Face mask for non-invasive mechanical ventilation with low value of CO.SUB.2 .rebreathing

Abstract

A face mask (also called full face) for respiratory therapy, in particular for non-invasive mechanical ventilation, has a low value of CO.sub.2 rebreathing. The mask includes a shaped shell to cover at least the mouth, the nose and the eyes of a patient when the mask is worn, and includes, on said shaped shell an inlet fitting for the connection to a pipe through which a ventilation apparatus supplies the mask with a mixture of air and oxygen, and an outlet fitting, separate from said inlet fitting, for the discharge of air exhaled by the patient. With this arrangement, the mask allows drastically reducing the phenomenon of carbon dioxide rebreathing, which is very harmful for the patient subjected to ventilation.

Claims

1. A face mask for non-invasive respiratory therapy of the full face type, comprising: a shaped shell configured so as to cover at least the mouth, the nose and the eyes of a patient when the mask is worn, said shaped shell having a perimeter provided with a sealing gasket, wherein said shaped shell comprises at least one inlet fitting for the connection to a pipe through which a ventilation apparatus supplies the mask with a mixture of air and oxygen, and at least one outlet fitting, separate from said inlet fitting, for the discharge of air exhaled by the patient, wherein said shaped shell comprises, approximately centrally, a shaped portion projecting from the front surface of said shell towards the outside, configured so as to be substantially at the nose and mouth of the patient when the mask is worn, wherein said shaped portion comprises a conical section and an outer front planar surface at an end of the conical section, wherein said outlet fitting for exhaled air extends from a first opening in said outer front planar surface of said shaped portion, and wherein said inlet fitting for the air coming from said ventilation apparatus extends from a second opening in a wall of said conical section of said shaped portion, the second opening being positioned lower on the shaped shell with respect to the outer front planar surface.

2. The face mask according to claim 1, further comprising on said perimeter of said shell a plurality of attachment points for the attachment of a neckband.

3. The face mask according to claim 2, wherein the plurality of attachment points includes five attachment points.

4. The face mask according to claim 3, wherein one of the attachment points is an attachment point centrally placed along the upper section of the perimeter of the mask, in the sagittal plane, such as to be in a substantially centered position on the forehead of the patient when the mask is worn.

5. The face mask according to claim 1, further comprising, on said shaped shell, a dedicated access for a nasogastric tube.

6. The face mask according to claim 5, wherein said dedicated access for a nasogastric tube consists of a hole to which an elastic membrane is stably applied, such membrane being provided in turn with an expandable hole and with a closure cap for said hole.

7. The face mask according to claim 1, wherein the first opening of the outlet fitting is positioned entirely above the second opening of the inlet fitting on said shaped portion.

8. The face mask according to claim 1, wherein the outlet fitting and the inlet fitting are positioned on said shaped portion such that the air exhaled does not pass through the second opening of the inlet fitting.

Description

LIST OF FIGURES

(1) The features and the advantages of the respiratory mask with a low value of carbon dioxide rebreathing according to the present invention will become apparent from the following detailed description, given by way of a non-limiting example, with reference to the accompanying schematic drawings, in which:

(2) FIG. 1 shows a front view of a face mask according to the present invention;

(3) FIG. 2 shows a perspective view of the face mask according to the present invention;

(4) FIG. 3 shows a diagram of the test modes with which the mask according to the present invention and a mask of the known type have been tested;

(5) FIGS. 4 and 5 show the results of the ventilation tests conducted by the Applicant, in particular the performances of a traditional single-fitting full face mask and of the new face mask according to the present invention are presented.

DETAILED DESCRIPTION OF THE INVENTION

(6) With reference to the figures, a face mask for non-invasive respiratory therapy is shown, indicated as a whole by the reference numeral 10 and comprising a shaped shell 11 covering at least the mouth, nose and eyes of a patient once worn.

(7) The shaped shell 11 is provided along a perimeter 13 with a sealing gasket 14 adapted to be placed in contact with the patient's face when the mask is worn.

(8) The mask 10 according to the invention therefore preferably comprises the rigid shaped shell 11 made of transparent polycarbonate (PC) or copolyester (PETG), and the gasket 14, preferably overmoulded, made of thermoplastic elastomer (TPE).

(9) Other materials according to the knowledge of the person skilled in the art can also be used alternatively or in conjunction with those just mentioned by way of example.

(10) The shaped shell 11 is also advantageously provided with at least an inlet fitting 17 for the mixture of air and oxygen coming from a ventilation apparatus, not shown, through a pipe, and an outlet fitting 15 for the outlet of the air, rich in carbon dioxide, exhaled by the patient.

(11) The outlet fitting 15 will preferably be of the so-called “non-vented” type, i.e. not provided with a hole for the escape of the carbon dioxide exhaled by the patient, which will instead be evacuated from the mask through said outlet fitting 15.

(12) According to a preferred embodiment of the present invention, the shaped shell 11 comprises a shaped portion 12 projecting from the front surface of said shell 11 towards the outside, approximately centrally, configured so as to be substantially at the nose and mouth of the patient when the mask 10 is worn.

(13) Preferably, said shaped portion 12 comprises a conical section 12′ terminating with an outer front surface 12″.

(14) According to the preferred embodiment of the face mask 10 according to the present invention illustrated herein by way of example in the accompanying figures, said outlet fitting 15 is formed on said front surface 12″ of said shaped portion 12, and said inlet fitting 17 is formed on said conical section 12′ of said shaped portion 12.

(15) More in particular, said inlet fitting 17 for the air is obtained on said conical section 12′ of said shaped portion 12 on the lower part with respect to said outlet fitting 15.

(16) The mask 10 according to the invention also preferably comprises a neckband, not shown in the figures, provided with a plurality of prongs.

(17) In order to allow the attachment, in a fixed or removable manner, of this neckband to the mask, the mask 10 according to the present invention will comprise on said perimeter 13 of said shell 11 a plurality of attachment points 18.

(18) The neckband preferably consists of a belt system configured to wrap the patient's nape when the mask is worn. Through the neckband, the mask 10 is firmly fixed on the patient's face to obtain the pneumatic seal of the gasket 14 on the face.

(19) According to a preferred embodiment of the present invention, the shaped shell 11 comprises five attachment points 18 for the neckband, in which two upper attachment points 18′ are placed in an upper portion of said shell 11 so that, when the mask is worn, they are at the level of the patient's eyes, symmetrically arranged with respect to a sagittal plane; two lower attachment points 18″ are placed laterally in the lower portion of the shell 11 so that, when the mask is worn, they are at the level of the patient's chin, symmetrically arranged relative to a sagittal plane; and a fifth attachment point 18′″ is placed centrally along the upper portion of the perimeter 13 of the mask 10, placed in the sagittal plane, so as to be at the patient's forehead when the mask is worn.

(20) According to a further aspect of the present invention, the face mask 10 for the non-invasive respiratory therapy according to the present invention comprises a dedicated access, not shown, for a nasogastric tube obtained directly on the shaped shell 11.

(21) Said dedicated access may preferably consist of a hole to which an elastic membrane is stably applied, such membrane being provided in turn with an expandable hole and with a closure cap for said hole.

(22) The elastic membrane may preferably be made in one piece with the shaped shell 11 by overmoulding a thermoplastic elastomer (TPE), so that the elastic membrane is an integral and indissoluble part of the shaped shell 11 of the mask itself and does not risk being separated therefrom due to the positive pressure inside the mask.

(23) In a bench test, a total face mask of the full face type known from the prior art, and the new face mask 10 according to the present invention, were then applied to a dummy connected to a breathing simulator (IngMar Medical ASL 5000).

(24) A known stream of CO2 was fed to the dummy's trachea.

(25) Several combinations of the ventilation parameters were tested, as shown in the diagram in FIG. 3: CPAP with continuous flow from 60 to 90 l/min and PEEP mechanical valve (the PEEP valve is a device for maintaining the positive expiratory end pressure) at 8 cmH2O, pressure support PSV of 6 and 11 cmH2O (Medtronic Puritan Bennett 840) with zero and 15 l/min Flow-By), respiratory rate of 15 and 30 bpm and CO2 flow rates of 200 and 300 ml/min, Current Volume or Tidal Volume set to 500 ml.

(26) Airway pressure, airflow and CO.sub.2 concentration (and CO2 flow as a product of the two) were recorded.

(27) As shown in the graphs in FIGS. 4 and 5, in which the results of the ventilation tests conducted by the Applicant are presented, the average volume of CO.sub.2 re-breathed (rebreathing) by the patient and the minimum concentration of inspiration of CO.sub.2 are significantly lower with the new mask compared to the traditional mask, in all the conditions examined, with the exception of two conditions, currently subjected to verification to confirm the validity of the data and determination of the causes.

(28) The bias flow of 15 l/min significantly reduced the rebreathing of CO.sub.2 with the new mask, while it had no effect with the traditional mask.

(29) The features of the face mask for non-invasive respiratory therapy with low value of CO.sub.2 rebreathing object of the present invention, as well as the relative advantages are clear from the description given herein.

(30) By way of example, among the main advantages of the mask according to the invention, it can be noted that the presence of the two inlet and outlet fittings 17, allows different configurations of the mask, not possible with known masks having only one fitting.

(31) For example: in the configuration with a double-pipe ventilator, the two ventilator pipes will be connected to each fitting 15, 17; in the configuration for CPAP with single-pipe ventilator or CPAP generator it is possible to connect to the inlet fitting 17 the ventilator pipe and a PEEP valve to the outlet fitting 15; in the configuration for CPAP with Venturi generator it is possible to connect the venturi to the inlet fitting 17 and a PEEP valve to the outlet fitting 15.

(32) Moreover, it is clear that the face mask according to the present invention thus conceived is susceptible to numerous modifications and variations, all falling within the invention; moreover, all details can be replaced with technically equivalent elements.

(33) In particular, the materials described as well as the sizes, can be whatever, according to the technical requirements.