Breathing circuit with embedded acoustic reflectometer

An instrument for continuously monitoring acoustic reflections from within and/or beyond an intubation tube positioned within the mouth of a patient while the patient is breathing comprising:

• an acoustic reflectometer configured to detect the acoustic reflections;
• an acoustic flow channel containing the acoustic reflectometer within it, the acoustic flow channel being configured to acoustically couple the acoustic reflectometer to an end of the intubation tube, but to substantially block the free flow of expiratory gas from the end of the intubation tube through the acoustic flow channel, wherein the end of the intubation tube and the acoustic flow channel share a central axis;
• a gas flow channel that is separate from the acoustic flow channel and that is configured to allow the free flow of expiratory gas from the end of the intubation tube through the gas flow channel;
• a gas valve configured to:
• block expiratory gas from flowing from the end of the intubation tube into the acoustic flow channel when in a closed position;
• and
• not cause a substantial disruption in acoustic energy traveling from the acoustic reflectometer within the acoustic gas channel into the end of the intubation tube when in an open position;
• a gas flow sensor configured to sense the flow of gas through the end of the intubation tube;
• and
• a gas valve controller configured to control the gas valve and to cause the gas valve to be in the closed position when the gas flow sensor detects the flow of expiratory gas from the end of the intubation tube.