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.

Assessment

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.

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. 

Pulse Oximetry

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 

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. 

Further Reading

Chaitow L, Bradley D, Gilbert C. Multidisciplinary Approaches to Breathing Pattern Disorders. Harcourt 2002. Ch 8.

Fried R, Grimaldi J. The Psychology and Physiology of Breathing. Springer Science and Business Media LLC 1993

Gravenstein et al. editors Capnography. Cambridge University Press, 2011

Jeter AM et al. Hypoventilation training for asthma: A case illustration. Springer Science and Business Media LLC 2011

Meuret AE et al. Feedback of End-tidal pCO2 as a Therapeutic Approach for Panic Disorder. Psychiatric Res. 2008 June; 42(7): 560–568

Raphael Kl et al. Bicarbonate Concentration, Acid-Base Status, and Mortality in the Health, Aging, and Body Composition Study. Clin J Am Soc Nephrology 11: 308–316, February 2016 Bicarbonate, Acid  

Ritz T et al. Controlling Asthma by Training of Capnometry-Assisted Hypoventilation (CATCH) vs Slow Breathing A Randomized Controlled Trial. CHEST 2014; 146 (5): 1237-1247.

Tolin DF et al. A multisite benchmarking trial of capnometry guided respiratory intervention for panic disorder in naturalistic treatment settings. Applied Psychophysiology Biofeedback (2017) 42:51–58