Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Patent
1992-01-24
1993-12-21
Burr, Edgar S.
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
12820424, 12820425, A61M 1600
Patent
active
052713881
DESCRIPTION:
BRIEF SUMMARY
This invention relates to improvements in or relating to medical ventilators and, more particularly, to a medical ventilator which is especially, but not exclusively, useful for high frequency ventilation or oscillation of a patient.
Medical ventilators are extensively used in varying circumstances to replace or assist the natural breathing process of a patient in whom this function is impaired.
Under some circumstances and for particular purposes, it is advantageous to ventilate the lungs of a patient at breathing rates which are higher than spontaneous breathing rates with the aid of a high frequency medical ventilator which may provide breathing rates of up to 3000 breaths per minute (bpm).
A known high frequency medical ventilator or oscillator comprises a ventilator duct which has a patient end for attachment to a patient tube adapted to be introduced into the trachea of a patient whose breathing is to be sustained or augmented by the ventilator. Respiratory gas is introduced into the ventilator duct through two fixed jets extending into the ventilator duct, one of the jets having an outlet orifice facing the patient end of the ventilator duct and the other jet having its outlet orifice facing away from the patient end of the duct. Pulses of respiratory gas are fed alternatively to the two jets so that the patient tube is alternately subjected to high and low pressure, causing an alternating upstream and downstream flow of gas to and from the lungs of the patient in a cyclical way. Other high frequency ventilators are normally closed systems and employ either piston or bellows devices.
While these known high frequency medical ventilators function more or less satisfactorily under some conditions, either they are bulky or the pressure waveform resulting from the alternate pulsing of the two oppositely facing jets is not entirely satisfactory. Also, the synchronization of the pulsed gases supplied to the two jets to maintain the required lung (alveolar) expansion is critical and may be difficult to arrange safely in a clinical situation. The complexity in the breathing circuit of a closed system has made it unsafe and difficult for routine clinical use.
It is an object of the present invention to provide an improved medical oscillatory ventilator which finds particular application as a high frequency ventilator and, to this end, the invention provides a medical ventilator comprising a ventilator duct having a patient end for attachment to a patient tube ; a respiratory gas supply jet extending into the patient duct and mounted for rotation about an axis transverse to the axis of the ventilator duct, the jet having a gas supply passage terminating in an outlet orifice arranged to direct gas into the ventilator duct in a direction transverse to the axis of rotation of the jet; means for rotating the jet about the axis of rotation; and means for continuously supplying gas to the passage in the jet as the jet rotates to produce a cyclically varying flow of gas to and from the patient end of the ventilator duct.
In an embodiment of the ventilator a gas supply chamber encircles a rotatably mounted shaft of the jet and communicates with the gas supply passage in the jet through radially extending openings in the shaft of the jet.
Preferably, the shaft of the jet is rotatably mounted in a bearing block which is formed with a gas supply conduit extending transversely of the axis of rotation of the shaft of the jet and which terminates in the gas supply chamber.
The means for rotating the jet conveniently comprises an electric motor.
In order that the invention may be readily understood, embodiments thereof will now be described by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a side view of a medical ventilator embodying the present invention, partly sectioned to show a rotatable jet within the ventilator duct;
FIG. 2 is a cross-sectional view on the line II--II of FIG. 1, with an electric motor of the ventilator unsectioned;
FIG. 3 is a cross-sectional view on the line of FIG.
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Chakrabarti Mihir K.
Whitwam James G.
Burr Edgar S.
Caduceus Limited
Lewis Aaron J.
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