LU101235B1 - Apparatus and method for determining the patency of a conduit at least partially occluded by an object - Google Patents

Abstract

Apparatus and method for determining the patency of a conduit associated with an object (T) inserted in said conduit. The apparatus includes: - a tubular duct (3) with an elastically deformable wall (5); - means for generating a gas flow (7) through said tubular duct (3); - compression means (9), associated with said tubular duct (3), arranged to generate a uniform external pressure on at least an axially extending portion of the wall (5) of the tubular duct (3) into which the object is inserted; and - means for measuring the flow rate (11) through said tubular duct (3). The apparatus and the related process can be used in particular to estimate the risk of occlusion of a duct correlated to the shape and size characteristics of a given object inserted in the duct.

Description

BL-5091 1 LU101235 Apparatus and method for determining the patency of a conduit at least partially occluded by an object Technical field The present invention relates to an apparatus and a process for determining the patency of a duct in which an object is inserted. A specific application of the equipment is aimed at determining the risk of occlusion of a duct related to the shape and size characteristics of an object inserted in this duct.

Background art The apparatus and the process according to the invention find application, particularly, in the design of objects of common use, having small dimensions and, therefore, susceptible of being ingested or inhaled by the user, thereby causing a risk of chocking. For example, the objects can be consumer products for use by adults or adolescents and, in particular, toys or parts of a toy intended for use by a child.

Chocking is still a leading cause of accidents in the pediatric age, with more than a thousand fatalities registered in the United States in the decade 1999-2009 and is the primary source of fatal accidents in less than 1-year-old children and the fourth cause of fatal accidents in 1 to 9-year-old children.

Although the toys represent a minimal proportion of the objects involved in chocking accidents (2-4%), according to the largest available database in the United States, in 2002, chocking was responsible for 54 % of all toy related fatalities, with an incidence of 43% for balloons.

Moreover, since mouthing is a pre-eminent activity in a playful and sensory context in the first years of a child's life, it is necessary to adopt the maximum effort in order to reduce the risk of chocking associated with toys.

BL-5091 2 LU101235 Currently, the strategy aimed at reducing this risk is mainly directed at the age group between 0 and 3 years and is based on two approaches: 1) the use of appropriate warnings that remark the chocking hazard due to the presence of parts that, due to their size, can be inhaled, and 2) the use of templates (or gauges) modeled in such a way that a part that does not fit into the gauge is deemed to be safe.

According to the recommendation of the European Standard Committee (CEN EN 71), concerning the "safety of toys”, the use of the "small part cylinder" is known. This rule regulates the minimum dimensions for toys or parts of toys that, when inserted in any position in the cylinder, must not be able to fit into it. Similarly, the "small ball standard" is an open circular gauge of 44.5 mm diameter used to test the safety of spherical and ovoid objects.

The currently used "small part cylinder”, however, proved to be inadequate to protect children in real situations, given that, in a reported case study, 23% of the fatal accidents recorded in the United States concerned objects deemed "safe" when tested with the aforementioned "small part cylinder", see Milkovich et al, Laryngoscope, 2008. The authors’ suggestion was to adopt an open and larger gauge having a diameter equal to 38.1 mm, since noaccident involving non-spherical objects larger than this size had ever been recorded.

However, it is evident that even this approach has intrinsic limits due to the fact that any object that can be placed in the mouth of a child can potentially create a choking hazard and, since the distance between the upper and lower incisor teeth in the children can easily exceed 5 centimeters, see Müller et al, 2013, (Müller et al., "Pediatr. Rheumatol. Online J. 2013; 11: 17)) a much larger gauge should be selected, especially, large enough to prevent the entry of the object into the mouth. An alternative approach to this problem is represented by the ISO 11540: 2014 (E) standard, "Writing and marking instruments - Specification for caps to reduce the risk of asphyxiation”, i.e. the standard for writing and marking instruments that defines the

BL-5091 3 LU101235 specifications for caps in order to reduce the risk of asphyxia.

The peculiarity of the ISO 11540 standard is linked to the fact that, for the first time, it is a regulation that is not aimed at ruling the dimensions that an object must possess in order to be declared "safe", but at ruling a function that the object must guarantee, that is the passage of air in the event that the object is impacted in the airways.

The standard requires that a pen cap, when inserted into an elastomeric tube of adequate size, i.e. having a diameter lower than 15% to 20% with respect to the diameter of the pen cap, must allow an air flow of 8 It / minute with a pressure variation of less than 1.333 Pa. The equipment illustrated in the ISO 11540 standard to be used for this test includes a test tube that mimics the airway. The fact that its diameter is smaller than the tested part should allow for a tight fitting adapted to simulate the impact of the foreign body at the level of the glottic plane or along the tracheal walls in the case of accidental inhalation.

However, the vast majority of the small toys and small parts which compose them present a great variety of sizes and shapes, quite different from the substantially constant dimensions and shapes of the pen caps. Furthermore, their size and shape make more probable their wedging at a higher level (more cranial) when compared to a pen cap. The impact area is in this case the so-called aditus ad laryngem, ie. a funnel-like region anteriorly delimited by the laryngeal face of the epiglottis, posteriorly by the hypopharyngeal wall and laterally by the two pharyngo-epiglottic and aryepiglottic folds. It is clear that the use of a "tube" to imitate the upper respiratory tract is a rather coarse simulation of this anatomical region: in fact, this region has walls with strong musculature and the mucosa being richly endowed with sensory receptors, reacts with a vigorous spastic contraction to the presence of a foreign body to protect the lower airways and to try to expel it from the respiratory tract.

Recently, the complex dynamic sequence of activation of pharyngeal muscle during swallowing has been clarified with the use of high-resolution pharyngeal manometry. In this research (Omari T. and Schaz in Current Opinion in Otoryngology & Head and Neck

BL-5091 4 LU101235 Surgery, 2018, 26-000-000) particular attention was paid to the measurement of pharyngeal luminal occlusive forces, which are one of the characteristics key to pharyngeal deglutition, allowing the derivation of the Swallow Risk Index, which represents a global measure of the swallowing function indicative of the swallowing functional reserve.

Due to these large anatomical and physiological differences between the pharyngeal region and the glottal / tracheal regions, the test of air passage with elastic tubes according to ISO 11540 is not representative of the real risk represented by a foreign body which, due to its size and shape, is blocked at the pharyngeal level in the event of accidental inhalation/ingestion.

US patent 8,276,091 describes a computerized system for simulating the risk associated with an object, based on the measurement of the contact force between a virtual object inserted in a virtual passage and the passage wall, which simulates the aero-digestive pathways. In one embodiment, the virtual object, depicted in the display, is manipulated by a cursor to be positioned at different positions of the virtual passage and a processor calculates the magnitude of the force generated by the interaction between the object and the tactile surface of the passage to generate the data indicating the risk of chocking. However, there is no knowledge of any scientific work in which the results obtained with this system are presented. One of the possible explanations is that any 3D model of the superior aero-digestive ways, reconstructed from images acquired from CT and MRI, carried out on subjects in the pediatric age, is able to document with remarkable precision the anatomic relationships and dimensions of the various structures and possibly also the variations in the ratio between the various structures during chewing/swallowing, but fails to reproduce the conditions in which a choking accident can occur when the foreign body has certain dimensional characteristics.

Summary of the invention An object of the present invention is therefore to provide a more realistic approach to the problem of chocking prevention and to allow a better identification of "safe" objects.

BL-5091 5 LU101235 Another object of the invention is to provide an apparatus and a process suitable for simulating the pharyngospasm induced by the wedging of a foreign body in a system that simulates the upper aero-digestive ways, suitable for use as an aid in the safety-oriented design of small objects and particularly toys.

The aforementioned and other objects and advantages are achieved by an apparatus and a process for determining the patency of a conduit into which an object is inserted, particularly in order to determine or estimate the risk of occlusion of this conduit associated with the morphological and dimensional features of the object inserted therein, said apparatus and process as being defined by the appended claims.

Preferred embodiments of the invention are defined in the dependent claims, the contents of which are an integral part of the present description.

Brief description of the drawings Further functional and structural characteristics of the apparatus and of the process according to the invention will be apparent from the detailed description which follows, made with reference to the annexed drawings, given as a non-restrictive example, in which: - figure 1 is a schematic representation of an apparatus according to the invention; - figure 2 illustrates a first embodiment of an apparatus according to the invention; - figure 3 illustrates the apparatus of figure 2 in the case in which a foreign object is inserted in the tubular duct 3 and the compression means 9 are generating a uniform external radial pressure on the wall of the tubular duct; - figure 4 shows a second embodiment of an apparatus including a plurality of pressure sub-chambers; - figure 5 shows an apparatus according to the invention in the embodiment in which the tubular duct is shaped as an upper air-digestive way; and - figure 6 is a representation of a test conduit shaped as a larynx for use in the apparatus according to the invention.

BL-5091 6 LU101235 Detailed description Before explaining in detail a plurality of embodiments of the invention, it should be clarified that the invention is not limited in its application to the construction details and to the configuration of the components presented in the following description or illustrated in the drawings. Further embodiments of the invention are workable and the invention can be reduced to practice or carried out practically in different ways. It should also be understood that the phraseology and terminology have a descriptive purpose and are not intended to be limiting. The use of "include" and "comprise" and their variations are to be intended as including the elements set out below and their equivalents, as well as additional elements and their equivalents.

Making initially reference to the schematic representation of Figure 1, an apparatus 1, realized in accordance with the invention comprises a tubular duct 3 with an elastically deformable wall 5, in which the occlusion test is performed, by introducing the object to be tested in the lumen of the duct. The duct 3 communicates from one side 6 with the ambient atmosphere and from the other side with a circuit for feeding a gas flow rate 8 comprising means for generating a flow of gas (air) 7 through the tubular duct 3. The fact that the airflow is applied in a caudal-cranial sense, while in reality it happens in a cranial-caudal sense, it is irrelevant both because the respiratory act is composed of inspiration and expiration, and because the test is performed both in insufflation and in compression/blowing. The flow generating means 7 are capable of generating a pressure between 5 and 50 kPa, preferably of at least 25 kPa, more preferably in the range 25 to 35 kPa, and can be, for example, a pressurized air tank; however, since the occlusion tests are preferably carried out both in suction and in compression, the flow generating means 7 preferably comprise a pump which, by means of suitable pneumatic means, allows operating in insufflation and in suction. Alternatively, in order to perform the insufflation and suction test, it is possible to use a device equipped with two separate gas flow supply circuits, one operating in insufflation and one operating in suction.

The apparatus further comprises, along the supply circuit, at least one flow regulating valve 23, a flowmeter 11 for measuring and recording the flow rate fed to the tubular duct

BL-5091 7 LU101235 3 and a pressure gauge 25 arranged for measuring and recording. - the variation of pressure through the tubular duct 3, caused by the presence of the object shown with T in figure 3. Compression means 9 are associated with the tubular duct 3 and are arranged to exert a uniform external pressure on at least an axially extending portion of the wall 5 of the tubular duct 3. The compression means comprise a pressure chamber 13, sealingly surrounding the tubular duct 3 and pressure generating means, adapted to vary the pressure inside said chamber. A pressure gauge 27 is also associated with the pressure chamber 13. The pressure chamber 13 can be made in the form of a transparent and sealed rigid cylinder

13. For example, the rigid cylinder can be made of transparent PMMA, i.e. in Plexiglas®, to allow the visualization of the object T inside the tubular duct 3, also preferably transparent.

The pressure chamber 13 is connected to the pressure generating means 15, arranged to generate a uniform external pressure on at least an axially extending portion of said wall 5 of the tubular duct 3 in which the object is inserted. Such pressure generating means may, for example, increase the air pressure in the pressure chamber 13 up to 26.7 kPa (200 mmHg) to compress the elastically deformable wall 5 of the tubular duct 3 so as to ensure a tight contact between it and the foreign object T which is inserted into the tubular duct 3 to be tested.

In a preferred embodiment (figure 4) the pressure chamber 13 can comprise a plurality of pressure sub-chambers 13A,..., 13N, independent and adjacent to each other in the axial direction of the tubular duct 3. Each - pressure sub-chamber 13A, ..., 13N surrounds a portion of the tubular duct 3 in which the foreign object is inserted. Furthermore, each pressure sub-chamber 13A, ..., 13N can be associated with respective pressure generating means 15 to generate respective predetermined pressures in the respective pressure sub- chambers.

The pressure generating means 15 can comprise a pump 15A (Figures 3 and 5), or, a compressor 15B (Figure 4) and a pressure regulator 15C (Figure 4).

BL-5091 8 LU101235 In the embodiment of Figure 4, in which the pressure chamber 13 comprises a plurality of sub-chambers, one or more pressure regulation devices 15D, connected to each sub- chamber through a plurality of ducts 19 with radial inlet in the sub-chambers, allows to generate different pressures in the sub-chambers to modulate, according to a predetermined pattern, the pressure exerted on portions of the tubular duct 3. The action of the pressure regulation devices 15D can be coordinated by a processing device 29 to simulate a spastic contraction and/or to adjust the intensity and timing of the compression.

In a simplified embodiment, the tubular duct 3, in which the tests are carried out to determine the risk associated with the object T, can be a circular cylindrical tube of elastomeric material, preferably transparent, for example a silicon or polyalkylsiloxane polymer tube with Shore A hardness generally from 13 to 65 Shore A, preferably comprised between 45 and 65 Shore A, more preferably of about 60 Shore A and with a wall thickness preferably between about 0.5 and 1 mm.

In this embodiment, the diameter of the lumen of the tubular duct is selected according to the "virtual diameter" (or "virtual circumference") of the object to be tested. Such "virtual diameter” can for example be determined empirically as a diameter corresponding to the length of a tape that completely wraps the object in one or more of its orientations under a predetermined load.

A device for determining this virtual diameter is described by the applicant in the concurrently filed patent application entitled "Device for measuring the size of an object and its use", the description of which is to be understood as incorporated herein by reference.

The aforesaid device comprises a support structure defining a gap in which a relatively inextensible tape is inserted in a linearly sliding manner, the tape extending outside the support structure forming a loop for inserting the object and having a first terminal end bound to the structure and a second end protruding from the support structure on the opposite side with respect to the loop, bound to a traction member (6), so that the traction

BL-5091 9 LU101235 exerted by said traction member determines the variation of the amplitude of the loop bringing the surface of the loop in contact with portions of surface of the object, when inserted in the loop.

The device provides a measure of the length of the loop that wraps the object under a constant and predetermined load exerted by the traction member; this length is assumed as the virtual circumference of the object, from which the virtual diameter (or equivalent diameter) is obtained by dividing by 3.14. In particular, the diameter of the tubular duct can be equal to the virtual diameter of the object or preferably lower than it in an amount comprised between 15 and 23%.

In another embodiment illustrated in Figure 4, in order to adopt a more realistic approach, the tubular duct 3 can be shaped as at least a portion of an airway of the human body. In particular, the tubular duct 3 indicated with 3D in Figures 4 and 5, can be shaped like a larynx, meaning with this term also the posterior oropharyngeal region, the hypopharynx and the subglottic region (Figure 6).

This 3D tubular duct can be manufactured by means of a three-dimensional mold of the upper aerodigestive ways derived from real data obtained from subjects of adequate age, for example by computerized tomography (CT) and by Magnetic Resonance Imaging (MRI) scans in pediatric subjects.

In a test phase, in order to achieve this result, a 3D modeling of the upper aerodigestive ways was derived from 120 CT scans performed in children of 2-10 years of age. The CT scans of the cervico-cranial region were anonymised and selected based on the absence of anomalies in the areas of interest and clarity of images.

The 3D tubular duct shaped as at least a portion of an airway of the human body can be molded in silicone or polyurethane polymer at room temperature, but also by thermoplastic injection molding for example in SBS.

In order to guarantee the seal and avoid pressure losses, the 3D tubular duct, which

BL-5091 10 LU101235 simulates the aero-digestive ways, can be molded with radial terminal flanges 33, 35 (Figure 6), which can be blocked by respective plates 31 screwed to the upper and lower ends of the pressure chamber.

The present invention further comprises a process for measuring the patency of a duct having an elastically deformable wall 5, usable, in particular to determine the risk of occlusion associated with the size and shape of an object inserted in said duct, which includes the operations of: - generating, by compression means 9, a uniform external radial pressure on at least an axially extending portion of the wall 5 of the tubular duct 3, so as to cause contact between the external surface of the object and said portion of the tubular duct 3 ; - feeding, by means for generating a gas flow rate 7, a pressurized gas through said tubular duct 3; and - measuring, by means for measuring the flow rate 11, the flow rate of gas corresponding to one or more predetermined pressure values exerted on said portion of the tubular duct 3. In the process according to the invention, implemented with the use of the previously described apparatus, the elasticity of the material used for the test tube that simulates the aero-digestive ways allows its deformation when an external pressure is applied. In this way it is possible to mimic the behavior of the pharyngeal muscular walls that contract when a foreign body is present, in the effort of swallowing or vomiting it.

Although a normal act of swallowing is characterized by sequential compression and relaxation waves in the pharyngeal area, in the case of a choking accident caused by a foreign body, the protective reflex activity usually produces a massive contraction that can be reproduced by a quick increase in the pressure of the air surrounding the test tube positioned in an airtight container under pressure.

In the process according to the invention, the purpose of which is obviously not to reproduce the physiological sequence of pharyngeal movements during a normal swallowing act, but to ensure that a sufficient passage of air is guaranteed even in the presence of a foreign body wedged in the pharyngo-laryngeal area, the risk associated with

BL-5091 11 LU101235 the object being tested is determined based on the determination of the patency of the duct, i.e. by determining the flow rate that is able to flow through the tubular duct when the object to be tested is inserted in the duct, at a predetermined pressure change or loss of load caused by the presence of the object. Unlike the static test method described in the ISO 11540 standard, the process according to the invention is thus based on a dynamic model in which the wall of the conduit surrounding the object is subjected to different degrees of compression so as to cause a more or less tight adhesion of the wall of the conduit that simulates the airways to the surface of the object to be tested.

By way of example, Figure 3 illustrates the situation in which the elastically deformable wall 5 ensures close contact with the foreign object T inserted in the tubular duct and subjected to an external pressure in the pressure chamber.

Following the determination of a threshold value for the flow rate, the risk assessment in terms of object safety can be carried out by associating the "safe" value when the flow rate exceeds the defined threshold value, or the"unsafe" value when the flow rate is less than this value. It is of course possible, following repeated tests, to associate to the object, depending on the value of the flow rate determined, a value or degree of safety related to the degree of occlusion of the pipe, caused by the object.

In particular, the pressure to be exerted on the wall of the conduit which simulates the airways, preferably, can reach a value of about 26.7 kPa (200 mm Hg), since this is the peak value recorded in adult subjects in the pharyngeal area during the swallowing of a bolus consisting of 5 ml of water, being reasonable to believe that, applying this pressure to a pharynx model of a child, whose musculature undoubtedly develops a lower contractile energy, a realistic representation of the pressure exerted by the faryngospasm is obtained. Further confirmation of the fact that a value of 26.7 kPa is adequate also derives from manometric studies conducted at the level of various areas of the oropharynx and hypopharynx, requiring subjects (healthy young adults) to perform both an “effortful swallow” and the Mendelsohn's maneuver, in which the subject must hold his tongue firmly against the palate while swallowing.

BL-5091 12 LU101235 At a pressure of 26.7 kPa, which determines a particularly severe condition for the evaluation of the passage of air, it is preferable to set a safety condition for the air flow rate of at least 16 | / min. in correspondence with a pressure variation not exceeding 1000 Pa, preferably not exceeding 700-1000 Pa.

In particular, the object subjected to the test is considered unsafe if the air flow is less than 16 1/ min. with a pressure variation greater than 1000 Pa at a pressure exerted on the duct of at least 26.7 kPa (200 mm Hg).

With the use of a tubular duct 3, shaped so as to reproduce the structure of a larynx, it is preferable that the test be carried out with models of larynx obtained for an age of the child equal to at least 3-4 years and equal to 6-7 years, requesting that the test be passed in both such circumstances. It is also preferable for the test to be carried out also by reversing the direction of the gas flow through the duct, ie. both in suction and in compression, requiring the test to be passed in both conditions.

The advantage achieved by the present invention is therefore to obtain a more realistic approach to the problem of preventing chocking and to allow a better identification of "safe" objects.

Several aspects and embodiments of an apparatus for determining the patency of a flow conduit and a method for determining the degree of occlusion of a flow conduit have been described. It is understood that each embodiment can be combined with any other embodiment. Furthermore, the invention is not limited to the embodiments described, but may be varied within the scope defined by the appended claims.

For example, although the compression of the tubular duct has been described in relation to the use of a pressure chamber, the pressure which causes the deformation of the tubular duct (or corresponding 3D model) can also be achieved with other systems, such as mechanical actuators or hydraulic systems and can be applied to only a portion of the duct or to adjacent portions simultaneously or sequentially.

Claims (16)

BL-5091 13 LU101235 CLAIMS

1. Apparatus for determining the patency of a conduit associated with an object (T) inserted in said conduit, comprising: - a tubular duct (3) with an elastically deformable wall (5); - means for generating a flow of gas (7) through said tubular duct (3); - compression means (9), associated with said tubular duct (3), arranged to generate a uniform external pressure on at least an axially extending portion of said wall (5) of said tubular duct (3) in which the object is inserted; and - means for measuring the flow rate (11) through said tubular duct (3).

2. Apparatus according to claim 1, wherein said compression means (9) comprises: - a pressure chamber (13) sealingly surrounding said tubular duct (3); and- pressure generating means (15) for generating a predetermined pressure in said pressure chamber (13) to compress said tubular duct (3).

3. Apparatus according to claim 2, wherein said pressure chamber (13) comprises a plurality of independent pressure sub-chambers (13A, ..., 13N) adjacent to each other in the axial direction of the tubular duct (3 ); each pressure sub-chamber (13A, ..., 13n) surrounding a portion of the tubular duct (3) into which the object is inserted; to each pressure sub-chamber (13A, ..., 13N), respective pressure generating means (15) being associated to generate respective predetermined pressures in the respective pressure sub-chambers.

4. Apparatus according to any one of the preceding claims, comprising a pressure gauge (25) for measuring and / or recording the pressure variation in said tubular duct caused by the presence of said object (T).

5. Apparatus according to any one of the preceding claims, in which the tubular duct (3) is shaped as at least a portion of an upper air-digestive way of the human body.

BL-5091 14 LU101235

6. Apparatus according to claim 4, wherein the tubular duct (3) is shaped like a larynx.

7. Apparatus according to any one of the preceding claims, in which the tubular duct (3) is made of elastomeric material, preferably a silicone polymer.

8. Apparatus according to any one of Claims 1 to 7, in which the said tubular duct (3) has an elastically deformable wall with Shore A hardness between 45 and 65 Shore A.

9. Apparatus according to any one of the preceding claims, in which said compression means (9) comprise a compressor (15B) and a pressure regulator (15C).

10. Apparatus according to any one of the preceding claims, in which the means for generating a flow of gas (7) comprise a pump which, with suitable pneumatic means, can be operated in compression and suction to cause inversion of the flow direction in said tubular duct (3).

11. Process for determining the risk of occlusion of a tubular duct (3) having an elastically deformable wall, wherein said risk is associated with the morphological and dimensional characteristics of an object (T) inserted in said tubular duct, characterized in that it includes the measurement of the flow rate of a gas through said tubular duct, said measurement being carried out by subjecting to an external pressure at least an axially extending portion of said wall (5) of said tubular duct (3) in which the object (T) is inserted.

12. The process according to claim 11 comprising the operations of: - generating a uniform external pressure on at least an axially extending portion of said wall (5) of said tubular duct (3), so as to create a tighter contact between the outer surface of the object and said portion of the tubular duct (3) thereby simulating the contraction of the pharynx in the presence of a foreign object; - feeding a gas flow through said tubular duct (3); and - measuring the gas flow rate corresponding to one or more predetermined values of pressure exerted on said portion of said tubular duct (3).

BL-5091 15 LU101235

13. The process according to claim 12, comprising the generation and application of differentiated pressures, according to a predetermined pattern, on adjacent axially extending portions of the wall (5) of said tubular duct (3).

14. The method according to any one of the claims 11 to 13, further comprising the measurement of the pressure variation caused by the presence of said object (T) in said tubular duct, in correspondence with a predetermined gas flow through said tubular duct.

15. Process according to any one of the claims 11 to 14, characterized in that said tubular duct is shaped according to a larynx model of subjects of various ages, including the pediatric one.

16. Process according to any of the claims 11 to 15 comprising the operation of comparing the value of the measured flow rate with a predetermined threshold value of said flow rate.