Nasal respiratory apparatus

A nasal respiratory apparatus comprising:

• an air chamber having a gas connection port, first and second nasal conduits, a nasal end tidal sample port, and an isolation wall, wherein:
• the gas connection port is configured to receive an externally supplied gas via a gas supply tube, the gas connection port being defined on a first wall of the air chamber;
• the first and second nasal conduits are in fluid communication with the gas connection port via the air chamber;
• the nasal end tidal sample port is defined on the first wall of the air chamber and is in fluid communication with both of the first nasal conduit and the second nasal conduit, the nasal end tidal sample port for receiving sample nasal gas from both the first nasal conduit and the second nasal conduit and the nasal end tidal sample port is for receiving sample nasal gas from one of a nasal conduit of the first and second nasal conduits and the nasal end tidal sample port configured to cause the sample nasal gas to exit the air chamber;
• and
• the isolation wall extends from the first wall of the air chamber toward an opposite and spaced apart wall of the air chamber, wherein the isolation wall is disposed between the gas connection port and the nasal end tidal sample port, wherein the isolation wall has a fixed end coupled to the first wall and a free end positioned within the air chamber, the free end being that is spaced apart from the first wall, the first and second nasal conduits, and the opposite and spaced apart wall of the air chamber, wherein a space between the free end and the nasal conduit that defines a flow path for the externally supplied gas to the first or the second nasal conduit during inhalation, and the isolation wall is configured to substantially prevent the externally supplied gas from entering the nasal end tidal sample port during exhalation.