Nasal/oral cannula system and manufacturing

A nasal/oral cannula for collecting a flow of exhaled gases and its method of manufacture are disclosed. The cannula comprises an elongated tubular body having a first and a second end portion, a surface and an internal volume; a wall internally disposed within said tubular body, said wall defining a first subvolume of said internal volume in the lengthwise direction of the tubular body; and an inlet through said surface, for introducing exhaled gases into said first subvolume. The first end portion defines an exit port for exhaled gases from said subvolume, and said wall is arranged directly adjacent to said inlet.

TECHNICAL FIELD

The present disclosure relates to a nasal/oral cannula for the collection of a flow of exhaled gases.

BACKGROUND

In health care, it is often desirable to analyze and monitor the gas composition of a patient's exhaled and/or inhaled breathing gases. For instance, measurement of respiratory CO2, O2, N2O, and anesthetic agents, such as halothane, isoflurane, enflurane, sevoflurane or desflurane, may be useful in the care of critically ill patients undergoing anesthesia. In some emergency care situations involving manual ventilation, it may typically be sufficient to monitor a patient's breathing with a simple CO2analysis.

Capnography is the monitoring of the concentration or partial pressure of carbon dioxide (CO2) in respiratory gases, and provides real-time information regarding CO2exhalation and respiratory rates as well as a rapid and reliable assessment of a patient's ventilatory, circulatory and metabolic function. Although the terms capnography and capnometry are sometimes considered synonymous, capnometry suggests measurement without a continuous written record or waveform. Typically in capnography and capnometry, a gas analyzing device is placed in the respiratory circuit of a patient to sample exhaled and/or inhaled breathing gases and calculate gas concentrations directly in the respiratory circuit.

Measurement of end tidal CO2can also provide useful information regarding CO2production, pulmonary (lung) perfusion, alveolar ventilation, respiratory patterns, and elimination of CO2from an anesthesia breathing circuit or ventilator. The gas sample measured at the end of a person's exhalation is called the “end-tidal” gas sample. The amount of CO2in a person's end-tidal breath can indicate the overall efficiency of the cardio-pulmonary system and quality of breathing. For example, an overly high concentration of CO2can indicate shallow breathing and poor oxygen intake. Thus, capnographs are used in hospitals and other medical institutions for monitoring the condition of a patient's respiratory system, pulmonary perfusion, and metabolism, and are often used for patients in intensive care or under anesthesia. Gas analyzers, including capnographs, can also be used in a wide range of other circumstances, for example ventilator management and weaning, metabolic measurements and nutritional assessment, and automated drug infusion safety.

The accuracy of the analysis of exhaled gases depends on the ability of a sampling system to move a gas sample from the patient to the gas analyzer while maintaining a smooth, laminar flow of gases, such that there are as few as possible alterations to the waveform representing the measured concentration of the gases. An accurate waveform depicting the concentration of the gas is critical for accurate patient monitoring and diagnosis.

Different types of oral/nasal cannulae are used to collect exhaled gas samples from patients in order to monitor respiration and other patient parameters. Some cannulae additionally deliver oxygen and/or other therapeutic gases, for example anesthetic gases, to the patient as needed.

SUMMARY

Cannulae such as those described above work well for the delivery of oxygen to a patient, since the flow of delivered oxygen is relatively high. However, when considering the collection of exhaled gases from the patient, the gas flow is considerably lower. Accordingly, these cannulae may produce a pronounced problem in the analysis of exhaled gases due to the presence of the space in the tube between the partition and the prong through which the exhaled gas enters. Such space is referred to herein as a “void volume” because it does not form part of the pathway for the flow of gases and hence is unproductive. The presence of such a void volume is a significant hindrance to the accurate analysis of exhaled gases because it creates turbulence and backflow within the cannula. Thus, such nasal cannulae may decrease the accuracy and efficiency of analysis of collected exhaled gases.

Further, available production methods for nasal/oral cannula systems are generally associated with limitations, for example related to suitable starting materials and manufacturing processes. Injection molding generally requires stiff and hard material, which makes it difficult to make complicated details, and also leads to uncomfortable end products. Dip molding allows the use of soft, more user-friendly materials, but similarly suffers from the disadvantage of imprecise production. Another problem with the existing production methods stems from the need for a vast number of different molds in order to produce cannula systems of different shapes and sizes. Also, the conventional use of glue in the assembly of modular systems leads to thick boundary layers between pieces, which may in turn have a disturbing effect on gas flowing through the system.

Accordingly, there is a need for a nasal/oral cannula which is easy to manufacture and which provides for accurate analysis of exhaled gases, possibly in combination with the supply of a treating gas, such as oxygen. In addition, there is a need for an improved method for manufacturing nasal/oral cannula systems, which allows for the use of comfortable and soft materials, as well as for a simple and flexible way of producing reliable cannula systems of different shapes and sizes.

The above-described problems with existing cannulae, among others, are resolved or reduced by some embodiments of the modular nasal cannula systems described herein. Similarly, the above-described manufacturing problems, among others, are resolved or reduced in some embodiments of the cannula manufacturing systems and techniques described herein.

In some aspects of the disclosure, a nasal/oral cannula for collecting a flow of exhaled gases comprising an elongated tubular body having a first and a second end portion, a surface and an internal volume; a wall internally disposed within said tubular body, said wall defining a first subvolume of said internal volume in the lengthwise direction of the tubular body; and an inlet extending through said surface, for introducing exhaled gases into said first subvolume is disclosed. In some embodiments, said first end portion defines an exit port for exhaled gases from said subvolume, and said wall is advantageously arranged adjacent to said inlet.

The arrangement of the wall adjacent to the inlet provides for a very advantageous cannula construction, since it minimizes the risk for disturbances in the gas flow. In particular, this arrangement of the wall minimizes or eliminates the void volume in the tubular body, which in turn provides for a smooth, laminar flow of gases in the cannula system and, as a consequence, reliable analysis results. In some embodiments, said wall is arranged to provide a flow path for exhaled gases from said inlet to said exit port, such that essentially the entire first subvolume forms part of said flow path.

In some embodiments, said tubular body may further comprise a length L, and said inlet may be arranged at a distance of less than L/2 from said first end portion. In other embodiments, said tubular body may comprise a length L, and said inlet may be arranged at a distance of about L/2 from said first end portion. In some embodiments, the nasal/oral cannula may further comprise a first additional inlets through said surface.

In some embodiments of the nasal/oral cannula, said internally disposed wall within said tubular body also defines a second subvolume of said internal volume in the lengthwise direction of the tubular body, and said second end portion defines an entrance port for allowing a treating gas into the second subvolume. In some embodiments the nasal/oral cannula may further comprise an outlet through said surface, for transferring a treating gas from said second subvolume to the respiratory system of a patient.

In some embodiments, a nasal/oral cannula system may comprise a nasal/oral cannula as described above and/or below, a first nozzle adapted for the transport of exhaled gases from the cannula, and a sampling tube adapted for the transport of exhaled gases from the cannula to an analyzer. In some embodiments, a nasal/oral cannula system may further comprise a second nozzle adapted for the supplementation of a treating gas to the cannula, and a treating gas tube adapted for the transport of a treating gas from a treating gas source to the cannula.

In some aspects of the disclosure, a method for the manufacture of a nasal/oral cannula system comprising the steps of: (1) providing, by injection molding of a manufacturing material, a cannula comprising an elongated tubular body having a first and a second end portion, a surface, and an inlet extending through said surface, said elongated tubular body comprising a wall internally disposed within said tubular body; (2) providing, by injection molding of a manufacturing material, a first nozzle, and (3) assembling said nasal/oral cannula system by solvent bonding, is disclosed.

In some embodiments of the method, said cannula is provided by providing a cannula mold shaped to create a desired outer shape of said cannula; providing a cannula cavity, including a wall cavity, within the cannula mold with the aid of a first and second insert and a first pin, said cannula cavity, including said wall cavity, corresponding to the shape of said cannula; and filling the cannula cavity, including said wall cavity, with said manufacturing material.

In some embodiments of the method, said wall cavity is placed in a desired position within said cannula mold by movement of the first and second inserts. This embodiment therefore provides for a simple and flexible way of disposing the wall in a suitable position within the tubular body of the cannula. In particular, this method provides for easy arrangement of the wall in practically all positions within the tubular body by a simple movement of the first and second cavity tools.

In some embodiments, the nasal/oral cannula system may further comprise an oral breath collector, and the method may further comprise the step of providing, by injection molding, an oral breath collector.

In some embodiments, said first nozzle is provided by providing a nozzle mold shaped to create a desired outer shape of said first nozzle; providing a nozzle cavity within the nozzle mold with the aid of two cavity tools, said nozzle cavity corresponding to the shape of said nozzle; and filling the nozzle cavity with said manufacturing material.

In some aspects of the disclosure, a manufacturing tool configured for use with a mold as described herein is disclosed. In some embodiments, the tool comprises a tool body, a mold as described above supported by the tool body, a first device supporting a first insert and arranged to move the first insert between a molding position and the retracted position, a second device supporting a second insert and arranged to move the second insert between the molding position and the retracted position, a third device supporting an insert pin and arranged to move the insert pin between the molding position and the retracted position, wherein the first and second devices are configured to introduce the first and second inserts to the desired position to form the wall in the cannula.

In some embodiments of the tool, the first and second inserts are lockable within respective first and second devices at a plurality of longitudinal positions so as to allow for adjustment of the position of the wall within the manufactured cannula.

In some embodiments of the tool, the third device is configured to support at least two insert pins in a plurality of different position within the third device so as to allow the tool to adapt for molds intended for cannulae of different sizes.

In some embodiments, the tool comprises a first portion and a second portion and is further configured such that the movement of the first portion relative to the second portion mechanically causes the first, second, and third devices to move between a molding position and a release position.

In some embodiments, the tool and the mold are configured to be adjustable in order to mold cannulas of different sizes and configurations. For example, in some embodiments, the mold includes adjustable inserts that can be positioned at different locations that correspond to different placements of a wall within the cannula. In some embodiments, the inserts are adjustable by adjusting their placement within first and second devices of the tool. In some embodiments, the mold includes adjustable pin inserts configured to vary the distance between hollow prongs of the cannula in order to adjust the size for adults, children, and infants. In some embodiments, the pin inserts are adjustable by changing their position within the third device of the tool.

Other aspects of the disclosure relate to a nasal/oral cannula system obtainable by any of the methods described above and/or below and to all possible combinations of the features recited above.

DETAILED DESCRIPTION

Nasal/oral or respiratory cannulae as described herein can provide for improved analysis of exhaled gases, for example CO2, from a patient. In particular, the structure of the nasal/oral cannulae can beneficially overcome the problem of “void volumes” that can lead to inaccurate analysis results.

One noteworthy aspect of the present disclosure is the particular placement of a gas-tight inner wall within the cannula in order to define inhalation and exhalation compartments. In the research work leading to the development of the embodiments of cannulae described herein, it was found that the placement of such a wall placed in close proximity to, adjacent to and/or adjoining the inlet for exhaled gases, provides for a substantially undisturbed gas flow and, as a consequence, reliable and accurate analysis results, as will be described more fully below.

By placing the wall in immediate or near immediate connection with the inlet, the void volume can be minimized or eliminated, which provides for a smooth, laminar flow of gases from the patient to a gas analyzer. When there are several inlets for exhaled gases, the wall can be placed in connection to the inlet which is located at the farthest distance from the point where the gases exit the cannula.

As will be described in greater detail below, cannulae, following the principles herein disclosed, can take the form of at least three principal different embodiments, among others:

Exhaled gases are collected from one of a patient's nostrils. The collection of exhaled gases from one nostril may be combined with the supplementation of a treating gas to the patient's other nostril.

Exhaled gases are collected from the mouth of a patient. The collection of exhaled gases from the mouth of a patient may be combined with the collection of exhaled gases from one or both nostrils of a patient, and optionally also with supplementation of a treating gas to the other nostril.

Exhaled gases are collected from both nostrils of a patient. The collection of exhaled gases from both nostrils of a patient may be combined with the collection of exhaled gases from the mouth of a patient.

These three non-limiting principal cannulae embodiments, as well as combinations thereof, will be described in further detail below with reference to the attached drawings. In the following description, specific details are given to provide a thorough understanding of the examples. However, in some embodiments, the examples may be practiced without these specific details.

FIG. 1Adepicts an embodiment of a cannula configured to collect gas from one of a patient's nostrils while also providing a treating gas to the patient's other nostril. It should be noted, however, that the concurrent supplementation of a treating gas is an optional feature of this embodiment.

The cannula system1A comprises a cannula1and first and second nozzles16,17. The cannula1comprises an elongated tubular body2for the collection of gases exhaled through a first nostril (not shown) of a patient. The tubular body2has a first end portion3and a second end portion4. The first end portion3may further define an exit port9for exhaled gases. The exhaled gases enter the tubular body2via an inlet8, which is configured as a hole extending through a surface5of the tubular body2. The tubular body2is preferably essentially cylindrical and has a length L measured between first end portion3and second end portion4. In this embodiment, the inlet8is preferably arranged at a distance of less than L/2 from said first end portion3. The inlet8is thereby adapted to receive exhaled gases from the first nostril of the patient. Gases exhaled by the patient through the first nostril enter the cannula through the inlet8and exit the cannula system1A through the exit port9and first nozzle16.

A wall7is internally disposed within the tubular body2in order to divide an internal volume6of the tubular body2into a first subvolume6A and a second subvolume6B. The first subvolume6A is arranged in the lengthwise direction toward the first end portion3of the tubular body2. In some embodiments, the inlet8preferably comprises a first hollow prong10, which allows for fluid communication into the subvolume6A of the tubular body2. The first hollow prong10A may be configured to be inserted into the first nostril of the patient. The hollow prong10A is preferably molded integrally with the tubular body2; however, the hollow prong10A may alternatively be sealingly adhered to the tubular body by other means, including use of an adhesive composition.

The wall7is arranged directly adjacent, or in close proximity, to the inlet8. As used herein, “adjacent” and “directly adjacent” to the inlet is meant to signify that the wall7is arranged in immediate contact with the inlet8so that no void volume for the flow of exhaled gases is created between the wall7and the inlet8, or that the wall7is arranged in near immediate contact with the inlet8so that void volume is acceptably low. This placement is described throughout, and especially in relation toFIG. 5, which will be discussed more fully below. Alternatively, the wall7can be located in close proximity to the inlet8in order to substantially reduce the void volume to acceptable limits.

When the inlet8comprises a hollow prong10, the wall7can be seen to constitute an extension of an inner side of the hollow prong10A from the tangential point11where the hollow prong10A is joined with the inner side of the tubular body2. The wall7thereby provides for an uninterrupted flow path for the exhaled gases from the inlet8to the exit port9where essentially the entire subvolume6A forms part of the flow path. Thus, gases exhaled by the patient through the first nostril enter the cannula through the inlet8and exit the cannula through the exit port9without significant interruption, turbulence, or back flow.

The embodiment of the cannula depicted inFIG. 1Ais also configured to provide for the supplementation of a treating gas to a second nostril (not shown) of the patient. In this embodiment, the wall7defines a second subvolume6B in the internal volume6of the tubular body2. The subvolume6B is arranged in the lengthwise direction toward the second end portion4of the tubular body2. The treating gas enters the second subvolume6B through an entrance port12, and exits the subvolume6B through an outlet13formed as a hole extending through the surface5. The treating gas is thereby transferred to the respiratory system of a patient. The outlet13preferably also comprises a hollow prong10B configured to deliver the treating gas to the second nostril of the patient.

FIG. 1Billustrates an exploded view of the components of the embodiment of the cannula system1A ofFIG. 1A. As illustrated, the cannula1and nozzles16,17can be separately manufactured, for example by injection molding. These separate components can then be assembled by solvent bonding. For example, an inserting end of nozzle16can be sized to fit within exit port9. An exterior surface of the inserting end of nozzle16may be coated or provided with a solvent for solvent bonding and then inserted into exit port9. Similarly, inserting end of nozzle17can be sized to fit within an entrance port12. An exterior surface of the inserting end of nozzle17may be coated or provided with a solvent for solvent bonding and then inserted into entrance port12. In alternative embodiments these components may be configured for a substantially fluid-tight press fit.

FIG. 2Adepicts an alternative embodiment of a cannula system1A according to the present disclosure that is configured to collect gases exhaled from the mouth and first nostril of a patient. It should be noted, however, that the concurrent collection of exhaled gases from the first nostril is an optional feature of this embodiment. The embodiment ofFIG. 2Acan also optionally be configured to provide a supplemental treating gas to the second nostril of the patient. The cannula system1A can comprise a cannula1, first and second nozzles16and17, and an oral breath collector15.

The cannula1comprises an elongated tubular body2for the collection of gases exhaled trough the mouth and/or first nostril of a patient (not shown). The tubular body2has respective first and second end portions3,4. The first end portion3defines an exit port9for exhaled gases. The exhaled gases enter the tubular body2via an inlet8configured as a hole extending through a surface5of the tubular body2. In some embodiments, the tubular body2is preferably essentially cylindrical and has a length L measured between the first and second end portions3,4, where the inlet8is preferably arranged at a distance of about L/2 from said first end portion3, such as substantially between the first and the second end portions3,4. The inlet8is thereby adapted to receive exhaled gases from the mouth of a patient.

In addition, the cannula may comprise a first additional inlet8A also configured as a hole extending through said surface5. The first additional inlet8A is preferably arranged at a distance of less than L/2 from said first end portion3, such as in proximity to the first end portion3. The first additional inlet8A is disposed on the opposite side of the cannula1of the inlet8; or, in other words, if the inlet is disposed on the bottom of the cannula1, the first additional inlet8A is disposed on the top. The first additional inlet8A is thereby adapted to receive exhaled gases from the first nostril of a patient. The first additional inlet8A preferably comprises a hollow prong10A configured for insertion into the first nostril of the patient. Thus, gases exhaled by the patient through the mouth enter the cannula through the inlet8and gases exhaled by the patient through the first nostril enter the cannula through the first additional inlet8A. The exhaled gases exit the cannula through the exit port9and first nozzle16.

A wall7is internally disposed within the tubular body2in order to define a first subvolume6A of the tubular body2into which exhaled gases are introduced. The subvolume is arranged in the lengthwise direction of the tubular body2toward the first end portion3of the tubular body2. Preferably, the inlet8comprises a hollow prong14, which allows for fluid communication into the first subvolume6A of the tubular body2. An oral breath collector15, a so-called “scoop,” may be connected to said hollow prong14. The oral breath collector15is configured to cover the mouth of a patient using the cannula system1A.

The wall7is arranged adjacent to the inlet8. As above, “adjacent” to the inlet8signifies that the wall7is arranged in immediate, or near-immediate, contact with the opening8so that no, or acceptably low, void volume for the flow of exhaled gases is created between the wall7and the inlet8. When the inlet8comprises a hollow prong14, the wall7can be seen to constitute an extension of an inner side of the hollow prong14from the tangential point18where the hollow prong14is joined with the inner side of the tubular body2.

The wall7thereby provides for a substantially uninterrupted flow path for the exhaled gases from the inlets8,8A to the exit port9, and essentially the entire subvolume6A forms part of the flow path. Thus, gases exhaled by the patient through the mouth and the first nostril enter the cannula through the inlets8,8A and exit the cannula through the exit port9without any substantial interruption, turbulence, or back flow.

In some embodiments, the cannula depicted inFIG. 2A, may also provide for the supplementation of a treating gas to a second nostril (not shown) of the patient. In this embodiment, the wall7defines a second subvolume6B in the internal volume6of the tubular body2. The subvolume6B is arranged in the lengthwise direction toward the second end portion4of the tubular body2. The treating gas enters the second subvolume6B through an entrance port12, and exits the subvolume6B through an outlet13formed as a hole extending through the surface5. The outlet13preferably comprises a hollow prong10B configured for insertion into the patient's second nostril. The treating gas may thereby be transferred to the respiratory system of a patient.

FIG. 2Billustrates an exploded view of the components of the cannula system1A of embodiment shown inFIG. 2A. As illustrated, the cannula1and nozzles16,17can be separately manufactured, for example by injection molding. These separate components can be assembled by solvent bonding. For example, an inserting end of nozzle16can be sized to fit within exit port9. An exterior surface of the inserting end of nozzle16may be coated or provided with a solvent for solvent bonding and then inserted into exit port9. Similarly, inserting end of nozzle17can be sized to fit within an entrance port12. An exterior surface of the inserting end of nozzle17may be coated or provided with a solvent for solvent bonding and then inserted into entrance port12. An aperture in the top of the oral breath collector15can be sized to receive hollow prong14, and the breath collector may include a portion on the interior of the breath collector that extends around hollow prong14once inserted. An exterior surface of the prong14can be coated or provided with solvent for solvent bonding and then inserted into the aperture of the oral breath collector15. In alternative embodiments, these components may be configured for a substantially fluid-tight press fit.

FIG. 3Adepicts an embodiment of a cannula system1A configured to collect the exhaled gas from both of a patient's nostrils. The cannula1comprises an elongated tubular body2for the collection of gases exhaled through the first and second nostrils (not shown) of a patient. The tubular body2has a first and a second end portion3,4. The first end portion3defines an exit port9for exhaled gases. The exhaled gases enter the tubular body2via an inlet8and a first additional inlet8A formed as holes extending through surface5of the tubular body2. The tubular body is preferably essentially cylindrical and has a length L, where the inlet8is arranged at a distance of more than L/2 from said first end portion3, such as in proximity to the second end portion4, and the first additional inlet8A is arranged at a distance of less than L/2 from said first end portion3, such as in proximity to the first end portion3. Thereby, the inlet8is adapted to receive exhaled gases from the second nostril of a patient, and the first additional inlet8A is adapted to receive exhaled gases from the first nostril of a patient.

Thus, gases exhaled by the patient through the second nostril enter the cannula through the inlet8and gases exhaled by the patient through the first nostril enter the cannula through the first additional inlet8A. The exhaled gases exit the cannula through the exit port9. Although the cannula1is illustrated with nozzle17, in some embodiments nozzle17may be omitted due to the positioning of the wall7such that gases cannot be received into the cannula1through nozzle17. In some embodiments, nozzle17may be replaced with a cap or an attachment for a securing device used to secure the cannula1to the patient. In some embodiments, nozzle17may be included, as illustrated, and connected to extension tubing for use in securing the cannula1to the patient even though no therapeutic gases are delivered through the extension tubing or nozzle17.

Preferably, the inlet8and additional inlet8A comprise hollow prongs10,10A. The prongs10,10A are configured for insertion into a patient's nostrils and are further configured to allow fluid communication into the subvolume6A of the tubular body2. The hollow prongs10,10A are preferably molded integrally with the tubular body; however, the hollow prongs10,10A may alternatively be sealingly adhered to the tubular body by other means, including by use of an adhesive composition.

A wall7is internally disposed within the tubular body2in order to define a first subvolume6A of the tubular body2into which exhaled gases are introduced. The first subvolume is arranged in the lengthwise direction toward the first end portion3of the tubular body2.

The wall7is arranged adjacent to the inlet8. Again, “adjacent” to the inlet8signifies that the wall7is arranged in immediate or near-immediate contact with the opening8so that no, or acceptably low, void volume is created between the wall7and the inlet8. When the opening8comprises a hollow prong10, the wall7can be seen to constitute an extension of an inner side of the hollow prong10A from the tangential point11where the hollow prong10A is joined with the inner side of the tubular body2. For example, the wall7can be directly adjacent to the inlet8or within an acceptable range. For example, the range can be 0.0 to 0.5 mm; 0.0 to 1.0 mm; 0.0 to 2.0 mm, or anywhere in between. In an embodiment, the wall7is placed closer to the inlet8than the outlet13.

The wall7thereby provides for an uninterrupted flow path for the exhaled gases from the inlets8,8A to the exit port9, and essentially the entire subvolume6A forms part of the flow path. Thus, gases exhaled by the patient through the first and second nostrils enter the cannula through the inlets8,8A and exit the cannula through the exit port9without any substantial interruption, turbulence, or back flow.

FIG. 3Billustrates an exploded view of the components of the cannula system1A embodied inFIG. 3A. As illustrated, the cannula1and nozzles16,17can be separately manufactured, for example by injection molding. These separate components can be assembled by solvent bonding. For example, an inserting end of nozzle16can be sized to fit within exit port9. An exterior surface of the inserting end of nozzle16may be coated or provided with a solvent for solvent bonding and then inserted into exit port9. Similarly, inserting end of nozzle17can be sized to fit within an entrance port12. An exterior surface of the inserting end of nozzle17may be coated or provided with a solvent for solvent bonding and then inserted into entrance port12. In alternative embodiments these components may be configured for a substantially fluid-tight press fit.

FIG. 4Adepicts an embodiment of a cannula system1A configured to collect exhaled gas from both nostrils of a patient, as well as from the patient's mouth. This embodiment is similar to that discussed above with reference toFIGS. 3A and 3Bbut it also comprises a second additional inlet8B, also formed as a hole extending through said surface5, as seen inFIG. 4A. The second additional inlet8B is arranged at a distance of about L/2 from said first end portion3, such as substantially between the first and second end portions3,4. Additionally, the second inlet8B is generally disposed on the cannula1opposite the inlet8and first additional inlet8A. In other words, if the inlet8and first additional inlet8A are disposed on the top of the cannula1, the second additional inlet8B will be disposed on the bottom. The second additional inlet8B is thereby adapted to receive exhaled gases from the mouth of a patient.

The second additional inlet8B preferably comprises a hollow prong14, which allows for fluid communication into the subvolume6A of the tubular body2. An oral breath collector15, a so-called “scoop,” may be connected to the hollow prong14and configured to cover the mouth of a patient using the cannula system1A. Thus, gases exhaled by the patient through the nostrils enter the cannula through the inlet8and the first additional inlet8A, and gases exhaled by the patient through the mouth enter the cannula through the second additional inlet8B. The exhaled gases exit the cannula through the exit port9and first nozzle16.

As described above with respect to the embodiment ofFIG. 3A, though the embodiment ofFIG. 4Ais illustrated with a second nozzle17, in some embodiments nozzle17may be omitted or replaced with a cap, other attachment, or securing device used to secure the cannula1to the patient. In some embodiments, nozzle17may be included, as illustrated, and connected to extension tubing for use in securing the cannula1to the patient even though no therapeutic gases are delivered through the extension tubing or nozzle17.

FIG. 4Billustrates an exploded view of the components of the cannula system1A embodied inFIG. 4A. As illustrated, the cannula1and nozzles16,17can be separately manufactured, for example by injection molding. These separate components can then be assembled by solvent bonding. For example, an inserting end of nozzle16can be sized to fit within exit port9. An exterior surface of the inserting end of nozzle16may be coated or provided with a solvent for solvent bonding and then inserted into exit port9. Similarly, inserting end of nozzle17can be sized to fit within an entrance port12. An exterior surface of the inserting end of nozzle17may be coated or provided with a solvent for solvent bonding and then inserted into entrance port12. An aperture in the top of the oral breath collector15can be sized to receive hollow prong14, and the breath collector may include a portion on the interior of the breath collector that extends around hollow prong14once inserted. An exterior surface of the prong14can be coated or provided with solvent for solvent bonding and then inserted into the aperture of the oral breath collector15. In alternative embodiments these components may be configured for a substantially fluid-tight press fit.

FIG. 5depicts a cutaway detail view of a portion of a tubular body2of a cannula comprising a wall7and an inlet8.FIG. 5may be illustrative of a portion of each of the embodiments shown inFIGS. 1A-4B. The wall7is arranged adjacent to the inlet8, such that the exhaled gases can generally only move in a single direction, towards the exit port9, upon entering the tubular body2of the cannula. Accordingly, this positioning of the wall7substantially eliminates any void volume within the tubular body2.

The wall7is internally disposed within the tubular body2such that the entire periphery of the wall7sealingly engages the inner surface of the tubular body2to form a gas-tight seal. The wall7is preferably molded integrally with the tubular body2; however, in some embodiments, the wall7may alternatively be sealingly adhered to the tubular body2by other means such as with an adhesive composition.

With reference toFIG. 5, the inlet8is configured as a hole extending through the surface5and generally forms a cylindrical volume; however, it may alternatively form, for example, a conical, square, or rectangular volume. The end of the inlet8on the inner side of the tubular body2comprises a first perimeter19facing the subvolume6A, and the end of the inlet facing the outer side of the tubular body2comprises a second perimeter20facing the source of exhaled gases.

The first perimeter19has a first edge19A facing the first end portion of the tubular body2, and a second edge19B facing the second end portion of the tubular body2(end portions are not shown inFIG. 5). When the inlet8forms a cylindrical volume, the perimeter19is essentially circular, and the first and second edges19A,19B constitute points on the perimeter19. When the opening forms, for example, a square volume, the perimeter19is essentially square, and the first and second edges19A,19B may constitute opposite sides of said square, or, alternatively, points in opposite corners of the square.

The wall7has a first side7A facing the first end portion of the tubular body2and a second side7B facing the second end portion of the tubular body2(end portions are not shown inFIG. 5).

The wall7is arranged adjacent to said inlet8, meaning that the first side7A of the wall7extends from a point21arranged in close vicinity to, or in contact with, said second edge19B of the perimeter19. Preferably, the distance from the second edge19B to the point21is less than 1.0 mm, more preferably less than 0.5 mm, and most preferably 0.0 mm.

As stated above, and as illustrated inFIGS. 1A-4B, when the inlet8comprises a hollow prong10,14the wall7can be seen to constitute an extension of an inner side of the hollow prong10,14from the tangential point11,18where the hollow prong10,14is joined with the inner side of the tubular body2. In this case, the tangential point11,18inFIGS. 1A-4Bcorresponds to the point21inFIG. 5, and reflects the case where the point21is in contact with the second edge19B of the perimeter19.

The wall7is preferably substantially perpendicularly arranged within the tubular body2. However, the wall7may also have an inclination within the tubular body2, or it may have a curved shape, adapted to provide a smooth, laminar flow of gases from the inlets8,8A8B to the outlet9. Thus, the wall7may be constructed in several different ways, as long as substantially no void volume for the gas flow is created within the subvolume6A.

Various differing embodiments, according to the principles of the present disclosure, of a cannula and cannula system have been described above with reference toFIGS. 1A through 5. The various embodiments, however, may have some common general characteristics, which may be adjusted as required. Some of these general characteristics will now be described. Reference numerals refer to like elements as shown in each ofFIGS. 1A-5.

In preferred embodiments, the tubular body2is essentially cylindrical in shape and has a length L extending between the first and second end portions of the tubular body. The expression “essentially cylindrical” is meant to signify that the tubular body has the geometrical shape of a cylinder; however, it also encompasses the case when the entire the tubular body or a portion thereof is curved or bent. The tubular body may also comprise other geometric shapes, for example a conical or rectangular shape.

The wall7generally divides the internal volume6of the tubular body2into a first subvolume6A and a second subvolume6B. However, the present disclosure also encompasses the case when the first subvolume constitutes the entire internal volume6, that is, the wall7is located at the second end4of the tubular body.

When an inlet8,8A,8B or an outlet13comprises a hollow prong10,10A,10B,14, it is preferred that the hollow prong has a conical shape and is arranged to protrude essentially perpendicularly from the tubular body2(as seen in any ofFIGS. 1A-4B). However, it is also contemplated that a hollow prong10,10A,10′,14may have different geometric shape, as long as fluid communication through the hollow prong10,10A,10B is allowed. Preferably, the interior volume of the hollow prong10,10A,10B,14is in the form of a cylinder.

The cannula1, including the hollow prongs10,10A,10B,14and the wall7, is preferably manufactured by injection molding of polyvinyl chloride (PVC) or polyurethane (PU).

When the cannula1contains two hollow prongs to be arranged in both nostrils of a patient, different sizes of the cannula1may be manufactured depending on whether the cannula is intended to be used for adults, children or infants. A suitable distance between the prongs on a cannula for adults is about 16 mm, a suitable distance between the prongs on a cannula for children is about 12 mm, and a suitable distance between the prongs on a cannula for infants is about 9 mm. If applicable, the size of the oral breath collector15and its position in relation to the prongs may likewise be adapted depending on whether it is intended to be used for adults, children or infants. In certain circumstances, in which a patient has trouble exhaling through the nose or prefers exhaling through the mouth, provision of the scoop15with the nasal cannula1can enable collection of larger quantities of exhaled gases from such a patient compared to use of a nasal cannula without a scoop.

Exhaled gases collected from the nostrils and/or mouth of a patient are led into the inlets8,8A,8B through hollow prongs10,10A,14. However, other constructions may be contemplated, for example exhaled gases collected from the nostrils or mouth of a patient may be led into the inlets8,8A,8B through flexible tubes or apertures extending through the surface of the tubular body.

The interior diameter of a tubular body2for use in a cannula1suitably lies in the range of about 2-4 mm, and preferably is about 3 mm. When a cannula is designed to comprise two or more inlets for collecting exhaled gases, it is advantageous to employ a tubular body2having diameter in the lower end of the range, such as in the range of about 2-3 mm. The present inventors have surprisingly found that a smaller diameter of the tubular body2, in combination with placing a wall in direct connection to the inlet8which is located at the farthest distance from the point where the gases exit the cannula, further adds to the effect of obtaining a very high accuracy in the analysis of exhaled gases.

When the cannula provides for the supplementation of a treating gas, for example oxygen, to the respiratory system of a patient, the treating gas may enter the respiratory system via the mouth and/or one or both nostrils of a patient. Preferably, the treating gas is supplied through a hollow prong to a nostril of a patient. However, the supplementation of a treating gas may also be effected, for example, by providing an aperture in the tubular body near the nostril of the patient. In addition, a treating gas may be supplemented to the mouth of a patient, for example via an additional hollow prong or via an aperture in the tubular body near the mouth of a patient.

For embodiments that relate to the simultaneous supplementation of a treating gas, a first nozzle16is adapted for the transport of exhaled gases from the cannula, and a second nozzle17is adapted for the supplementation of a treating gas to the cannula. The first nozzle16is generally adapted for a flow of about 50 ml/min, while the second nozzle17is generally adapted for a flow of up to 5 liters per minute. The first nozzle16is generally connected via an extension tube (not shown) to conventional analyzing means for analyzing at least one component (for example CO2) of the exhaled gases. The second nozzle17is generally connected via an extension tube (not shown) to a conventional supply of a treating gas (for example oxygen or an anesthetic agent). Although in some embodiments, each nozzle may be configured for the same flow.

For embodiments that do not relate to the supplementation of a treating gas, the first nozzle16is adapted for the transport of exhaled gases from the cannula, while the second nozzle17may be adapted as required. For example, the second nozzle17may be of the same kind or of a different kind as the first nozzle16. In some embodiments, the second nozzle17may be omitted. Additionally, in some embodiments that do not relate to the supplementation of a treating gas may lack the subvolume6B the wall7is disposed at the second end portion4of the tubular body.

The nozzles are preferably manufactured by injection molding of polyvinyl chloride (PVC) or polyurethane (PU). The nozzles16,17are preferably slightly curved, which allows for the alignment of extension tubes in a desired direction.

The present disclosure thus provides for a convenient way of providing several different constructions with a limited number of pieces.

As used herein, the term “cannula” in its most general form refers to the elongated tubular body, including an inlet and a wall internally disposed within the tubular body. In various embodiments, the cannula may additionally comprise one or more additional inlets and/or outlets, as well as two or more prongs.

As used herein, the term “cannula system” refers to the cannula as defined above, in combination with at least one nozzle, and optionally, may additionally include at least one extension tube, such as a sampling tube or a treating gas tube.

The nasal/oral cannula can be used in a nasal/oral cannula system1A incorporating the Nomoline™ sampling line provided by Masimo, as described in more detail below.

FIG. 6illustrates an embodiment of a gas sampling system implementing an embodiment of a cannula described herein.

The cannula605can include prongs for placement in a patient's nostrils and, though not shown, in some embodiments can include an additional prong coupled to an oral breath collector. The cannula605can have any of the internal wall placements described above for provision of therapeutic gases and/or collection of exhaled gases from one or both nostrils. The cannula may be secured to one or both of nozzles610A,610B depending upon the placement of wall and the design of the system for securing to a patient. As illustrated, a first section of extension tubing615A,615B is in fluid communication with and extends from each of nozzles610A,610B in a direction to pass over the ears of a patient and then be secured using slide bolo620under the chin of a patient. It will be appreciated that other known securing techniques can be implemented with the cannula605. Extension tubing615A can be used in some examples for provision of therapeutic gases through nozzle610A and an outlet of cannula605to a first nostril of a patient. Extension tubing615B can be used to receive exhaled gases from one or both nostrils of the patient via cannula605, prong(s), and nozzle610B.

In some embodiments, extension tubing615B can be coupled to a sampling line630, for example, the Nomoline™ sampling line provided by Masimo. Water vapor within the sampled exhaled gases of a patient can naturally condense within the respiratory circuit, as well as within the sample tubing of the gas analyzer640. If allowed to reach the gas analyzer sample cell, the condensate can affect measurement accuracy and/or permanently damage the instrument. In order to protect the gas analyzer640from the effects of condensed water, patient secretions, and bacterial contamination, sampling line630can be provided between the patient and the gas analyzer640. The sampling line630can allow water in the exhaled gases to evaporate into the surrounding air, while leaving the oxygen, carbon dioxide, and/or anesthetic or other gases to be measured unaffected. Exhaled gases can enter the sampling line630from the extension tubing615B. As the exhaled gases pass through the sampling line630, a polymer can absorb water from the patient's gas sample and evaporate it into surrounding air. The remaining gas sample can be passed through a filter that substantially blocks the passage of water and/or bacteria while permitting passage of exhaled gases and any therapeutic agents in the exhaled gases. In other embodiments the sampling line630can be omitted, and the extension tubing615B can be coupled directly to a gas analyzer640.

Gas analyzer640can receive exhaled gases from the sampling line630(or directly from the extension tubing615B) and analyze the exhaled gases, for example to determine various gas concentrations. Gas analyzer640can be a sidestream gas analyzer available from Masimo Corporation of Irvine, Calif., for example an ISA™ Sidestream Analyzer. Although discussed primarily herein in the context of CO2, gas analyzer640can be configured for measuring other gas concentrations and/or patient parameters, for example respiration rate.

FIG. 7Aillustrates a block diagram of one embodiment of a nasal cannula kit710. The kit710includes one or more preassembled cannula(e) with nozzles712, one or more preassembled cannula(e) with nozzles and an oral breath collector714, extension tubing716, and securement device718. In some examples, cannulae712,714with varying internal wall positionings can be provided in a single kit and labeled such that a clinician can select the cannula appropriate for a current patient need. In some examples, all cannulae712,714within a kit may have the same internal wall positioning. Some embodiments of kit710may include just one type of preassembled cannula(e) with nozzles712and preassembled cannula(e) with nozzles and an oral breath collector714. The number and type of separate sections of extension tubing716can correspond to the number of nozzles on all of the cannulae712,714included in the kit710and to the internal wall positioning of the cannulae712,714. Similarly, the type and number of securement devices718can correspond to the types and number of cannulae712,714included in the kit710, as well as to the sizes of the cannulae712,714(for example, adult sized cannula versus infant sized cannula) and/or intended uses of the cannulae712,714(for example, for mobile patients or immobilized patients). The kit710can be packaged as a sterile kit, for example using sterilized trays and/or blister packs, and may provide individual components in separately-accessible sterilized compartments.

FIG. 7Billustrates a block diagram of one embodiment of a gas sampling kit700. The gas sampling kit700can include one or more nasal cannula kits710as described above, one or more gas sampling lines720, and one or more capnographs730. An example of a gas sampling line720is Nomoline™ available from Masimo, and an example of a capnograph730is an ISA™ Sidestream Analyzer available from Masimo. In some embodiments, gas sampling lines720may not be reusable and a gas sampling line720can be provided for each cannula in the nasal cannula kits710. Gas sampling lines720may be provided in individually-accessible sterilized packaging, for example a blister pack or sterilized tray. In some embodiments, the capnograph730may be reusable and a kit700may include a single capnograph730.

FIG. 8Aillustrates an example positioning of an embodiment of a cannula805on a patient800. As illustrated, the prongs of cannula805are positioned in the patient's nostrils and a nozzle810A,810B is coupled to each side of the cannula805. Extension tubing815A,815B is each in fluid communication with one of nozzles810A,810B, extending over the ears of the patient800and then downward under the chin of the patient800to be secured by slide bolo820. Accordingly, the prongs of the cannula805are substantially fixed in position in the nostrils of the patient800.

The illustrated manner of securing cannula805to patient800represents one of many available suitable securing manners known in the art. In other embodiments, an elastic strap may be provided to secure the cannula805to the patient800, the extension tubing815A,815B may pass over and/or behind the head of patient800, or the extension tubing815A,815B may be secured to the cheeks of the patient's face. In some examples only a single nozzle810B may be used (for example, where the cannula805includes an internal wall positioned to collect exhaled gases from both nostrils of the patient800or in other uses in which no therapeutic gas is provided) and accordingly extension tubing815A may be omitted and a single-sided securing technique can be used to fix the prongs of the cannula805in the nostrils of the patient800.

FIG. 8Billustrates an example positioning of another embodiment of a cannula805on a patient800. As illustrated, the cannula805includes an oral breath collector825positioned over the mouth of the patient800. The illustrated scale between the oral breath collector825and the patient800represents one embodiment, and larger or smaller breath collectors825can be used depending on the size of the patient and other design requirements.

The various embodiments of cannulae as described herein, some of which are depicted inFIGS. 1A-4Bmay advantageously be manufactured according to the methods described herein below. These methods provide for a very convenient and efficient way of achieving the different cannulae and nozzles described above.

In one embodiment of the method, the modules of a cannula system are injection molded separately and then assembled by solvent bonding. Injection molding is a manufacturing process for producing parts by injecting manufacturing material in a liquid state into a mold and allowing it to cool and harden. In the manufacturing of a cannula system in accordance with the techniques described herein, different molds shaped in desired designs are therefore provided. The molds generally consist of two components, that, when assembled with relevant cavity tools, form a cavity corresponding to the desired design. Manufacturing material enters the mold through an opening that allows the material to flow into the mold.

In the research work leading to the cannula manufacturing systems and techniques described herein, it was found that the combination of injection molding and solvent bonding provides for a very convenient procedure for manufacturing a nasal/oral cannula system. In particular, the use of solvent bonding for assembling the pieces leads to very smooth boundaries between the components of the cannula system, which is advantageous for maintaining a smooth, laminar flow of gases through the system. The disclosed manufacturing methods provide for a cannula system which, from a comfort point of view, is as good as, or better than, a cannula system produced by conventional dip molding, while providing all the advantages associated with injection molding.

The manufacturing of an embodiment of cannula in accordance withFIGS. 1A and 1Bwill now be described in further detail with reference toFIG. 9A, which shows an exploded perspective view a cannula mold and corresponding inserts and pins. Reference numbers not shown inFIG. 9Acorrespond to elements of the embodiment of a cannula shown inFIGS. 1A and 1B. Those of skill in the art will understand that the mold and manufacturing principles disclosed herein may be modified and applied for the manufacturing of other embodiments of cannulae (for example, the embodiments depicted inFIGS. 2A-4B).

A mold100for injection molding a nasal/oral cannula1comprises a first and a second mold body element101,102. The first mold body element101has a first end surface103and a second end surface104, three side surfaces105and a contact surface106. The second mold body element102similarly has a first end surface107and a second end surface108, three side surfaces109, and a contact surface110. The contact surfaces106and110of the mold body elements101and102are intended to be arranged facing towards each other when the mold is arranged in a molding position. The mold is divided in at least two body elements to make it possible to open the mold and remove the injection molded cannula. The first and second mold body elements101,102have substantially the same cuboidal shape so as to fit together when the mold is arranged in the molding position.

Within the mold, a cavity111is formed in the first and second mold body elements101,102. The cavity111is shaped to create a desired outer shape of the elongated tubular body2of the cannula1. The cavity111is elongated in shape and extends along a substantially straight axis A arranged in the plane of the contact surfaces106and110of the mold body elements101,102(when the mold body elements are placed into contact with each other, or, in other words, in the molding position) and parallel to the side surfaces105,109of the cuboidal mold100. The cavity has a substantially circular cross section and is ended by a first and a second end surface112,113arranged transverse to the longitudinal axis A. One half of cavity111is disposed in the first mold body element101and the other half of cavity111is disposed in the second mold body element101, such that when the mold body elements are brought into the molding position the entire cavity111is formed in substantially the shape of a cannula1to be formed.

A first elongated insert114having an inner end115facing the cavity111and an outer end116arranged outside the mold is configured to extend through an opening117in the first end wall112of the cavity. The shape of the opening117and the cross sectional shape of the first insert114may correspond to provide a sealing fit between the two components and prevent molding material from exiting the mold.

The first insert114may have a cross-sectional area smaller than the cross-sectional area of the cavity111so as to form a space within the cavity around the insert, i.e., the shape of the tubular body2of the casted cannula.

In the opposite end of the cavity111a second elongated insert118having an inner end119facing the cavity111and an outer end120arranged outside the mold may similarly be configured to extend through an opening121in the second end wall113of the cavity. The second insert118may also have a cross-sectional area smaller than the cross-sectional area of the cavity to form a space within the cavity around the insert. In some embodiments, the cross-sectional area of the second elongated insert118may be designed to match or substantially match a shape of the opening121to prevent leakage of injected molding material through the opening121.

The first and second inserts114,118are movably arranged in the openings117,121in respective end walls of the cavity111between a molding position and a release position. In the molding position, the first and second inserts are arranged in the cavity with their inner ends facing each other (as shown inFIG. 9B). The inner ends are arranged at a distance from each other such that a space corresponding to the interior wall7of a cannula may be formed between the inner ends of the inserts once the molding material is supplied to the cavity. The respective inner ends of the inserts are generally designed to arrange the interior wall7of the cannula to be substantially perpendicularly disposed within the tubular body2. However, as discussed above, the respective inner ends of the inserts may alternatively be designed to provide an inclined wall or a wall having a curved shaped.

In order to form the inlets and/or outlets8,13in the surface5of the cannula1, the mold furthermore may comprise a first insert pin123having a forward end124facing the cavity and an outer end125arranged outside the mold. The insert pin123is movably arranged in the mold between a molding position and a release position. In the molding position, the forward end124of the insert pin123is arranged in the cavity with the forward end124in contact with either the first or second insert116,119to form an inlet/outlet8,13in the surface5of the cannula1(as shown inFIG. 9B). In the release position, the insert pin123is retracted from the cavity to release the cannula from the mold (as shown inFIG. 9A). The mold furthermore comprises a second insert pin126which may be similar to the first insert pin123, i.e., having a forward end127in the cavity and an outer end128outside the mold. The second insert pin126is disposed so as to be longitudinally separated from the first insert pin123to form a second inlet/outlet8,13in the tubular body2of the cannula. The second insert pin126may extend along an axis B2substantially parallel to the axial direction B1of the first insert pin123. The axes B1and B2extend substantially perpendicular to the longitudinal axis A of the cavity111.

In an embodiment, the mold100comprises a first insert pin arranged to form an opening in the surface5of the tubular body2cannula1. However, in the illustrated embodiment ofFIGS. 9A and 9B, the mold100is designed for a cannula comprising two hollow prongs10,10B, and one inlet8and one outlet13. These features are formed by the first and second prong recesses130,131of mold100, as well as first and second pin inserts123,126.

The first and second prong recesses130,131extend coaxially with the first and second insert pins123,126. The first and second prong recesses130,131have a larger cross sectional area than the first and second insert pins123,126so as to form a space around the insert pins within the cavity111. The first and second prong recesses130,131may have a conical shape with larger cross sectional area close to the center of the cavity than in the area of the end surfaces. In some embodiments, the cross-sectional area of the first and second insert pins123,126may be designed to match or substantially match a shape of the corresponding opening132,133to prevent leakage of injected molding material.

The first and second insert pins123,126are movably arranged in corresponding openings132,133in the first and second end surfaces105,190. The forward ends124,127of the insert pins123,126are generally designed to provide a tight seal against the first or second inserts114,118. For example, when the inserts114,118have a cylindrical shape, the forward ends124,127of the insert pins may have a concave design. The creation of a hollow passage in a hollow prong10,10A,10B,14is thus independent of the outer design of the hollow prong10,10A,10B,14created by the prong recesses130,131which outer design may, for example, be conical. In addition, various sizes of the hollow passages may easily be achieved by using insert pins of various sizes.

If there is a need for further inlets/outlets along the tubular body of the cannula, further insert pins and prong recesses may be arranged in the mold along the cavity.

The mold100furthermore comprises at least one inlet passage140configured to allow the introduction of molding material in to the mold cavity111. The inlet passage may be configured as a hole extending from the exterior of the mold to the cavity111to make it possible to deliver material under pressure to the cavity. In some embodiments, the inlet passage140may be positioned between the prong recesses130,131, but it could also be disposed in other positions.

After positioning the first and second inserts114,118, as well as the inserts pins123,126in their respective molding positions, the mold100is filled with manufacturing material by introducing the manufacturing material into the mold100through the inlet passage140under pressure. The total time cycle for producing a cannula may be from about 10 seconds to about 1 minute.

The inner diameter of the tubular body2is suitably in the range of 2-4 mm, preferably about 3 mm, and thus, the first and second inserts114,118used for providing the wall7in a desired position within the tubular body2suitably have an outer diameter in the range of 2-4 mm, preferably about 3 mm. The first and second inserts114,118may also have different outer diameters, for example, the diameter of first insert114may be bigger, such as about 4 mm, while the diameter of second insert118may be smaller, such as about 2 mm.

The inner diameter of the hollow prongs10,10A,10B,14is suitably about 1-2 mm, and thus, the insert pins123,126used for providing the hollow space suitably have an outer diameter of 1-2 mm.

Depending on whether the cannula is intended to be used by adults, children or infants, different sizes of cannulae may be manufactured. In particular, the distance between the hollow prongs to be arranged in the nostrils (inFIGS. 1A and 1B, the hollow prongs denoted10,10B) may be varied. A suitable distance between the hollow prongs10,10B on a cannula for adults is about 15-17 mm, preferably 16 mm, a suitable distance between the hollow prongs10,10B on a cannula for children is 11-13 mm, preferably about 12 mm, and a suitable distance between the prongs10,10B on a cannula for infants is about 8-10 mm, preferably about 9 mm. In order to easily produce these three different variants of the cannula1, three different variants of the cannula mold100may be provided.

Notably, the first and second inserts114,118and first and second insert pins123,126used during production may advantageously be identical for use in all three described variants of cannula mold100.

The techniques described herein may also be modified to provide for the production of a cannula1which further comprises an oral breath collector15, as shown inFIGS. 2A, 2B, 4A, and 4B. The manufacturing of an oral breath collector15may also be performed by injection molding. The oral breath collector15may be manufactured in different sizes, depending on whether the cannula system is intended for infants, children or adults.

In embodiments of the cannula comprising an oral breath collector15, the cannula mold100for producing a cannula is shaped to include features for forming an additional inlet8B comprising a hollow prong14molded integrally with the tubular body2. The hollow space in the hollow prong14is created with a pin insert as described above.

The manufacturing of the nozzles16,17may also be performed by injection molding. The manufacturing of the nozzles16,17in accordance withFIGS. 1A and 1Bwill now be described in further detail with reference toFIG. 10.

A nozzle mold K for producing a nozzle16,17is shaped to create a desired outer shape of the nozzle. Preferably, the nozzles16,17are slightly curved and have an end portion with a reduced diameter configured to fit tightly into the first or second end portions3,4of the tubular body2of the cannula1upon assembly of the cannula system1A.

An elbowed cavity in a nozzle16,17is provided by providing cavity tools L, M by the inlet and outlet portions of the nozzles16,17, and then moving them towards each other until they are located in a position which provides for the formation of an elbowed cavity in the nozzle16,17. The respective ends of the cavity tools L, M are designed to provide a tight seal against each other when reaching their final positions.

In order to provide for a user-friendly design of the cannula system1A, that follows the contours of the face, and also to provide for an expedient channel for the flow of gases through the cannula system, the first nozzle16suitably has an elbowed cavity. The manufacturing processes disclosed herein present a very convenient and efficient way of providing an elbowed cavity, namely by the use of the two cavity tools L, M which are introduced into the nozzle from two different directions. The cavity tools L, M may thus be of a straight form, while the resulting cavity has an elbowed form. Elbowed cavities of different sizes may easily be created by a simple substitution of cavity tools.

The cavity tool M is suitably shaped to provide an end portion with a reduced diameter within the nozzle16,17, in order for an extension tube, such as a sampling tube or a treating gas tube, to be tightly fitted into the nozzle16,17upon assembly of the cannula system1A. The end portion with a reduced diameter is created by forming the cavity tool to have two different diameters, M1, M2in its length direction, wherein (with reference toFIG. 10) M1is greater than M2.

The first nozzle16is adapted for the transport of exhaled gases from the cannula, and is generally adapted for a gas flow of about 50 ml/min. The cavity tools M, L used for providing a first nozzle16are therefore generally cylindrical and has the following diameters in the cross-sections M1, M2, L1marked inFIG. 10: M1from 1.5-2.5 mm, preferably about 2 mm; M2from 0.5-1.5 mm, preferably about 1 mm; and L1from 1-2 mm, preferably about 1.5 mm.

The second nozzle17is adapted for the supplementation of a treating gas to the cannula1, and is generally adapted for a gas flow of about 5 liters/min. The cavity tools M, L used for providing a second nozzle17are therefore generally cylindrical and has the following diameters in the cross-sections M1, M2, L1marked inFIG. 10: M1from about 2.5-3.5 mm, preferably about 3 mm; M2from about 1.5-2.5 mm, preferably about 2 mm, and L1from about 1.0-2.0 mm, preferably about 1.5 mm.

The outer cross-sectional dimension of the nozzle16,17at the end portion with a reduced diameter, marked as K1inFIG. 10, is about 2-4 mm, preferably about 3 mm, that is, it essentially corresponds to the inner diameter of the tubular body2, which is also about 2-4 mm, preferably about 3 mm.

The first nozzle16is generally connected via a sampling tube (not shown) to conventional analyzing means for analyzing at least one component (for example CO2) of the exhaled gases. The sampling tube generally has an outer diameter of about 1.5-2.5 mm, preferably about 2 mm, and an inner diameter of about 0.5-1.5 mm, preferably about 1 mm. The outer diameter of the sampling tube essentially corresponds to the diameter of the cross-section M1of the first nozzle16, and thus the sampling tube fits tightly in the first nozzle16.

The second nozzle17is generally connected via a treating gas tube (not shown) to a conventional supply of a treating gas (for example oxygen). The treating gas tube generally has an outer diameter of about 2.5-3.5 mm, preferably about 3 mm, and an inner diameter of about 1.5-2.5 mm, preferably about 2 mm. The outer diameter of the treating gas tube essentially corresponds to the diameter of the cross-section M1of the second nozzle17, and thus the treating gas tube fits tightly in the second nozzle17.

In the step of assembling the nasal/oral cannula system1A by solvent bonding, the desired components (for example cannula, nozzle(s) and/or extension tube(s)) are dipped in a suitable solvent, and then the components are mounted in the desired position. Depending on the intended use of the cannula system1A, the components included may vary. The most general form of a cannula system1A includes a cannula1and a first nozzle16.

Exemplary solvents for use in solvent bonding of PVC are tetrahydrofuran and cyclohexanone, either used separately, or in combination. If used in combination, a suitable ratio is tetrahydrofuran mixed with cyclohexanone in a volume ratio of 2-8% to 92-98%, such as 5% to 95%, respectively.

The present disclosure is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, although all the embodiments shown in the drawings comprise two nasal prongs, it is envisioned that a single prong could be sufficient, and that in embodiments where an oral breath collector is used for collection of exhaled gases, there need not even be any prongs (or corresponding inlets) at all. An inlet receiving exhaled gases from the patient's mouth via a scoop may thus constitute the only inlet into the subvolume6A.

Turning now toFIGS. 11A-11C, a tool for injection molding of a nasal/oral cannula, such as that embodied inFIGS. 1A and 1Bwill now be described.FIG. 11Ashows a cutaway perspective view of an embodiment of a tool for injection molding a cannula with the tool configured in a molding position.FIG. 11Bshows the embodiment of the tool pictured inFIG. 11Atransitioning from a closed, molding position to an open/release position.FIG. 11Cshows the embodiment pictured inFIGS. 11A and 11Bconfigured in an open/release position that allows the injection molded cannula to be removed from the mold. In each ofFIGS. 11A-11C, a portion of the tool is cut away to better illustrate the interior or the tool where the mold as described above is arranged. The illustrated tool in theFIGS. 11A-11Cis configured to manufacture two cannulae simultaneously; however, the principles disclosed may be modified to produce only a single cannula or more than two cannulae.

A tool200, according to the present disclosure, is configured for use with embodiments of the mold described above. The tool200may comprise a tool body201formed by first and second tool body elements202,203. The first tool body element202may be a base, and the second tool body element203may be configured to be selectably coupled to a top surface of the first tool body element202.

The first tool body element202is configured with a recess configured to receive and support the first mold body element101. The second tool body element203is similarly configured with a recess configured in size and shape to support the second mold body element102. The first and second tool mold body elements202,203are configured so that when they are in the closed, molding position pictured inFIG. 11A, the two mold body elements101,102are brought together to form interior cavity111.

The recesses in the first and second tool mold body elements202,203configured to receive the first and second mold body elements101,102may, in some embodiments, further be configured to receive and work with different mold variations (for example, the molds configured to produce adult, child, and infant sized cannulae according to the dimensions and principles described above). This may achieved by configuring each mold so that the outer shape of each mold is the same, while only the interior cavity111varies.

Further, the first and second tool body elements202,203are configured to provide a rigid support structure for the different components (for example, the inserts and pin inserts described in relation toFIGS. 9A-10) required to operate the mold100according to the principles herein disclosed.

The tool200may furthermore comprise a first device204arranged on one side of the mold100. The first device204is configured to support the first insert114and arranged to move the first insert between its molding position (where it is inserted into the mold, as seen inFIG. 5B) and the retracted position (where the first insert is arranged outside the mold, as seen inFIG. 5A), or at least outside the cavity111so as to not interfere with the removal of the manufactured cannula. On the opposite side of the mold a second device205(as seen only inFIG. 11C), which is similar to the first device204, configured to support the second insert118.

The tool further comprises a third device206arranged along one of the elongated sides105,109of the mold100. The third device206is configured to support at least the first insert pin123and/or second insert pin126, and move the first and/or second insert pins123,126between the molding position and the retracted position where the insert pins123,126are arranged outside the mold100, or at least outside the prong recess so as to not interfere with removal of the manufactured cannula.

In some embodiments, the operation and movement of the tool as well as the supply/injection of molding material is controlled by a control unit, not shown, that is connected to all different components within the tool. Accordingly, the control unit monitors the operation of the first, the second and third devices204,205,206, as well as the supply of molding material and removal of manufactured cannulae from the cavity of the mold. The control unit could be arranged on the tool body or remote from the tool. In some embodiments, the control unit may further comprise a computer running software configured to control and monitor the operation of the tool and direct the manufacturing processes described herein.

As previously described, the mold100and tool200according to the present disclosure make it possible to select and vary the position of the internal wall7within the cannula by controlling the position of the first and second inserts114,118in the molding position. Positioning of the first and second inserts114,118is controlled by the first and second devices204,205. In some embodiments, in order to minimize the complexity of the tool200, the tool may be configured so that the first and second inserts114,118are only movable between their molding and the release positions. And, in certain embodiments, the first and second inserts114,118may be configured to move (by configuring the tool200and corresponding first and second device204,205) in response to the opening and closing of the tool200. This operation will now be described with particular reference toFIG. 11B, which illustrates the motion of the various components as the tool200is moved from a closed, molding position to an open position.

In this embodiment of the tool200, the first and second devices204,205of the tool each comprise an elongated cylindrical recess207(as seen inFIG. 11B) extending coaxially with the longitudinal axis A of the mold (the longitudinal axis A can be seen inFIGS. 5A and 5B). The length of the recess may exceed the length of the first and second inserts114,118. The first and second inserts114,118are inserted into the cylindrical recesses207and an insert locking device, not shown in the figures, may be provided to fix the inserts in place. In some embodiments the locking device may be a pin. In some embodiments, the locking device may be adjustable, so that the first and second inserts can be adjusted and locked into a plurality of selectable different positions. This may advantageously allow the tool and mold to work for the injection molding of cannulae with walls in different positions.

In another embodiment, the length of the first and second inserts114,118is fixed to correspond to a desired longitudinal position of the wall in the manufactured cannula instead of adjusting the position in which the inserts are locked in the first and second device204,205. This embodiment may provide a reliable solution for producing a single type of cannulae with a single wall position that could be used over a long period of time without adjustment.

Insert pins123,126are similarly disposed within recesses within third device206. As long as the outside design and size of the mold100remains constant there is no need to adjust the position of the insert pins123,126in the third device206along the axes B1and B2. If adjustments are desired, the same solutions as described above in relation to the first and second inserts could also be used for the insert pins.

However, it should be noted that the third device206must be adapted to molds designed for cannulae of different sizes since the distance between the two hollow prongs may be varied. This could be achieved by supporting the insert pins in different longitudinal positions along axis A within the third device206, thereby adapting the tool to molds intended for cannulae of different sizes. For example, third device206could provide a plurality of recesses spaced at intervals corresponding to the desired widths. Pin inserts can then be placed in the recesses corresponding to the desired width.

Returning now to a description of the movement of the first and second inserts114,118and first and second insert pins123,126, in order to ensure that the movement of the first and second inserts114,118, as well as the insert pins123,126is done properly, the tool200may be configured to first introduce the first and second inserts114,118into the molding position within the cavity of the mold before the insert pins123,126are moved into position. Accordingly, the illustrated tool200is configured such that the movement of the first and second tool body elements202and203between the molding and release positions mechanically generates the desired movement of the first second devices204,205prior to the movement of the third device206.

Referring specifically toFIG. 11B, this movement may be achieved with a first guide arm210secured in the second tool body element203and extending through a first guide passage211in the first device204such that when the first and second tool body element202and203are moved to the molding position, i.e. closed position, the first guide arm210will force the first device204and the first insert114into the mold achieving the molding position. Similarly, a second guide arm212and a second guide passage213are disposed on the opposite side of the mold100to generate the movement of the second device205between the molding and release position. The tool200furthermore comprises a third guide arm214secured in the second tool body element203and extending through a third guide passage215in the third device206to move the insert pins123,126between the molding position and the release position.

After the molding is completed, the first and second tool body elements202and203are separated and the guide arms210,212and214generate the desired movement of the first and second inserts and the insert pins to the release position and the manufactured cannula may be removed from the cavity111in the mold100. Once the cannula is removed the mold and tool is ready for the next production cycle. This design advantageously reduces the number of components that need to be powered and controlled separately which reduces the overall cost for the tool and reduces the risk of malfunction and unintended interruptions in the production.

The desired movement of the first and second tool body elements202,203may be generated by electrical engines or hydraulic cylinders (not shown) controlled by the control unit.