RESPIRATORY ASSISTANCE APPARATUS

Abstract

A respiratory assistance apparatus (4) is provided, adapted to deliver gases to a user or patient (1). The apparatus (4) comprises a housing (10) provided with a chamber (5) and a heater (25), the chamber (5) comprising at least one gas port (15) connected to, or arranged to be connected to, at least one intermediate passageway (12). The apparatus (4) is operative according to a disinfection mode of predetermined profile in which the heater (25) heats liquid in the chamber (5) to produce vapour at or above a target dewpoint temperature and/or humidity level. The apparatus (4) is arranged such that the vapour is delivered to the intermediate passageway (12) to disinfect the intermediate passageway (12) with moist heat throughout a predetermined duration of the disinfection mode. Associated attachments and methods are also provided.

Claims

1.-85. (canceled)

86. A respiratory assistance apparatus adapted to deliver a gases flow to a user or patient, the apparatus comprising: a housing provided with a heater; a chamber comprising at least one chamber port configured to be connected to at least one intermediate passageway, the housing being configured to receive the chamber; and a controller that controls the respiratory assistance apparatus to operate according to a disinfection mode, during the disinfection mode, the controller controls the heater to heat a liquid in the chamber to produce vapor at or above a target dewpoint temperature, the apparatus being arranged such that, in use during the disinfection mode, the vapor produced by heating the liquid in the chamber is delivered to the at least one intermediate passageway connected to the chamber through the at least one chamber port to disinfect the at least one intermediate passageway with hot vapor, the vapor being at a temperature above the target dewpoint temperature, and the controller controlling the respiratory assistance apparatus to operate in a drying mode subsequent to the disinfection mode to dry the at least one intermediate passageway.

87. The respiratory assistance apparatus of claim 86 wherein the chamber is removably mountable on the respiratory assistance apparatus, the at least one chamber port comprises a chamber outlet port, and the chamber further comprises a chamber inlet port arranged to be in fluid communication with a gases source in the housing.

88. The respiratory assistance apparatus of claim 86 further comprising a removeable disinfection tube to deliver vapor to the at least one intermediate passageway, the respiratory assistance apparatus being configured to be controlled according to the disinfection mode when: a first end of the at least one intermediate passageway is connected to the chamber outlet port; and the first end of the at least one intermediate passageway is connected to the chamber outlet port with the removable disinfection tube.

89. The respiratory assistance apparatus of claim 88, wherein the removable disinfection tube comprises a separate heater element.

90. The respiratory assistance apparatus of claim 86 further comprising at least one sensor that measures a parameter of gases flowing in or proximate to the at least one intermediate passageway.

91. The respiratory assistance apparatus of claim 86, wherein the controller controls the respiratory assistance apparatus to operate in the drying mode by using heat generated by the heater when the liquid in the chamber has been completely used.

92. The respiratory assistance apparatus of claim 86, wherein the controller controls the respiratory assistance apparatus to operate in the drying mode by using heat generated by a separate heater element.

93. The respiratory assistance apparatus of claim 86, wherein the controller controls the respiratory assistance apparatus to operate in the drying mode by increasing a gases flow rate through the at least one intermediate passageway such that the gases flow rate is higher during the drying mode than during the disinfection mode.

94. The respiratory assistance apparatus of claim 86, wherein the controller controls the respiratory assistance apparatus to operate in the drying mode with at least one of a predetermined duration, a clinician or user-controlled duration, or a duration controlled in dependence on moisture levels detected in the at least one intermediate passageway.

95. The respiratory assistance apparatus of claim 86 further comprising a safety cap provided with a connector that fluidly couples the safety cap to a downstream end of the at least one intermediate passageway, a duct forming a vapor flow path into the safety cap, and the safety cap condensing vapor received from the duct, and the safety cap comprising a condensing surface onto which vapor from the duct condenses.

96. The respiratory assistance apparatus of claim 86 further comprising a compressor in fluid communication with the chamber, the compressor urging gases through the chamber to the at least one intermediate passageway, and prior to termination of the disinfection mode, the controller controls the compressor to provide a ramped increase in flow to dry and/or cool the at least one intermediate passageway.

97. The respiratory assistance apparatus of claim 86, wherein the controller controls the compressor to slowly discharge any remaining vapor or steam from the chamber near an end of the disinfection mode and then subsequently provides a higher flow rate to cause accelerated drying and/or cooling.

98. The respiratory assistance apparatus of claim 86, wherein the controller determines completion of the disinfection mode based on stored cycle times for a given respiratory assistance apparatus configuration and a predetermined or detected level of liquid present in the chamber at a start of the disinfection mode.

99. The respiratory assistance apparatus of claim 86, wherein the target dewpoint temperature is greater than 70° C.

100. The respiratory assistance apparatus of claim 86, wherein the disinfection mode has a predetermined profile that includes a duration of the disinfection mode, the target dewpoint temperature being set sufficiently high that the vapor provides sufficient moist heat to disinfect the at least one intermediate passageway at least over the duration of the disinfection mode.

101. The respiratory assistance apparatus of claim 100, wherein the target dewpoint temperature is inversely proportional to the duration of the disinfection mode.

102. The respiratory assistance apparatus of claim 100, wherein the target dewpoint temperature and the duration of the disinfection mode are predetermined.

103. The respiratory assistance apparatus of claim 100, wherein the target dewpoint temperature and the duration of the disinfection mode are variable according to a user selection of one of the target dewpoint temperature or the duration of the disinfection mode.

104. A method of disinfecting at least a part of a respiratory assistance apparatus, the respiratory assistance apparatus being adapted to deliver gases flow to a user or patient, the method comprising: providing the respiratory assistance apparatus, the respiratory assistance apparatus comprising a housing provided with a heater; a chamber comprising at least one chamber port that connects to at least one intermediate passageway, the housing configured to receive the chamber; and a controller; connecting the at least one intermediate passageway to the at least one chamber port; and using the controller to control the respiratory assistance apparatus to operate according to a disinfection mode; the respiratory assistance apparatus operating according to the disinfection mode comprising: subjecting at least a portion of the respiratory assistance apparatus to a humidified gases flow at or above a target dewpoint temperature, the subjecting comprising: using the controller to control the heater to heat a liquid in the chamber to produce vapor at or above the target dewpoint temperature; and delivering the vapor through the at least one chamber port to the at least one intermediate passageway; the method further comprising controlling the respiratory assistance apparatus to be operative in a drying mode subsequent to the disinfection mode to dry the at least one intermediate passageway.

105. The method according to claim 104, wherein the target dewpoint temperature is greater than 70° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] A number of embodiments of the invention will now be described by way of example with reference to the drawings.

[0077] FIG. 1 is a perspective view of a respiratory assistance apparatus in accordance with the invention, in use with an inspiratory tube and patient interface.

[0078] FIG. 2 is a partially exploded perspective view of a respiratory assistance apparatus in accordance with the invention.

[0079] FIG. 3 is a perspective view of a further respiratory assistance apparatus in accordance with the present invention, with the device in a partially disassembled condition.

[0080] FIG. 4 is a perspective view of the apparatus of FIG. 3 in an assembled condition.

[0081] FIG. 5 is a perspective view of the apparatus of FIGS. 1 and 2, including a cap closing a patient outlet.

[0082] FIG. 6 is a perspective sectional view of a cap for use with an apparatus in accordance with the invention.

[0083] FIG. 7 is a further perspective view of an apparatus in accordance with the present invention.

[0084] FIG. 8 is a perspective view of a respiratory assistance apparatus in accordance with the invention, including a safety cap.

[0085] FIG. 9 is a sectional view of the safety cap of FIG. 8.

[0086] FIG. 10 is a perspective sectional view of the cap of FIG. 9, with a condensate reservoir of the safety cap removed.

[0087] FIG. 11 is a perspective sectional view of the safety cap of FIGS. 9 and 10, with a condensate reservoir of the safety cap removed and an alternative top part.

[0088] FIG. 12 is a perspective sectional view of a lower part of the safety cap of FIGS. 9 and 10, with an upper part of the safety cap removed.

[0089] FIG. 13 is a perspective view of the lower part of the safety cap of FIG. 12, with an upper part of the safety cap removed.

[0090] FIG. 14 is a perspective view of the safety cap of FIGS. 9 and 10.

[0091] FIG. 15 is a perspective view of the safety cap having the alternative top part of FIG. 11.

[0092] FIG. 16 is an overview of a steam disinfection control system of a respiratory assistance apparatus and method in accordance with the invention.

[0093] FIG. 17 is a schematic of the steam disinfection control system of FIG. 16.

[0094] FIG. 18 is a flow diagram showing steps used in the steam disinfection control system of FIGS. 16 and 17.

[0095] FIG. 19 is a flow diagram of a temperature control system forming part of the steam disinfection control system of FIGS. 16 to 18.

[0096] FIG. 20 is a flow diagram of a gases flow control system forming part of the steam disinfection control system of FIGS. 16 to 19.

[0097] FIG. 21 is a schematic view of a resistance detection circuitry used in connection with the safety cap of FIGS. 8 to 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0098] Throughout the description like reference numerals will be used to refer to like features in different embodiments.

[0099] The present invention provides a respiratory assistance apparatus that provides a convenient, effective and reliable method of disinfecting at least a portion of the apparatus with moist heat during a disinfection mode, which portion may define, at least in part, a transport path for a humidified gases flow generated by the apparatus. According to some embodiments, the at least a portion of the apparatus comprises an internal passageway provided at least partially inside the apparatus. The present invention also provides a method of disinfecting a respiratory assistance apparatus and attachments for use with such method of disinfecting the respiratory assistance apparatus.

[0100] A chamber is provided on or at the apparatus in which liquid can be heated to produce vapour or steam, the vapour being delivered to the at least a portion of the apparatus (such as the internal passageway) to disinfect that portion with moist heat. The invention provides for the chamber being the same humidification chamber used to humidify the gases flow prior to delivery to the patient during normal use of the apparatus to provide respiratory assistance. The invention also or alternatively provides for a separate chamber to be used. In this latter example, in the disinfecting mode, the humidification chamber may be removed, and replaced with a disinfecting chamber. The disinfecting chamber may be a reusable, refillable chamber, or may be supplied pre-filled with the required amount of disinfecting liquid and pre-sealed.

[0101] The invention provides for the use of water and therefore vapour or steam to disinfect said at least a portion of the apparatus with moist heat. Other liquids, or combinations of liquids, could be used as required.

[0102] The invention provides for the source of liquid that is used for disinfection to be a self contained part of the apparatus, namely located on or at the apparatus in use of the disinfection mode.

[0103] Referring to the Figures, a respiratory assistance apparatus 4 comprises a housing 10 which may be generally cuboidal and may be arranged to be placed on a table or tray, or mounted on a wall or some other support, as required or preferred.

[0104] A supply gases inlet 9 is provided, for example on the rear of the housing, and is in fluid communication with a gases source such as a blower, fan or compressor (not shown), preferably mounted in the housing 10 for delivering a gases flow. There may be ductwork within the housing which connects the gases source with the supply gases inlet 9, and that ductwork may be of a length and path direction selected as required.

[0105] The housing 10 is further provided with a supply gases outlet 11, which may project from the front of the housing 10, from which the gases flow exits.

[0106] Preferably, adjacent the supply gases outlet 11 is a patient inlet 13 which may also project from the front of the housing 10, which leads to a patient outlet 8 which may project from the top of the housing 10. The patient inlet 13 and the patient outlet 8 are connected by an intermediate passageway, which in this example comprises an elbow 12 that is bent along its length through 90°. The patient inlet 13 and patient outlet 8 may be otherwise positioned depending on the apparatus configuration, with the elbow 12 configured to provide fluid communication between the patient inlet 13 and the patient outlet 8. Thus, the elbow 12 may be of some alternative configuration, including but not limited to straight, curved, or bent in more than one location.

[0107] In this example, a humidifier is provided having a chamber 5 comprising a chamber inlet port 26 and a chamber outlet port 15. The ports 26, 15 are provided on the rear of the chamber 5, and sealingly engage with the supply gases outlet 11 and the patient inlet 13, respectively, such that in use the gases flow enters the chamber 5 from the supply gases outlet 11 through the chamber inlet port 26 and exits the chamber 5 to the patient inlet 13 through the chamber outlet port 15.

[0108] The chamber 5 may be removably mounted on the housing 10, and in one example, may be slidably mounted on the front of the housing 10 by sliding the chamber 5 towards the rear of the housing 10 until the ports 11, 26 and the ports 13, 15 engage. In another example, the chamber 5 may be permanently mounted on the housing 10.

[0109] A heater 6 is provided which in this example comprises a heater plate 25 on the housing 10, below the chamber 5. Other forms of heater are envisaged and these may include a heater element built into the chamber 5 itself or a non-contact heater such as an induction heater for example.

[0110] A controller may be provided in the housing 10 which is arranged to control the gases source and the heater. It will be appreciated that by providing appropriate communication means, control may be effected, at least in part, remote from the apparatus.

[0111] The apparatus 4 is operative according to at least two modes: a respiratory mode and a disinfection mode.

[0112] In the respiratory mode, the gases source is controlled to provide a gases flow to the chamber 5. The gases flow passes into the chamber inlet port 26, across the chamber 5, and out of the chamber outlet port 15. The heater 25 is controlled to heat liquid in the chamber 5 such that the incoming gases flow passes over the liquid and is humidified by vapour generated from the heated liquid. This heated and humidified gases flow exits the chamber 5 via the chamber outlet port 15 and is delivered to a patient 1 via the elbow 12 and the patient outlet 8. While various interfaces are known and may be selected based on operational parameters and user preferences, FIG. 1 shows a particular inspiratory tube 3 having a heating element 7 running therethrough, and coupled at one end to the patient outlet 8 and at the other to a patient interface 2 (shown as a nasal cannula).

[0113] In the disinfection mode, the gases source may be switched off, or may be controlled to continue delivering a gases flow into the chamber 5 at the same or a different flow rate. The heater is controlled to heat liquid in the chamber 5 to produce steam or vapour at or above a target dewpoint temperature. The vapour fills the chamber 5 and is delivered into the elbow 12 and through the patient outlet 8. The vapour in the elbow 12 provides the moist heat that serves to disinfect the elbow 12 and the patient outlet 8. The disinfection mode is operative for a predetermined duration in which the heater 25 is controlled such that vapour continues to be generated and supplied to the elbow 12 throughout the duration of the disinfection mode.

[0114] The target dewpoint temperature is set sufficiently high that the vapour provides the moist heat necessary to disinfect the elbow 12, at least over the duration of the disinfection mode. The target dewpoint temperature is inversely proportional to the duration of the disinfection mode, at least within a preferred temperature range of 70° C. to 100° C. Thus, a fixed target dewpoint temperature and disinfection mode duration may be predetermined, or may be variable according to a user selection of one of the target dewpoint temperature or the disinfection mode duration. A lookup table may be provided which relates the duration required for a range of target dewpoint temperatures. As an example only, a range of dewpoint temperatures between 70° C. and 90° C. may achieve sufficient disinfection efficacy over a disinfection mode duration of between 15 and 45 minutes, preferably around 30 minutes. As will be appreciated, to ensure sufficient disinfection efficacy, a safety margin may be applied to the dewpoint temperature and/or duration.

[0115] In this example, the disinfection mode therefore requires no external components, or modifications to the apparatus 4, instead using the components of the humidifier in a different manner to achieve disinfection. No external disinfection hoses or the like are required, and it is not required to remove the chamber 5 from the housing 10.

[0116] Optionally, an end cap 30 is provided which is arranged to be mounted on the end of the elbow 12 at the patient outlet 8.

[0117] The cap 30 comprises an engaging formation 31 arranged to engage with the end of the elbow 12 at the patient outlet 8 to mount the cap 30. The cap 30 may further comprise a flow restrictor 32 arranged to restrict flow through the elbow 12 when the cap 30 is so mounted, to provide back pressure in the elbow 12 during the disinfection mode. The cap 30 may further comprise an antibacterial filter. The cap 30 may also comprise an identifier such as a RFID tag, or a resistor which is used by the apparatus 4 to determine if the cap 30 is mounted on the elbow 12.

[0118] The apparatus 4 may comprise a chamber sensor operative to generate a signal indicative of whether the chamber 5 is mounted on the apparatus 4. The chamber sensor may be operative to generate a signal indicative of whether a specific chamber or type of chamber is mounted on the apparatus 4. The chamber sensor may comprise the combination of a pressure/flow sensor and a flow restriction on the specific chamber, the flow restriction restricting gases flow through the chamber which can be detected by the pressure/flow sensor.

[0119] The apparatus 4 may comprise a patient interface sensor operative to generate a signal indicative of whether a patient interface is connected to the apparatus 4, and to activate the disinfection mode only when the signal is indicative that a patient interface is not connected to the apparatus 4. The patient interface sensor may be operative to detect the presence of the cap 30 on the end of the elbow 12 at the patient outlet 8, and to generate the signal indicative that a patient interface is connected to the apparatus 4, when no cap 30 is detected.

[0120] The apparatus 4 may comprise a disinfection mode sensor operative to generate a signal indicative that the apparatus 4 is to operate according to the disinfection mode. The disinfection mode sensor may be operative to generate the signal by detecting at least one of: the cap 30 being mounted on the end of the elbow 12 at the patient outlet 8; the chamber 15 being mounted on the housing 10; and/or a user input.

[0121] The apparatus 4 may comprise a chamber liquid level detector operative to generate a signal indicative of a liquid level in the chamber 5. The apparatus 4 may be operative, in dependence upon the liquid level signal detected, to vary at least one of: the flow rate of the gases flow; the target dewpoint temperature of the vapour; and/or the duration of the disinfection mode.

[0122] The liquid level detector may indicate when the disinfection liquid has been entirely used, so as to determine whether a sufficient duration and dewpoint temperature combination has been achieved to provide the desired disinfection efficacy.

[0123] The apparatus 4 may provide a drying mode, initiated subsequent to the disinfection mode, wherein the elbow 12 and/or other components of the gases flow path are dried. This may be achieved using heat generated by the heater when all of the liquid in the chamber 5 has been entirely used, or via a separate heater element, or via increasing the gases flow rate through the elbow 12, for example. The duration of the drying mode may be predetermined, user controlled, or controlled in dependence on moisture levels detected in the elbow 12.

[0124] A drying mode may also be provided to dry the moisture from components of the gases flow path, such as by operating the blower for a sufficient period after the liquid has been completely used, or after the heater plate has been switched off and the remaining liquid cools and its evaporation approaches an equilibrium state.

[0125] In another example, another method of disinfecting the elbow 12 is provided. This example uses a separate disinfection chamber 35 which is mounted on the housing 10 for the duration of the disinfection mode. This method can therefore be used on an apparatus not provided with a humidification chamber 5, or otherwise requires removal of the humidification chamber 5 when provided.

[0126] In this example, the disinfection chamber 35 is mounted on the housing 10 with the chamber inlet port 37 sealingly connected to the supply gases outlet 11 on the housing 10. A disinfection hose 41 is connected between the chamber outlet port 39 and the end of the elbow 12 at the patient outlet 8. End cap 30 is mounted on the end of the elbow 12 at the patient inlet 13.

[0127] During the disinfection mode, the heater heats liquid in the disinfection chamber 35 to produce vapour at or above a target dewpoint temperature. The vapour flows from the disinfection chamber 35, along the disinfection hose 41 and into the end of the elbow 12 at the patient outlet 8. The vapour flows along the elbow 12, disinfecting the elbow 12, and exits via the end cap 30 on the end of the elbow 12 at the patient inlet 13.

[0128] The disinfection chamber 35 may be supplied pre-charged with a suitable volume of disinfecting liquid, or may be provided with an injector inlet or the like through which a suitable volume of disinfecting liquid may be introduced into the chamber 35.

[0129] Referring additionally to FIGS. 8 to 15, a safety cap 41 is provided for mounting on the end of the elbow 12 at the patient outlet 8 of the apparatus 4 during a disinfection mode. The safety cap 41 is used during a disinfection mode in which the humidifier chamber 5, or the disinfection chamber 35, is mounted on the apparatus 4 to generate vapour that passes through the apparatus 4, through the elbow 12, and exits the apparatus 4 via the patient outlet 8. It will be appreciated that without safety measures, vapour exiting the patient outlet 8 could scald a user or other person near the apparatus 4. Similarly, portions of the apparatus 4 impinged by the vapour could become dangerously warm. Broadly speaking, the safety cap 41 provides a means of mitigating these risks by dispersing the vapour, so that it is not concentrated in a small area, and by condensing the vapour.

[0130] The safety cap 41 comprises a connector 43 arranged to connect the safety cap 41 with the patient outlet 8 at one end of the elbow 12 and a duct 44 extending through the connector 43 to form a gases flow path with the patient outlet 8. The vapour duct 44 is provided, at a position distal from the connector 43, with at least one vapour outlet 45 through which vapour exits the duct 44 in a generally radially outward direction but is retained within the safety cap 41. A concave inner roof 47 provides a condensing surface positioned above the end of the duct 44 and above the vapour outlet 45 such that vapour from the vapour outlet 45 rises and contacts the roof 47. The vapour condenses on the roof 47, and the condensate drops from the roof 47 and is collected in a condensate reservoir 49 below.

[0131] The risk of vapour directly contacting a user adjacent the apparatus 1 is therefore reduced by virtue of the tortuous path defined by the safety cap 41, and at least a portion of the vapour is safely condensed and collected within condensate reservoir 49 for later disposal.

[0132] The safety cap 41 is arranged to provide a vapour flow path that dissipates the heat from the vapour and/or prevents emission of a hazardous stream of vapour, at least during normal operating conditions. In particular, the vapour duct 44 initially directs the vapour upwardly away from the patient outlet 8, along a central axis of the safety cap 41. The end of the duct 44 is closed by domed end wall 61 (as described further below) such that vapour then flows generally radially outwardly through vapour outlet(s) 45, and subsequently upwardly into contact with roof 47.

[0133] The vapour duct 44 and vapour outlet 45 prevent vapour from flowing up the duct 44 directly into contact with the roof 47 and creating a hot spot on the roof 47. Directing the vapour radially away from the vapour duct 44 also prevents any condensate from undesirably flowing back down the duct 44 and into the patient outlet 8.

[0134] The roof 47 forms a condensing surface which is impacted by the vapour and which has a surface area that is considerably greater than the cross-sectional area of the duct 44, so that heat energy of the vapour is not concentrated on a particular area of the roof 47. The roof 47, together with other components forming the safety cap 41, serves to dissipate heat from the condensing vapour.

[0135] In the illustrated example, the safety cap 41 is of multi-piece construction broadly comprising a base piece forming a lower part 44A of duct 44 and connector 43, the condensate reservoir 49 mounted on the base piece around connector 43, and a cap piece comprising an upper part 44B of duct 44 and roof 47. These pieces may be arranged to be connected together in any suitable manner, including using push fit or snap fit type connections. One or more pieces may alternatively be constructed as a single component.

[0136] Connector 43 is a tubular connector comprising a duct connector 51 and an optional electrical connector 53. Connector 43 may be of the same or similar structure to a gases tube connector of the type used to connect a gases tube to the apparatus 1 in normal use, i.e., between the apparatus 1 and a patient interface. When pushed onto the apparatus 1, the duct connector 51 receives part of the patient outlet 8 of the apparatus 1 to form a vapour flow path, whilst the electrical connector 53, when provided, forms an electrical connection with the apparatus 1. Resilient clips 54 releasably engage with corresponding formations on the apparatus 1 to secure the connector 43 onto the apparatus 1. Clips 54 can be pressed inwardly to release the connector 43 from the apparatus 1.

[0137] The electrical connector 53 includes any power and/or sensor connections as are required between the safety cap 41 and the apparatus 1. The electrical connector 53 may include an identifier to enable the apparatus 1 to recognize that the safety cap 41 is connected to the apparatus 1. Once the safety cap 41 is recognized, the apparatus 1 may automatically begin a disinfection mode for example. The apparatus 1 may be arranged to prevent activation of a disinfection mode until the safety cap 41 has been connected and recognized by the apparatus 1. In one example, the electrical connector 53 may include an identification resistor which is used to detect the presence of the safety cap 41 on the apparatus 1.

[0138] Condensate reservoir 49 comprises a substantially annular catch tray extending around connector 43. The catch tray 49 is generally circular or elliptical when viewed from above, and is of larger diameter than roof 47 to minimize spillage of condensate dropping from the roof 47. The catch tray 49 further preferably comprises a spout 55 from which condensate can be poured to empty the tray 49 after vapour disinfection. The catch tray 49 may also be used to measure a predetermined volume of fluid prior to commencement of a disinfection mode. The catch tray 49 may comprise measuring indicia for this purpose, and/or the volume of the catch tray 49 may correspond to the volume of fluid required. Thus the fluid may be measured in the catch tray 49 and then poured into the humidifier chamber 5, or the disinfection chamber 35, using the spout 55. The periphery of the catch tray 49 may comprise one or more tabs or other gripping formations 57 to facilitate gripping of the tray 49 by a user.

[0139] The upper cap piece comprises upper duct part 44B which is mounted on, and fluidly connected to, lower duct part 44A. Upper duct part 44B is closed off by domed end wall 61. Below the domed end wall 61 are a plurality of vapour outlets 45 which in this example comprise equi-spaced slits formed in the duct wall. Any number and/or size and/or shape of vapour outlets 45 can be provided as required. The roof 47 is joined to the upper duct part 44B by a plurality of radially outwardly extending spokes 63, a vapour outlet 45 being provided between each pair of spokes 63. Spokes 63 add thermal mass and heat transfer conduits to the safety cap 41 to assist in cooling the vapour by absorbing heat therefrom. The size and/or number of the spokes 63 may be selected accordingly. The periphery of the concave roof 47 leads to a downwardly directed skirt 65 which assists in directing condensate down into the catch tray 49, minimizing spillage. Skirt 65 also prevents or reduces the amount of vapour ejected via the vapour outlets 45 that escapes the cap 41 and is able to contact a user, maintaining safe operation, at least during normal operating conditions.

[0140] With reference to FIGS. 11 and 15 in particular, roof 47 may be transparent or opaque.

[0141] Safety cap 41 may optionally further comprise one or more fins or other formations on the exterior of at least part of the cap 41, to prevent a user directly contacting the cap surface and/or to increase heat dissipation from the cap surface, for example roof 47. The inside of the roof 47 may comprise a hydroscopic structure to promote formation of condensation. The roof 47 and/or skirt 65 could comprise microstructures to channel condensate droplet movement down to catch tray 49 as quickly and/or directly as possible.

[0142] While the Figures show a particular embodiment of a safety cap according to the invention, various modifications or alternatives are included within the scope of the invention. For example, other structures that serve to disperse the vapour to prevent localized hot spots are also included within the scope of the invention, as are other structures that promote condensation.

[0143] With reference to FIGS. 16 to 21, apparatus 1 is arranged to operate according to a disinfection mode. This mode may be activated automatically, for example, when safety cap 41 is mounted on the apparatus 1, or activated when selected by a user. The disinfection mode may be prevented from activating until the apparatus 1 detects the safety cap 41, the cap 30, or some other attachment used in the disinfection mode.

[0144] Referring to FIG. 16, the disinfection mode is controlled via a disinfection controller 71 which receives information from sensors and interacts with a gas flow control system 73 and a gas temperature control system 75. More particularly, flow control system 73 may be operable to control a pressure and/or flow of gas along a gas flow path through the apparatus, at least when in the disinfection mode. It will be appreciated that the same or separate circuitry may be used to control flow when in a respiratory mode. Conversely, the temperature control system 75 may control heating of liquid used in disinfection mode, such as via a heater plate provided in thermal communication with a chamber holding said liquid. According to some embodiments, heating may be provided along the gas flow path to maintain a desired dewpoint temperature and prevent condensation forming. Such heating may comprise a resistance wire heating element provided in a wall defining the gas flow path. Again the same or different circuitry may be employed to similar effect when in a respiratory mode.

[0145] With particular reference to FIGS. 17 and 21, the disinfection controller 71 may be initiated by detecting when the safety cap 41 is connected to the apparatus 1 using an identifier on the safety cap 41. In one example, this detection may be via a measurement of the electrical resistance of a resistor in the electrical connector 53 of cap 41. The detected resistance of the resistor is compared by the disinfection controller 71 to a predetermined resistance value associated with the safety cap 41. For example if the detected resistance exceeds the predetermined resistance value, this signals to the disinfection controller 71 that the safety cap 41 is connected to the apparatus 1. The disinfection controller 71 may then automatically initiate a disinfection mode. The disinfection controller 71 may alternatively use the resistance comparison to allow or prevent an operator from initiating a disinfection mode. As will be appreciated, other forms of detection may be used. For example, apparatus 1 may be operable to detect the presence of an RFID tag form part of the safety cap 41. Optical identification means may alternatively be provided. Alternatively, the detection may be omitted with the disinfection mode being initiated by user input. Such control may additionally or alternatively be used for other embodiments of the invention that do not include the safety cap 41. For example, it may be used to detect the presence of cap 30 or some other attachment used in the disinfection mode.

[0146] Flow control system 73 controls the motor speed of the blower, fan or compressor of apparatus 1, at least when in a disinfection mode. The flow control system 73 processes gas flow signals from flow sensors which may be positioned at one or more points along the gas flow path. Additionally or alternatively, flow may be determined based on a signal from a blower motor speed sensor. The apparatus 1 may comprise lookup tables that translate a given motor speed into a flow for determined apparatus configurations (e.g. whether cap 30 or safety cap 41 is connected).

[0147] Chamber detection system 74 may be configured to process the outputs from the gas flow sensor and the blower motor speed sensor to determine whether or not the humidifier chamber 5, or the disinfection chamber 35, or safety cap 41, or cap 30, or some other attachment is connected to the apparatus, and whether to initiate the disinfection mode accordingly. Known flow profiles of components may be stored in a memory of the apparatus 1 and used to determine which components are connected based on a comparison with detected flow.

[0148] Gas temperature control system 75 controls the heat produced by the heater plate of the humidifier of apparatus 1 using a signal from a gas temperature sensor at or near the patient outlet 8, and/or a signal from a heater temperature sensor at or near the chamber. The gas temperature sensor may be provided in or at the elbow 12, or elsewhere disinfection is required.

[0149] Liquid out detection system 76 may be configured to detect when there is no more liquid in humidifier chamber 5 using signals from the ambient temperature sensor and the heater plate temperature sensor.

[0150] With reference to FIGS. 18 to 20, a preferred embodiment of an algorithm 181 used by the controller 71 is described that uses the systems 73, 74, 75 and 76, and sensors described above.

[0151] The algorithm 180 may begin at step 181 with checks that the apparatus is properly configured for performing the disinfection cycle. For example, controller 71 may detect whether safety cap 41 (or other disinfection mode equipment) and chamber 5 are fitted to apparatus 1. There may also be a check that there is liquid in the chamber 5. The latter may comprise not just detecting a presence or absence of a liquid but a level thereof. While any form of liquid level detector may be used, liquid level may be determined based on the amount of energy used to generate a given change in temperature. For example, current or power supplied to the heater plate may be monitored and a water level inferred based on whether a particular temperature increase is achieved within a predetermined time range. Too rapid a rise in temperature may indicate too little liquid in the chamber. Conversely, a less than expected rise in temperature within a given time period may indicate that too much liquid has been provided. As discussed elsewhere, it is preferable that the disinfection cycle terminates with a drying cycle and too much liquid may prevent this or undesirably lengthen the cycle.

[0152] At step 181, the heater plate is controlled to heat the liquid and generate vapour which flows from the chamber, through the elbow 12 and into duct 44 of safety cap 41, via patient outlet 8. Steps 181 and 182 may be combined to some extent where liquid level is determined based on the heater plate duty cycle. Vapour is maintained in the elbow 12 at a temperature above a minimum threshold, such as 70° C. for example, for a time period necessary for a sufficient level of disinfection. During warm up of the apparatus 1 and the disinfection part 183 of the cycle, preferably, flow controller 73 may deactivate the compressor used to enhance flow of gas through the apparatus, with flow being generated due to expansion resulting from vaporization. Alternatively, the flow controller 73 may control the compressor to only generate a relatively small increase in flow. Equipment used for respiratory assistance is configured to generate relatively low temperature humidified gases flows that are suitable for receiving in a patient airway. Higher temperatures are required for disinfection. Reducing or inhibiting flow enhancement provided by the compressor can enable vapour to be generated with the required dewpoint temperature using substantially the same apparatus as that used for providing respiratory assistance and without requiring additional heating. For some compressors used for providing respiratory assistance, low levels of flow may be generated by applying power to a motor of the compressor in pulses, with “ON” pulses in which power is supplied thereto being interspersed by “OFF” cycles when no power is supplied to the motor. Braking may additionally or alternatively be provided.

[0153] Completion of the disinfection part 183 of the cycle may be determined based on stored cycle times for a given apparatus configuration and a predetermined or detected level of liquid present in the chamber 5 at the start of the process. Once detected, a cool down and drying phase 184 is initiated that ensures that the walls defining the gas pathway are dry and that they are cooled to a sufficient degree to be comfortably handled by a user and/or used to provide respiratory assistance. This phase 184 preferably comprises increasing the flow enhancement provided by the compressor to dry moisture from the apparatus and then to draw relatively cooler air through the apparatus to cool it. However, rapidly increasing the flow may generate a strong jet of heated humidified gas which may be hazardous. For example, even where safety cap 71 is used, a rapid increase in flow rate may result in a heated vapour stream or cloud forming about the safety cap 71 unless the safety cap 71 is designed to cope with such high flow rates. Thus, according to preferred embodiments, the flow controller 73 gradually ramps up or increases flow to gradually clear the apparatus 1 of high energy vapour.

[0154] At step 185, an absence of liquid in chamber 5 is detected and the disinfection mode is terminated provided that the temperature of walls forming the gas pathway have been sufficiently cooled. For example, a temperature at the elbow 12 may be required to have fallen below a predetermined threshold. The heater plate and the compressor are turned off. A signal may be generated to indicate to the operator that the disinfection mode has finished.

[0155] The apparatus 1 may be arranged to log one or more parameters of the disinfection process, including but not limited to successful completion of a disinfection cycle, unsuccessful completion of a disinfection cycle, if unsuccessful the reason therefor, a length and/or temperature and/or temperature profile used in the cycle. Such data may be displayed on the apparatus 1 or communicated to remote processing equipment used to collate, analyze or present the data. Thus apparatus 1 may be adapted for wired and/or wireless communication of the data.

[0156] From the foregoing it will be seen that apparatus and methods are provided which allow reliable, effective disinfection of an intermediate passageway of a respiratory assistance apparatus, which do not require removal of the intermediate passageway, or any manual intervention or manual cleaning of the passageway. Additionally, apparatus and methods are provided in which disinfecting vapour is generated in situ on the apparatus. Examples are also provided in which the components of the humidifier which are already present on the apparatus, are used in a disinfection mode.

[0157] Unless the context clearly requires otherwise, throughout the description, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of “including, but not limited to”.

[0158] Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope of the invention. The invention may also be said broadly to consist in the components, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said components, elements or features. Furthermore, where reference has been made to specific components or integers of the invention having known equivalents, then such equivalents are herein incorporated as if individually set forth.

[0159] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.