Pneumatic single-lumen medical gas conserver

Abstract

A pneumatic single-lumen medical gas conserver combines the advantages of typical single-lumen and dual-lumen conservers. In particular, a pneumatic single-lumen conserver can provide a rapid response to patient inhalations without the need for a more expensive dual-lumen cannula hose. In addition, after delivering oxygen the conserver has a specific pneumatically-implemented delay period before being able to detect the next inhalation to inhibit “double pulse” deliveries. In addition to a conserving or pulse flow mode, the conserver can provide a user-selectable gas flow at a continuous or constant flow mode.

What is claimed is: 
     
         1 . A pneumatic gas conserver for providing a volume of gas, comprising:
 a supply port for receiving a flow of a gas;   a patient port for providing a flow of gas to a patient through a cannula;   a sensing valve configured to detect an inhalation in order to trigger delivery of the gas to the patient port; and   a check valve disposed between the sensing valve and the patient port, the check valve being configured to decouple the sensing valve from the patient port in response to the sensing valve detecting the inhalation.   
     
     
         2 . The gas conserver of  claim 1 , wherein the check valve decouples the sensing valve from the patient port before the gas is delivered to the patient port. 
     
     
         3 . The gas conserver of  claim 1 , wherein the decoupled sensing valve is gaseously isolated from the delivered gas. 
     
     
         4 . The gas conserver of  claim 1 , further comprising a gas regulator in gas communication with the supply port. 
     
     
         5 . A pneumatic gas conserver for providing a volume of gas, comprising:
 a patient port for coupling to a cannula;   a supply port for receiving a regulated flow of a gas;   a delivery valve disposed between the supply port and the patient port for controlling the flow of gas to the patient port;   a control valve configured to actuate the delivery valve;   a sensing valve in gas communication with the control valve and the patient port for detecting an inhalation to trigger the control valve to begin a delivery cycle; and   a check valve disposed between the sensing valve and the patient port for decoupling the sensing valve from the patient port in response to detection of the inhalation by the sensing valve.   
     
     
         6 . The gas conserver of  claim 5 , further comprising a gas regulator for providing the regulated flow of gas from a pressurized supply of the gas, the gas regulator in gas communication with the supply port. 
     
     
         7 . The gas conserver of  claim 6 , wherein the gas regulator provides a user selectable flow of gas from a plurality of flow settings. 
     
     
         8 . The gas conserver of  claim 5 , further comprising a user-operable flow valve for selecting between a pulse delivery mode and a constant flow mode. 
     
     
         9 . The gas conserver of  claim 8 , wherein the constant flow mode causes the flow of gas to bypass the delivery valve. 
     
     
         10 . The gas conserver of  claim 5 , wherein the control valve is tuned to provide a fixed delivery cycle. 
     
     
         11 . The gas conserver of  claim 10 , wherein the control valve includes an adjustable needle to vent gas. 
     
     
         12 . The gas conserver of  claim 10 , further comprising a timing orifice disposed in the gas flow path from the supply port to the control valve. 
     
     
         13 . The gas conserver of  claim 5 , wherein the sensing valve includes a flexible membrane. 
     
     
         14 . A pneumatic gas conserver for providing a volume of gas, comprising:
 a housing connectable to a supply of gas;   a gas flow regulator within the housing for providing a regulated flow of gas from the supply of gas, the regulated flow including a user-selectable flow rate from a plurality of selectable flow rates;   a patient port within the housing for providing gas communication to a patient;   a user-operable mode selector within the housing for providing the regulated flow of gas to the patient port at the selected flow rate in either a pulse flow mode or a constant flow mode; and   a pneumatic delivery circuit within the housing for receiving the regulated flow of gas and delivering the received flow to the patient port in accordance with the mode selector; and   wherein the pneumatic delivery circuit includes a check valve in mechanical communication with a control valve and disposed between a sensing valve and said patient port for decoupling the sensing valve from said patient port in response to detection of patient inhalation by the sensing valve.   
     
     
         15 . The conserver of  claim 14 , wherein the delivery circuit includes a delivery valve. 
     
     
         16 . The conserver of  claim 15 , wherein the regulated flow of gas bypasses the delivery valve when the mode selector is in the constant flow mode setting. 
     
     
         17 . The conserver of  claim 15 , wherein the regulated flow of gas travels through the delivery valve when the mode selector is in the constant flow mode setting.