Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Reexamination Certificate
1999-02-03
2001-07-24
Dawson, Glenn K. (Department: 3761)
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
C128S205130, C128S205180, C128S204180, C128S203120, C128S203280
Reexamination Certificate
active
06263873
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bellows arrangement for a ventilator/anesthesia system of the type wherein the bellows arrangement has a rigid container in which a bellows is arranged, with a first end of the bellows fastened to one end of the container, and the second end being displaceable relative to the first end, and wherein the container can be attached to a propellant source and the bellows can be connected to a respiratory circuit at the aforementioned first end.
2. Description of the Prior Art
An anesthesia system with a bellows arrangement of the aforementioned type is illustrated and described in U.S. Pat. No. 5,678,540. The anesthesia system includes a respiratory circuit which can be connected to a patient, the aforementioned bellows arrangement, and a propellant source for controlling the flow of respiratory gas in the respiratory circuit. The interior of the bellows is connected to the respiratory circuit, as described above, and the space between the bellows and the wall of the container is connected to a propellant source.
For the initiation of an inhalation phase, the propellant source feeds a propellant to the space between the bellows and the container. When the pressure in this space is higher than the pressure in the bellows, the bellows begins to be compressed, causing respiratory gas to be fed to the patient. An exhalation phase follows an inhalation phase. During an exhalation phase, the propellant is released from the space between the bellows and the container, causing a relative pressure excess in the respiratory circuit and in the bellows to arise. The bellows then starts to expand, allowing the respiratory gas to flow out of the patient's lungs. This is repeated for each breathing cycle. Similar systems with bellows arrangements of this type are illustrated and described in published Swedish Application 466 635 and in European Application 0 557 134. Since the container is usually transparent, the movement sequence of the bellows is visible to the environment. In an expansion, or a compression, the bellows can wobble and/or its free end can end up in an oblique position, which does not affect the function, though it can disturb the hospital personnel.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a bellows arrangement of the type initially described wherein it is guaranteed, in a simple and inexpensive manner, that the bellows always moves smoothly.
This object is achieved in a bellows arrangement of the type initially described wherein a second end of the bellows is provided with at least one guidance fixture which is disposed in the container in every position of the second end to insure that, during an expansion or a compression of the bellows, the second end is always displaced along the center axis of the bellows in parallel fashion. The movements of the second end in the axial direction are stabilized by the guidance fixture, and so a wobbling of the bellows or an oblique position of the free end can not occur.
In one embodiment of the inventive bellows arrangement the connection to the respiratory circuit is tubular and is a part of the container, and the guidance fixture is an elongated part which is attached to the second end and is directed toward the first end. This elongated part has a length, diameter and placement so that, in all positions of the bellows, it is disposed in the tubular part of the connection such that it can be frictionlessly displaced therein, and the elongated part is constructed such that it allows gas to pass through the connection in the filling or evacuating of the bellows. Utilization of the already existing connection for the respiratory circuit results in an extremely simple construction for the bellows guidance, while at the same time a compact bellows arrangement is obtained by the direction and position of the guidance fixture.
The guidance fixture can inventively be a tubular part, but preferably is a part with a stellate cross-section. It is essential that the guidance fixture be constructed such that it allows gas to pass through the connection in the filling of the bellows or in the evacuation of the bellows.
In a further embodiment of the inventive bellows arrangement, the guidance fixture is at least one elongated part which is attached to the second end of the bellows and is directed away from the first end, and the container has a recess of a shape and placement so that, in all positions of the bellows, the elongated part is disposed in the recess such that it can be frictionlessly displaced therein.
In this further exemplary embodiment, the guidance fixture also can be a tubular part or a part with a stellate cross-section. The guidance element can alternatively be a rod or peg.
Additional stabilizing of the movements of the bellows in the axial direction is achieved in an embodiment wherein the second side is provided with two or more guidance fixture with corresponding recesses in the container.
REFERENCES:
patent: 5678540 (1997-10-01), Kock et al.
patent: 5683232 (1997-11-01), Adahan
patent: 6123072 (2000-09-01), Downs
patent: 0 557 134 (1993-08-01), None
patent: 466 635 (1992-03-01), None
patent: WO 97/01367 (1997-01-01), None
Dawson Glenn K.
Schiff & Hardin & Waite
Siemens-Elema AB
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