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Capnography Assessment and Biofeedback

As part of your private consultation we offer a breathing assessment including capnography. Capnography is a biofeedback tool that measures a range of breathing parameters for diagnosing and unlearning dysfunctional breathing.


A thorough assessment of your breathing provides objective measurements as well as starting points for your own observations. We use tools like capnography and pulse oximetry for this purpose. Both help to show and measure breathing behaviour. In capnography, a device called a capnometer is connected to a computer and picks up information about your breathing via a nasal cannula.

Capnography Assessment

The client observes their breathing pattern in real time on the screen. A typical session lasts 30 minutes and will include assessment and training through bio-feedback. A pulse oximeter on the client’s left-hand records pulse and oxygen saturation.

In addition to parameters such as breathing rate and rhythm the capnometer measures end tidal carbon dioxide (EtCO2).  EtCO2 is the percentage of CO2 in the exhaled air and gives an approximation of the concentration in blood. An optimal level of CO2 in arterial blood is vital for delivering oxygen to every cell in the body. If CO2 levels are too low this can starve the body of oxygen. This is due to the vaso and bronco dilating properties of CO2 and the Bohr Effect .

Lower than normal levels can contribute to a wide range of disorders including, but not limited to asthma, allergies, allergic rhinitis, sleep apnoea, panic attacks, anxiety disorders, migraine headaches and hypertension.

In pulse oximetry, a small sensor is attached to your finger. This measures the pulse and O2 saturation in peripheral blood.  Combined, the two measurements of O2 and CO2 provide a near complete picture of breathing behaviour.

During an assessment your breathing may be tested in a variety of ways. This is so that we can establish how your breathing reacts to stimulus and if there is a breathing dysfunction. Dysfunctional breathing habits may be irregular breathing, like sighing or gasping, aborted breathing, deep inhales, among others. Some of these habits may only be detected using capnography.

The Capnogram

A capnogram is a visual representation of your breathing on a computer screen or print-out as provided by the capnometer. The concentration of CO2 is measured as partial pressure in mmHg (millimetres of mercury). Normal levels of CO2 are 35-45mmHg. Most physiology reference text books give a norm of 40mmHg. Dysfunctional breathing contributes to lower than normal CO2 levels. Excessive CO2 levels are uncommon unless the lungs have problems releasing air like during an asthma attack or in the case of COPD. 


Capnogram showing dysfunctional breathing pattern in a client with anxiety and moderate hypertension. The trace indicates a rapid irregular breathing pattern with 30 mm EtCO2 (normal is 35-45)

Pulse Oximetry

Pulse Oximetry

A finger-tip pulse oximeter showing O2 saturation (left-hand number) and pulse

Normal levels of O2 are 96-98% saturation. A 99-100% saturation may indicate a tendency for the haemoglobin to hold too tightly to oxygen so it is less likely to be released to cells. This is indicative of a breathing pattern characterised by over-breathing (hyperventilation). 


Biofeedback is the process of observing your body’s responses in real time with the help of technology. In this case, both capnography and pulse oximetry can allow you to observe your breathing behaviour in real time. This provides you with immediate and objective feedback while you are exploring how your body reacts to changes in your breathing. Learning to self-regulate your breathing happens very quickly in this way. Biofeedback can also be used to test that you are doing your breathing exercises correctly. 

Guided breathing using capnography is an exciting new tool for learning breathing behaviours to relieve and prevent symptoms of breathing-related disorders including asthma, allergies, allergic rhinitis, sleep apnoea, insomnia, panic attacks, anxiety disorders, migraine headaches and hypertension. 

Helping people with breathing disorders since 2001

20 Arthur Street, Freemans Bay, Auckland 1011, New Zealand  |  Phone +64 9 360 6291  |  Email

Download our leaflets [PDFs]:  Do you suffer from asthma or allergies? »    Do you snore or suffer from sleep apnoea? »

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