Apparatus for measuring properties of gases supplied to a patient

Abstract

The gases temperature supplied to a patient when the patient is undergoing treatment such as oxygen therapy or positive pressure treatment for conditions such as Obstructive Sleep Apnea (OSA) or Chronic Obstructive Pulmonary Disease (COPD) is often measured for safety and to enable controlling of the humidity delivered to the patient. The invention disclosed is related to measurement of properties, particularly temperature (thermistor), of gases flowing through a heated tube, supplying gases to a patient, which utilises the heating wire within the tube.

1 . (canceled) 
     
     
         2 . A delivery tube for supplying a flow of gases from a gases supply to a patient, the delivery tube comprising:
 a wall defining a lumen;   a heater wire provided within or around the delivery tube and extending at least a portion of a length of the delivery tube;   an electrical circuit configured to determine at least one property of the flow of gases, the electrical circuit comprising a temperature sensor and a diode, the temperature sensor and the diode being connected in parallel; and   a printed circuit board, the temperature sensor being positioned on the printed circuit board and being connected with the heater wire, wherein:
 at least a portion of the electrical circuit is located within the delivery tube; 
 at least one portion of the printed circuit board is positioned in the path of the flow of gases in the lumen, the temperature sensor being positioned on said at least one portion of the printed circuit board; and 
 the printed circuit board is positioned at or near a first end of the delivery tube, the first end being nearest the patient. 
   
     
     
         3 . The delivery tube of  claim 2 , wherein the tube is configured to connect to a humidifier or blower device. 
     
     
         4 . The delivery tube of  claim 2 , wherein the temperature sensor is a thermistor. 
     
     
         5 . The delivery tube of  claim 2 , wherein:
 when a heating voltage is applied to the heater wire, the diode conducts current flow through the heating element which provides heating to the delivery tube; and/or   when a measurement voltage is applied, a current in the heater wire does not flow through the diode but does flow through the temperature sensor.   
     
     
         6 . The delivery tube of  claim 2 , wherein the at least one portion of the printed circuit board is overmoulded with plastic for sealing and mounted in the flow of gases through the delivery tube. 
     
     
         7 . The delivery tube of  claim 2 , wherein temperature sensor is in series with the heater wire. 
     
     
         8 . The delivery tube of  claim 2 , wherein the temperature sensor is positioned at or near a radial center of the lumen. 
     
     
         9 . A respiratory therapy system configured to provide respiratory gases to a patient to treat one or more respiratory conditions of the patient, the respiratory therapy system comprising:
 a blower;   a humidifier in fluid communication with the blower to receive a flow of gases from the blower and the humidifier configured to humidify the flow of gases; and   a delivery tube in fluid communication with the humidifier and configured to convey the flow of gases to the patient, wherein the delivery tube is a tube.   
     
     
         10 . A delivery tube for supplying a flow of gases from a gases supply to a patient, the delivery tube comprising:
 a wall defining a lumen;   a heater wire provided within or around the delivery tube and extending at least a portion of a length of the delivery tube;   an electrical circuit connected to the heater wire, the heater wire being utilised within the electrical circuit to determine a temperature of the flow of gases, the electrical circuit being configured to provide a signal to a controller through the heater wire indicative of the temperature of the flow of gases;   a portion of the electrical circuit being located within tube;   the electrical circuit includes a temperature sensor for measuring a temperature of the gases flow, the temperature sensor being coupled to the heater wire;   the temperature sensor located at a patient end of the tube; and   a moulding enclosing at least the temperature sensor, and the moulding extending into a region conveying the stream of gases through the conduit.   
     
     
         11 . A conduit as per  claim 10 , wherein the electrical circuit comprises a temperature sensor arranged in series with the heater wire. 
     
     
         12 . A conduit as per  claim 10 , wherein the overmolding comprises a housing protruding from a wall of the conduit into the stream of gases. 
     
     
         13 . A conduit as per  claim 10 , wherein the electrical circuit is positioned on a printed circuit board, and wherein the overmolding encloses at least part of the printed circuit board; and the printed circuit board at least partially extends into the flow of gases supplied to the patient through the. 
     
     
         14 . A conduit as per  claim 13 , wherein the electrical circuit comprising a temperature sensor and a diode, the temperature sensor and the diode being connected in parallel, wherein the temperature sensor is positioned on a printed circuit board; and
 wherein the printed circuit board is positioned at or near a first end of the delivery tube, the first end being nearest the patient; and wherein at least one portion of the printed circuit board is positioned in the path of the flow of gases in the lumen, the temperature sensor being positioned on said at least one portion of the printed circuit board.   
     
     
         15 . A respiratory therapy system configured to provide respiratory gases to a patient to treat one or more respiratory conditions of the patient, the respiratory therapy system comprising:
 a gases supply for providing a stream of gases;   a blower;   a humidifier in fluid communication with the blower to receive a flow of gases from the blower and the humidifier configured to humidify the flow of gases;   a conduit configured to connect to the gases supply and to deliver the flow of gases to the patient;   a nasal cannula removably connectable to the conduit, wherein the flow of gases are delivered to the patient from the conduit via the nasal cannula;   a heater wire located throughout a length of the conduit;   an electrical circuit connected to the heater wire, the heater wire being utilised to determine at least one property of the flow of gases, the electrical circuit being configured to provide a signal to a controller through the heater wire indicative of the at least one property of the flow of gases wherein:
 the controller is configured to determine the at least one property of the flow of gases, at least a portion of the electrical circuit being configured to be positioned within the flow of gases; and 
 an overmolding enclosing at least part of the electrical circuit, the overmolding extending into a region conveying the flow of gases through the conduit. 
   
     
     
         16 . The respiratory therapy system of  claim 15 , wherein the overmolding comprises a housing protruding from a wall of the conduit into the stream of gases. 
     
     
         17 . The respiratory therapy system of  claim 15 , wherein:
 the electrical circuit is positioned on a printed circuit board, and wherein the overmolding encloses at least part of the printed circuit board; and   the printed circuit board at least partially extends into the flow of gases supplied to the patient through the conduit.   
     
     
         18 . The respiratory therapy system of  claim 15 , wherein the electrical circuit is configured to measure at least one of temperature, pressure, gas composition, or humidity of the flow of gases. 
     
     
         19 . The respiratory therapy system of  claim 15 , the electrical circuit comprising a temperature sensor and a diode, the temperature sensor and the diode being connected in parallel, wherein the temperature sensor is positioned on a printed circuit board. 
     
     
         20 . The respiratory therapy system of  claim 15 , wherein the printed circuit board is positioned at or near a first end of the delivery tube, the first end being nearest the patient; and wherein at least one portion of the printed circuit board is positioned in the path of the flow of gases in the lumen, the temperature sensor being positioned on said at least one portion of the printed circuit board.