GB2529518A

GB2529518A - Apparatus and gas pressure reservoirs

Info

Publication number: GB2529518A
Application number: GB1510806.1A
Authority: GB
Inventors: Robert James Burchell; Mark Charles Oliver; Mark Sinclair Varney
Original assignee: Smiths Medical International Ltd
Current assignee: Smiths Medical International Ltd
Priority date: 2014-07-03
Filing date: 2015-06-19
Publication date: 2016-02-24
Also published as: GB201510806D0; GB201411898D0

Abstract

A resuscitator includes a gas pressure reservoir 200 provided by a length of pressure tubing 201 that may be bent into a coil or helix or configured in different ways to make use of available space. The tubing 201 may be of a plastics material and may have plastics gas connection fittings 232,233. A compressor may charge the pressure reservoir 200 via an inlet with a breathing gas that is then supplied to the patient via an outlet. The pressure tubing reservoir may offer cost savings and weight savings over conventional metal vessel reservoirs.

Description

Intellectual Property Office Application No. GB1510806.1 RTTVI Date:t5 December 20t5 The following terms are registered trade marks and should be read as such wherever they occur in this document: Pneupac CornpPAC (page 4) Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

APPARATUS AND GAS PRESSURE RESERVOIRS

This invention relates to apparatus and gas pressure reservoirs.

The invention is more particularly, but not exclusively, concerned with resuscitators including gas pressure reservoirs.

Some resuscitators or ventilators (the terms resuscitator and ventilator are used interchangeably herein) used to provide a supply of breathing gas to a patient include a gas reservoir that is pressurised with the breathing gas. These reservoirs are in the form of a cylindrical metal bottle closed at one end and with a reduced diameter open neck at the opposite end to which a gas-pressure resistant connection is made by means of metal screw-thread fittings. Typical low pressure reservoirs are required to withstand pressures of up to l000kPa whereas high pressure reservoirs are required to withstand pressures of up to 20000kPa. They have to comply with local and international safety reguiations for pressure vessels and be certified appropriately. The reservoirs are usually specially made to the size necessary to provide the volume needed and to fit the available space within the resuscitator.

Because of this, the reservoir is a relatively expensive component. Other compressed gas apparatus, apart from resuscitators, include similar gas pressure vessels with similar problems. Design codes and application standards together with the cost of materials mean that steel is the usual material chosen for pressure vessels, made without any weldings and treated to be anti-corrosive. Recently, lightweight gas cylinders have become available made from composite materials, such as filament-wound composite using carbon fibre held in place with a polymer. The composite material may be wound around a metal liner, forming a composite overwrapped pressure vessel. The very high tensile strength of carbon fibre means that such vessels can be very light but they are more difficult to manufacture and, hence, are expensive.

It is an object of the present invention to provide gas pressure apparatus with an alternative form of reservoir, and a reservoir for such apparatus.

According to one aspect of the present invention there is provided gas pressure apparatus including a gas inlet, means for providing gas to a pressure reservoir from the inlet at a pressure above atmospheric pressure, a gas outlet and means for providing gas from the reservoir via the gas outlet, wherein the reservoir is in the form of a length of pressure tubing.

The length of pressure tubing is preferably at least ten limes its external diameter.

The length of pressure tubing is preferably bent into a curved configuration, such as a coil or helix. The tubing is preferably bent to extend within a notional envelope, the length of the tubing exceeding the length of the notional envelope multiple limes. The gas outiet may be cotmected to both ends of the tubing. Alternatively, one end of the tubing may be closed and gas connection made to the other end of the tubing only, The tubing may be of a plastics material. Connection may be made to the or each end of the tubing by one or more plastics fittings. The means for providing gas to the reservoir may include a compressor. The apparatus may be a resuscitator arranged to provide breathing gas to a patient outlet.

According to another aspect of the present invention there is provided a resuscitator including a gas inlet, a compressor for supplying gas to a pressure reservoir from the inlet at a pressure above atmospheric pressure, the reservoir including a length of bent pressure tubing, the tubing having a length that is at least ten times its external diameter, and the resuscitator including an outlet connected with the reservoir arranged to provide breathing gas to a patient.

According to a further aspect of the present invention there is provided a pressure reservoir comprising a length of pressure tubing for apparatus or for a resuscitator according to the above one aspect of the present invention.

A resuscitator and a reservoir formed of pressure tubing according to the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a circuit diagram of a conventional resuscitator; Figure 2 is a perspective view of the reservoir used in the resuscitator of Figure 1; Figure 3 is a perspective view of a reservoir according to the present invention; Figure 4 is a perspective view of an alternative reservoir; and Figure 5 is a perspective view of another alternative reservoir.

With reference first to Figure 1 there is shown schematically the circuit of a conventional resuscitator, that of the Pneupac C0mpPAC® (Pneupac CompPAC is a Registered Trade Mark of Smiths Medical International Limited) resuscitator sold by Smiths Medical International Limited. It is not necessary for an understanding of the present invention fully to understand the complete operation of the resuscitator so this will only be described briefly. The resuscitator is arranged to provide a gas outlet to a patient either from a primary oxygen supply, such as a cylinder of compressed oxygen, or from ambient air such as when the primary oxygen supply is not available, when it is exhausted or in situations when it is too dangerous to use compressed gas cylinders.

The resuscitator has an outer housing 1 supporting three gas inlets 2, 3 and 4. The first of these 2 is connected in use to an external cylinder 5 of compressed oxygen. The second inlet 3 is connected to a source of supplementary oxygen, such as a hospital wall oxygen supply 6. The third inlet 4 is open to atmosphere so that ambient air can be drawn into the resuscitator. A filter 8, such as an NBC filter, may be connected with the inlet 4 to prevent contamination entering the gas circuit. The three inlets 2, 3 and 4 all connect with inlets of a compressor 10, driven by an electric motor 11. The electric motor 11 is driven by signals from a compressor control system 12, which in turn receives power either from an internal battery 13 or an external power supply 14. The outlet 15 of the compressor 10 connects via a one-way valve 16 to the inlet 17 of a gas pressure reservoir 20. The conventional reservoir 20 and the novel reservoir of the present invention will be described in more detail later.

The outlet of the reservoir 20 is supplied via a filter 30 and a pressure regulator 31 to the inlet of an oscillator 32, the frequency of which is controlled by a knob 33 mounted on the housing 1. The alternating gas outlet from the oscillator 32 is supplied to a series arrangement of three flow regulators 34, 35 and 36. This gas is mixed with air from the inlet 4 supplied via a manual switch 37 controlled by an air mix knob 38 on the housing 1. The manual switch 37 receives ambient air via a primary oxygen/no air mix switch 39 when this is in a position to allow air to flow from the inlet 4 to the manual switch. The third regulator 36 is adjustable by a volume control knob 40 to control the gas flow rate to the high pressure inlet 41 of a venturi mixer 42 connected to a patient outlet 43. The venturi mixer 42 has an entrainment inlet 44 connected to the air inlet 4so that ambient air is entrained by the high pressure gas supplied to the high pressure inlet 41. The patient outlet 43 connects with a primary and secondary relief valve 44 and 45. The primary valve 44 includes an alarm, such as a whistle. When pressure rises above a set level the valve 44 opens to vent gas and the alarm sounds. The secondary relief valve 45 opens at a higher pressure than the primary valve 44 in the event that the primary valve fails or is unable to vent gas pressure sufficiently rapidly.

The conventional gas pressure reservoir 20 used in the resuscitator circuit in Figure 1 is shown in more detail in Figure 2. The reservoir 20 is in the form of a cylindrical metal bottle with a diameter along most of its length of between about 30mm and 100mm and a length of between about 100mm and 300mm, that is, its length is typically between about 3-times its diameter giving typical volumes in the range lO0-l000nil, One end 21 of the bottle 20 is closed and its opposite end tapers to a reduced diameter open neck 22. The open end 22 of the bottle 20 is connected to gas supply tubing 23 by a metal gas fitting 24.

Although Figure 1 shows the reservoir bottle 20 as having three separate connections, this is only schematic and, in practice, there is only one inlet, via the open end 22, the inlet and outlet connections both being made via the associated tubing 23.

This conventional bottle-shape gas pressure reservoir 20 has various problems. It is difficult to manufacture to meet pressure vessel regulations, making it relatively expensive.

It requires testing and regular maintenance adding to the cost of ownership. The reservoir is usually made of metal making it relatively heavy and thereby adding to the overall weight of the resuscitator, The present invention relates to a novel form of reservoir 200 and to a resuscitator including such a reservoir, one example of the reservoir being shown in Figure 3.

The reservoir 200 takes the form of a length of tubing 201, which is shown as bein9 attached at both ends to the inlets 2, 3 and 4 (via the compressor 10) and to the outlet 43 via the associated tubing 230 and 231 by respective gas fittings 232 and 233, which may be of plastics. It is not essential for both ends of the tubing 201 to be connected in this way since one end could simply be capped closed. The tubing 201 is typically of a conventional stock tubing designed for pressure applications and may be made of a plastics material such as a fluoropolymer (PTFE, PFA, FEP, etc), other polymers such as nylon, vinyl, polyethylene or the like, rubber or silicone. The tubing 201 typically has an internal diameter of 2-5mm, a external diameter of 3-10mm and a length of 1-lOOm. A typical lOm length of 5mm ID tubing would have an internal volume of 200ml, which is substantially the same as that of the conventional bottle reservoir 20. The tubing 201 may be configured in various different ways in other to make best use of the available space within the housing 1 and to enable the overall size of the housing to be minimised. As shown in Figure 3 the tubing 201 is coiled into a helical shape 234 with one end 235 extending back axially down the centre of the helix. The tubing 201 is, therefore, bent to extend within a notional envelope "F' of cylindrical shape with the length of the tubing exceeding the length "L" of the envelope by multiple times.

Figure 4 shows an alternative configuration where the tubing 401 is bent into a flat, circular coil 436 to extend within a notional flat, disc-shape envelope B' where, again, the length of the tubing exceeds the length (or diameter) L' of the envelope.

Figure 5 shows a further alternative flat configuration where the tubing 501 is bent backwards and forwards into a serpentine or boustrophedon shape 537 to extend within a notional flat, rectangular or square envelope B", with the length of the tubing exceeding the length L" of the envelope.

The flat shapes shown in Figures 4 and 5 could be curved about their length or width if this enables a better use to be made of the available space within the housing.

The tubing reservoir according to the present invention is capable of providing the same internal gas volume as the previous bottle reservoirs and is capable of withstanding the same pressures. Pressure tubing, however, is inherently safer than cylindrical pressure vessels because damage or failure of the tubing results in a much slower, less catastrophic loss of pressure than a cylindrical pressure vessel. Poorly controlled release of compressed gas can cause metal vessels to burst catastrophically. Plastic will often deform before bursting. As a result of this, pressure tubing is not as strictly regulated as conventional pressure vessels and requires minimal testing. The pressure tubing is available as a stock item from many suppliers and does not have to be specially manufactured like cylindrical pressure vessels, making it considerably cheaper to use. The tubing requires less testing during manufacture and servicing and can be maintained or replaced readily leading to a lower cost of ownership for the user. A reservoir made from plastics pressure tubing can also be lighter than an equivalent metal bottle reservoir, enabling the overall weight of the resuscitator to be reduced.

The invention is not confined to resuscitators but could be used in other apparatus including a gas compressor where it is necessary to provide a gas pressure reservoir, such as liquid spray apparatus, pneumatic supplies for tools, actuators and the like.

Claims

CLAIMS1. Gas pressure apparatus including a gas inlet (2, 3, 4), means (10) for providing gas to a pressure reservoir (200, 401, 501) from the inlet at a pressure above atmospheric pressure, a gas outlet (43) and means for providing gas from the reservoir (200, 401, 501) via the gas outlet (43), wherein the reservoir is in the form of a length of pressure tubing (201,401,501).
2. Gas pressure apparatus according to Claim 1, wherein the length of pressure tubing (201, 401, 501) is at least ten times its external diameter.
3. Gas pressure apparatus according to Claim I or 2, wherein the length of pressure tubing (201,401, 501) is bent into a curved configuration.
4. Gas pressure apparatus according to Claim 3, wherein the curved configuration is a coil or a helix.
5. Gas pressure apparatus according to any one of the preceding claims, wherein the tubing (201,401, 501) is bent to extend within a notional envelope (E, B', B"), and wherein the length of the tubing exceeds the length (L, L', L") of the notional envelope multiple times.
6. Gas pressure apparatus according to any one of the preceding claims, wherein the gas outlet (43) is connected to both ends of the tubing (201, 401, 501).
7. Gas pressure apparatus according to any one of Claims 1 to 5, wherein one end of the tubing is closed and gas connection is made to the other end of the tubing only.
8. Gas pressure apparatus according to any one of the preceding claims, wherein the tubing (201, 401, 501) is of a plastics material.
9. Gas pressure apparatus according to any one of the preceding claims, wherein connection is made to the or each end of the tubing by one or more plastics fittings (232, 233).
10. (las pressure apparatus according to any one of the preceding claims, wherein the means for providing gas to the reservoir (200, 401) may include a compressor (10).
11. Gas pressure apparatus according to any one of the preceding claims, wherein the apparatus is a resuscitator arranged to provide breathing gas to a patient outlet (43).
12. A resuscitator including a gas inlet (2, 3,4), a compressor (10) for supplying gas to a pressure reservoir (200, 401, 501) from the inlet at a pressure above atmospheric pressure, wherein the reservoir includes a length of bent pressure tubing (201, 401, 501), the tubing having a length that is at least ten times its external diameter, and wherein the resuscitator includes an outlet (43) connected with the reservoir (200, 401, 501) arranged to provide breathing gas to a patient.
13. A resuscitator substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.
14. A resuscitator substantially as hereinbefore described with reference to Figures 1 to 3 as modified by Figure 4 or 5 of the accompanying drawings.
15. A gas pressure reservoir comprising a length of pressure tubing (20, 401, 501) for apparatus or for a resuscitator according to any one of the preceding claims.
16. Any novel and inventive feature as hcreinbefore decribed.