Dyspnea on Exertion (Exertional Dyspnea): Causes and Treatment

Exertional dyspnea and its pathophysiology

Man with dyspnea and chest painDyspnea on exertion is caused by various factors. However, low body oxygenation is the key parameter, which is always present in people with this symptom. Mouth breathing and chest breathing are among the main additional causes of exertional dyspnea since they reduce body and brain oxygenation and create the sensation of air hunger (shortage of air) like in people with heart disease and cancer. However, those who have diabetes or COPD (e.g., asthma or bronchitis) and many other chronic conditions are also most likely to experience this debilitating symptom, as many studies found.

What do we know about their body oxygenation and breathing at rest? Why do people with chronic diseases, but not healthy people, experience exertional dyspnea? What are the main problems with oxygen transport in the sick? Consider this evidence.

Minute ventilation rates (chronic diseases)

Condition Minute
Number of
All references or
click below for abstracts
Normal breathing 6 L/min - Medical textbooks
Healthy Subjects 6-7 L/min >400 Results of 14 studies
Heart disease 15 (+-4) L/min 22 Dimopoulou et al, 2001
Heart disease 16 (+-2) L/min 11 Johnson et al, 2000
Heart disease 12 (+-3) L/min 132 Fanfulla et al, 1998
Heart disease 15 (+-4) L/min 55 Clark et al, 1997
Heart disease 13 (+-4) L/min 15 Banning et al, 1995
Heart disease 15 (+-4) L/min 88 Clark et al, 1995
Heart disease  14 (+-2) L/min 30 Buller et al, 1990
Heart disease 16 (+-6) L/min 20 Elborn et al, 1990
Pulm hypertension 12 (+-2) L/min 11 D'Alonzo et al, 1987
Cancer 12 (+-2) L/min 40 Travers et al, 2008
Diabetes 12-17 L/min 26 Bottini et al, 2003
Diabetes 15 (+-2) L/min 45 Tantucci et al, 2001
Diabetes 12 (+-2) L/min 8 Mancini et al, 1999
Diabetes 10-20 L/min 28 Tantucci et al, 1997
Diabetes 13 (+-2) L/min 20 Tantucci et al, 1996
Asthma 13 (+-2) L/min 16 Chalupa et al, 2004
Asthma 15 L/min 8 Johnson et al, 1995
Asthma 14 (+-6) L/min 39 Bowler et al, 1998
Asthma 13 (+-4) L/min 17 Kassabian et al, 1982
Asthma 12 L/min 101 McFadden, Lyons, 1968
COPD 14 (+-2) L/min 12 Palange et al, 2001
COPD 12 (+-2) L/min 10 Sinderby et al, 2001
COPD 14 L/min 3 Stulbarg et al, 2001
Sleep apnea 15 (+-3) L/min 20 Radwan et al, 2001
Liver cirrhosis 11-18 L/min 24 Epstein et al, 1998
Hyperthyroidism 15 (+-1) L/min 42 Kahaly, 1998
Cystic fibrosis 15 L/min 15 Fauroux et al, 2006
Cystic fibrosis 10 L/min 11 Browning et al, 1990
Cystic fibrosis* 10 L/min 10 Ward et al, 1999
CF and diabetes* 10 L/min 7 Ward et al, 1999
Cystic fibrosis 16 L/min 7 Dodd et al, 2006
Cystic fibrosis 18 L/min 9 McKone et al, 2005
Cystic fibrosis* 13 (+-2) L/min 10 Bell et al, 1996
Cystic fibrosis 11-14 L/min 6 Tepper et al, 1983
Epilepsy 13 L/min 12 Esquivel et al, 1991
CHV 13 (+-2) L/min 134 Han et al, 1997
Panic disorder 12 (+-5) L/min 12 Pain et al, 1991
Bipolar disorder 11 (+-2) L/min 16 MacKinnon et al, 2007
Dystrophia myotonica 16 (+-4) L/min 12 Clague et al, 1994

Note that advanced stages of asthma can lead to lung destruction, ventilation-perfusion mismatch,
and arterial hypercapnia causing further reduction in body oxygen levels.

Medical people Chronic hyperventilation (or having an automatic deep-breathing pattern) leads to alveolar hypocapnia (lack of CO2), which causes low oxygen levels in body cells. Therefore, these people have more problems during physical exertion since any forms of exercise require additional oxygen, causing dyspnea on exertion.

Healthy or normal breathing is very small and slow. It is imperceptible or unperceivable (only about 500 ml for tidal volume, and 10-12 breaths/min with 6 L/min for minute ventilation at rest for a 70-kg person). Patients with dyspnea commonly have over 12 L/min (double the norm) for their ventilation rates at rest and over 18 breaths/min for respiratory frequency.

Overbreathing leads to greatly increased work of breathing due to large minute ventilation rates and causes many other adverse effects, apart from exertional dyspnea.

Causes of exertional dyspnea

Exacerbating causes in the pathophysiology of exertional dyspnea are:
- oral breathing (due to reduction in NO or nitric oxide absorption and alveolar CO2)
- thoracic breathing (due to reduction in the arterial oxygenation causing hypoxemia)
- presence of chronic inflammation and sputum in airways, causing further narrowing or obstruction of air movement.

Older man with dyspnea on exertion due to exercise Physical exertion, due to anaerobic cell respiration at rest and elevated resting blood lactate, worsens gas exchange and causes further overbreathing and additional losses in alveolar CO2. This leads to acute exertional dyspnea/dyspnea.php'> -->dyspnea. Acute dyspnea leads to even heavier and faster breathing due to a negative feedback in breathing control caused by a prominent O2 drive (hunger for air), instead of normal CO2-based control of respiration. Respiratory receptors located in the brain sense low brain oxygenation, creating the sensation of air hunger and trying to increase ventilation.

Treatment of dyspnea on exertion

This YouTube video clip "Dyspnea" explains causes and treatment of dyspnea in people with chronic diseases.

Significant reduction in exertional dyspnea has been found in numerous clinical trials after the application of various breathing techniques -->breathing patterns devices that gradually change automatic (basal) breathing patterndyspneast, reduce the degree of hyperventilation, and increase body-oxygen levdyspneanerally, patients with exertional dyspnea need to achieve more than 20 s for the body-oxygen test to prevent dyspnea at rest and on exertion.

Get flash player to play to this file

Ripamonti C. Management of dyspnea in advanced cancer patients. Support Care Cancer. 1999; 7: p. 233-243.
"Dyspnea has been defined as an “uncomfortable awareness of breathing"

Coyne PJ, Viswanathan R, Smith TJ, Nebulized fentanyl citrate improves patients' perception of breathing, respirdyspneaate, and oxygen saturation in dyspnea, J Pain Symptom Manage 2002; 23: p. 157–160.
“Dyspnea is exceedingly common. Ruben and Mor found that 70% of 1500 cancer patients suffered dyspnea during their last four weeks of life.”

Reuben DB, Mor V, How much of a problem is dyspnoea in advanced cancer? Palliat Med 1991; 5: 20–26.
“Introduction. Although a number of articles on dyspnoea in terminal cancer have appeared, [1-8] in terms of publications, this symptom remains a poor relation when compared with pain. Anyone, however, who has looked after dying people will be aware that dyspnoea is a common and often distressing symptom, particularly if severe. In such cases patients may feel that they may die from lack of air - even pain does not have this connotation. This is demonstrated in Comroe’s definition of dyspnoea as ’difficult, laboured, uncomfortable breathing; it is an unpleasant type of breathing, though it is not painful in the usual sense of the word. It is subjective, and, like pain, it involves both perception of the sensation by the patient and his reaction to the sensation.”

Dudgeon DJ, Managing dyspnea and cough, Hematol Oncol Clin North Am 2002 Jun; 16(3): p.557-577.
"Dyspnea, like pain, is a subjective experience that incorporates physical elements and affective components. Management of breathlessness in patients with cancer requires expertise that includes an understanding and assessment of the multidimensional components of the symptom, knowledge of the pathophysiologic mechanisms and clinical syndromes that are common in cancer, and familiarity with the indications and limitations of the available therapeutic approaches. Relief of breathlessness should be the goal of treatment at all stages of cancer. Good control of dyspnea will improve the patient's quality of life." 

Or go to Hyperventilation Symptoms

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