Respiratory measurement system with continuous air purge

An analyzer module adapted for use with a patient respiratory system that includes a conduit through which the patient inhales and exhales a gas, the module comprising:

• a) a first tube adapted to be connected to the conduit;
• b) a second tube adapted to be connected to the conduit and spaced from the first tube;
• c) a pressure transducer connected to the first tube opposite the conduit;
• d) a differential pressure transducer connected to the second tube opposite the conduit and to the first tube opposite the conduit;
• e) a microprocessor operably connected to the pressure transducer and a differential pressure transducer, the microprocessor capable of calculating an airflow rate based on signals generated by the pressure transducer and the differential pressure transducer;
• and
• f) a continuous purge mechanism connected to the analyzer module, the mechanism including a low pressure gas source, and a third tube connected between the gas source and the first tube and the second tube, the third tube including a pair of resistors between the gas source and the first and second tube.

In a respiratory measurement system, a pneumatic subassembly for purging with a continuous stream of low pressure and low volume air lumen tubing connecting an air flow rate sensor to an analyzer module, the lumen tubing including at least a first lumen tube and a second lumen tube, said pneumatic subassembly comprising:

• a) an air pump and an air reservoir for producing a volume of relatively high pressure air;
• b) a first pneumatic resister pneumatically connected to the air pump and air reservoir and to the first lumen tube;
• and
• c) a second pneumatic resister pneumatically connected to the air pump and air reservoir and to the second lumen tube;
• whereby a small volume of air migrates from the volume of relatively high pressure air through the first and second resisters and into the lumen tubing.