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?
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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.