Breathlessness Causes, Reasons, and Solutions

Breathlessness is a sensation of air hunger and an uncomfortable awareness of one's own breathing at rest or on exertion due to low oxygenation of tissues and the negative feedback of the respiratory receptors in the human brain. Other similar terms are "dyspnea" and "shortness of breath". Breathlessness and labored breathing are common in people with chronic diseases, such as advanced diabetes, cancer, cystic fibrosis, HIV-AIDS, heart disease, COPD, bronchitis, and many other conditions. It can appear on exertion, after meals, during night sleep, or at pregnancy.

Causes of breathlessness

There are many contributing reasons that can lead to breathlessness. However, in cases of chronic diseases, there are 3 main causes of breathlessness that relate to mouth breathing, chest breathing and ineffective breathing patterns. This last cause plays the central role since its elimination leads to disappearance of breathlessness. Consider these clinical results.

Minute ventilation rates (chronic diseases)

Condition	Minute ventilation	Number of people	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
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
Cancer	12 (±2) l/min	40	Travers et al, 2008
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
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
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
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
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

In all these cases, breathlessness is caused by chronic hyperventilation (or an automatic deep breathing pattern) leading to alveolar hypocapnia (lack of CO2) and cell hypoxia, which creates air hunger and provokes the respiratory center to further intensify breathing.

Breathing of healthy people is small: only 500 ml for tidal volume, 10-12 breaths/min for the respiratory rate, and 6 L/min for minute ventilation for a 70-kg person). But patients with breathlessness and labored breathing have over 12 L/min (more than double the norm) for their ventilation rates and over 18 breaths/min for respiratory frequency. That causes constriction of airways and hypoxic and tense respiratory muscles.

What causes breathlessness on exertion?

Exertion increases minute ventilation rates and this causes losses in alveolar CO2. Hypocapnia either worsens ventilation-perfusion ratio (in case of lung problems) or immediately constricts arterial blood vessels, causing reduced oxygen delivery to all vital organs. In both cases, increased breathing reduces oxygen transport to tissues. Breathlessness on exertion is particularly strong in cases of mouth breathing that leads to more losses in CO2 and additional losses in absorption of nasal nitric oxide.

Chest breathing is another crucial factor that leads to chronic breathlessness due to drastic reduction in blood oxygenation, sometimes leading to hypoxemia.

What causes breathlessness after eating

The main physiological effect of meals and eating is also increased ventilation due to biochemical stress caused by food substances that require assimilation and redistribution. Increased respiratory volumes cause the same effects as it is described above for exertional dyspnea.

Why anxiety, night sleep, and pregnancy trigger breathlessness

Overbreathing is a normal physiological reaction to stress. As a result of stress and anxiety, the human body has reduced oxygenation of cells and diminished carbon dioxide in the lungs. Transition into a horizontal position also results in lowered alveolar CO2, leading to decreased cellular oxygen tensions. Numerous studies proved that end-tidal CO2 is lowered in pregnancy, causing the same effects as described above.

As a result, in all these cases, the main physiological mechanism remains the same: all these factors increase minute ventilation rates, causing reduced oxygen levels in body cells.

The main causes of breathlessness and labored breathing (why it is hard to breathe):
- constriction of airways due to hypocapnia in the airways
- reduced oxygen levels in the diaphragm and chest muscles due to reduced oxygen transport
- tense states in the diaphragmatic and chest muscles due to arterial hypocapnia.

Exacerbating reasons in the pathophysiology of labored breathing and breathlessness are:
- mouth breathing (due to reduction in nitric oxide absorption and alveolar CO2)
- chest breathing (due to reduction in arterial oxygenation)
- presence of inflammation and mucus in airways, causing further narrowing or an obstruction of air flow (as in COPD).

This YouTube video explains the main causes and successful treatment of breathlessness or shortness of breath.

Exertion, mouth breathing, physical exercise with mouth breathing, chest breathing, meals (eating and especially overeating), overheating, anxiety, stress, attempts to inhale deeply, deep breathing exercises with CO2 losses, poor posture, night sleep and many other factors are known causes of hyperventilation. Hence, they worsen breathlessness and labored breathing.

Successful treatment of breathlessness

Over 160 Russian medical doctors tested thousands of people with breathlessness and labored breathing and found that all of them had less than 20 seconds for the body-oxygen test. These doctors also discovered that breathing normalization (achieving normal breathing parameters) leads to complete elimination of breathlessness and labored breathing with air hunger.

As their clinical experience revealed, with over 20 s for the body-oxygen test, patients do not experience these negative symptoms. This result has been achieved in many clinical trials after the application of various breathing therapies and devices (the Buteyko method, Frolov breathing device therapy, and others).

Reference pages: Breathing norms and medical facts:
- Breathing norms: Parameters, graph, and description of the normal breathing pattern
- 6 breathing myths: Myths and superstitions about breathing and body oxygenation (prevalence: over 90%)
- Hyperventilation: Definitions of hyperventilation: their advantages and weak points
- Hyperventilation syndrome: Western scientific evidence about prevalence of chronic hyperventilation in patients with chronic conditions (37 medical studies)
- Normal minute ventilation: Small and slow breathing at rest is enjoyed by healthy subjects (14 studies)
- Hyperventilation prevalence: Present in over 90% of normal people (24 medical studies)
- HV and hypoxia: How and why deep breathing reduces oxygenation of cells and tissues of all vital organs
- Body-oxygen test (CP test) : How to measure your own breathing and body oxygenation (two in one) using a simple DIY test
- Body oxygen in healthy: Results for the body-oxygen test for healthy people (27 medical studies)
- Body oxygen in sick : Results for the body-oxygen test for sick people (14 medical studies)
- Buteyko Table of Health Zones: Clinical description and ranges for breathing zones: from the critically ill (severely sick) up to super healthy people with maximum possible body oxygenation
- Morning hyperventilation: Why people feel worse and critically ill people are most likely to die during early morning hours

References: pages about CO2 effect:
- Vasodilation: CO2 expands arteries and arterioles facilitating perfusion (or blood supply) to all vital organs
- The Bohr effect: How and why oxygen is released by red blood cells in tissues
- Cell oxygen levels: How alveolar CO2 influences oxygen transport
- Oxygen transport: O2 transport is controlled by vasoconstriction-vasodilation and the Bohr effects, both of which rely on CO2
- Free radical generation: Reactive oxygen species are produced within cells due to anaerobic cell respiration caused by cell hypoxia
- Inflammatory response: Chronic inflammation in fueled by the hypoxia-inducible factor 1, while normal breathing reduces and eliminates inflammation
- Nerve stabilization: People remain calm due to calmative or sedative effects of carbon dioxide in neurons or nerve cells
- Muscle relaxation: Relaxation of muscle cells is normal at high CO2, while hypocapnia causes muscular tension, poor posture and, sometimes, aggression and violence
- Bronchodilation: Dilation of airways (bronchi and bronchioles) is caused by carbon dioxide, and their constriction by hypocapnia (low CO2)
- Blood pH: Regulation of blood pH due to breathing and regulation of other bodily fluids
- CO2: lung damage: Elevated carbon dioxide prevents lung injury and promotes healing of lung tissues
- CO2: Topical carbon dioxide can heal skin and tissues
- Synthesis of glutamine in the brain, CO2 fixation, and other chemical reactions
- Deep breathing myth: Ignorant and naive people promote the idea that deep breathing and breathing more air at rest is beneficial for health
- Breathing control: How is our breathing regulated? Why hypocapnia makes breathing uneven, irregular and erratic.

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References (shortness of breath or breathlessness)

Thorax. 2011 Mar;66(3):240-6.
Neural respiratory drive, pulmonary mechanics and breathlessness in patients with cystic fibrosis.
Reilly CC, Ward K, Jolley CJ, Lunt AC, Steier J, Elston C, Polkey MI, Rafferty GF, Moxham J.

Rev Esp Cardiol. 2005 Oct;58(10):1142-4.
[The circulating NTproBNP level, a new biomarker for the diagnosis of heart failure in patients with acute shortness of breath].
[Article in Spanish]

Aust Fam Physician. 2005 Jul;34(7):541-5.
Shortness of breath - is it chronic obstructive pulmonary disease?
McDonald CF.
Institute for Breathing and Sleep, Austin Hospital, Heidelberg, Victoria, Australia.

Int J Cardiol. 2002 Sep;85(1):133-9.
Origin of symptoms in patients with cachexia with special reference to weakness and shortness of breath.
Coats AJ.

Medsurg Nurs. 2000 Aug;9(4):178-82.
Helping patients with COPD manage episodes of acute shortness of breath.
Truesdell S.
Division of Pulmonary and Critical Care Medicine, Henry Ford Hospital, Detroit, MI, USA.
The most disabling and frightening symptom experienced by patients with COPD is dyspnea. Even with the use of bronchodilators, the symptom may not be completely relieved. Patients often develop their own strategies for managing shortness of breath, including the use of a breathing technique called pursed-lip breathing. Although most nurses are familiar with this breathing technique, they often have difficulty assisting patients to use it during acute episodes of shortness of breath. A strategy is described which nurses can use to assist patients in implementing pursed-lip breathing effectively during episodes of acute dyspnea.

Or go to Causes of Hyperventilation

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