Respiratory gas supply apparatus and method

A mehtod for supplying supplemental respiratory gas through a single hose cannula to an in vivo respiratory system, comprising the steps of:

• A. connecting a means for sensing pressure to the cannula hose to measure pressure within the cannula hose;
• B. monitoring the pressure within the cannula hose until a time, t.sub.0, of an initial occurrence of a pressure less than atmospheric pressure;
• C. determining the rate of change of pressure at the time t.sub.O ;
• D. at a time t.sub.1, not prior to time t.sub.O, disconnecting the pressure sensing device from the cannula hose;
• E. waiting a predetermined period of time .DELTA. t.sub.1, until a time t.sub.1 ';
• F. at time t.sub.1 ', connecting a source of supplental gas to the cannula hose to begin a supplemental gas administration interval of providing supplemental gas to the in vivo respiratory system;
• G. continuing to provide supplemental gas to the in vivo system for a time interval .DELTA. t.sub.sup, based upon the rate of change of pressure determined in step C, in accordance with a predetermined relation, until a time t.sub.2 ;
• H. at time t.sub.2, disconnecting the source of supplemental gas from the cannula hose to end the supplemental gas administration interval;
• I. waiting a predetermined period of time .DELTA. t.sub.2 after time t.sub.2, until a time t.sub.2 ';
• J. at time t.sub.2 ', reconnecting the pressure sensing means to the cannula hose to again monitor the pressure within the cannula hose;
• and,
• K. successively repeating steps A through J a plurality of times to provide supplemental gas to the in vivo respiratory system on a continuing basis.

A method for supplying supplemental respiratory gas through a single hose cannula to an in vivo respiratory system, comprising the steps of:

• A. connecting a means for sensing pressure to the cannula hose to measure pressure within the cannula hose;
• B. monitoring the pressure within the cannula hose until a time, t.sub.O, of an initial occurrence of a pressure less than atmospheric pressure;
• C. waiting a predetermined period of time, .DELTA. t.sub.c, until a time t.sub.1 ;
• D. determining the magnitude of a pressure, P.sub.1, occuring within the cannula hose during the time .DELTA.t.sub.c ;
• E. at time t.sub.1, disconnecting the pressure sensing means from the cannula hose;
• F. at a time t'.sub.1, not prior to time t.sub.1, connecting a source of supplemental gas to the cannula hose to begin a supplemental gas administration interval of providing supplemental gas to the in vivo respiratory system;
• G. continuing to provide supplemental gas to the in vivo system for a time interval .DELTA. t.sub.sup, based upon the value P.sub.1 in accordance with a predetermined relation, until a time t.sub.2 ;
• H. at time t.sub.2, disconnecting the source of supplemental gas from the cannula hose to end the supplemental gas administration interval;
• I. at time t.sub.2 ', reconnecting the pressure sensing means to the cannula hose to again monitor the pressure within the cannula hose;
• and,
• J. successively repeating steps A through I a plurality of times to provide supplemental gas to the in vivo respiratory system on a continuing basis.

A method for supplying supplemental respiratory gas through a single hose cannula to an in vivo respiratory system, comprising the steps of:

• A. connecting a means for sensing pressure to the cannula hose to measure pressure within the cannula hose;
• B. monitoring the pressure within the cannula hose until a time, t.sub.O, of an initial occurrence of a pressure less than atmospheric pressure;
• C. waiting a predetermined period of time, .DELTA. t.sub.c, after time t.sub.O, until a time t.sub.1 ;
• D. determining the magnitude of a pressure, P.sub.1, occurring within the cannula hose during the time .DELTA.t.sub.c ;
• E. at time t.sub.1, disconnecting the pressure sensing device from the cannula hose;
• F. at time t.sub.1 ', connecting a source of supplemental gas to the cannula hose to begin a supplemental gas administration interval of providing supplemental gas to the in vivo respiratory system;
• G. continuing to provide supplemental gas to the in vivo system for a time interval .DELTA. t.sub.sup, based upon the value P.sub.1 in accordance with a predetermined relation, after t.sub.1 ', until a time t.sub.2 ;
• H. at time t.sub.2, disconnecting the source of supplemental gas from the cannula hose to end the supplemental gas administration interval;
• I. at a time t'.sub.2 ;
• not prior to time t.sub.2, reconnecting the pressure sensor device to the cannula hose to again continuously monitor the pressure within the cannula hose;
• and,
• J. sucessively repeating steps A through I a plurality of times to provide supplemental gas to the in vivo respiratory system on a continuing basis.

A method for controlling the supply of a supplemental respiratory gas through a single hose cannula to an in vivo respiratory system, comprising the steps of:

• A. connecting a means for sensing pressure to the cannula hose to measure pressure within the cannula hose;
• B. monitoring the pressure within the canula hose until a time, t.sub.0, of an initial occurrence of a pressure less than atmospheric pressure;
• C. at time t.sub.1, not prior to t.sub.0, disconnecting the pressure sensing device from the cannula hose;
• D. at a time t.sub.1 ', not prior to t.sub.1, connecting a source of supplemental gas to the cannula hose to begin a supplemental gas administration interval of providing supplemental gas to the in vivo respiratory system;
• E. continuing to provide supplemental gas to the in vivo system for a time interval .DELTA.t.sub.sup, until a time t.sub.2 ;
• at time t.sub.2, disconnecting the source of supplemental gas from the cannula hose to end the supplemental gas administration interval;
• H. waiting a predetermined period of time .DELTA.t.sub.2, until a time t.sub.2 ';
• I. successively repeating the steps A through H a plurality of times to provide supplemental gas to the in vivo system on a continuing basis.

An apparatus for supplying supplemental respiratory gas from a gas source through a single hose cannula to an in vivo respiratory system during successive respiratory cycles, each cycle beginning with a respiratory demand by the in vivo respiratory system characterized by a negative pressure occurrence at an interface between the cannula hose and the in vivo system, comprising:

• means for sensing pressure and generating a pressure indicative signal representative of the magnitude of the pressure sensed;
• alternative communication means responsive to first control signals to switch between two alternative modes, a first mode communicating said pressure sensing means with the cannula hose so that a pressure with in the hose can be monitored and a second mode communicating said pressure sensing means with ambient atmospheric pressure;
• means for connecting the apparatus to a source of supplemental gas;
• valve means responsive to second control signals to switch between two alternative positions, said valve means isolating the source of supplemental gas from the cannula hose when in the first position and allowing supplemental gas from the source to flow into the cannula hose when in the second position;
• control means, including timing means, for receiving said pressure indicative signal and selectively generating said first and second control signals, said control means responsive to initiation of operation of the apparatus to generate said first control signal to place said alternative communication means in said first mode and said second control signal to place said valve means in said first position to cause said pressure sensing means to sense a pressure within the cannula hose, said control means thereafter receiving said pressure indicative signal and generating said first and second control signals in accordance with said pressure indicative signal, said control means responsive to initial reception of a pressure indicative signal indicative of a pressure less than atmospheric pressure, at a time t.sub.0, to initiate a sequential, supplemental-gas-administration cycle by generating a firt control signal at a time t.sub.1, a predetermined time interval .DELTA. t.sub.c after time t.sub.O, to switch said alternative communication means to its second mode;
• generating a second control signal at a time t.sub.1 ', a predetermined time interval .DELTA. t.sub.1 after time t.sub.1, to switch said valve means from said first position to said second position to begin an interval of supplemental respiratory gas administration;
• generating said second control signal at a time t.sub.2, a time interval .DELTA. t.sub.sup after time t.sub.1 ', to switch said valve means from the second position to the first position to end the interval of supplemental gas administration and thereby define a period of supplemental gas administration, .DELTA.t.sub.sup ;
• generating a first control signal, at a time t.sub.2 ', a predetermined time interval .DELTA. t.sub.2 after time t.sub.2, to switch said alternative communication means to its first mode to communicate the pressure sensing means with the cannula hose and allow said pressure sensing means to generate a pressure indicative signal indicative of the pressure within the cannula hose;
• said control unit thereafter responsive to said pressure indicative signal to initiate continuing, successive, supplemental-gas-administration cycles in response to demand by the in vivo respiratory system.

An apparatus for supplying supplemental respiratory gas through a single hose cannula to an in vivo respiratory system comprising:

• means for sensing pressure and generating a pressure indicative signal representative of the magnitude of the pressure sensed;
• means for providing alternative fluid communication, said alternative communication means having two modes, a first mode in which said alternative communication means provides fluid communication between said pressure sensing means and an interior portion of the cannula hose so that said pressure sensing means senses a pressure in the portion of the cannula hose and generates a pressure signal indicative thereof, and a second mode in said alternative communication means provides fluid communication between said pressure sensing means and an ambient atmosphere so that said pressure sensing means generates a pressure indicative signal indicative of ambient atmospheric pressure, said alternative communication means responsive to a first and second control signal to switch to the first and second mode, respectively;
• means for controlling a flow of supplemental gas, said gas flow control means in fluid communication with a source of supplemental respiratory gas and having two positions, a first position in which said flow control means isolates the supplemental gas source from the cannula hose and a second position in which said gas flow control means provides fluid communication between the gas source and the cannula hose so that supplemental respiratory gas flows into the cannula hose, said gas flow control means responsive to a third and fourth control signal to switch to the first and second position, respectively;
• means for receiving said pressure indicative signal, determining when said pressure indicative signal is indicative of a negative pressure less than atmospheric pressure, and, upon receiving such a negative pressure indicative signal, generating a cycle signal continuously until its termination at the end of a cycle time interval;
• means for controlling the mode of said flow control means in response to said cycle signal, said mode control means operative to receive said cycle signal and generate said third and fourth control signals in such a manner as to switch said flow control means in the second position and maintain said flow control means in said second position continuously from a time said cycle signal is initially generated until a gas disconnect time following the time of initial generation of said cycle signal by a predetermined gas-connect-delay interval, switching said flow control means from said first position to said second position at said gas connect time and maintaining said flow control means in said second position continuously while said cycle signal continues to be generated over a remainder of the cycle time interval, and upon the termination of said cycle signal, switching said flow control means from the second position to the first position and maintain said flow control means in the second position until said cycle signal is again generated;
• and
• means for controlling the mode of said alternative communication means in response to said cycle signal, said mode control means operative to receive said cycle signal and to generate said first and second control signals in such a manner as to switch said alternative communication means from the first mode to the second mode immediately upon generation of said cycle signal and to continuously maintain said alternative communication means in said second position while said cycle signal is generated over the cycle time interval and for an additional predetermined fixed sensor-connect-delay interval, and thereafter switching said alternative communication means to the first mode and maintaining said flow control means in the first mode continuously until the cycle signal is again generated.

In a supplemental respiratory gas supply apparatus for providing supplemental respiratory gas to an in vivo respiratory system through a cannula hose in response to demands of the in vivo system characterized by an occurrence of negative pressure at a point of interface between the cannula hose and the in vivo system, the system having a means for sensing pressure within the cannula hose, a source of supplemental respiratory gas and a control means, said control means operational to connect said gas source to the cannula hose to introduce supplemental gas into the hose over periods of supplemental gas supply intervals and to disconnect said source from said hose to end the duration of supply intervals, a method of control comprising the steps of;

• monitoring the pressure within the cannula hose to detect an initial occurrence of negative pressure;
• determining the largest magnitude of negative pressure occurring over a sample period following said initial occurrence of negative pressure;
• and
• thereafter introducing supplemental gas into the hose for a supply interval of a duration determined by said largest magnitude of negative pressure.

A method for controlling a supplemental respiratory gas supply apparatus for providing supplemental respiratory gas to an in vivo respiratory system through a cannula hose in response to demands of the in vivo system characterized by an occurrence of negative pressure at a point of interface between the cannula hose and the in vivo system, the system having a means for sensing pressure within the cannula hsoe, a source of supplemental respiratory gas and a control means, said control means operational to connect said gas source to the cannula hose, to introduce supplemental gas into the hose over periods of supplemental gas supply intervals and to disconnect said source from said hose to end the duration of supply intervals, comprising the steps of;

• monitoring the pressure within the cannula hose to detect an initial occurrence of negative pressure;
• determining the rate of change of pressure at the time of said initial occurrence;
• and,
• thereafter introducing supplemental gas into the hose for a supply interval of a duration determined by said rate of charge of pressure.

A method for controlling a supplemental respiratory gas supply apparatus for providing supplemental respiratory gas to an in vivo respiratory system through a cannula hose in response to demands of the in vivo system characterized by an occurrence of negative pressure at a point of interface between the cannula hose and the in vivo system, the system having a means for sensing pressure within the cannula hose, a source of supplemental respiratory gas and a control means, said control means operational to connect said gas source to the cannula hose to introduce supplemental gas into the hose over periods of supplemental gas supply intervals and to disconnect said source from said hose to end the duration of supply intervals, comprising the steps of;

• monitoring the pressure within the cannula hose to detect an initial occurrence of negative pressure;
• determining the magnitude of an instant pressure occurring within the hose at a predetermined time after said initial occurrence;
• and
• thereafter introducing supplemental gas into the hose for a supply interval which is determined by the magnitude of said pressure.