DE202020004578U1 - Device for ventilation - Google Patents

Abstract

Device for artificial respiration of a patient by means of a varying negative pressure with a cuff (1) at least partially enclosing the body and a drive, characterized in that the cuff (1) is elastic and at least partially encloses the body (2) directly and airtight.

Description

The invention relates to a ventilation device.

If a patient's breathing stops or is too weak, it can be supported by artificial respiration. Today this is done by means of positive pressure via sealed face masks, or by inserting a tube into the trachea (intubation). This form of ventilation with positive pressure is particularly problematic in the case of inflammation of the lungs and causes damage to the lungs when used over long periods of time.

An alternative is to support breathing by varying the external pressure on the chest and abdomen. The literature mentions numerous approaches to solving this problem, but most of them have not found their way into clinical practice or are no longer used.

In the US1834580 (A ) describes a device known as the "iron lung", which encloses the body up to the neck in a pressure-tight vessel and supports breathing with pulsating negative pressure. The "iron lung" is particularly gentle for long-term ventilation, but is no longer used due to the complexity of the equipment.

the US2456724A describes a chamber sealed at its edges that encloses the patient's torso. While the expenditure on equipment is reduced here, the freedom of movement of the patient is severely restricted by the airtight, rigid chamber. Furthermore, the individual body size requires an individualization of the apparatus.

the US2581893 (A ) describes an apparatus with a curved chamber that is attached to the front of the patient's torso and subjected to alternating air pressure. Here, too, the patient's freedom of movement is severely restricted due to the airtight, rigid chamber and individualization of the apparatus is required.

the DE1103523 describes a rigid, domed chamber spanning the thorax and abdomen with flexible closures to seal same. This can be subjected to underpressure and overpressure. The disadvantage is the rigid chamber, which requires individualization for the patient and massively restricts their freedom of movement.

the US2529258A describes a rigid cuff enclosing the upper body, which is provided with internal bellows in order to be able to exert pressure on the body. The disadvantage here is that only pressure can be exerted on the body. Thus, only exhalation can be supported, but not inhalation.

the DE1103523 describes a belt specifically intended to be worn around the abdomen to support diaphragmatic breathing. It contains an inflatable chamber designed to raise the diaphragm by applying pressure to the abdominal area. The disadvantage here is that only pressure can be exerted on the abdomen. Thus, only exhalation can be supported, but not inhalation.

In summary, it can be stated that solutions that allow negative pressure to act on the body have hitherto been associated with a rigid design in order to prevent the negative pressure chamber from collapsing under negative pressure. This is associated with limitations in handling and for the comfort of the patient.

the DE102016107670B3 describes a flexible appendage wrap that can be expanded by fluid pressure for the purpose of facilitating donning and doffing. To this end, it is necessary for air to be able to flow into the space between the limbs and the covering when the covering expands.

The present invention is therefore based on the object of realizing ventilation by means of negative pressure that is less expensive in terms of apparatus, is easy to handle in clinical practice and is not very restrictive for the patient. The object is solved with the features of claim 1.

The solution provides a cuff that at least partially encloses the body, the cuff being elastic and directly and airtightly enclosing the body. The vacuum chamber attached to the body therefore has no volume worth mentioning. The cuff is provided with a drive which expands it elastically. Since the body is enclosed airtight, it is also expanded and thus artificially ventilated. As with natural breathing, exhalation takes place passively due to the ambient pressure and can also be supported by an active contraction of the cuff.

The cuff preferably encloses the patient's abdominal region, and thus acts on diaphragmatic breathing. It is also possible to act on the thoracic cavity, but this requires higher forces due to the rigidity of the thorax and is hardly applicable to female patients due to the anatomy.

Collapsing or buckling of the cuff under negative pressure is prevented by the constant contact of the cuff on the body.

As a drive for the elastic deformation of the cuff by means of fluid pressure, the operating principle is that already mentioned DE102016107670B3 suitable. It consists of a two-layer structure with a pressure chamber in between, with the walls of the chamber being fixed at a fixed distance from one another by means of webs or fibers. Consequently, when fluid pressure is applied, the chamber can only expand outwards. If the chamber is deflected, the deflection will increase when fluid pressure is applied. It is also advantageous for the application according to the invention that the shape of the chamber is stabilized when it is subjected to internal pressure.

Another possible drive is an electrostrictive drive. It consists of expandable, flat electrodes with an elastic dielectric in between. When an electrical voltage is applied, attractive forces arise between the electrodes, which leads to compression of the dielectric. Due to its elasticity, the area of the dielectric increases. In order to achieve effective forces and strains, a small thickness of the dielectric and high voltages are required. For the technical use in the present invention, the stacking of several layers of the dielectric, each with alternating polarity of the electrodes lying in between, makes sense in order to generate sufficient forces. The use of high voltage represents a potential hazard for the patient, which must be limited with suitable protective measures.

Mechanical drives are also possible. A solution for this is offered by a flat auxetic structure, i.e. a structure that also expands transversely to the direction of tension when it is pulled. The auxetic structure can be applied to an elastic membrane, which in turn is part of the cuff placed on the body.

Activation can occur for the present invention by pulling in the circumferential direction of the cuff, followed by expansion transverse to the direction of pull. Due to the curved shape, this creates an additional bulge in the cuff.

The invention is explained below with reference to the figures.

1 shows the cuff (1) applied to the body (2). The sealing lip (3) surrounding the chamber on all sides can be seen. For attachment to the body, the sealing lip can be expanded in such a way that it encloses the body like a tube. In order to adapt to different anatomies, a very high degree of elasticity is required, as is known from very soft silicone elastomers or block copolymers mixed with plasticizers. Silicone elastomers offer the advantage of being sterilizable. The driven portion of the cuff should be sized to cover at least the abdominal area from the costal arch to the level of the iliac crest. This avoids the bulging of the abdominal cavity caused by invading soft tissue elsewhere reducing the effect of artificial respiration. The sleeve should already have a clearly convex curve when it is not applied, so that an airtight fit of the sealing lip (3) on the body (2) is guaranteed. The sealing lip (3) should clearly protrude. With correct dimensioning, the sealing lip rests stress-free outside the area that can be expanded by fluid pressure and is pressed onto the skin of the body (2) by the atmospheric air pressure.

2 shows a fastening bandage (11) surrounding the cuff (1) as a fastening alternative. The fastening bandage can be adapted to the individual anatomy with straps, Velcro strips or the like. The bandage offers the advantage of being able to attach the cuff (1) to the body more easily and to be able to adjust it better to individual anatomies. If necessary, the function of the cuff (1) can be improved by partially stiffening the bandage (11).

3 shows the fluid pressure driven embodiment in section. The sleeve (1) and the sealing lip (3) can be seen. The cuff (1) itself consists of two elastic membranes (4, 4') which are connected to one another by a support structure (5). Soft elastomers, such as silicones, thermoplastic elastomers, polyurethanes or soft PVC, are suitable as material for the membranes (4, 4') in order to adapt to the body individually and comfortably and to provide the necessary stretching. Spacer fabrics with a bi-elastic cover layer that are glued to the membranes (4, 4') or cast into them are possible solutions for the support structure (5). However, the support structure can also be formed from the material of the membranes. Likewise, the walls of the support structure can be formed by a hose arranged in a spiral or meandering manner, as a result of which a separate membrane (4') remote from the body can then be dispensed with.

The cavity created by the support structure (5) in the cuff (1) is subjected to a pressure (P) via the connection (8) for actuation.

The negative pressure required for ventilation can be derived from the practice of ventilation via the airways. According to https://www.amboss.com/de/wissen/Maschinelle_Beventilator, the overpressure for mechanical ventilation should be set to between 15 and 20 mbar. It can be assumed that a negative pressure of this magnitude must be applied via the cuff (1) in order to bring about artificial respiration.

Since the internal pressure (P) of the cuff (1) acts equally on the membranes (4) and (4'), the resulting negative pressure on the body-facing membrane (4) results from the difference in the membrane surfaces. Accordingly, the negative pressure acting on the body (2) depends on the internal pressure (P), the curvature of the cuff (1) and the distance between the membranes (4) and (4'). High pressures in the patient environment represent a potential hazard that must be minimized. In order to keep the required pressure (P) low, the distance between the membranes (4, 4') should not be selected too small given the curvature defined by the body. Distances of approx. 10mm have proven to be practical.

The control of ventilation pressure is of great importance in clinical practice. As already mentioned, the ventilation pressure can be set via the pressure P if the curvature and the pressure required to overcome the elasticity of the cuff (1) are known.

If the patient's breathing is only to be supported, the cuff (1) can also be used as a sensor for the respiratory rate. At reversal points in breathing, the respiratory musculature works against the artificial respiration and thus creates deviations in the constant pressure profile. When inhaling, for example, the pressure in the cuff increases steadily. If the patient begins to breathe out, the cuff (1) has to work against the breathing muscles, which leads to an excessive pressure. So if the time differential of the pressure (P) is measured, this measurement can be used to synchronize the pressure curve of the pressure (P) with the patient's respiration.

4 shows schematically the embodiment with an electrostrictive drive in section. The sleeve (1) with the circumferential sealing lip (3) and the embedded flat electrodes (6, 6') can be seen. These are designed to be elastic and multi-layered, with one layer of the electrode (6) following one layer of the electrode (6'). If a voltage is applied between the electrodes (6) and (6') via the supply line (7), they attract each other electrostatically. The elastomer located between the electrodes of the cuff (1) gives way to the resulting pressure by expanding transversely to the polarization.

Elastomers with high elasticity and high dielectric strength are particularly suitable as material for the sleeve (1). Silicone elastomers, for example, are suitable. Graphite, carbon nanotubes or silver particles, for example, are suitable for producing the conductivity of the elastic electrodes (6, 6').

As with the fluid pressure driven variant, the electrostrictive drive variant can use the time differential of the voltage as a sensor signal to synchronize breathing with the patient's actual breathing.

5 shows schematically the embodiment with a mechanical drive. The basis is an auxetic structure (8) made of rods (12) which are connected to one another in an articulated manner at their ends. The structure is coupled to tension bars (10, 10') on both sides. On its underside, the auxetic structure (8) is connected to the membrane (4), which in turn forms the sealing lip (3) at its edges and rests on the body (2). The cuff (1) according to the invention is actuated by exerting tension on the tension bars (10). This can be done in the circumferential direction of the enclosed body (2), for example with a cable which is motor-driven. The auxetic structure responds to the tensile forces by stretching in the direction of the pull as well as transverse to the pull direction. Since the structure rests on the curved body (2), this leads to a further bulge, which acts on the body (2) by means of negative pressure. As in the previous embodiments, a soft elastomer is suitable for the membrane (4) with the sealing lip (3). The auxetic structure can advantageously be made of a stronger plastic. The articulated connection between the rods (12) can be made by means of film hinges. Such a structure can advantageously be manufactured additively, as a result of which a fine-particle auxetic structure can be created without increased effort being associated with this.

Reference List

1

cuff

2

body

3

sealing lip

4, 4'

membrane

5

support structure

6, 6'

electrode

7

supply line

8th

connection

9

auxetic structure

10, 10'

draw bar

11

bandage

12

Rod

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US 1834580 A [0004]
• US 2456724A [0005]
• US 2581893 A [0006]
• DE 1103523 [0007, 0009]
• US 2529258 A [0008]
• DE 102016107670 B3 [0011, 0016]

Claims (13)

Device for artificial respiration of a patient by means of a varying negative pressure with a cuff (1) at least partially enclosing the body and a drive, characterized in that the cuff (1) is elastic and at least partially encloses the body (2) directly and airtight. device after claim 1 , characterized in that the cuff (1) covers at least the abdominal area from the costal arch to the level of the iliac crest Device according to one or more of the preceding claims, characterized in that the cuff (1) with its sealing lip (3) completely encloses the abdominal area of the body (2). device after claim 1 , characterized in that the cuff (1) does not completely enclose the abdominal region of the body (2) and is attached to the body (2) by means of an additional bandage (11). device after claim 4 , characterized in that the bandage (11) contains stiffeners. Device according to one or more of the preceding claims, characterized in that the drive takes place by means of fluid pressure (P). Device according to one or more of the preceding claims, characterized in that the drive consists of 2 membranes (4, 4') which form a sealed chamber and are connected by means of a support structure (5). Device according to one or more of the preceding claims, characterized in that the drive consists of at least one elastic hose which is connected to the membrane (4) resting on the body (2). Device according to one or more of the preceding claims, characterized in that the fluid pressure (P) is measured and used to control or synchronize ventilation. device after claim 9 , characterized in that the time differential of the fluid pressure (P) is used to control the course of the pressure supply. Device according to one or more of the preceding claims, characterized in that the drive is based on electrostrictive forces. Device according to one or more of the preceding claims, characterized in that the drive contains an auxetic structure (9). device after claim 11 , characterized in that the auxetic structure is actuated by means of tensile forces acting in the circumferential direction of the body (2).

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