GB2095121A - Anaesthesia apparatus having manual or automatic ventilation - Google Patents

Abstract

Anaesthesia apparatus comprises a vessel 48 connected to a fresh gases supply tube 34 and an exhaled gases tube 32. A flow control device 12 connects the tubes to a face mask and is such that gas is preferentially drawn by the patient from the supply tube during inhalation and is preferentially directed into the supply tube during exhalation. A bag 50 is connected to the exhaled gases tube and the interior of the bag is connected to the fresh gases supply tube. An outlet port 54 from the vessel is provided for connection to a manual or automatic ventilating means and a further port 52 is connected by way of a valve 56 to exhaust. The valve is infinitely adjustable between a position in which the further port is closed and a position in which substantially unrestricted flow can take place through said further port. <IMAGE>

Description

SPECIFICATION Anaesthesia apparatus This invention relates to anaesthesia apparatus.

According to the present invention there is provided anaesthesia apparatus comprising a vessel having first, second, third and fourth ports, a valve connected to the first of said ports for controlling flow from said vessel through said first port, said valve being adjustable between a position in which said first port is closed and a position in which substantially unrestricted flow through the first port is permitted, an exhaled gases tube connected to said vessel by way of said second port thereby permitting exhaled gases to flow from the exhaled gases tube into the vessel, a breathing bag within the vessel, and a fresh gases supply tube, the third port connecting the interior of the breathing bag to said fresh gases supply tube along which, in use of the apparatus, fresh gases flow, said fourth port being for connection to means for ventilating a patient.

Said valve, when between said two positions, permits leakage through said first port so that manually controlled ventilation is possible.

The anaesthesia apparatus can further include a breathing mask and a structure between said tubes and the breathing mask, said structure being such that, on the patient inhaling, gases are preferentially drawn from the fresh gases supply tube to deflate said bag, and on the patient exhaling, gases are preferentially directed into said supply tube to inflate said bag, exhaled gases flowing into the exhaled gases tube after said bag has been fully inflated and back pressure builds up in the fresh gases supply tube.

Said structure preferably includes a jet extending into that end of the fresh gases supply tube which is adjacent the face mask for directing exhaled gases into the fresh gases supply tube.

Said fresh gases supply tube can be within said exhaled gases tube.

Said valve preferably includes a body and a plunger member which is displaceable axially of the body, the effective area of a flow path through the body from an inlet thereof to an outlet thereof depending on the position of the plunger with respect to the body.

Said plunger member, in one constructional form, can have a tapering head which co-operates with an annular valve seat. To enable the resistance of the plunger to displacement with respect to the body to be adjusted, there can be a sealing ring which encircles the plunger member and means for enabling the degree of compression of the sealing ring to be varied, an increase in the compressive force on the sealing ring causing it to grip the plunger member more tightly and increase its resistance to sliding movement.

For a better understanding of the present invention and to show how same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:~ Figure 1 is a diagrammatic representation of anaesthesia apparatus in accordance with the present invention; Figure 2 is diagrammatic representation of part of a further form of apparatus according to the present invention; and Figure 3 is a detail of a still further form of apparatus.

Referring firstly to Figure 1, an inhalation anaesthesia apparatus is designated generally by reference numeral 10. The apparatus 10 includes a gas flow control device 12 and the device 12 itself comprises a main body 14 and a hollow tapering member 16. The body 14 comprises an outer sleeve 1 8 which is joined by a tapering portion 20 to a connector 22. Secured to the connector 22 is a face mask 24. The body 14 also includes an inner sleeve 26 mounted within the body 14 by means for one or more radial struts 28. The body 16 has a bore 30 which constitutes a jet. As seen in Figure 1, the member 16 projects from the connector 22 in the opposite direction to the face mask 24.

An outer tube 32 of a co-axial tube system has one of its ends connected to the free end of the sleeve 18. An inner tube 34 is connected at its corresponding end to the free end of the sleeve 26. The free end of the sleeve 26 projects beyond the free end of the sleeve 18 to facilitate attachment of the tubes 32 and 34 thereto. The tube 34 is a fresh gases supply tube and the tube 32 is an exhaled gases outlet tube. The sleeve 26 can be considered to form part of the fresh gases supply tube.

The tubes 32 and 34 lead to co-axial connectors 36 and 38 respectively of a unit generally designated 40. In addition to the connectors 36 and 38 the unit 40 includes a fresh gases inlet 42 and is connected to two ports 44 and 46 of a constant volume cylindrical vessel 48.

The interior of the vessel is connected by way of the continuously open port 44 to the interior of the outer tube 32. The inner tube 34 is connected via the connector 38 and the inlet 42 of the unit 40 to a source (not shown) of fresh gases and, by way of the continuously open port 46, to a reservoir bag 50 which is within the vessel 48.

The vessel 48 has two further ports which are designated 52 and 54. A valve 56 is provided between the port 52 and a duct 58 which leads to a scavenging system (not shown). The valve 56 comprises a cylindrical body 60 which is co-axial with the port 52. The free end of the body 60 is externally threaded and an internally tapered cap 62 is screwed onto the body 60. A valve operating plunger member 64 passes through a central aperture of the cap, there being a sealing ring 66 encircling the member 64.

Within an internal groove of the body 60 there is a resilient valve. seat 68 which co-operates with the tapering head of the member 64.

The sealing ring 66 seals between the cap 62 and the body 60 and between the cap 62 and the member 64. The setting of the valve 56 is infinitely variable between a fully open position in which substantially unrestricted flow through the port 52 to the duct 58 is possible and a fully closed position.

When the cap 62 is tightened the ring 66 is squeezed inwardly to grip the member 64. Thus the resistance to movement of the member 64 can be controlled by tightening or loosening the cap 62. This resistance prevents the member 64 shifting after its position has been set.

At the outer end of the member 64 there is a knob 70 which facilitates displacement of the member 64. The wider diameter end of the head of the member 64 guides the member's movements in the body 60.

To permit full flow through the valve, the member 64 is displaced by means of the knob 70 so that its tapering head no longer significantly restricts flow from the port 52 to the duct 58. By pressing on the knob 70, the tapering head of the member 64 progressively obstructs free flow through the valve. When the tapering head, along its entire circumference, encounters the seat 68, the valve is closed. The position of the member 64 can readily be determined by checking on the amount by which it protrudes from the cap 62, and adjustment can be made by a simple sliding action.

While the ports 52 and 54 are shown in the side wall of the vessel 48, it is preferred that the vessel 48 include an air-tight lid with four ports in it. The unit 40 in this form comprises two downwardly directed spigots which enter two of the ports in the lid.

The port 54 connects by way of a duct 72 to a bag 74 which is used for controlled ventilation.

The port 54, after removal of the bag 74, can be connected to fully automatic ventilation apparatus (not shown).

In operation, during spon#aneous respiration, fresh gases are inhaled by the patient through the supply tube 34 and the bore 30. Exhaled gases are directed through the bore 30 back into the supply tube 34. Most of the dead space gases followed by the alveolar gases are preferentially directed into the inner tube 34 and distend the bag 50 until the pressure increases sufficiently to cause the remainder of the exhaled gases to pass through the annular gap between the sleeve 26 and the tip of the member 1 6 into the outer tube 32. Because the valve 56 is fully open the exhaled gases flow through the duct 58 to the scavenging system.

When the patient inhales gases flow preferentially from the tube 34 into the member 16.

If it is desired to perform controlled ventilation, using the bag 74 to provide the pressure necessary to inflate the lungs, the valve 56 is partially shut by pushing the member 64 inwardly.

A controlled leak of alveolar gas is thereby obtained during manual ventilation. As the bag 74 is manually compressed to provide the pressure needed to inflate the lungs, external pressure is exerted on the bag 50 which collapses thereby expelling gas along the tube 34 to the patient's lungs. Simultaneously there is some gas flow along the tube 32. The nature of the device 12 and the resistance to flow offered by the annular space between the tubes 32 and 34 ensures that by far the greater part of the gases reaching the mask 24 flow from the tube 34.

If fully automatic ventilation is to be performed, then the valve 56 is fully closed. It will be understood that any respirator used has its own gas elimination system and that the valve 56 remaining open can only interfere with the operation of this.

In Figure 2 the co-axial tubes 32 and 34 of Figure 1 are replaced by parallel, spaced tubes 76 and 78. The flow control device, designated 12.1, is similar to that of Figure 1 and where applicable like parts have been designated with the same numbers with the addition of the suffix .1. Because of the arrangement of the tubes 76 and 78 the sleeves 18.1 and 26.1 are side by side rather than co-axial. Likewise the connectors 36.1 and 38.1 of the unit 40.1 are side by side rather than co-axial.

It will be understood that the ports 44, 46, 52 and 54 can be re-arranged if desired. For example, the ports 52 and 54 could be the outlets of a pair of tee-pieces connected between the port 44 and the unit 40 and not necessarily each open directly into the vessel 48.

The preferential gas flow control device 12 can if desired be replaced by a lightly loaded one-way valve 80 (Figure 3) in the pipe which leads from the port 44 to the unit 40. The valve 80 remains closed during exhalation until sufficient pressure has built-up in the bag 50. Application of this pressure to the valve 80 causes it to open. When the valve 80 opens, exhaled gases flow from the tube 32 through the valve and into the vessel 48.

In this form no flow from the vessel 48 to the patient is possible.

Claims (10)

1. Anaesthesia apparatus comprising a vessel having first, second, third and fourth ports, a valve connected to the first of said ports for controlling flow from said vessel through said first port, said valve being adjustable between a position in which said first port is closed and a position in which substantially unrestricted flow through the first port is permitted, an exhaled gases tube connected to said vessel by way of said second port thereby permitting exhaled gases to flow from the exhaled gases tube into the vessel, a breathing bag within the vessel, and a fresh gases supply tube, the third port connecting the interior of the breathing bag to said fresh gases supply tube along which, in use of the apparatus, fresh gases flow, said fourth port being for connection to means for ventilating a patient.

2. Anaesthesia apparatus as claimed in claim 1, in which said valve, when between said two positions, permits leakage through said first port so that manually controlled ventilation is possible.

3. Anaesthesia apparatus as claimed in claim 1 or 2 and including a breathing mask and a structure between said tubes and the breathing mask, said structure being such that, on the patient inhaling, gases are preferentially drawn from the fresh gases supply tube to deflate said bag, and on the patient exhaling, gases are preferentially directed into said supply tube to inflate said bag, exhaled gases flowing into the exhaled gases tube after said bag has been fully inflated and back pressure builds up in the fresh gases supply tube.

4. Anaesthesia apparatus as claimed in claim 3, in which said structure includes a jet extending intojthat end of the fresh gases supply tube which is adjacent the face mask for directing exhaled gases into the fresh gases supply tube.

5. Anaesthesia apparatus as claimed in claim 1 or 2, and including a one-way valve for permitting flow from the exhaled gases tube to the vessel but not in the reverse direction, said valve opening upon the pressure in the exhaled gases tube reaching a predetermined value.

6. Anaesthesia apparatus as claimed in any preceding claim, in which said fresh gases supply 'tube is within said exhaled gases tube.

7. Anaesthesia apparatus as claimed in any preceding claim, in which the valve for controlling flow through said first port includes a body and a plunger member which is displaceabie axially of the body, the effective area of a flow path through the body from an inlet thereof to an outlet thereof depending on the position of the plunger with respect to the body.

8. Anaesthesia apparatus as claimed in claim 7, in which said plunger member has a tapering head which co-operates with an annular valve seat.

9. Anaesthesia apparatus as claimed in claim 7 or 8, in which there is a sealing ring which encircles the plunger member and means for enabling the degree of compression of the sealing ring to be varied, an increase in the compressive force on the sealing ring causing it to grip the plunger member more tightly and increase its resistance to sliding movement.

10. Anaesthesia apparatus substantially as hereinbefore described with reference to Figure 1, Figure 2 or Figure 3 of the accompanying drawings.