Abstract:
A connector has a main body with a breathing gases passageway extending therethrough. A connection at one end of the passageway is configured to engage with the expiratory tube connection of a ventilator. The other end of the passageway is connected to the expiratory arm of a breathing circuit. A flow restricting valve member is associated with the connection to the ventilator for substantially closing off the breathing gases passageway on disconnection of the connector from the ventilator.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates to connectors, and in particular to connectors for connecting the expiratory tube of a breathing circuit to a ventilator. 
     A medical breathing circuit includes an inspiratory gases tube and an expiratory gases tube. The inspiratory tube has one end thereof connected to the patient, for example through an endotracheal breathing tube extending into the trachea and ending just above the lungs. The other end thereof connected to a ventilator. The connection to the ventilator may be direct or a self contained humidifier may be interposed. The expiratory tube is connected at one end to the end otracheal tube, and at the other end to the ventilator. The ventilator, running in “pressure support/control” or “volume support/control ” modes, carefully controls the pressure of the gas supplied to the inspiratory tube to control the patient breathing, and maintains a positive airway pressure at all times to ensure lung inflation. An unfortunate consequence arises when the expiratory tube becomes detached from the ventilator, as the ventilator increases the supply flow rate in response to the sudden loss of pressure in the breathing circuit. The air supply becomes at once inefficient, and the increased turbulence of the higher flow level causes a more effective heat transfer from the heating system, and causes the inspiratory gases to be raised to a higher temperature than is otherwise desirable. Flow rates of about 0.5 to 10 liters per minute would be typical of such a circuit when used in a neonatal breathing circuit. 
     It is an object of the invention to provide a connector for the expiratovy tube of a breathing circuit which will obviate the above disadvantage or will at least provide healthcare providers with a useful choice. 
     In a first aspect, the invention includes a main body having a breathing gases passageway extending therethrough, connection means at one end of the passageway configured to engage with the expiratory tube connection of a ventilator, the other end of the passageway being connected or connectable to the expiratory tube of a breathing circuit, and flow restriction means associated with the connection means, for substantially closing off the breathing gases passageway upon disconnection of the connection means from the expiratory tube connection of a ventilator. 
     In a further aspect, the invention is a connector for series connection within the expiratory flow path of a breathing circuit. The connector includes a main body having a breathing gases passageway extending therethrough, connection means at one end of the passageway configured to engage with a connector of a subsequent component in the breathing circuit and the other end of the passageway being connected or connectable to a previous component in the breathing circuit; and flow restriction means associated with the connection means, for substantially but not completely closing off the breathing gases passageway upon disconnection of the connection means from the subsequent component connector. 
     To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One preferred form of the invention will now be described with reference to the accompanying drawings in which: 
     FIG. 1 is a side elevation assembly drawing in cross section through a connector according to the preferred embodiment of the present invention, showing the three components that fit together to form the connector, 
     FIG. 2 is a perspective view assembly drawing to show the external appearance of the main connector body and the valve member, 
     FIG. 3 is a side elevation in cross section of through the connector of the preferred embodiment of the invention with the valve in an open position, and showing the position of the ventilator connection in use, 
     FIG. 4 is a side elevation in cross section of through the connector of the preferred embodiment of the invention with the valve in its closed position, and 
     FIG. 5 is a diagram showing the breathing circuit, including ventilator, humidifier, endo tracheal tube (and patient), and the inspiratory and expiratory tubes. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The connector of the preferred embodiment of the present invention is shown in FIG. 1 in cross section. The connector broadly comprises assembly of three parts. A main connector body  1  with connections  5  and  6  for connecting it to the inlet connector and to the expiratory respiration tube respectively. In the preferred embodiment the connector main body is rotationally symmetric. The spring  3  fits within the open end  5  of the main body  1  which in use connects to the ventilator. One end of the spring  3  abuts an annular face  20  of a constriction within the connector main body, and is located and centered by an annular wall  9  which surrounds a passageway  8  passing through the constriction. A valve member  2  is the third main component, and passes through the passageway  8  so that end  11  thereof lies in the opening  6  of the connector on one side of the constriction and end  13  lies in opening  5  of the connector on the other side of the constriction, and tubular valve body  2  passes through the passageway  8 . The spring  3  is effectively contained between the surface  19  of valve member  2  and the surface  20  of the constriction in the main body. The tubular valve body  2  has a small outwardly extending flange at the end  11  thereof, and under the action of the spring  3  the back face  10  of the flange abuts against the valve seat face  7  of the constriction of the connector main body  1  to retain the valve member  2  within the main body  1  and to form a substantial seal against gases passing therearound, the connector being that instance in the configuration shown in FIG.  4 . 
     Referring to FIG. 3 when the connector is fitted to the inlet fitting  40  of a ventilator the leading edge  41  of the fitting  40  presses against the outer face  14  of the valve member flange  13  to compress the spring  3  and open the valve. In its opened position airflow from the expiratory conduit can pass up the outsides of the valve member between the end  6  of the main body  1  and the tubular valve body  2  as indicated by arrows  21 , through the ports  16  into the inside passage  17  of the tubular valve body  2  as indicated by arrows  22 , out of the valve member  2  through outlet  15  into the ventilator end  5  of the connector main body  1  and thence to the ventilator. This flow path involves relatively large ports and passageways and does not provide a significant constraint against gas flow. 
     When, as shown in FIG. 4, the connector is not connected to the ventilator, the spring  3  pushes against the inside face  19  of the valve member end  13  so that the tubular valve body  2  is predominantly or exclusively contained within the ventilator side  5  of the connector main body  1 , and the annular face  10  of the valve member seats against the annular face  7  of the constriction of the connector main body. To ensure that some gases may still flow through the breathing circuit a small aperture  12  is provided in the end  11  of the valve member so that gases may flow from the expiratory tube end  6  of the connector main body through the aperture  12  as indicated by arrow  24  and thereby into the tubular valve body  2  to be expelled through outlet  15  as indicated by arrow  25 . 
     Each of the valve main body  1  and valve member  2  may be simply manufactured by injection moulding, for example a polyethylene plastics material or other suitable plastics material. The spring  3  may be of a standard spring material, A chamfer  18  on the leading face of end  11  of the valve member  2  allows easy assembly, essentially by a snap fit of the valve member  2  through the main passageway  8  of the main body  1 . 
     The respiratory humidification circuit is shown diagrammatically in FIG. 5, and includes the ventilator  30 , humidifier  31 , endotracheal breathing tube  32  and the associated respiratory breathing tubes  33 ,  34  and  35 . A patient  36  is shown. As indicated in FIG. 5 the connector of the present invention is used to connect between the expiratory breathing tube  35  and the inlet port of the ventilator  30  and is indicated by reference numeral  37 . In normal use with the connector  37  properly connected to the inlet port of the ventilator  30  the connector provides a substantially unconstrained gases flow therethrough at normal ventilation flow levels of approximately 0.5 to 10 liters per minute for a neonatal breathing circuit, or 2 to 10 liters per minute for older patients. If the connector  37  should become detached from the ventilator  30  the valve member  2  will close, in the manner described above, and gases flow will be constrained to those losses arising at joints in the system, which are not significant, and that passing through the aperture  12  of the valve member  2  in the connector  37 . This provides a substantial flow restriction so that the pressure in the breathing circuit is maintained at a sufficient level that the ventilator does not substantially increase the gases flow into the expiratory circuit tube.