GB2411121A - Portable ventilating apparatus - Google Patents

Abstract

Portable mechanical ventilating apparatus comprising a hollow, flexible dome 2 mounted on a base 3 forming a gastight chamber for containment of breathable gas which is manually compressible to expel the gas into a patient's lungs. Preferably a flexible bellows 4 is mounted on the base 3 inside the dome 2 forming one cavity 5 within the bellows 4 and another cavity between the bellows 4 and dome 2. The bellows 4 may move independently from the dome 2 and may contain a recoil device 6, preferably in the form of a spring to return it to the extended position. The bellows 4 and spring 6 may also be depressed by a pressurised driving gas 10 entering the cavity between the bellows 4 and dome 2. The dome 2 may be transparent and may include a handle for manual compression and a shoulder strap.

Description

A portable ventilating apparatus

Description

The invention relates to an apparatus for the ventilation of a patient (mechanical ventilation of the lungs).

Anaesthesia or resuscitation breathing apparatus is used to provide anaesthetic gas or oxygen to a patient during a surgical procedure or during a period of respiratory insufficiency for lo example due to pneumonia or after chest injury. Anaesthetic gas means a respirable gas containing an inhalation anaesthetic vapour with oxygen enrichment. In the course of an operation or resuscitation a patient may breathe spontaneously or have respiration assisted manually or by a mechanical ventilator. The latter two methods are also called intermittent positive pressure ventilation (I.P.P.V.) to distinguish this mode from the negative pressure created during spontaneous (normal) ventilation. I.P.P. V. is the sequence of an inspiratory phase flowed by an expiratory phase, called the respiratory cycle. When a mechanical ventilator is incorporated in a breathing system, the patient may breathe spontaneously through the system (ventilator switched off) or receive controlled or mechanical ventilation when it is switched on. Controlled ventilation may be required during or after many surgical procedures according to the patient's condition, the type of operation being performed, during the treatment of respiratory disease or in a period of resuscitation.

Most anaesthesia ventilators operate on the 'bag-in-bottle' principle whereby a flexible 'bag' in the form of a bellows is located inside a transparent rigid container (the 'bottle'). An increase in pressure of a non-respirable driving gas in the intervening space causes a reduction of volume in the patient's respirable gas inside the bellows, thereby directing this gas towards the lungs during the inspiratory phase. During the expiratory phase the bellows is returned to the upper position ready for the next cycle by the expired gas returning from the patient. The pressure above the bellows is automatically cycled to atmospheric and the gas is expelled.

Portable resuscitation ventilators and non-portable intensive care ventilators cannot be used for inhalation anaesthesia, require a continuous supply of compressed oxygen to function and cannot be hand operated. When the gas is exhausted they are non-operational and the last s resort of 'mouthto-mouth' or 'mouth-to-tube' resuscitation is required. Hand operated portable self inflating resuscitation bags are widely used in emergency ventilation with or without added oxygen but none can be used for mechanical ventilation. Their use for giving anaesthesia is very limited.

lo The present invention seeks to provide an improved anaesthesia and respiratory support system being a design for a portable mechanical ventilator suitable for use with any patient breathing system for anaesthesia or resuscitation which consists of a flexible dome or cylinder with a moving bellows located inside. The invention would be made from moulded plastic components It may be powered by compressed air from a remote cycling compressed air Is source (which does not form part of this invention) or by hand in the event of the source becoming exhausted or mechanical failure or for resuscitation or any emergency by a medical attendant manually compressing the dome. The dome is flexible and self inflating and by resuming its original shape draws respirable gas or room air into the ventilator chamber between breaths.

It will be appreciated that the ventilator may be used in the course of anaesthesia or in other circumstances where respiratory support is needed for a patient, such as post-operatively, in intensive care, for primary respiratory disease or in resuscitation. A medical attendant may be anyone with responsibility for respiratory care such as an anaesthetist, intensive care 2s physician, paramedic, nurse, ambulance crew etc. The design uses simple lightweight moulded plastic components, could be used while hanging vertically from the shoulder and could be made disposable, for single patient use such as when a contamination risk might exist.

According to a first aspect of the present invention, there is provided a flexible dome mounted on a base which may be arranged with a patient breathing system to allow gas from that system to be forced out of and drawn into the chamber formed by the dome by, respectively, compression or deformation of the dome and by its elastic recoil and re formation It will be appreciated that the dome may be cylindrical, ovoid or spheroid in shape.

A handle or recess may be located on the dome to assist the re-formation phase of the breathing cycle The lower edge of the dome has a gas tight attachment to a ventilator base. Inlet and outlet lo valves permit entry and exit of respirable gas to and from the above chamber and direct one way flow in the breathing system. It will be appreciated that these ports may have other configurations, such as a single port with to-and-fro connections to a breathing system, may be located on the side of the ventilator and may also connect to a draw over, circle or other type of breathing system. The respirable gas in the chamber may be anaesthetic gas from an anaesthetic machine though it will be appreciated that the present invention can be used for patient ventilation with any respirable gas including room air.

According to a second aspect of the present invention, a bellows, also made of flexible material may be mounted on a flange on the base within the dome in a gas tight manner such that the respirable gas drawn into the ventilator chamber (defined by the bellows) can freely enter the interior of the bellows but cannot enter the space between the bellows and dome.

According to a third aspect of the present invention, a returning device, which may be a function of the elastic recoil of the bellows or may be a spring, such as a large diameter metal 2s helical spring, causes the bellows to assume an extended position urging against the underside of the flexible dome when the pressure above the bellows is atmospheric. A spring may be located inside the internal bellows, its lower end on the ventilator base and its upper end urging against the underside of the top of the bellows. The dome may be transparent so that the movement of the bellows is visible to the user. It will be appreciated that any return device to maintain the bellows in the top position, urging against the underside of the dome, may be used.

According to a fourth aspect of the present invention, a tube may perforate the ventilator base and open into the space between the bellows and dome by perforating the gas tight seal between these two. The tube may be connected to a source of non-respirable driving gas, such as air from a cycling pneumatic ventilator control device, this compressed air being isolated from the respirable gas in the chamber. An increase in pressure from this driving gas source passes through the tube and may thereby force down the bellows within the dome against the spring and cause the volume of the chamber to be reduced. The dome, while being lo flexible to being compressed with consequent decrease in internal volume, does not allow significant outward distension or increase in volume. During the inspiratory phase of controlled ventilation, the inner bellows is forced down by gas entering the space between the bellows and dome. Respirable gas in the chamber may thereby be forced through the outlet port into a patient breathing system to ventilate a patient's lungs. During the expiratory phase the elastic recoil of the bellows reverses the flow of the gas in the tube and draws fresh respirable gas into the ventilator chamber. It will be appreciated that the tube supplying compressed driving gas may pass through the ventilator chamber or be directly connected to the flexible dome in order to reach the space between dome and bellows.

The ventilator allows three functions during patient respiration as follows. 1. Free flow of respirable gas through, or bypassing, the ventilator allows the patient to breathe spontaneously through a breathing system. 2. The medical attendant may administer I.P.P.V.

to the patient by compressing the dome (inspiration phase) and allowing the elastic dome and bellows recoil to draw fresh gas into the chamber (expiration phase). 3. Mechanical ventilation may be started by turning on the remote pneumatic ventilator control.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings I to 6 in which: Figure I is a sectional view of a first embodiment of a patient ventilating apparatus according to the present invention, with the dome and internal bellows in the upper position. Figs la and I b show alternative configurations with a breathing circuit with one way valves.

Figure 2 is a sectional view of a first embodiment of a patient ventilating apparatus, according to the present invention, showing the inspiratory phase of manually assisted ventilation with the dome and bellows being deformed by downwards hand pressure exerted by the medical attendant.

Figure 3 is as Figure I but with the internal bellows in the lower position depressed against lo the spring (and the elastic recoil of the patient's chest) during the inspiratory phase of controlled ventilation. Fig 3a shows the compressed gas tube connected directly to the flexible dome.

Figure 4 is a perspective view of embodiments shown in Figs 1-3 also showing a handle to assist the re-formation of the dome.

Figure 5 is a sectional view of a second Embodiment showing a hemispherical dome and internal bellows for a patient ventilating apparatus according to the present invention with a strap to hang the invention from a medical attendant's shoulder while moving with a patient, the unit being vertical Figure 6 is a perspective view of the first Embodiment of a patient ventilating apparatus according to the present invention located on an anaesthesia work station.

Referring to Figures 1, 2 and 3 Embodiments of a patient ventilating apparatus (1) are arranged with a flexible dome (2) mounted on a base (3) with an internal bellows (4) mounted on a flange in the base, the three forming a chamber (5) such that by downward pressure on the dome the user (medical attendant) may deform the dome and thereby force gas in the chamber out via a patient breathing system (8) fitted with one way valves (9) to direct flow.

Such valves are configured according to the type of patient breathing system.

The bellows (4) may have fitted inside a helical spring (6) the lower end of which is mounted on the base (3) and the upper end urges against the underside of the bellows and maintains the top of the latter pressed against the underside of the dome (2) or it may so urge by function of s its own elasticity.

A pipe (7) perforates the base and the bellows mounting flange and communicates with the space between the bellows (4) and the dome (2).

lo A source (10) of compressed gas cycled for inspiration and expiration from a ventilator control unit is connected to the pipe (7) and thereby increases pressure in the space between the dome (2) and bellows (4) during the inspiratory phase of I.P.P.V. As the dome does not significantly stretch outwards, the increased pressure causes the internal bellows to be forced down against the resistance of the spring (6) the elastic resistance of the bellows and that of patient's chest, reducing the volume of the chamber (S) and thus displacing the respirable gas in the chamber towards the patient (P) resulting in inflation of the lungs. During the expiratory phase, the pressure in the pipe (7) falls to atmospheric and the bellows (4) returns to the upper position, at the same time expelling the previously compressed gas back out of the pipe (7) and drawing fresh respirable gas into the chamber from the patient breathing system, according to the direction of the one way valves (9). An airway pressure gauge (11) shows the pressure in the chamber during the respiration cycle.

Referring to Figure 3, the bellows (4) is shown forced down against the spring (6) by the cycled compressed gas in the flexible pipe (7) thereby reducing the volume of respirable gas in 2s the chamber (5) and displacing this gas towards the patient.

Figure 4 shows a perspective view of the invention with a handle (12) on top of the dome to assist upwards movement.

Figure 5 shows a hemispherical shaped dome operating on the same principles and a shoulder strap (13) to enable the unit to used vertically while walking with a patient.

Figure 6 shows the ventilator located on the work surface of an anaesthesia work station ( 14) with the cycling pneumatic ventilator control unit (10) mounted above, underneath a top shelf s or the control unit and ventilator may be used free standing on any bed side trolley.

Claims (16)

1. Claims I)A patient ventilating apparatus comprising a hollow dome of

   flexible material mounted on a base thereby defining a gaslight chamber for containment of respirable gas where manual compression of the dome causes gas in the chamber to be expelled and provide mechanical ventilation of a patient's lungs.
2. 2)A ventilator as in claim 1 where a flexible bellows is mounted on the base inside the dome.
3. 3)A ventilator as in claim 1 where a flexible bellows is mounted on the base inside the dome defining a chamber within the bellows and a compartment outside the bellows but within the dome.
4. 4)A ventilator as in claim 1 where a flexible bellows is mounted on the base inside the dome defining a chamber within the bellows and a compartment outside the bellows but within the dome, the said two spaces being separated with a gas tight seal.
5. 5)A ventilator as in all previous claims where the bellows may move independently from the dome.
6. 6)A ventilator as in all previous claims where the bellows automatically assumes an extended position in the dome due to elastic recoil.
7. 7)A ventilator as in all previous claims provided with a spring to maintain the said bellows in an extended position inside the dome.
8. 8)A ventilator as in all previous claims where the spring is mounted on the base inside the bellows with its upper end urging against the bellows.
9. 9)A ventilator as in all previous claims where the said bellows and spring can be depressed by the force of a cyclically operating pressurized driving gas from a remote source to provide the inspiratory phase of intermittent positive pressure ventilation s (I.P.P.V.).
10. IO)A ventilator as in all previous claims where the said pressurized driving gas is delivered by a pipe opening into the space between the bellows and the dome.
11. lo 11) A ventilator as in all previous claims where the dome is transparent.
12. 12)A ventilator as in all previous claims having a device to enable the user to raise the dome and draw gas into the space inside.
13. 13)A ventilator as in all previous claims where the device is a knob or handle on the surface of the dome or a recess set in the surface.
14. 14)A ventilator as in all previous claims having a hanging device to enable the unit to be carried in a different position such as suspended from the shoulder.
15. 15) A ventilator as in all previous claims where the hanging device is a strap.
16. 16) A patient ventilator substantially as described herein with reference to Figs 1-6 of the accompanying drawings.