WO1999025409A1

WO1999025409A1 - Jet ventilator

Info

Publication number: WO1999025409A1
Application number: PCT/GB1998/003405
Authority: WO
Inventors: Pieter Rousseau Fourie
Original assignee: Harwill Industries (Pty.) Ltd.; Gemmell, Peter, Alan
Priority date: 1997-11-14
Filing date: 1998-11-16
Publication date: 1999-05-27
Also published as: AU1163699A

Abstract

This invention relates to a jet ventilator system to ventilate patients during surgical procedures. The jet ventilator system of the invention comprises a driving gas source (10), a flow regulator (18) by means of which the driving gas flow may be regulated and a trigger (22) to control the flow, the trigger (22) being integral with the flow regulator (18). The integration of the flow regulator (18) with the trigger (22) enables the integration of a multiplicity of ventilator functions into a single, integrated ventilator system. To this end, the ventilator system may include an eductor (30) adapted to educt fluid into the driving gas stream during use by mixing the incoming fluid with the driving gas in the eductor (30). Preferably the system includes dedicated air and fluid eductors. The fluid eductor can be connected to a surgical suction device at its inlet end and, at its outlet end, to a waste disposal facility. The jet ventilator system of the invention includes a control system with time switched regulators constituted by an inspiratory regulator, an expiratory regulator and a manual override switch that is integrated with the flow regulator (18).

Description

JET VENTILATOR

Background to the invention

This invention relates to a jet ventilator.

Jet ventilators use the venturi effect to entrain a secondary gas (normally air) by means of a driving gas (normally oxygen) to ventilate patients during surgical procedures, normally only during short procedures.

The ventilation of patients during bronchoscopy procedures or during transport, especially during short periods such as from theatre to an intensive care ward, is still a cumbersome procedure and requires the use of a transport ventilator. The latter apparatus is usually difficult to obtain, complex to operate and expensive. Furthermore, when the need arises to ventilate a patient that is in a compromised position such as during CAT scanning procedures, under a vehicle after an accident or in a crevice after a mountain accident, the use of a transport ventilator becomes a complicated and challenging experience.

At present patients requiring portable ventilation are usually bagged using a portable ventilator device. This device consists of a one-way valve attached to a large rubber bag that acts as a reservoir. Oxygen supply can be connected to the rubber bag to increase the delivery of oxygen to the patient. While this device provides a relatively easy method of ventilating a patient under emergency conditions, it is user dependant and it cannot be used for long periods since it will eventually exhaust the operator. In addition, the mechanical forces applied during the procedure can dislodge ancillary ventilation apparatus such as endotracheal tubes and, in pediatric patients in particular, can damage sensitive lung tissue.

As an alternative, it is possible to ventilate a patient using a bronchoscope jetting device consisting of a small nozzle that injects driving oxygen into the bronchoscope. Because of the venturi effect, the injected oxygen draws air in at the proximal end of the bronchoscope, which mixes air with the oxygen. The mixed gas is then delivered to the patient at the distal end of the bronchoscope. Jetting devices of this kind are easy to use during bronchoscopic procedures, but they find application only during such procedures.

The applicant is also conversant with the so-called Carden jetting device. It includes a driving gas, normally oxygen obtained from a portable oxygen cylinder provided with an appropriate pressure regulator. In addition, the device includes a variable pressure regulator, a pressure gauge and a trigger. Jetting is regulated by manipulation of the variable pressure regulator either on its own or in combination with the trigger. However, the device suffers from the disadvantage that the trigger and regulator are remote from one another and that makes the device cumbersome to use. In addition, the Carden jetting device is essentially a manually operated system and it is therefore limited in its application.

It is an object of this invention to address these shortcomings in these existing devices. Summary of the invention

According to this invention, a jet ventilator system comprises a driving gas source, a flow regulator by means of which the driving gas flow may be regulated and a trigger to control the flow, the trigger being integral with the flow regulator.

The integration of the flow regulator with the trigger enables the integration of a multiplicity of ventilator functions into a single, integrated ventilator system.

To this end, the ventilator system may include an eductor adapted to educt fluid into the driving gas stream during use by mixing the incoming fluid with the driving gas in the eductor.

The eductor may comprise a simple open-ended eductor tube one end of which is closed and adapted to accept a driving gas nozzle and the other, open end being adapted for connection to patient assisted breathing apparatus, the eductor tube having a drawn air inlet opening into a side of the eductor tube.

The eductor described above can serve as both an air eductor and a fluid eductor.

Alternatively, however, the system may include dedicated air and fluid eductors. The eductors may conveniently be disposable and made from injection moulded plastics.

the fluid eductor can be connected, either permanently or at the point of use, to a surgical suction device at its inlet end and, at its outlet end, to a waste disposal facility. The use of a fluid eductor permits the integration of a waste disposal facility in the jet ventilator system of the invention.

In addition, the jet ventilator system of the invention lends itself readily to automation.

To this end, the jet ventilator system may include a control system that includes time switched regulators constituted, at least, by an inspiratory regulator and an expiratory regulator, the control system including a manual override switch integral with the flow regulator that is adapted for manual actuation by means of which automatic operation of the control system can be overridden.

Brief description of the drawings

In the drawings:

Figure 1 is a diagrammatic illustration of the basic components of the jet ventilator of the invention;

Figure 2 illustrates (in Figures 2A, 2B and 2C) , the jetting device of the invention integrated into a single hand-held unit;

Figure 3 illustrates eductors for the jetting device of the invention, with Figure 3 illustrating a basic eductor, Figure 3B illustrating an integrated air eductor and Figure

3C illustrating a fluid eductor;

Figure 4 illustrates (in Figures 4A to 4G) a number of accessories that can be used in conjunction with the jetting device of the invention;

Figure 5 is a waste bag adapted for use with the jetting device of the invention;

Figure 6 is a fluid flow diagram of an automatically timed embodiment of the invention that permits the integration of the jet ventilator, the eductor and the accessories referred to above into an integrated ventilation system; and

Figure 7 is a diagrammatic representation of a housing for the automatically timed embodiment of Figure 6.

Description of embodiments of the invention

The jet ventilator of the invention is illustrated in its most basic form in Figure 1 and comprises in essence, a source of driving gas which gas is led, by way of tubing, through an integrated regulator and trigger unit to a driving jet nozzle.

The driving gas is normally oxygen obtained from an oxygen cylinder 10 fitted with a pressure regulator 12.

Gas from the cylinder 10 is led, by way of a tube 14, to an integrated flow regulator and trigger assembly 16 that comprises a variable flow regulator 18, a pressure gauge 20 and a trigger lever 22 by means of which the gas flow may be switched on and off. The flow regulator 18 is controlled and adjusted by means of a control knob 24.

The flow regulator 18 is intended to control the oxygen supply to the patient in order to control oxygen delivery and therefore the end inspiratory pressure (degree of inflation) of the patient. Flow through the flow regulator 16 is manually adjusted by means of the control knob 24. A typical oxygen supply pressure range is between 0 and 10 bar.

The trigger lever 22, when depressed, enables the flow of oxygen to the patient.

A tube 26 connected to the outlet of the regulator and trigger assembly 16 terminates in a driving jet nozzle 28 consisting of a 16-gauge needle. The jet nozzle constituted by the needle 28 can be used on its own. In the preferred form of the invention, however, the nozzle 28 is located or integrated within the eductor illustrated in Figure 3.

The eductor 30 consists of an open-ended eductor tube 32, one end of which is closed and adapted to accept the nozzle 28 by way of a nozzle mounting 34. A drawn air inlet 36 is provided on the side of the eductor tube 32.

In use, the passage of driving gas through the eductor tube 32 will entrain and draw in air through the drawn air inlet 36. The open end of the eductor tube 32 is adapted for secure ent to a number of conventional ancillary ventilation devices. By increasing the length of the connecting tube 26, the eductor 30 can be connected to the hand held jet trigger 22 at some distance, thereby allowing the effective ventilation of patients at a distance.

In use with the eductor 30, the nozzle 28 allows air to mix with the oxygen. In addition, the drawn air inlet 36 of the eductor 30 will serve as a backflow blow off mechanism that assists in avoiding overinflation of the patient.

The embodiment of the invention illustrated in Figures 2B and 2C combines the components of the jet ventilator of Figure 1 and an eductor similar to the eductor 30, into a unit and adds an integral pressure extension that will be described below.

The manner in which the basic components of the ventilator of Figure 1 can be combined into the integrated ventilator of Figure 2 is illustrated in figure 2A. In this drawing, similar components are numbered similarly.

The integrated ventilator itself 110 is shown in Figures 2B and 2C. The integrated ventilator is shown partly disassembled in Figure 2B and fully assembled in Figure 2C.

Figure 2A which shows the components of the jet ventilator of Figure 1 connected to an eductor 30. A pressure extension 38 is shown as an additional fitting adapted for connection to the eductor 30.

The pressure extension 38 comprises a tube 40 that is open at both ends. A metering nozzle 41 is let into the pressure extension tube 38 and a pressure gauge 42, that can be used to determine patient inspiratory pressure, is or can be mounted on the metering nozzle 41.

This allows the monitoring of inspiratory pressure, particularly end inspiratory pressure, proximal to an endotracheal tube, for instance.

In turn, this allows more effective patient ventilation since the end inspiratory pressure indicates, to a large extent, the degree of inflation of the lungs. In addition, the practitioner can determine the extent of any possible overdistension of the lungs. The danger of overinflation is a matter of concern particularly when ventilating infants and the monitoring of end inspiratory pressure in these situations is mandatory.

The pressure gauge 42 can be located on the pressure extension 38, but it can also be located at the flow regulator 16. In such an event, the pressure gauge 42 will be connected to the pressure extension 38 by means of plastic tubing, for instance, that is connected to the metering nozzle 41. Connection of the pressure extension 38 in this manner, again, aids in the effective ventilation of a patient at a distance.

The embodiment of the invention shown in Figure 2 illustrates one method of combining the components of the jet ventilator of Figure 1 into a unit with an integral pressure extension.

Referring to Figure 2B, the integrated ventilator 110 comprises a variable flow regulator section 118, a pressure gauge 120 and a trigger 122 by means of which the gas flow may be switched on and off. The flow regulator section 118 is controlled and adjusted by means of a control knob 124.

The integrated ventilator 110 includes a fluid connector 109 for connection to a source of driving gas supplied to the regulator section 118 from where it is directed to an outlet nozzle 128.

A combined eductor and pressure extension 146 is removably attached to the flow regulator section 118. It is shown partially removed in Figure 2B. The combined eductor and pressure extension 146 can, however, be clipped or otherwise connected to the flow regulator section 118 such that the two parts are integral and operate as a unit, each part performing the functions specified above.

For most situations where a ventilator is needed, however, the requirement is for a unit that incorporates all the apparatus making up the ventilator, including an oxygen cylinder. In order to provide such a unit, it is most convenient to have all the component apparatus together in a carry case or the like.

The eductors 30.1 and 30.2 illustrated in Figures 3B and 3C are components that facilitate such integration.

The integrated eductor of Figure 3B is essentially an air eductor 30.1 that consists of a venturi with an opening upstream of the venturi throat which educts (entrains or sucks in) air during use. Eduction is accomplished by joining the incoming air with the driving gas in a constriction in the tube (the throat of the venturi) where a low pressure area is created that draws the incoming air into the driving gas.

The air eductor 30.1 is injection moulded out of a suitable plastics material, which will depend on the driving gas to be used.

The driving jet nozzle 28.1 is integrally moulded with the eductor tube 32.1.

The driving jet nozzle 28.1 of the air eductor 30.1 is located just upstream of the open, flared eductor mouth 32.1A of the air eductor 30.1 by means of three mounting fins 29.

The throat portion 32. IB of the air eductor 30.1 flares out in a flared mixing zone 32.1C and opens out into an enlarged pressure extension tube portion 32. ID within which a pressure metering nozzle 41.1 is let into the air eductor 30.1.

In use, the metering nozzle 41.1 is connected to a pressure gauge forming part of the flow regulator by means of tubing that can be clipped to the side of the air eductor 30.1 by means of tube clips 31. This allows the monitoring of inspiratory pressure, particularly end inspiratory pressure.

A separate luer 32.1 is provided for connection of the air eductor 30.1 to an endotracheal tube or other breathing assistance apparatus.

The air eductor 30.1 is designed to provide, in a relatively small, compact and disposable device, an eductor that yields an optimised mixed flow (of driving oxygen and entrained air) for a minimum primary flow (of driving oxygen) while still achieving end inspiratory pressures acceptable for assistance to a wide range of patients, preferable from neonates to adults.

One of the advantages sought to be obtained is that the air eductor 30.1, being economical with driving gas, will enable patient assistance of greater duration for the same quantity of gas.

In order to obtain the increased efficiency of the air eductor 30.1, the following dimensional ratios have been found most advantageous: -lithe cross sectional area of the air eductor throat 32. IB (internal) to the cross sectional area of the driving jet nozzle 28.1 (exit aperture) :- between 20 :1 and 30 : 1 and preferably 25 : 1

the length of the air eductor throat 32. IB to the internal diameter of the air eductor throat 32. IB:- between 5 :1 and 10 : 1 and preferably 7.5 : 1

the length of the eductor mouth 32.1A to the internal diameter of the air eductor throat

32. IB:- between 1 :1 and 2 : 1 and preferably 1.5

: 1

angle of flare (cone angle) of the inner wall of the eductor mouth 32.1A - between 162° and 168°

angle of flare (cone angle) of the flared mixing zone 32.1C - 10°

In addition, the external wall of the driving jet nozzle 28.1 is coned at an angle corresponding to the cone angle of the eductor mouth 32.1A to yield an educted air inlet path of relatively constant cross section.

The eductor of Figure 3C is a fluid eductor 30.2 that is injection moulded in two parts, an eduction plenum 33 and a venturi 35.

In the venturi throat 37, suctioned fluids (and air) are led into the eductor by way of a tube connected to the inlet 39 of the eduction plenum 33. The driving gas stream issues from a driving gas nozzle 28.2.

In use, the tube will be connected to a surgical suction device such as a Yankauer by means of a suction line (not shown) connected to the eduction plenum 39. A driving gas line (not shown) will be connected to a driving gas nozzle 43 that delivers the driving gas to the nozzle 28.2.

Eduction is accomplished by mixing of the incoming fluids (liquids and air) with the driving gas in the throat 37 of the venturi 35.

The mixed fluids, air and driving gas is then ejected through the outlet 47 of the fluid eductor 30.2 to a continuation of the suction line (not shown) to a waste bag or the like.

The fluid eductor 30.2 is injection moulded out of a suitable plastics material. The driving jet nozzle 28.2 is integrally moulded with the eduction plenum 33.

The fluid eductor 30.2 is designed to provide, in a relatively small, compact and disposable device, an eductor that yields an optimised mixed flow (of driving oxygen and entrained fluids and air) for a minimum primary flow (of driving oxygen) .

Using the simple eductor 30 of Figure 2A as an example, Figure 4 illustrates the manner in which the eductors 30 can be connected to a number of surgical devices. The eductor 30.1 of Figure 3B can be connected either directly or across the luer 32. IE.

The eductor 30 can be connected to a bronchoscope 700, as is illustrated in Figure 4B. The eductor 30.1 of Figure 3B can be connected to a bronchoscope in similar fashion.

The eductor 30 can be used in a bronchoscope 702 in conventional fashion, as is illustrated in Figure 4A, by removing the nozzle 28 from the _.eductor 30.

The eductor 30 can also be connected to an endotracheal tube 600 (as is illustrated in Figure 4C) ; a face mask 500 (as is illustrated in Figure 4D) ; a tracheostomy valve 400 (as is illustrated in Figure 4E) ; or a Guedel airway 300 (as is illustrated in Figure 4F) .

The eductor 30.1 of Figure 3B can be connected to an endotracheal tube, a face mask, a tracheostomy valve or a Guedel airway 300 in similar fashion.

By detaching the ventilator from the patient and substituting a suction bag 800, as is illustrated in Figure 4G, the patient can be suctioned to remove blood or mucus from the lungs or trachea. To do this, the suction bag 800 is connected to the outflow end of the eductor 30 and a suction tube or Yankauer 802 is connected to the drawn air inlet 36 that presents a source of mild suction. In this way, the eductor 30 serves as a fluid eductor.

An alternative suction facility is illustrated in Figure 5. In this drawing, the bag 800.1 is housed within a sheathing bag 800.2 that has an opening flap 800.3. The sheathing bag 800.2 can be hung up by the opening flap 800.3, the latter being provided with hooks or hanging formations (not shown) for this purpose.

A vent port 800.4 is formed in the bag 800.1. The vent port 800.4 is covered with a cover that will permit the venting of the driving gas in use, while preventing the escape of suctioned fluids.

The preferred bag material is 100 μ PVC. The preferred vent port cover material is a hydrophobic PTFE fabric. The fabric pore size must be sufficiently large to permit venting of the driving gas without undue driving gas pressure build-up in the bag, since this will affect the functioning of the fluid eductor. However, the pore size should be sufficiently small to prevent leakage of the suctioned fluids. The vent port cover material presently preferred is GORE-TEX™, a woven and coated laminate material, with a 1 μm pore size.

The bag 800.1 is pre-assembled with the tubing required. The preferred tubing is non-kinking silicone tubing that is suitable for use with medical oxygen. A suction line 800.5 constituted by a length of suction tubing is connected to the bag 800.1 by means of a connector 800.6. It is possible to form the fluid eductor integrally with the connector 800.6. However, it is more convenient merely to secure, in the suction line 800.5, a separate fluid eductor such as the fluid eductor 30.2 illustrated in Figure 3C.

In such an event, the fluid eductor 30.2 is connected in line in the suction line 800.5 with the Yankauer end of the line 800.5 connected to the eduction plenum 39 of the eductor 30.2. A driving gas line 800.8 is connected to the driving gas nozzle 43 of the fluid eductor 30.2 to deliver the driving gas to the driving gas nozzle thereof. The educted fluids, air and driving gas are then ejected through the outlet 47 of the fluid eductor 30.2 to the bag end of the suction line 800.5 for discharge into the waste bag 800.1.

The components of the suction facility illustrated in Figure 5 are intended for once off use. After being used only once, the driving gas line 800.5 is removed from the gas cylinder and the bag 800.1, all tubing (the suction line 800.5 and the driving gas line 800.8) and the Yankauer 800.7 are all bundled up into the sheath bag 800.2. The flap 800.3 is closed (a sealing arrangement may be provided for this purpose) and the whole lot is disposed of inside the sheath bag 800.2.

If the suction facility is used at the same time as the ventilator is being used, both the suction facility and the ventilator will be tapped off the gas cylinder at source so as not to degrade or interfere with the operation of the ventilator.

Because of the danger of cross contamination and the difficulty and expense of sterilising the patient circuit of a ventilator after each use, the jet ventilator of the invention is designed so that the patient circuit is disposable, thereby eliminating the risk of infection.

Sometimes the need arises for the practitioner to use both hands in order, for instance, to secure an endotracheal tube or introduce an intravenous infusion line while operating the jet ventilator.

To accommodate this need, the jet ventilator control system 210 illustrated in Figures 6 and 7 includes two time switched regulators 202, 204, one (202) for the inspiratory time and one (204) for the expiratory time. By setting these two regulators 202, 204, the patient can be ventilated at a fixed frequency and inspiratory/expiratory ratio while the operator attends to the other needs of the patient.

In addition, the control system 210 includes an oxygen flow valve 206 with a number of predetermined settings. These settings could be preset to accommodate the flow rates and inflation volumes recommended for neonates, children and adults. The preset settings are intended to assist operators other than highly trained personnel to use the ventilator.

The flow valve 206 can be made to be infinitely variable between these settings.

The automatic operation of the control system can be overridden by means of a manual override facility constituted by an override switch 222 similar to the trigger 22, 122 described with reference to Figures 1 and 2.

The manual override switch 222 can be used to ventilate the patient at any desired frequency. The operator merely depresses the override switch 222 to permit oxygen flow and releases the switch 222 to interrupt the flow of oxygen. If, at any time, the override switch 222 is not depressed, the control system reverts back to the preset automatic frequency.

The automatic system will only be used when necessary and always in the presence of an attending physician.

Claims

Cl ims

1. A jet ventilator system comprising a driving gas source (10) , a flow regulator (18) by means of which the driving gas flow may be regulated and a trigger (22) to control the flow, characterised in that the trigger (22) is integral with the flow regulator (18) .

2. A jet ventilator system according to claim 1 which includes an eductor (30, 30.1, 30.2) adapted to educt fluid into the driving gas stream during use by mixing the incoming fluid with the driving gas in the eductor.

3. A jet ventilator system according to claim 2 in which the eductor (30) comprises an open-ended eductor tube (32) , one end of which is closed and adapted to accept a driving gas nozzle (28) and the other, open end being adapted for connection to patient assisted breathing apparatus, the eductor tube (32) having a drawn air inlet (36) opening into a side of the eductor tube 32.

4. A jet ventilator system according to either of claims 2 or 3 that includes a pressure extension (38) comprising an open-ended tube (40) on which a pressure gauge (42) is mounted.

5. A jet ventilator system according to claim 4 in which the pressure gauge (42) is located in the vicinity of the flow regulator (18) , the pressure gauge (42) being connected to the pressure extension (38) by means of a conduit.

6. A jet ventilator system according to either of claims 4 or 5 in which the pressure extension (38) is integrated with the eductor (30) .

7. A jet ventilator system according to claim 1 that includes an air eductor (30.1) comprising a driving jet nozzle (28.1) located upstream of an eductor tube made up of a flared, eductor mouth (32.1A) that is open to the nozzle (28.1), a narrowed throat portion (32. IB) and a flared mixing zone (32.1C) that opens out into an enlarged pressure extension tube portion (32. ID).

8. A jet ventilator system according to claim 7 in which a pressure metering nozzle (41.1) is let into the extension tube portion (32. ID) of the air eductor (30.1), the metering nozzle (41.1) being adapted for connection to a pressure gauge forming part of the flow regulator.

9. A jet ventilator system according to either of claims 7 or 8 in which:

the ratio of the internal cross sectional area of the air eductor throat (32. IB) to the internal cross sectional area of the driving jet nozzle (28.1) is between 20:1 and 30:1;

the ratio of the length of the air eductor throat (32. IB) to the internal diameter of the air eductor throat (32. IB) is between 5:1 and 10:1

the ratio of the length of the eductor mouth (32.1A) to the internal diameter of the air eductor throat (32. IB) is between 1:1 and 2:1;

the angle of flare (cone angle) of the inner wall of the eductor mouth (32.1A) is between 162┬░ and 168┬░; and

the angle of flare (cone angle) of the inner wall of the flared mixing zone 32.1C is 10┬░.

10. A jet ventilator system according to claim 9 in which:

the ratio of the internal cross sectional area of the air eductor throat (32. IB) to the internal cross sectional area of the driving jet nozzle (28.1) is 25:1.

the ratio of the length of the air eductor throat (32. IB) to the internal diameter of the air eductor throat (32. IB) is 7.5:1; and

the ratio of the length of the eductor mouth (32.1A) to the internal diameter of the air eductor throat (32. IB) is 1.5:1.

11. A jet ventilator system according to any one of claims 7 to 10 in which the external wall of the driving jet nozzle (28.1) is coned at an angle corresponding to the cone angle of the eductor mouth (32.1A) .

12. A jet ventilator system according to any one of claims 7 to 11 that is integrally moulded out of plastics material.

13. A jet ventilator system according to any one of claims 1, 2 or 7 to 12 that includes a fluid eductor (30.2) comprising a driving gas nozzle (28.2), an eduction plenum (33) and a venturi throat (37) , the eductor (30.2) being adapted for the driving gas to educt suctioned fluids that, in use, may be conveyed into the eductor (30.2) by way of a conduit connected to an inlet (39) of the eduction plenum (33) .

14. A jet ventilator system according to claim 13 in which the fluid eductor (30.2) is connected, at its inlet end, to a surgical suction device.

15. A jet ventilator system according to either of claims 13 or 14 in which the fluid eductor (30.2) is connected, at its outlet end, to a waste bag or the like.

16. A jet ventilator system according to any one of claims 13 to 15 in which the fluid eductor (30.2) is injection moulded in two parts out of plastics material, the driving jet nozzle (28.2) and eduction plenum (33) being integrally moulded in one part.

17. A jet ventilator system according to any one of the preceding claims that includes a waste disposal facility including a waste bag (800.1) housed within a sheathing bag (800.2) adapted to contain, for disposal, the bag (800.1) and all tubing and suction devices used in suctioning the patient.

18. A jet ventilator system according to claim 17 in which the waste bag (800.1) is formed with a vent port

(800.4) with a cover adapted to permit the venting of the driving gas in use, while preventing the escape of suctioned fluids.

19. A jet ventilator system according to any one of the preceding claims including a control system (210) that includes time switched regulators (202, 204) constituted, at least, by an inspiratory regulator

(202) and an expiratory regulator (204) , the control system (210) including a manual override switch (222) integral with the flow regulator (18) that is adapted for manual actuation by means of which automatic operation of the control system (210) can be overridden.

20. A jet ventilator system according to claim 19 in which the control system (210) includes a gas flow valve (206) with predetermined flow rate settings.

21. A jet ventilator system according to either of claims 19 or 20 in which the control system (210) reverts back to the preset automatic frequency if, at any time during use, the override switch is not actuated.

22. An air eductor according to any one of claims 7 to 12 for a jet ventilator system.

23. A fluid eductor according to any one of claims 13 to 16 for a jet ventilator system.

24. A waste disposal facility according to either of claims 17 or 18 for a jet ventilator system.

25. A control system according to any one of claims 19 to 21 for a jet ventilator system.

26. A jet ventilator system according to any one of claims 1 to 6 including an air eductor according to any one of claims 7 to 12, a fluid eductor according to any one of claims 13 to 16 and a waste disposal facility according to either of claims 17 or 18.

27. A jet ventilator system according to claim 26 that includes a control system according to any one of claims 19 to 21.

28. A jet ventilator system substantially as described in this invention with reference to the accompanying drawings.

29. An air eductor for a jet ventilator system substantially as described in this invention with reference to the accompanying drawings.

30. A fluid eductor for a jet ventilator system substantially as described in this invention with reference to the accompanying drawings.

31. A waste disposal facility for a jet ventilator system substantially as described in this invention with reference to the accompanying drawings.

32. A control system for a jet ventilator system substantially as described in this invention with reference to the accompanying drawings.