Transcutaneous capnography

Measurement of CO₂ in the blood to assess the quality of breathing. This examination takes place at the sleep centre.

A transcutaneous capnography is always performed in combination with a polysomnography or as part of a home ventilation check-up. You cannot book an appointment for this yourself.

Purpose of the examination

Measuring CO₂ in the blood is an efficient way to assess the quality of breathing.

When our body uses energy, it produces CO₂ as a waste product. This CO₂ is then expelled from the body through exhalation. However, if our breathing worsens, more CO₂ remains in the blood.

Why not a blood gas test?

  • The classic method for measuring CO₂ in the blood is the blood gas test. This involves taking blood from an artery in the wrist and analysing it.

    The result of this test gives the CO₂ value at a single point in time. However, at the sleep centre we want to assess this over a longer period, both with and without ventilation. We also want to avoid repeatedly pricking the patient.

Course of the examination

  • A small sensor is attached to the earlobe or chest and is connected via a wire to the capnograph.
  • The sensor is slightly heated so that CO₂ can pass through the skin and dissolve into the contact fluid.
  • The sensor can then measure the CO₂ in the blood.

The examination lasts between 30 minutes and 12 hours, depending on the information required.

This is painless, but the patient cannot walk around freely during the examination.

Last edit: 5 august 2025