Re-breathing apparatus for non-invasive cardiac output, method of operation, and ventilator circuit so equipped

A re-breathing apparatus comprising:

• a gas reservoir comprising:
• a first chamber, said first chamber being adapted to contain gas, having a variable volume, and having at least one outlet through which said gas may flow as said volume is increased or decreased;
• a second chamber, said second chamber being adapted to contain gas, having a variable volume, and having at least one outlet through which said gas may flow as said volume is increased or decreased;
• a drive mechanism to increase the volume of one of said first and second chambers by a specified amount and decrease the volume of the other said chamber by substantially said specified amount;
• and
• a diverting adapter comprising:
• a main flow passage having a first end and a second end,
• a first diverting passage communicating with said first chamber and said main flow passage;
• and
• a second diverting passage communicating with said second chamber and said main flow passage;
• wherein said main flow passage of said diverting adapter is configured to communicate with a primary respiratory path of a breathing circuit at said first and second ends thereof.

A breathing circuit comprising:

• a primary respiratory path configured for communication with a patient;
• an inspiratory hose communicating with said primary respiratory path, through which fresh gases may be provided to said patient;
• an expiratory hose communicating with said primary respiratory path, through which expired gases may be vented away from said patient;
• a dual-chamber reservoir comprising a first chamber adapted to contain gases and a second chamber adapted to contain gases;
• a diverting adapter comprising a main flow passage, a first diverting passage communicating with said first chamber and said main flow passage, and a second diverting passage communicating with said second chamber and said main flow passage, said main flow passage of said diverting adapter disposed in communication with said primary respiratory path;
• and
• a drive mechanism;
• wherein said first and second chambers are operable in response to said drive mechanism to increase a volume of one of said first and second chambers by an amount and substantially simultaneously decrease a volume of the other of said first and second chambers by substantially said amount.

A diverting airway adapter for use in a re-breathing circuit, comprising:

• main flow passage having a first end and a second end;
• a first diverting passage for communicating between said main flow passage and a first chamber of a gas reservoir system of a re-breathing circuit;
• and
• a second diverting passage for communicating between said main flow passage and a second chamber of said gas reservoir system of said re-breathing circuit;
• wherein said diverting airway adapter is configured for connection into a primary respiratory path of said re-breathing circuit at said first and second ends of said main flow passage, wherein said first diverting passage provides for a flow of gases between said primary respiratory path and a first re-breathing circuit connection to said first chamber, and wherein said second diverting passage provides for a flow of gases between said primary respiratory path and a second re-breathing circuit connection to said second chamber.