WO1996034590A1

WO1996034590A1 - Apparatus for producing lung expansion or assisted ventilation

Info

Publication number: WO1996034590A1
Application number: PCT/GB1996/001070
Authority: WO
Inventors: Simon Hayek
Original assignee: Dranez Anstalt
Priority date: 1995-05-05
Filing date: 1996-05-03
Publication date: 1996-11-07
Also published as: GB9509192D0; AU5509596A

Abstract

Apparatus for producing expansion or assisted ventilation of the lungs of a patient comprises means such as an adhesive patch (10) for attachment to the thorax and or abdomen of a patient and means for producing movement of said attachment means (10) such as magnets (26) or a partially evacuatable chamber having said attachment means as a floor for said chamber.

Description

APPARATUS FOR PRODUCING LUNG EXPANSION OR ASSISTED VENTILATION

The present invention relates to apparatus for producing expansion or assisted ventilation of the lungs of a patient.

There are many medical situations in which it is necessary to assist or support the breathing of a patient by mechanical ventilation of the patient's lungs. There are other conditions which are treated by "continuous negative airway pressure" (CNAP) . To produce ventilation, an external ventilator may be used which comprises a chamber in which cyclic air pressure changes may be produced. The chamber may be so large as to embrace the whole of the patient's body from the neck downwards or at the other extreme may be a so-called "cuirass" ventilator chamber fitting over the patient's chest area only. A wide range of pressure regimes may be employed in such ventilation. The pressure changes may be of a fre¬ quency which is similar to that of natural breathing or may be much higher in frequency. Negative pressure in the chamber is used to expand the patient's lungs and positive pressure may be used to re-compress the patient's lungs. The mean pressure employed may be zero or may be negative, thus tending to produce an average nett expansion of the patient's lungs. Such apparatus may also be used for CNAP with a constant negative pressure being applied to the chamber. Such techniques are used for treatment of pneumonia, asthma, bronchopulmonary displasia, septicemia, HIV/PCP, ARDS (adult respiratory distress syndrome), bronchiolitis, Down's syndrome, cerebral palsy, and COPD (chronic obstructive pulmonary disease) .

A problem associated with the use of ventilator chambers is the difficulty in providing a chamber which is convenient for use and yet achieves a sufficiently reliable air-tight seal against the patient's body. Thus, whole body chambers of the "iron-lung" type are inconvenient from the point-of- view of sheer size and cost and the difficulty of gaining access to the patient's body for treatment. Cuirass ventilator chambers on the other hand require to be sealed over a long periphery and typically therefore need to be made in a number of sizes so as to produce a reasonable fit to the patient and to be maintained in correct adjustment.

It has now been appreciated that for either producing CNAP or assisted ventilation, it is possible to avoid the difficulty of producing an air-tight seal against the patient's body by directly attaching to the patient's body means by which the patient's chest or abdomen may be directly pulled outwardly to produce lung expansion.

Thus, the present apparatus provides apparatus for producing expansion or assisted ventilation of the lungs of a patient comprising means for attachment to the thorax and/or the abdomen of a patient and means for producing movement of said attachment means so as product expansion or periodic expansion and contraction of the lungs of a patient.

Preferably, the attachment means comprises an adhesive patch for application to the patient. Once such a patch has been put in place over the patient's chest and/or abdomen, it may be pulled in a direction away from the patient's body so as to produce the required lung expansion. If cyclic venti¬ lation is required, the attachment means may be permitted to be drawn back by natural relaxation of the patient's lungs or may be directly pushed back by said movement producing means prior to being moved once again the expansion producing direction.

Many means may be devised for producing the required movement of the attachment means in place on the patient.

According to a first preferred practice of the invention, the means for producing movement of the attachment means is adapted to attract the attachment means so as produce the required lung expansion. This may take place without there being any physical connection between the attachment means and the means for producing movement, for instance if the attraction is by magnetism. One or both of the attachment means and the means for producing movement may comprise one or more magnets and the other may be magnetically attractable in a passive sense or may comprise magnets positioned to attract the magnets of the other means. Thus, such an adhesive patch as is discussed above may contain a layer of flexible, thin sheet mild steel or iron or other suitable material to be attracted by a magnet forming part of the means for producing movement. Alternatively, such a patch may carry one or more magnetically attractable bodies which may be of greater thickness and these may be magnets. For attracting the said attachment means, the means for producing movement may comprise one or more support members holding one or more magnetic attractors at a distance from the attachment means in use and said distance may be adjustable. For instance, the means for producing movement may comprise one or more flexible arms or a bridge of adjust-able height carrying one or more magnets.

The magnets may be permanent magnets or may be electro- magnets. Either by dynamically varying the separation between the attachment means and the means for producing movement or by varying the strength of magnetic attraction by varying the intensity of actuation of electromagnets, the magnetic attraction may be controlled electronically to maintain a desired constant or varying amount of magnetic attraction and hence of lung expansion.

Another method of producing movement of the attachment means where said attachment means constitutes an adhesive patch applied to the patient is to make the adhesive patch form the floor of a partially evacuatable chamber similar to the type of chamber used in a cuirass ventilator. However, instead of attempting to seal the chamber to the patient's skin, there can be a permanent seal between the adhesive patch and the walls of the chamber. For CNAP it is then only necessary to partially the evacuate the chamber. For ventilation, cyclic pressure changes may be induced in the chamber by a known type of pressure oscillator.

Alternatively, one can use a direct physical connection between the attachment means and the means for producing movement thereof. Thus, a motion transmitting member (such as an arm, rod, cord, wire or other equivalent means) may be attached to the attachment means and may be withdrawn by the application of a constant force to a desired extent or may be attached to a source of varying force to produce cyclic movement and ventilation. Constant force may be obtained through the use of spring or a weight or hydraulically or pneumatically. This list is by no means exhaustive. Cyclic movement may be obtained hydraulically, pneumatically or through the mechanical action of for instance a crank. Once again the list is by no means exhaustive.

The attachment means is preferably applied to cover the patient's abdomen since this region is the move easily moved to produced ventilation or lung expansion.

Where a cyclic pressure movement regime is employed, this may take place about a mean lung volume value which is greater than or equal to that of the patient's lungs without venti¬ lation. Preferably, to simulate a ventilation regime in accordance with the teachings of European Patent No. 0192337, such ventilation movement takes place at a frequency of greater than 1 Hz about a mean lung volume greater than the patient's lung volume without ventilation. This will simulate the high frequency oscil-lation about a negative base line pressure described in that Patent specification.

The present invention will be further described and illustrated with reference to the accompanying drawings in which:

Figure 1 shows two alternative forms of CNAP apparatus according to the invention, both being applied to the same patient; and Figure 2 shows one main component of one of the two forms of apparatus shown in Figure 1 in perspective view. As shown in Figures 1 and 2, a first apparatus according to the invention comprises an attachment means 10 in the form of a patch of flexible material adhered to the skin of a patient's abdomen. The patch comprises as an upper layer a thin plate of flexible mild steel 12 and an underlayer of plastics 14 coated on its under surface with a suitable adhesive. Prior to use, the adhesive may be protected by release paper.

As a second component illustrated in Figure 2, the apparatus comprises a bed 16 extending beneath the patient in use and having a foam insert 18 extending across its upper surface for the patient's comfort. On either side of the central region occupied by the foam 18 is a short upstanding pillar 20 from which extends a flexible arm 22 terminating in a head 24 containing a magnet 26. The curvature of the arms 22 is adjustable to vary the height of the magnets 26 above the plate 12 so as to vary the force of magnetic attraction used to uplift the patient's abdomen and by drawing down the diaphragm to expand the patient's lungs. The magnets 26 as illustrated are permanent magnets but could be electromagnets. The magnetic force applied through the magnets 26 could then be varied electronically either to adjust the amount of magnetic attraction used to produce a constant degree of elevation of the plate 12 or to attract an release the plate 12 periodically for assisted ventilation. In the alternative embodiment illustrated in Figure 1, a cuirass ventilator chamber 30 is provided with a flexible plastics membrane sealed to the edges 32 of the chamber and providing a floor for the chamber. On its underside, the membrane is coated with a suitable adhesive and is adhered to the patient's chest, thereby removing any further need for sealing of the chamber to the patient. Oscillating air pressure or a constant negative air pressure is applied through the hoses 34 to achieve CNAP or ventilation. Of course, in practice it would not be usual to employ both illustrated forms of apparatus on the same patient. Whilst the invention has been described with reference to the specific embodiments illustrated in the accompanying drawings, many variations and modifications thereof are possible within the scope of the invention.

Claims

1. Apparatus for producing expansion or assisted venti¬ lation of the lungs of a patient comprising means for attachment to the thorax and or abdomen of a patient and means for producing movement of said attachment means so as to produce expansion or periodic expansion and contraction of the lungs of the patient.

2 . Apparatus as claimed in Claim 1, wherein said attachment means comprises an adhesive patch for application to the patient.

3. Apparatus as claimed in Claim 1 or Claim 2, wherein said means for producing movement is adapted to connect physically to said attachment means.

4. Apparatus as claimed in Claim 1 or Claim 2, wherein said means for producing movement is adapted to attract said attachment means for producing lung expansion.

5. Apparatus as claimed in Claim 4, wherein said attraction between said attachment means and said means for producing cyclic movement is magnetic attraction.

6. Apparatus as claimed in Claim 4, wherein said means for producing movement comprises a partially evacuatable chamber having said attachment means as a floor for said chamber, together with means for producing reduced pressure or cyclic pressure changes in said chamber, whereby reduction of gas pressure in said chamber produces expansion of the lungs of the patient. Apparatus as claimed in any preceding claim, wherein said expansion and contraction takes place about a mean volume which is greater than or equal to the patient's mean lung .volume without ventilation.

Apparatus for producing CNAP substantially as described with reference to and as illustrated in respect of either embodiment in the accompanying drawings.