Nasal pressure cannula, adult

The pressure cannula does not measure a temperature, it measures a pressure. Airflow past its openings creates a depression proportional to the flow, and that signal, far finer than the thermal one, is what allows a partial flow reduction to be seen. In other words: a hypopnoea.

That is why the AASM made it the recommended sensor for hypopnoea, and why it is fitted in addition to the thermal sensor, not instead of it. The two channels work on different events.

Length is chosen on context. The 210 cm goes to the lab, where the polygraph sits away from the bed and the patient has to be able to turn over. The 60 cm is made for ambulatory work, where the recorder is worn on the belt or over the shoulder: two metres there would be just enough to tangle.

The Luer filter protects the polygraph pressure sensor. Nasal secretions travel up the tubing, and it is the transducer that eventually suffers. On an expensive device the integrated-filter versions are cheap insurance. Reference 15809 lets you add the filter to cannulas that do not have one.

The Nox-compatible version carries the fitting expected by Nox Medical polygraphs. The other references mount on standard Luer, which is what nearly every other system asks for.

All these cannulas are single use. They are in direct contact with the airway and are not reprocessed.