve and/or function with symmetry with respect to a plane.
An especially low surface energy is necessary especially when not only hydrophobic but also oleophobic behavior is required. This is the case especially with nonsolid oily contaminants (Lotus Effect™).
To produce such a surface, the textured, hydrophobic surface with elevations and depressions is treated with an additive that has a particle size of 0.0001 to 20 μm and an organic matrix that contains at least one thermoplastic, elastomeric, or thermosetting plastic.
Preferred microparticles have an irregular fine structure in the nanometer range on the surface and a particle diameter of 0.02 to 100 μm, preferably 0.1 to 50 μm, and especially 0.1 to 10 μm. However, suitable microparticles can also have a diameter of less than 500 nm or can be agglomerates or aggregates built up from primary particles. These agglomerates or aggregates have a size of 0.2 to 100 μm.
It can be advantageous for the microparticles to have hydrophobic properties. The hydrophobic properties can be based on the material properties of the materials themselves, which are present on the surfaces of the particles, or they can be produced by treating the particles with a suitable compound. The microparticles can have been furnished with functional properties before or after the application to or binding on the surface of the device or injection-molded part.
The invention also includes a method for producing plastic granules and powders.
If products made of polyolefins are to be lacquered, printed, coated, or adhesively bonded, it is necessary to pretreat the molded parts, since printing inks and adhesives do not adhere sufficiently well to the nonpolar surface of these plastics. Thermal or wet-chemical methods are customarily used. The desired oxidation of the surface can also be realized by an electronic-type plasma treatment.
A plasma method makes it possible to treat polyolefin granules and powders, so that a subsequent treatment of the parts can be eliminated. Very thin nanolayers, e.g., of polytetrafluoroethylene (PTFE (Teflon)), can be deposited on various substrates by an HF-CVD process. Different material surfaces can be provided with the desired functional properties in this way.
The chemical sol-gel process, which yields nanomaterials, is a variant of inorganic synthetic chemistry which until now has found little use in the development of materials. It uses liquid starting materials and a low-temperature process to produce inorganic or inorganic-organic materials with wide ranges of composition and structure.
The goal of using ceramics for the nanotexturing of surfaces is to alter the properties of known materials or to provide known materials with new functions, e.g., to produce columnar structures in the range of 20-300 nanometers on metal and plastics by stamping processes. This causes a change in interfacial properties. The formation of hemispherical structures with a radius of 250-350 nm on, for example, glass surfaces, significantly reduces their reflection of light. This effect is based on the creation of a continuous transition between the surrounding air and the glass surface, which can be achieved in this way only by nanostructures.
A combination of microtexturing and nanotexturing can be used simply and easily to alter the surfaces.
The solvent that contains the particles can be applied to the polymer surface, e.g., by spraying, by doctoring, by dropping, or by immersing the polymer surface in the solvent that contains the particles.
The method of the invention can be used to produce a polymer surface with favorable flow properties, which has an artificial, at least partially hydrophobic surface structure that consists of elevations and depressions formed by particles fixed on the polymer surface.
The particles can also be present in the form of aggregates or agglomerates. In this regard, according to DIN 53 206, aggregates are understood to be primary particles joined together along their surfaces or edges, while agglomerates are understood to be primary particles with point contact.
The structures described above can be produced, e.g., by an injection-molding process in combination with a conventional injection-molding die produced by the LIGA process. The LIGA process is a texturing process that is based on basic processes of x-ray lithography, electroforming, and molding. The process differs from micromechanics in that the structures are not produced in the base material by an etching process but rather can be molded inexpensively by a die. In the present case, the LIGA process is used to produce the die.
In addition, undesired changes in the physical properties of the substrates can be largely eliminated in this way, since only a very thin coating on the surface of the substrate is changed. The method of the invention can be readily combined with other methods of surface finishing treatment. For example, it is possible, after the thermally assisted application of the polymers, to render the surface hydrophilic with water and acids.
The material properties of the various plastics are affected to only an insignificant extent. Characteristics such as the continuous use temperature, creep strength, and thermal and electrical insulation are preserved. The compound can be used under all conceivable conditions of production, processing, and use. It is used with semifinished products made of PEEK, PPSU, POM-C, and PET and with injection-molded parts, extruded sections, and calendered sheets.
Alternatively and/or in addition to the aforementioned properties, the molded bodies of the invention can have the following properties. It is also contemplated that a molded body of the invention can have several properties, at least in certain sections.
flame-retardant
low kinetic friction
flow-optimized
anticorrosive
electrochemically active
low reflection
electrochromic
photochromic
piezoelectric
conductive
scratch-resistant
antireflective
Alternatively and/or in addition to the aforementioned method for producing molded bodies of the invention, the following processes can be used.
plasma process
laser process
sol-gel process
galvanic processes
production of nanostructures by self-organization
nanotexturing of materials and surfaces
vacuum evaporation (electron-beam evaporation)
vacuum evaporation (resistance crucible evaporation)
cathode sputtering
CVD processes (chemical vapor deposition)
PVD processes (physical vapor deposition
LIGA process
thermal oxidation
microelectroforming (hard alloy depositions)
injection molding of plastic microcomponents
vacuum coating
chemical electroplating
in-mold coating
precoating
In addition, the invention includes a method for producing molded bodies of the invention. Advantageous embodiments of the method of the invention are specified in the dependent claims.
Specific embodiments of the invention are illustrated in the accompanying schematic drawings.
In the embodiment illustrated in
Resistance-reducing grooved surfaces (riblets) consist of microscopically small grooves that are aligned parallel to the flow. The grooves must be dimensioned in such a way that they act as a hydraulically smooth surface for the flow. The resistance-reducing effect consists in hindrance of the turbulent transverse components of the flow at the wall. The riblet surfaces of the invention can reduce turbulent wall friction by up to 10%.
A correlation between flow velocity and groove spacing exists inasmuch as narrower grooves have a greater probability of being smaller than the half lateral wavelength and thus generate smaller turbulence. In accordance with the invention, therefore, it is proposed that the riblet surfaces have different riblet dimensions and/or different riblet spacing in the area of the ventilator, depending on the flow conditions prevailing there.
Test results show reduced resistance of the grooved film of 5-10% compared to the smooth structure.
The lowering of resistance by the grooved structure can be explained by the occurrence of different, textured subregions in the boundary layer. These boundary layers have an effect on the turbulence.
In the laminar lower flow layer, strips of high velocity alternate with strips of low velocity. These structures affect the turbulence behavior at the boundary layer. The spaces between the strips can be calculated as follows:
W=100 1
l=v/UT
W: groove spacing
l: characteristic length of the lower layer
v: kinematic viscosity
UT: friction velocity
The friction velocity is defined as: Reynolds number=inertial forces/frictional forces. It describes the hydrodynamic similarity of a body as a function of the viscosity of the medium surrounding it.
The invention provides for the use of surfaces with high Reynolds numbers. The inertia of the medium is constant; high Reynolds numbers are produced by very low frictional forces near the surface, which are achieved by the characteristic grooved structure.
In summary, it can be said that grooves with smaller spacing are used in regions of faster flow than in regions of slow flow; the grooves are aligned with the flow and overlap one another.
Another aspect of the invention in that the surfaces of the invention experience hardly any contamination, i.e., a lotus effect is observed.
The air resistance can be described by the formula:
W=rho/2×cw×A×V2.
If one wishes to achieve faster flow with a certain power, this can also be accomplished by reducing the cw value and the area A (the air density rho is predetermined by air pressure and temperature). While the area can be reduced only to a certain limit, there is a great deal of potential in the case of the cw value. The air resistance W can be broken down into a pressure component and a friction component.
The pressure drag involves defects of form and the turbulence resulting from them. If complete pressure equalization can no longer occur due to burble, a drag arises which is known as pressure drag. However, it can be reduced to a minimum by perfect shaping.
Another objective of the present invention is to make the shape close to the absolute optimum, so that the “streamlines” close again with practically no pressure losses / vortices. This increases the friction component, to which it is therefore necessary to devote more attention. The frictional resistance arises from shear stresses between the body and the medium flowing around it.
The frictional resistance can be broken down into a laminar component and a turbulent component. In the front part of the lining, the flow is initially laminar, but then, depending on the shape and surface, it becomes turbulent flow at a certain point, which means a definite increase in resistance in the region which follows. Consequently, an effort must be made to keep the flow in the boundary layer laminar for as long as possible. This can be accomplished by the use of laminar profiles, in which the greatest width is not reached until at least 50% of the total length, so that the flow is accelerated for a longer period of time, and laminar flow can be maintained more easily in this acceleration interval.
Another possible means of maintaining laminar flow consists in optimization of the surface in the front region by, for example, riblet surfaces. If, on the other hand, the flow is separated at a certain point by a defect of form, it is possible, by increasing the roughness in this area, to capture the flow again by this well-defined energy input and thus reduce the resistance (the pressure drag).
Alternatively, the turbulent part of the boundary layer can be made at least partially laminar by removing “mini-vortices” that develop through small drill holes in the surface.
In accordance with the invention, it is also proposed that numerical fluid mechanics be used to determine wall shear stresses, coefficients of friction, wall friction, air resistance, and their contributions to the total resistance.
The specific embodiment according to
Measurement results obtained with the use of the measuring device shown in
The testing device used as the flowmeter was the Timeter PM-No. 107-015. The SI PM No. 205-029 was used as the pressure gage. In addition, a device was used, the Weinmann SOMNOcomfort model, which was modified to allow a constant speed to be set. The test setup illustrated in
The flow resistance of the test objects was measured for volume flows of 50 L/min and 100 L/min. The measure of the flow resistance is the level of the dynamic pressure in front of the test object compared to the ambient pressure. The dynamic pressure is conducted to the pressure gage, where it is measured, through a thin hose, which is connected in front of the test object in the flow channel. The two volume flow values (50 L/min and 100 L/min) were produced by a modified SOMNOcomfort, whose speed can be set to a constant value, and checked by the Timeter. All of the intended openings (discharge openings) and unintended openings (interfaces, e.g., between elbow and turn sleeve) were sealed before the start of the measurement.
In addition to the surface shaping in accordance with the invention, the flow guidance is also quite important. Especially in the case of a patient interface in the form of a mask, an angled connector is often used for connection to the ventilator hose. The geometry of the angle and of the hose connection is a significant factor affecting the resulting flow resistance. With respect to the reduction of the flow resistance, a connection angle of<70° and a connection diameter of>18 mm have been found to be especially advantageous. Furthermore, the automatic control precision can be increased, and energy savings can be achieved.
The importance of fluid-mechanical shape optimization decreases nonlinearly with flow velocity. However, it is precisely in the range of high ventilation pressures and high flows that a fluid-mechanically favorable shape has an especially strong effect on energy savings, sound reduction, and the quality of therapy.
Additional tests were aimed at reducing the sound-emitting effect of edges over which flow is occurring. Sound arises at edges over which flow is occurring by conversion of some of the turbulent wall pressure fluctuations to propagable pressure waves. Since this process is causally related to the nonuniform change in the boundary conditions at the edge, a change of the edge characteristics towards a more uniform transition from the hard wall into the free flow was also seen here as a potential solution to the problem of noise reduction.
In
The geometry of the flow guide elements 18 can be varied to adapt to the specific application specifications. In particular, the thickness, the density, the length, and the flexibility can be varied. In particular, a flexible design of the flow guide elements 18 has been found to be important.
In accordance with another embodiment, it is also proposed that flow-optimized trailing edges 19 be used alternatively or additionally to the flow guide element 18. Especially trailing edges 19 made of a porous material have been found to be advantageous. It is also possible to make the flow guide elements 18 from a porous or open-pored material. Ideally, this is done in combination with a flexible design of the flow guide elements 18. The use of the flow guide elements 18 resulted in experimental noise reduction of up to 12 dB.
Another area of application for optimization of the flow guidance is related to the generation of the respiratory gas and the components used for this purpose. The rotor of the fan is the most important source of sound, and the sound is strongly dependent on the clearance of the rotor perimeter. By systematic reduction of the clearance (up to 85% of the initial state), it was possible to achieve considerable noise reduction, which is due to a great extent to the reduction of the flow-off speed at the trailing edge that is associated with the clearance reduction.
The flow-off noises at the terminal and lateral edges and the transitions can be considerably reduced by suitable edge design (e.g., brushes, porous terminal edges).
The measurements of the pressure drop of variously optimized ventilators at varied flow yield specific pressure-flow characteristic curves.
The different lines in
a—standard
b—brushes
c—sharkskin
d—geometry of the PI-hose connector
e—brushes+shark skin+geometry of the PI-hose connector
The pressure drop means additional, ineffective respiratory work. This additional respiratory work must be performed by the:
(a) patient,
(b) ventilator, or
(c) ventilator and patient.
If the patient must take over the work, there is a risk of early respiratory exhaustion. If the ventilator takes over the work, it must perform additional work during an inspiration, which can result in increased power consumption, increased sound generation, and diminished automatic control precision. During expiration, the pressure in the PI must be reduced in such a way that expiration is not hindered and effective elimination of CO2 is possible.
An expiratory device 30 is installed in an expanded area of the connecting hose 26 that faces away from the ventilator housing 22. An expiratory valve can also be used.
The surface coatings can be produced by various methods, which have already been partly explained above in connection with examples. The surface coatings can be produced by introducing particles, as described above, but it is also possible to use vapor deposition techniques, lamination techniques, or plasma coating techniques. It is likewise possible to use the aforementioned methods for applying liquid coatings in pure form or diluted with solvents. Surface treatments, for example, those involving the use of mechanical means, laser beams, or electron beams, are also possible.
These elevations are arranged in various forms on the surface to form regular structures. In one embodiment, the invention comprises, for example, the following accessory parts that can be used for ventilation applications:
Humidifier (
Ventilators produce an air volume flow of up to 400 L per minute. The dimensions of a ventilator, the patient hose, and the patient interface are basically fixed within narrow limits. Therefore, the amount of power consumed in producing the air flow increases at a disproportionately high rate with increasing velocity of flow. At the same time, the generation of noise increases with increasing velocity of flow.
The reduction of noise generation, measured at a distance of 1 meter, can typically amount to at least 5% or at least 1 dB(A). In regard to the reduction of power consumption, it is intended especially that the reduction should be at least 2%. In another variant, the amount of time needed for a necessary cleaning should be reduced by at least 10%.
Therefore, in accordance with the invention, it is proposed that the frictional forces of the surfaces be reduced in order to save energy and/or limit noise generation. The resistance-reducing surfaces of the invention consist of microscopically small surface structures, for example, grooves, which are preferably aligned parallel to the direction of flow of the medium. Surfaces of this type are known in the natural world, for example, shark's skin. The surface structures are dimensioned in such a way that they act as a hydraulically smooth surface for the flowing medium. The resistance-reducing effect consists in hindrance of the turbulent components of the flow.
The surface structures are preferably spaced essentially equal distances apart. These essentially equal distances are in the range of 100 nm to 200 μm, and preferably in the range of 5 μm to 100 μm. It is especially preferred for the surfaces of the invention to have reduced resistance on the order of>1.0%.
In accordance with the invention, the air-conveying part of a ventilator and/or hose has, at least in certain sections, a textured surface with regular and/or irregular elevations and/or has a surface that reduces the friction of a flowing medium and/or has a flow-optimized surface.
To prevent the respiratory passages from becoming dry, the respiratory air is typically humidified. Since patients perceive warmed air to be pleasant, and since the air can hold more water vapor when it is heated, for example, by a heating element 35, a water supply tank that is used as a liquid reservoir 36 of the humidification system is typically heated indirectly and/or directly, for example, by the metallic base of the water supply tank or, for example, by means of an immersion heating element 35. A respiratory gas humidifier can be externally connected to a ventilator on the outside by a coupling 25 and/or it can be installed inside a ventilator. Due to hygienic requirements that must be met, it must be possible to remove the humidifier for cleaning and nevertheless to guarantee a sufficient seal from the water. The humidifier consists of an upper part 38, which serves essentially for conveying the air and also for connecting the ventilator 22 and the connecting hose 26, and a lower part 39 that holds the water supply. The upper part 38 has a liquid filling hole 40 with a closure 41.
A gas line 42, which is preferably designed as a pressure measurement line and/or oxygen supply line, can be arranged in the vicinity of the humidifier. The gas line 42 is connected with the humidifier by a gas coupling 43. The humidifier can be coupled with a connecting hose 26 by a connecting adapter 44. Communication with the ventilator 22 can be realized by a plug connector 45 between the humidifier and the ventilator. A display 46 can be positioned near the humidifier.
An oxygen line 49 is mounted on the outside of the connecting hose 26 and is connected with an oxygen supply valve 47. The supply valve 47 is connected to an oxygen source (not shown) by a supply line 50. A control line 51 connects the supply valve 47 with an interface 29 of the ventilator 22.
In the embodiment illustrated in
The oxygen supply valve preferably has a self-cleaning and/or hydrophilic and/or oleophobic and/or low-friction and/or conducting surface.
A patient interface will now be explained as the next example of an application. In the embodiment illustrated in
Body 52 of the mask and/or protruding edge 53 of the mask and/or expiratory system 54 and/or coupling element 33 and/or joint 55 and/or forehead support 56 and/or forehead support mount 57 and/or forehead pad 58 and/or fastening device 62 for a head harness, securing ring, and/or release cord. The mask does not necessarily have to have all of the individual components for it to be functional.
The protruding edge 53 of the mask rests against the patient's face and provides the necessary seal. The body of the mask is connected with a coupling element 33 by means of a joint. A forehead support 57 with a forehead pad 58 is used to ensure reliable positioning of the ventilator mask on the patient's head. The forehead support is connected with the body of the mask by a mount 53.
Various other patient interfaces can be used as alternatives to a mask. The following are named as examples: nasal pillows, tubes, tracheostoma, catheter.
Hereinafter, masks and all mask components, as well as other patient interfaces, such as nasal pillows, will be combined under the term patient interfaces.
At least certain sections of the patient interfaces preferably have an antiseptic and/or self-cleaning and/or hydrophobic and/or oleophobic and/or photocatalytic and/or scratch-resistant and/or nonfogging and/or nonirritating to the skin and/or low-friction and/or electrically conducting surface.
It is especially preferred that the area near the end of the patient interface that faces the air flow be furnished with suitable smooth plastics and/or lacquered surfaces and/or coated plastics and/or surfaces with texturing on the nanometer to micrometer scale in such a way that reduced friction can be realized.
The invention can also be used together with a filter. Especially in ventilators but also in other types of medical apparatus, filters are used, mainly in the air intake area, to retain particulate matter, dust particles, and microorganisms. The filters are intended to prevent contamination of the apparatus and contamination of the patient. Alternatively and/or additionally, filters are used in the area between the apparatus and the patient or user, especially to avoid hygienic contamination. The filters usually take the form of replaceable plug-in filters. So-called combination filters are also used, which can be designed, for example, as coarse filters and fine filters. If a filter is not regularly cleaned and/or replaced, retained particulate matter, dust particles, and microorganisms can increase the flow resistance of the filter, which causes the efficiency of the apparatus to decrease or contaminants to be carried to the patient. State-of-the-art filters must be frequently replaced, which is time-consuming and expensive.
In accordance with the invention, it is proposed that the filters be provided with functional surfaces. This increases the service life of the filters and thus lowers costs.
It is preferred that the area near the end of the filter that faces the air flow be furnished with suitable smooth plastics and/or lacquered surfaces and/or coated plastics and/or surfaces with texturing on the nanometer to micrometer scale in such a way that reduced friction can be realized. It is also preferred to finish HME filters (heat and moisture exchange filters) in such a way that they have reduced frictional resistance and/or that they are antiseptic and/or self-cleaning and/or oleophobic and/or photocatalytic.
Functional surfaces have also been found to be effective for hoses. Especially in ventilators but also in other types of medical apparatus, such as suction devices, hoses are used to convey a medium, especially in the area of a connection between the user/patient and the device. The hoses usually take the form of replaceable plug-in hoses. If a hose is not regularly cleaned and/or replaced, retained particulate matter, dust particles, contaminants, and microorganisms can increase the flow resistance, which causes the efficiency of the apparatus to decrease or contaminants to be carried to the patient. State-of-the-art hoses must be frequently cleaned and/or replaced, which is time-consuming and expensive. Cleaning must be performed frequently and thoroughly to eliminate contamination effectively.
In accordance with the invention, it is proposed that the hoses be provided with functional surfaces. This increases the service life of the hoses and at the same time reduces the amount of time needed to clean them, thereby reducing costs.
It is preferred that the area near the end of the hose that faces the air flow/medium flow be furnished with suitable smooth plastics and/or lacquered surfaces and/or coated plastics and/or surfaces with texturing on the nanometer to micrometer scale in such a way that reduced friction can be realized. It is also preferred that hoses have an electrically conducting surface.
Claims
1. A ventilator, which has at least one flow path and comprises several interconnected components, which are successively arranged along the flow path, which runs through these components, wherein the flow resistance of each individual component (1) is optimized to achieve a low resultant total flow resistance of all components (1).
2. A ventilator in accordance with claim 1, wherein the component (1) has a surface profile (3).
3. A ventilator in accordance with claim 1, wherein that the surface profile (3) has a lotus structure.
4. A ventilator in accordance with claim 1, wherein the surface profile (3) has a shark skin structure.
5. A ventilator in accordance with claim 1, wherein the surface profile (3) has longitudinal grooves.
6. A ventilator in accordance with claim 5, wherein the longitudinal grooves have different widths relative to one another.
7. A ventilator in accordance with claim 5, wherein the longitudinal grooves are separated from one another by different distances.
8. A ventilator in accordance with claim 5, wherein the longitudinal grooves are formed as sawtooth grooves.
9. A ventilator in accordance with claim 5, wherein the longitudinal grooves are formed as trapezoidal grooves.
10. A ventilator in accordance with claim 5, wherein the longitudinal grooves are formed as L-shaped grooves.
11. A ventilator in accordance with claim 1, wherein at least two components (1) have flow paths with a continuous transition into each other.
12. A ventilator in accordance with claim 1, wherein the flow path (12) has a porous trailing edge (19) in the vicinity of at least one cross-sectional constriction.
13. A ventilator in accordance with claim 1, wherein the flow path (12) is provided with a flow guide element (18) in the vicinity of at least one cross-sectional change.
14. A ventilator in accordance with claim 13, wherein the flow guide element (18) is designed as a brush-shaped edge.
15. A ventilator in accordance with claim 13, wherein the flow guide element (18) is formed as a soft lamella.
16. A ventilator in accordance with claim 13, wherein the flow guide element (18) is porous.
17. A ventilator in accordance with claim 1, with a molded body, especially as a part of an apparatus or as a component or accessory part of a medical device for ventilation, sleep therapy, cardiotherapy and/or cardiovascular therapy, emergency supply, or oxygen supply, including diagnostics in all of the specified areas, wherein at least certain sections of its surface have a functional property or impart a functional property.
18. A molded body in accordance with claim 1, wherein the functional property is of a physical nature or has a physical effect.
19. A molded body in accordance with claim 1, wherein the functional property is at least also physical in nature or at least also has a physical effect.
20. A molded body in accordance with claim 1, wherein the functional property consists in an effect that reduces surface adhesion.
21. A molded body in accordance with claim 1, wherein the functional property consists in an effect that lowers the surface energy or the flow resistance of the surface or in an effect that lowers the noise generation of liquids or gases flowing along the surface.
22. A molded body in accordance with claim 1, wherein the functional property consists in an effect that lowers the kinetic friction on or at the surface.
23. A molded body in accordance with claim 1, wherein the functional property consists in an effect that alters (makes easier or more difficult) the wettability or the fogging tendency.
24. A molded body in accordance with claim 1, wherein the functional property consists in a hydrophilic effect.
25. A molded body in accordance with claim 1, wherein the functional property consists in an oleophobic effect.
26. A molded body in accordance with claim 1, wherein the functional property consists in an effect that enhances the self-cleaning ability.
27. A molded body in accordance with claim 1, wherein the functional property consists in an antireflective effect or in an effect that lowers surface reflection at least for certain wavelengths and/or certain polarizations and/or certain angles of incidence.
28. A molded body in accordance with claim 1, wherein the given functional property is already realized by suitable formation of one or more limited parts or sections of the surface of the molded body.
29. A molded body in accordance with claim 1, wherein at least two of the functional properties selected from the group consisting of
- a) wherein the functional property is of a physical nature or has a physical effect;
- b) wherein the functional property is at least also physical in nature or at least also has a physical effect;
- c) wherein the functional property consists in an effect that reduces surface adhesion;
- d) wherein the functional property consists in an effect that lowers the surface energy or the flow resistance of the surface or in an effect that lowers the noise generation of liquids or gases flowing along the surface;
- e) wherein the functional property consists in an effect that lowers the kinetic friction on or at the surface;
- f) wherein the functional property consists in an effect that alters (makes easier or more difficult) the wettability or the fogging tendency;
- g) wherein the functional property consists in a hydrophilic effect;
- h) wherein the functional property consists in an oleophobic effect;
- i) wherein the functional property consists in an effect that enhances the self-cleaning ability;
- j) wherein the functional property consists in an antireflective effect or in an effect that lowers surface reflection at least for certain wavelengths and/or certain polarizations and/or certain angles of incidence are simultaneously realized in the molded body, at least with respect to the same part or section of the surface.
30. A molded body in accordance with claim 1, wherein at least two of the functional properties selected from the group consisting of
- a) wherein the functional property is of a physical nature or has a physical effect;
- b) wherein the functional property is at least also physical in nature or at least also has a physical effect;
- c) wherein the functional property consists in an effect that reduces surface adhesion;
- d) wherein the functional property consists in an effect that lowers the surface energy or the flow resistance of the surface or in an effect that lowers the noise generation of liquids or gases flowing along the surface;
- e) wherein the functional property consists in an effect that lowers the kinetic friction on or at the surface;
- f) wherein the functional property consists in an effect that alters (makes easier or more difficult) the wettability or the fogging tendency;
- g) wherein the functional property consists in a hydrophilic effect;
- h) wherein the functional property consists in an oleophobic effect;
- i) wherein the functional property consists in an effect that enhances the self-cleaning ability;
- j) wherein the functional property consists in an antireflective effect or in an effect that lowers surface reflection at least for certain wavelengths and/or certain polarizations and/or certain angles of incidence are separately realized in the molded body, at least with respect to two separate parts or sections of the surface.
31. A molded body in accordance with claim 29, wherein the multiple functional properties are produced with the same material or with the same method of surface shaping or treatment or with an analogous (physical, chemical, or biological) effective mechanism.
32. A molded body in accordance with claim 1, wherein the functional properties or at least one of the specified functional properties is produced or enhanced with at least two different materials or with at least two different methods of surface shaping or treatment used together or with at least two different (physical, chemical, or biological) effective mechanisms used together.
33. A molded body in accordance with claim 1, wherein the molded body is transparent, at least partially or at least in certain sections, even in the area of the functional surface.
34. A molded body in accordance with claim 1, wherein the molded body consists at least partially of plastic or consists of plastic in certain sections.
35. A molded body in accordance with claim 1, wherein the surface of the molded body contains a polymer as an active substance at least partially or in certain sections.
36. A molded body in accordance with claim 1, wherein the surface of the molded body is furnished with a coating.
37. A molded body in accordance with claim 36, wherein at least a portion or section of the surface of the molded body has a surface energy of less than 35 mN/m.
38. A molded body in accordance with claim 1, wherein at least a portion or section of the molded body has a textured surface with regular elevations or depressions.
39. A molded body in accordance with claim 1, wherein at least a portion or section of the molded body has a textured surface with irregular elevations or depressions.
40. A molded body in accordance with claim 1, wherein at least a portion or section of the molded body has a textured surface with both regular and irregular elevations or depressions.
41. A molded body in accordance with claim 38, wherein the elevations and/or depressions have a height or depth of 5 nm to 200 μm and/or are separated by a distance of 5 nm to 200 μm.
42. A molded body in accordance with claim 38, wherein the elevations and/or depressions have a height or depth of 20 nm to 25 μm and/or are separated by a distance of 20 nm to 25 μm.
43. A molded body in accordance with claim 38, wherein the elevations and/or depressions have a height or depth of 50 nm to 4 μm and/or are separated by a distance of 50 nm to 4 μm.
44. A molded body in accordance with claim 1, wherein the molded body is an apparatus casing, a hose, a gas or liquid line or flow control system, a gas or liquid reservoir, a patient interface, an atomizer, a nebulizer, a humidifier, an oxygen valve, a filter, a sound absorber, a suction device, a collecting container, or a defibrillator housing, or a part, a component, or an accessory part (including fastening, conveying, and storage devices) of any of the devices specified above.
45. A molded body in accordance with claim 1, wherein the generation of noise in at least one operating variant is simultaneously reduced by the functional property.
46. A molded body in accordance with claim 45, wherein the reduction of noise generation, measured at a distance of 1 meter, is at least 5% or at least 1 dB(A).
47. A molded body in accordance with claim 1, wherein the power consumption in at least one operating variant is simultaneously reduced by the functional property.
48. A molded body in accordance with claim 47, wherein the reduction of power consumption is at least 2%.
49. A medical apparatus for ventilation, sleep therapy, emergency supply, or oxygen supply with several molded bodies in accordance with claim 1, wherein the functional property is realized in several molded bodies, independently of the material that is used or the physical, chemical, or biological surface shaping or treatment.
50. A medical apparatus for ventilation, sleep therapy, emergency supply, or oxygen supply with several molded bodies in accordance with claim 1, wherein the functional property is realized in several molded bodies, independently of the material that is used but with the same-physical, chemical, or biological surface shaping or treatment.
51. A method for producing a molded body or a medical apparatus in accordance with claim 1, wherein the molded body is produced by plastic injection molding, and then at least certain sections of the molded body are coated.
52. A method in accordance with claim 51, wherein microparticles are used which have a particle diameter of 0.02 to 100 μpm, preferably 0.1 to 50 μm, and especially 0.1 to 10 μm.
53. A method in accordance with claim 51, wherein a solvent that contains particles is applied by spraying, doctoring, dropping, or immersing.
54. A method in accordance with claim 51, wherein the surface is rendered hydrophilic.
55. A method in accordance with claim 51, wherein the particles are pressed into the surface.
56. A method in accordance with claim 55, wherein a mold is provided with particles before the injection molding, and the particles are pressed in during the injection molding.
57. A method in accordance with claim 51, wherein the surface of the molded body is modified at least in certain sections by means of a molding operation.
58. A method in accordance with claim 57, wherein the molding operation is carried out by the LIGA process.
59. A ventilator with an air delivery system, to which a patient interface can be connected by a respiratory gas hose, wherein at least one area of at least one part of the total device, which consists of the ventilator, the respiratory gas hose, and the patient interface, has a surface that has flow-optimized and/or textured and/or porous properties.
Type: Application
Filed: Sep 2, 2005
Publication Date: Apr 3, 2008
Inventors: Karl Andreas Feldhahn (Hamburg), Gerd Schulz (Schenefeld), Thomas Marx (Hamburg), Arnold Frerichs (Buxtehude), Martin Eifler (Gluckstadt), Martin Bechtel (Winsen/Luhe)
Application Number: 11/660,173
International Classification: A61M 16/00 (20060101);
