Patent ID: 12220536

DETAILED DESCRIPTION

FIG.1illustrates a combination infant positive airway pressure (PAP) or continuous positive airway pressure (CPAP) and resuscitation system, generally referred to by the reference numeral10. The system10is capable of providing PAP or CPAP therapy to a neonate or an infant patient12for an extended period of time, while also permitting resuscitation breaths to be delivered to the infant patient12if or when necessary. Preferably, both the PAP or CPAP therapy and the resuscitation breaths are delivered through a single patient interface14without requiring removal of the interface14from the infant patient12. The present system10is disclosed herein in the context of continuous positive airway pressure (CPAP) therapy; however, the system10could also provide other types or modes of positive airway pressure (PAP) therapy. Accordingly, references to CPAP therapy herein are understood to also include other types of PAP therapies, unless specifically noted otherwise.

The illustrated system10includes a source of breathing gas20, which can be a gas cylinder (not shown), a wall supply20, or any other suitable source of breathing gas. The breathing gas can be air, oxygen, a blend of air and oxygen, or any other suitable gas for use in respiratory therapy. The source of breathing gas20provides a flow of breathing gas at an initial feed pressure or within an initial feed pressure range. The flow rate of the flow of breathing gas can be adjusted by a suitable flow meter or gas blender22to a suitable level for the desired therapy.

A suitable conduit, such as a gas supply line24supplies the flow of breathing gas to an inspiratory pressure device26, which can be a resuscitator. More preferably, the inspiratory pressure device26is an infant resuscitator, such as an infant resuscitator sold by Fisher and Paykel Healthcare, the Assignee of the present application, under the NEOPUFF trademark. Although referred to herein as a “resuscitator” for convenience, it is understood that the term can encompass other suitable types of inspiratory pressure devices capable of providing a breathing gas at a controlled output pressure.

Preferably, the resuscitator26is capable of receiving a flow of breathing gas from the source of breathing gas20and outputting the flow of breathing gas at a controlled pressure greater than atmospheric pressure. In particular, the resuscitator26can output the flow of breathing gas at a peak inspiratory pressure (PIP), which preferably can be up to about 75 cmH2O or greater. Preferably, the resuscitator26includes an adjustment mechanism, such as an adjustment valve28, which allows the PIP to be adjusted to a desired pressure level. Preferably, the resuscitator26also incorporates a pressure relief valve30that regulates a maximum pressure within the system10. The pressure relief valve30can be adjustable such that the maximum system pressure can be adjusted. For example, an adjustment range can be between about 5-70 cmH2O. The pressure relief level can be factory set to a particular value, such as about 40 cmH2O, for example. However, in alternative arrangements, a separate pressure regulator could be provided within the system10to regulate the maximum system pressure. Such a pressure regulator is described in U.S. Pat. No. 6,644,313, which is incorporated by reference herein in its entirety. In embodiments having a blower unit, a pressure relief valve may not be necessary because the maximum achievable pressure of the system can be regulated by the blower unit. The blower unit can be designed so that the maximum pressure it can produce is lower than a desired pressure relief level. In other embodiments, the maximum achievable pressure of the blower unit can be limited by software in the system.

The flow of breathing gas outputted from the resuscitator26preferably is delivered to an optional humidifier system32by a suitable conduit, such as an inspiratory tube or supply tube34. In some embodiments, the resuscitator and the humidifier system can be integrated into a single unit, as discussed below. The humidifier system32provides humidity or vaporized liquid, such as water, to the flow of breathing gas received from the resuscitator26to output a flow of humidified breathing gas to the patient interface14through a suitable conduit, such as a supply tube36. The humidifier system32can include a humidifier unit or humidifier40and a humidity chamber42. The humidity chamber42holds a volume of liquid, such as water, which is heated by the humidifier40to create a vapor within the humidity chamber42that is transferred to the flow of breathing gas. The humidity chamber42can be an auto-fill variety, in which a source of liquid44is connected to the humidity chamber42to refill the volume of liquid, as appropriate. A suitable humidifier40is the MR850 Humidifier sold by the Assignee of the present application. A suitable humidity chamber42is the MR225 or MR290 humidity chamber sold by the Assignee of the present application. The humidifier system32can output a flow of humidified breathing gas at a desired temperature and absolute humidity, such as an optimal temperature of about 37 degrees Celsius and absolute humidity of about 44 mg/L, or within a desirable or acceptable range of the optimal temperature and absolute humidity.

The supply tube36can be a heated supply tube such that a temperature of the flow of breathing gas is maintained at an elevated level within the supply tube36and to avoid or limit condensation within the supply tube36or patient interface14. A heating element cable46can connect a heating element of the supply tube36to the humidifier40(or other power/heat source) to power the heating element. A sensor or probe48can be coupled to the humidifier40and supply tube36to detect the temperature and/or flow rate of the flow of breathing gas through the supply tube36. Preferably, the sensor48is spaced from the inlet end of the supply tube36and can be located at the outlet end of the supply tube36. The sensor48can include a wire that couples the sensor48to the humidifier40. The humidifier40can utilize information from the sensor48to control the operating parameters of the humidifier40, for example, to maintain the temperature and/or humidity of the flow of breathing gas within the supply tube36at a desirable level or range.

From the humidifier system32, the flow of breathing gas is supplied to the patient interface14, which can be any suitable type of interface capable of supplying a breathing gas to the respiratory system of the patient. The illustrated interface14is a lateral nasal interface, which includes nasal cannula or nasal prongs that are inserted into the nostrils of the infant patient12. In a lateral interface, the inlet and outlet are laterally spaced on opposing sides of the nasal cannula or prongs and a midline of the infant patient12.FIG.1Aillustrates an alternative nasal interface14A, which can be referred to as a midline nasal interface. The midline nasal interface14A positions the inlet and the outlet of the interface14A are located in line with the nasal cannula or nasal prongs and substantially along the midline of the infant patient12. The inlet and outlet of the interface14A can be positioned side-by-side; however, in a preferred arrangement, the inlet and outlet are stacked one on top of the other. One suitable interface14A is an infant nasal tube or mask in combination with nasal prongs sold by the Assignee of the present application under the trademark FLEXITRUNK. However, other suitable patient interfaces14can also be used, such as a face mask that covers both the nose and mouth of the infant patient12(e.g., RD Series Infant Resuscitation Masks sold by the Assignee of the present application) or an appropriate interface device in combination with an endotracheal tube. An infant resuscitation mask is described in U.S. Pat. No. 7,341,059, which is hereby incorporated by reference in its entirety.

Preferred interfaces14provide a sealed system that delivers the flow of breathing gas to the infant patient12and receives expiratory gases from the patient12. Preferably, the system10is a biased flow system in which breathing gas is constantly flowing within the system10generally in a direction from the inlet of the patient interface14to the outlet of the patient interface14. Thus, the infant patient12can inhale a portion of the flow of breathing gas and the remainder is passed through the patient interface14. Exhaled or expiratory gases can mix with the flow of breathing gas and exit the patent interface14along with the unused portion of the flow of breathing gas. For convenience, the gases exiting the patient interface14are referred to as expiratory gases or the flow of breathing gas, although it is understood that either or both of patient exhaled gases and unused breathing gases can be present at any particular point in time.

Expiratory gases flow from the patient interface14to an expiratory pressure device60, which is configured to regulate the minimum pressure within the system10, preferably to a level above ambient or atmospheric pressure. Preferably, the expiratory pressure device60is connected to the patient interface14by a suitable conduit, such as an expiratory hose62. However, in an alternative arrangement, the expiratory pressure device60can be connected directly to or integrated with the patient interface14.

Preferably, the expiratory pressure device60is configured to provide a minimum pressure or minimum backpressure within the system10and, in particular, at the patient interface14, which can be referred to as the positive end expiration pressure (PEEP). In the illustrated system10, the PEEP is equivalent to, or generally equivalent to, the continuous positive airway pressure (CPAP). Accordingly, such a device can be referred to as a CPAP generator. However, preferably, the expiratory pressure device60is an oscillatory valve capable of providing pressure oscillations relative to a mean PEEP pressure. It is believed that such pressure oscillations are beneficial to the infant patient12and may result in improved gas exchange and reduce the infant patient's12work of breathing. Thus, an oscillatory pressure expiratory pressure device60is particularly preferred. One type of oscillating pressure expiratory pressure device60is a fluid resistance valve, in particular a liquid or water resistance valve, which is often referred to as a bubbler. In general, a water resistance valve delivers the expiratory gases to an outlet that is submerged in a water reservoir resulting in a resistance to the exit of the expiratory gases that is greater than that caused by ambient or atmospheric pressure and related to the depth of the outlet relative to a surface of the water within the water reservoir. In some arrangements, the depth of the outlet is adjustable to allow the PEEP to be adjusted to a desired level. One suitable bubbler is the Bubble CPAP generator sold by the Assignee of the present application. Additional details of a suitable bubbler device are described in U.S. Pat. No. 6,805,120, which is incorporated by reference herein in its entirety. Preferably, the bubbler (or other oscillatory pressure device) is capable of producing vibrations in the infant patient's chest at a frequency of between about 5-30 Hz.

The illustrated system10also includes an occlusion device or occlusion valve70that is configured to selectively block the flow of gases within the system10and preferably block the flow of expiratory gases, such as within the patient interface14, expiratory tube62or expiratory pressure device60. Preferably, the occlusion valve70is located upstream of the expiratory pressure device60and downstream of the patient interface14, such as within the expiratory tube62. Preferably, the occlusion valve70is located at or near the patient interface14, such as within about 500 millimeters or less of the patient interface14. However, in other arrangements, the occlusion valve70can be integrated with the patient interface14or expiratory pressure device60. The occlusion valve70is configured to block the exit of gases from the system10to a sufficient extent such that the gas pressure within the system10rises above the PEEP. With the exit of gases from the system10blocked, the inspiratory pressure device26can increase the pressure in the system10preferably to or near the set PIP level. The occlusion valve70can completely or substantially completely block the flow of gas within the system10, or can block or interrupt the flow to a sufficient extent to allow the inspiratory pressure device26or integrated unit90to raise the pressure toward the PIP. Preferably, the occlusion valve70can block the flow of gas within the system10to a sufficient extent that the inspiratory pressure device26or integrated unit90can raise the pressure within the system10to or substantially to the PIP pressure. However, to quickly and accurately achieve the PIP pressure, it is desirable that the occlusion valve70completely or substantially completely block the flow of gas within the system10. Although described as a sealed system, it is understood that some leakage of gas may occur from the system10, such as between the patient interface14and the patient12, for example. In addition, pressure losses may occur throughout the system10such that the pressure is not the same throughout the entire system10. Accordingly, it is understood that the PEEP or PIP may vary between the point of measurement and some other point within the system10. Therefore, it is understood that discussion of specific pressures or pressure ranges herein, such as PIP or PEEP, incorporates a range of acceptable variation, which can result from pressure leakage, pressure loss or measurement error.

In operation, the occlusion valve70can be utilized to perform a resuscitation procedure or resuscitation therapy by raising the pressure within the system10to at or near the PIP pressure to deliver a resuscitation breath to the infant patient12in a manner similar to a conventional resuscitation procedure. However, advantageously, with the present system10, resuscitation breaths can be provided to an infant patient12that is undergoing CPAP therapy immediately and without requiring additional equipment or set-up. Furthermore, the CPAP therapy can be immediately resumed after the resuscitation procedure. Preferably, the resuscitation breaths can be provided through the same patient interface14as the CPAP therapy without removal or exchange of the interface and with breathing gases flowing in the same direction within the system10as the CPAP therapy. The occlusion valve70can be used to provide repeated resuscitation breaths to the infant patient12at or near PIP pressure with intervening periods of PEEP. The resuscitation breaths delivered by use of the occlusion valve70can be at any suitable rate, such as about 40-60 breaths per minute. The relative duration of the resuscitation breath time at PIP pressure to the exhalation time at PEEP can be any suitable ratio, such as 40:60, 50:50, 60:40, or any value in between. The resuscitation procedure typically lasts for less than 30 minutes or less than 15 minutes. Often, the resuscitation procedure lasts between about 3-5 minutes. Thus, the present system10is particularly advantageous in reducing the switchover time between CPAP therapy and resuscitation therapy, which avoids delay in providing resuscitation therapy once it is recognized as necessary or desirable.

The occlusion valve70can be of any suitable arrangement or structure to selectively accomplish a partial or complete occlusion of gas flow within the system10. Preferably, the occlusion valve70allows the cycling between an occluded or closed position and an open position at a suitable rate, such as the rates described herein. In some arrangements, the occlusion valve70is a manual valve that is operated by manually by a caregiver. Accordingly, preferably the occlusion valve70facilitates repeated cycling between the open and closed position multiple times per minute.

For example,FIG.2illustrates a push button valve arrangement70having a manually operated push button72that actuates a valve body74movable between an open position and a closed position. The valve body74can simply move into or out of a flow passage P of the system10(linear movement or translation) to selectively allow and occlude gas flow within the system10. In some embodiments, the valve arrangement can include a safety feature to help prevent accidental actuation. For example, the push button may be lockable in the open position by rotating the push button a quarter turn. In order to use the valve arrangement, the user can rotate the push button to unlock before actuating. Preferably, the valve body74is biased to the open position by a biasing member, such as a spring76, so that gas flow is normally unobstructed. The valve body74can be movable to the closed position (e.g., using the manual push button72) when it is desired to deliver a resuscitation breath at PIP. In other arrangements, the valve70could be a rotatable valve, such as a stopcock.FIG.3illustrates another possible occlusion valve arrangement70, in which a compliant section of tubing78that has sufficient resilience to remain open in the absence of an external force (FIG.3A), but can be collapsed to a closed position in response to an external squeezing force (FIG.3B), such as a force applied by a clamping mechanism79. In still other arrangements, the valve70could be automatically movable (e.g., electronically actuated).

As described, the occlusion valve70can be positioned in any suitable location within the system10. The system10can be considered to have an inspiratory circuit and an expiratory circuit. In the illustrated arrangement, the inspiratory circuit can include all or portions of the source of breathing gas20, the gas supply line24, the inspiratory pressure device26, the supply tube34, the humidifier system32, and the supply tube36. The expiratory circuit can include all or portions of the expiratory tube62and the expiratory pressure device60. A portion of the patient interface14can be predominantly occupied by a flow of inspiratory breathing gas prior to inspiration by the infant patient12or prior to availability to the infant patient12, while another portion of the patient interface14can be predominantly occupied by a flow of expiratory gas exhaled by the infant patient12or that has bypassed the infant patient12. Accordingly, the patient interface14can be considered to form a part of each of the inspiratory circuit and the expiratory circuit. A portion of the patient interface14can also include a mixture of inspiratory gas and expiratory gas, at least for certain time durations, and may not be considered part of either of the inspiratory circuit or the expiratory circuit or may be considered as a part of each.

The various components of the system10, including those described above, can be arranged and/or mounted in any suitable manner. Some or all of the components can be stationary (e.g., wall mounted) or movable. In the illustrated arrangement, some of the components are mounted to a support pole80, which includes a base portion82having a plurality of rollers or casters84to provide mobility. A suitable pole80is the 900MR292 or 900MR293 pole sold by the Assignee of the present application. In the illustrated arrangement, the inspiratory pressure device26, the humidifier system32and the expiratory pressure device60are mounted to the support pole80. Although not specifically illustrated, the source of water44preferably is also supported by the support pole80. In other arrangements, some of the components could be mounted on another support pole80. The source of breathing gas20and the flow meter or gas blender22can be mobile or can be stationary (e.g., wall mounted). In one arrangement, for example, the resuscitator26can be integrated with an infant warmer, such as the 900 Series infant warmers sold by the Assignee of the present invention.

To set up the system10for use, the components can be gathered and mounted to the support pole80or other support structure, if necessary or desired. The components can be connected to a power source, if necessary, and turned on. The inspiratory pressure device26can be coupled to the source of breathing gas20through the flow meter or gas blender22by the gas supply line24. The humidifier system32can be coupled to the inspiratory pressure device26by the supply tube34. The source of water44can be coupled to the humidity chamber42. The patient interface14can be coupled to the humidifier system32by the supply tube36. The expiratory pressure device60can be coupled to the patient interface14by the expiratory tube62. The occlusion valve70can be integrated into the expiratory tube62; however, the occlusion valve70can also be assembled to the expiratory tube62(such as intermediate two tube portions of the expiratory tube62) or otherwise assembled in a suitable location within the system10, as described above.

If necessary, the expiratory pressure device60can be filled with a liquid, such as about 500 milliliters of water. If adjustable, the expiratory pressure device60can be initially adjusted to a maximum pressure level (maximum PEEP). The humidifier system32can be adjusted to a desired temperature and absolute humidity, such as about 37 degrees Celsius and 44 mg/L. The flow meter or gas blender22can be adjusted to a desired flow rate, preferably less than 15 liters per minute (LPM). In embodiments having a blower unit, the flow meter or gas blender can be integrated with the blower unit. More preferably, the flow rate is adjusted to between about 6-8 LPM.

If necessary or desirable, the pressure relief valve30of the inspiratory pressure device26can be adjusted to a suitable pressure relief level. The pressure relief valve30can be factory set to a pressure relief level, such as about 40 cmH2O. The pressure relief valve30can be set to a lower level, such as between about 5-70 cmH2O and, more preferably, 30-40 cmH2O. To set the level of the pressure relief valve30, the PIP adjustment of the inspiratory pressure device26is adjusted to a maximum level. The patient interface14can be blocked or connected to a test lung apparatus, such as the RD020-01 test lung apparatus sold by the Assignee of the present application. The occlusion valve70can be actuated to allow the pressure within the system10to rise to the pressure relief level, which can be adjusted to a desired level. With the occlusion valve70still actuated, the PIP can be adjusted to a desirable level, preferably less than about 75 cmH2O. More preferably, the PIP is between about 10-40 cmH2O or 20-30 cmH2O. In one application, the PIP pressure is adjusted to about 20 cmH2O, using the PIP valve28. The occlusion valve70can be moved to an open position such that the system pressure is reduced to the PEEP value as determined by the expiratory pressure device60. The PEEP level can be adjusted to a desirable pressure, such as less than about 25 cmH2O, by adjusting a depth of the gas outlet within the water reservoir. Preferably, the PEEP level is adjusted to less than about 15 cmH2O, less than about 9 cmH2O or less than about 5 cmH2O. In one application, the PEEP level is set to about 5 cmH2O. If necessary, the test lung apparatus can be removed and the system10is ready for use.

To use the system10, the patient interface14can be applied to an infant patient12following an appropriate methodology. For example, a face mask can be positioned over the nose and mouth of the infant patient12and, if desired, held in place by hand, a strap or other retention device. If an endotracheal tube is used, the interface14or portion of the interface14can be coupled to the endotracheal tube. In the illustrated arrangement, the nasal prongs can be coupled to the nasal mask or tube and the nasal prongs can be inserted into the nostrils of the infant patient12. The nasal mask14can be held in place by any suitable retention mechanism, such as a chin strap or head strap.

Once the patient interface14is in place on the infant patient12, the CPAP therapy can be commenced. A flow of breathing gas is supplied to the infant patient12by the patient interface14at the CPAP or PEEP level, as regulated by the expiratory pressure device60. As discussed, preferably the expiratory pressure device60is configured to produce pressure oscillations within the system10, which is believed to have an improved therapeutic effect on the infant patient12. The CPAP therapy can continue for a desired period of time.

If necessary or desirable, resuscitation therapy can be administered. As described above, the occlusion valve70can be actuated to block the exit of expiratory gases from the system10and cause the pressure within the system10to rise toward or to the PIP pressure to deliver a resuscitation breath to the infant patient12. The occlusion valve70can be moved to an open position, or allowed to return to an open position, to return the system to the PEEP. In some arrangements, the actuation of the occlusion valve70is accomplished manually. The actuation and release of the occlusion valve70can be repeated at a desired frequency, such as between about 40-60 breaths per minute, for a suitable duration, such as about 3-5 minutes. However, if necessary or desirable, the duration of the resuscitation therapy can be up to 15-30 minutes, or longer. At the conclusion of the resuscitation therapy, the system10can automatically return to the CPAP mode at the PEEP. Accordingly, with the illustrated system10, resuscitation therapy can be immediately commenced on an infant patient12that is undergoing CPAP therapy without requiring the set-up of additional equipment and without requiring the replacement of the patient interface14.

FIGS.4and5illustrate a modification of the system10ofFIG.1. Because the system ofFIGS.4and5is similar to the system10ofFIG.1in many respects, the same reference numbers are used to indication the same or corresponding components. In the system ofFIGS.4and5, the resuscitator26(or other inspiratory pressure device) is integrated with the humidifier32in a resuscitator/humidifier unit90(hereinafter “integrated unit90”). In addition, preferably, the source of breathing gas20is or includes ambient air from an environment adjacent the integrated unit90. Therefore, the integrated unit90preferably comprises a flow generator or flow source, such as a fan, gas pump or blower92(FIG.5), which generates a flow of air. In some embodiments, however, the integrated unit90can be connected to a source of breathing gas, such as a gas cylinder or a wall supply, instead of or in addition to the flow generator. In some arrangements, the system can utilize supplemental breathing gases (oxygen or other suitable respiratory gases) that are blended in combination with air. However, in many arrangements, only air is used and the source of breathing gas (reference number20inFIG.1) can be omitted.

In the illustrated arrangement, the integrated unit90generates a flow of breathing gas (e.g., air) and outputs the flow of breathing gas at a controlled pressure greater than atmospheric pressure to the humidifier, which humidifies the flow of breathing gas. The flow of humidified breathing gas is delivered to the patient12via the supply tube36and patient interface14. Exhaled and unused gases are delivered to the expiratory pressure device60via the expiratory hose62. The expiratory pressure device60can provide a minimum pressure or minimum backpressure within the system and, in particular, at the patient interface14preferably to or near the PEEP pressure. The occlusion valve70can be used to block the flow of breathing gas such that the inspiratory pressure device26can increase the pressure in the system preferably to or near the set PIP level. The system ofFIGS.4and5preferably operates in substantially the same manner as described above with respect to the system10ofFIG.1.

With reference toFIG.5, in addition to the blower92, the integrated unit90preferably includes a filter94upstream from the blower92. The filter94is of a suitable arrangement to separate impurities or other undesirable elements from the ambient air that is used to generate the flow of air within the system. The filter94and the blower92preferably can be coupled to or contained within a housing96that contains portions of the humidifier40and supports the humidifier chamber42. The pressure adjustment valve28and a manometer98, or other pressure gauge or measurement device, can be coupled to or contained within a housing100that is separate from the housing96. Preferably, the housing100can be removable from the housing96. When the housing100is removed, the integrated unit90can be used as a blower92and humidification system32without the resuscitation feature. In the illustrated arrangement, the housing100defines or contains a conduit102for delivering the flow of breathing gas from the blower92to the humidification chamber42of the humidifier system32. When the housing is removed, an auxiliary conduit (not shown) can be utilized in place of the conduit102. Alternatively, an auxiliary conduit can be integrated with or otherwise incorporated with the housing96that is utilized when the housing100is removed. A valve arrangement could be configured to automatically switch between the conduit102and the auxiliary conduit depending on the presence or absence of the housing100.

With reference toFIG.6, in another modification of the systems ofFIG.1andFIGS.4and5, the flow generator (hereinafter “blower92”) is integrated with the humidifier40of the humidification system32. However, unlike the system ofFIGS.4and5, the resuscitator26is a separate system component from the humidifier40, humidification chamber42or the entire humidifier system32. Thus, in the system ofFIG.6, the blower92is connected to the resuscitator26via the supply line24to deliver the flow of air (or other breathing gas) from the blower92to the resuscitator26. The flow of air then flows from the resuscitator26to the humidification chamber42of the humidifier system32and to the patient12as described above. If the resuscitator26is not necessary or desired, the blower92can be connected to the humidification chamber42of the humidifier system32, without passing through the resuscitator26, via a suitable internal or external auxiliary conduit, as described above.

Although described in the context of an infant patient system, the illustrated system can be used in, or modified for use in, other applications or contexts, as well. Thus, although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In particular, the skilled artisan will appreciate, in view of the present disclosure, that certain advantages, features and aspects of the system may be realized in a variety of other applications, many of which have been noted above. Additionally, it is contemplated that various aspects and features of the invention described can be practiced separately, combined together, or substituted for one another, and that a variety of combination and subcombinations of the features and aspects can be made and still fall within the scope of the invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims.