Hyperventilation

Hyperventilation occurs when the rate or tidal volume of breathing eliminates more carbon dioxide than the body can produce.[1][2][3] This leads to hypocapnia, a reduced concentration of carbon dioxide dissolved in the blood. The body normally attempts to compensate for this homeostatically but if this fails or is overridden, the blood pH will rise, leading to respiratory alkalosis. The symptoms of respiratory alkalosis include: dizziness, tingling in the lips, hands or feet, headache, weakness, fainting and seizures. In extreme cases it may cause carpopedal spasms, a flapping and contraction of the hands and feet.[3][4]

Factors that may induce or sustain[2] hyperventilation include: physiological stress, anxiety or panic disorder, high altitude, head injury, stroke, respiratory disorders such as asthma, pneumonia or hyperventilation syndrome,[5] cardiovascular problems such as pulmonary embolisms, anemia, an incorrectly calibrated medical respirator[1][3] and adverse reactions to certain drugs. Hyperventilation can also be induced intentionally to achieve an altered state of consciousness such as in the choking game, or in an attempt to extend a breath-hold dive.

Hyperventilation
Other namesOverbreathing
SpecialtyPulmonology

See also

References

  1. ^ a b Guyton, Arthur C.; Hall, John E. (2005). Textbook of medical physiology (11th ed.). Philadelphia: W.B. Saunders. p. 397. ISBN 0-7216-0240-1.
  2. ^ a b Longo, Dan; et al. (2012). Harrison's principles of internal medicine (18th ed.). New York: McGraw-Hill. p. 2185. ISBN 978-0071748896.
  3. ^ a b c Brandis, Kerry (30 Aug 2015). "6.2 Respiratory Alkalosis - Causes". Acid-base Physiology (Reviewed in 2006 by the American Thoracic Society).
  4. ^ Byrd, Jr, Ryland P (5 August 2016). "Respiratory Alkalosis: Background, Pathophysiology, Epidemiology". eMedicine.
  5. ^ "eMedicine - Hyperventilation Syndrome: Article by Edward Newton, MD". Retrieved 29 November 2016.

External links

External resources
Apnea

Apnea is the cessation of breathing. During apnea, there is no movement of the muscles of inhalation, and the volume of the lungs initially remains unchanged. Depending on how blocked the airways are (patency), there may or may not be a flow of gas between the lungs and the environment; gas exchange within the lungs and cellular respiration is not affected. Voluntarily doing this is called holding one's breath.

Breathing

Breathing (or ventilation) is the process of moving air into and out of the lungs to facilitate gas exchange with the internal environment, mostly by bringing in oxygen and flushing out carbon dioxide.

All aerobic creatures need oxygen for cellular respiration, which uses the oxygen to break down foods for energy and produces carbon dioxide as a waste product. Breathing, or "external respiration", brings air into the lungs where gas exchange takes place in the alveoli through diffusion. The body's circulatory system transports these gases to and from the cells, where "cellular respiration" takes place.The breathing of all vertebrates with lungs consists of repetitive cycles of inhalation and exhalation through a highly branched system of tubes or airways which lead from the nose to the alveoli. The number of respiratory cycles per minute is the breathing or respiratory rate, and is one of the four primary vital signs of life. Under normal conditions the breathing depth and rate is automatically, and unconsciously, controlled by several homeostatic mechanisms which keep the partial pressures of carbon dioxide and oxygen in the arterial blood constant. Keeping the partial pressure of carbon dioxide in the arterial blood unchanged under a wide variety of physiological circumstances, contributes significantly to tight control of the pH of the extracellular fluids (ECF). Over-breathing (hyperventilation) and under-breathing (hypoventilation), which decrease and increase the arterial partial pressure of carbon dioxide respectively, cause a rise in the pH of ECF in the first case, and a lowering of the pH in the second. Both cause distressing symptoms.

Breathing has other important functions. It provides a mechanism for speech, laughter and similar expressions of the emotions. It is also used for reflexes such as yawning, coughing and sneezing. Animals that cannot thermoregulate by perspiration, because they lack sufficient sweat glands, may lose heat by evaporation through panting.

Buteyko method

The Buteyko method or Buteyko Breathing Technique is a form of complementary or alternative physical therapy that proposes the use of breathing exercises primarily as a treatment for asthma and other respiratory conditions. The method takes its name from Ukrainian doctor Konstantin Pavlovich Buteyko, who first formulated its principles during the 1950s. This method is based on the assumption that numerous medical conditions, including asthma, are caused by chronically increased respiratory rate or deeper breathing (hyperventilation). However, this theory is not widely supported in the medical community due to the lack of evidence supporting either the theory behind the method or that it works in practice. This method purportedly retrains the breathing pattern through chronic repetitive breathing exercises to correct the hyperventilation, which, according to the method's proponents, will therefore treat or cure asthma as well as any other conditions purportedly caused by hyperventilation. At the core of the Buteyko method is a series of reduced-breathing exercises that focus on nasal-breathing, breath-holding and relaxation.

Opinion is divided on whether the Buteyko method confers any health benefits: some evidence suggests it may help alleviate asthma symptoms and improve quality of life.

Central neurogenic hyperventilation

Central neurogenic hyperventilation (CNH) is an abnormal pattern of breathing characterized by deep and rapid breaths at a rate of at least 25 breaths per minute. Increasing irregularity of this respiratory rate generally is a sign that the patient will enter into coma. CNH is unrelated to other forms of hyperventilation, like Kussmaul's respirations. CNH is the human body's response to reduced carbon dioxide levels in the blood. This reduction in carbon dioxide is caused by contraction of cranial arteries from damage caused by lesions in the brain stem. However, the mechanism by which CNH arises as a result from these lesions is still very poorly understood. Current research has yet to provide an effective means of treatment for the rare number of patients who are diagnosed with this condition.

Chvostek sign

The Chvostek sign () is a clinical sign of existing nerve hyperexcitability (tetany) seen in hypocalcemia. It refers to an abnormal reaction to the stimulation of the facial nerve. When the facial nerve is tapped in front of tragus the facial muscles on the same side of the face will contract momentarily (typically a twitch of the nose or lips) because of hypocalcemia (i.e. from hypoparathyroidism, pseudohypoparathyroidism, hypovitaminosis D) with resultant hyperexcitability of nerves. Though classically described in hypocalcemia, this sign may also be encountered in respiratory alkalosis, such as that seen in hyperventilation, which causes decreased serum Ca2+ with a normal calcium level due to a shift of Ca2+ from the blood to albumin which has become more negative in the alkalotic state.

The Trousseau sign of latent tetany is also often used to detect early tetany.

Dizziness

Dizziness is an impairment in spatial perception and stability. The term dizziness is imprecise: it can refer to vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness.One can induce dizziness by engaging in disorientating activities such as spinning.

Vertigo is the sensation of spinning or having one's surroundings spin about them. Many people find vertigo very disturbing and often report associated nausea and vomiting. It represents about 25% of cases of occurrences of dizziness.

Disequilibrium is the sensation of being off balance and is most often characterized by frequent falls in a specific direction. This condition is not often associated with nausea or vomiting.

Presyncope is lightheadedness, muscular weakness, and feeling faint as opposed to a syncope, which is actually fainting.

Non-specific dizziness is often psychiatric in origin. It is a diagnosis of exclusion and can sometimes be brought about by hyperventilation.A stroke is the cause of isolated dizziness in 0.7% of people who present to the emergency department.

Exercise-induced bronchoconstriction

Exercise-induced asthma, or E.I.A., occurs when the airways narrow as a result of exercise. The preferred term for this condition is exercise-induced bronchoconstriction (EIB); exercise does not cause asthma, but is frequently an asthma trigger.

Freediving blackout

Freediving blackout, breath-hold blackout or apnea blackout is a class of hypoxic blackout, a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold (freedive or dynamic apnea) dive, when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have caused it. It can be provoked by hyperventilating just before a dive, or as a consequence of the pressure reduction on ascent, or a combination of these. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers and have not experienced problems before. Blackout may also be referred to as a syncope or fainting.

Divers and swimmers who black out or grey out underwater during a dive will usually drown unless rescued and resuscitated within a short time. Freediving blackout has a high fatality rate, and mostly involves males younger than 40 years, but is generally avoidable. Risk cannot be quantified, but is clearly increased by any level of hyperventilation.Freediving blackout can occur on any dive profile: at constant depth, on an ascent from depth, or at the surface following ascent from depth and may be described by a number of terms depending on the dive profile and depth at which consciousness is lost. Blackout during a shallow dive differs from blackout during ascent from a deep dive in that deep water blackout is precipitated by depressurisation on ascent from depth while shallow water blackout is a consequence of hypocapnia following hyperventilation.

Hyperpnea

Hyperpnea is increased depth and rate of breathing. It may be physiologic—as when required to meet metabolic demand of body tissues (for example, during or after exercise, or when the body lacks oxygen at high altitude or as a result of anemia)—or it may be pathologic, as when sepsis is severe.

Tachypnea is sometimes distinguished from hyperpnea when tachypnea is meant as rapid and shallow breaths, whereas hyperpnea is meant as rapid and deep breaths. This distinction is not always followed; the words can be synonymous. Similarly, some speakers maintain a distinction between hyperpnea and hyperventilation, whereby in hyperpnea, the increased breathing rate is desirable as it meets the metabolic needs of the body, but in hyperventilation, the rate of ventilation is inappropriate for the body's needs (except in metabolic acidosis, when CO2 needs to be breathed off). The resulting decrease in CO2 concentration results in the typical symptoms of light-headedness, tingling in peripheries, visual disturbances etc., whereas in hyperpnea in the contradistinguished sense, there are generally no such symptoms. This distinction, too, is not invariably followed.

Hyperventilation syndrome

Hyperventilation syndrome (HVS); also chronic hyperventilation syndrome (CHVS) and dysfunctional breathing hyperventilation syndrome is a respiratory disorder, psychologically or physiologically based, involving breathing too deeply or too rapidly (hyperventilation). HVS may present with chest pain and a tingling sensation in the fingertips and around the mouth (paresthesia) and may accompany a panic attack.

People with HVS may feel that they cannot get enough air. In reality, they have about the same oxygenation in the arterial blood (normal values are about 98% for hemoglobin saturation) and too little carbon dioxide (hypocapnia) in their blood and other tissues. While oxygen is abundant in the bloodstream, HVS reduces effective delivery of that oxygen to vital organs due to low-CO2-induced vasoconstriction and the suppressed Bohr effect.

The hyperventilation is self-promulgating as rapid breathing causes carbon dioxide levels to fall below healthy levels, and respiratory alkalosis (high blood pH) develops. This makes the symptoms worse, which causes the person to breathe even faster, which then, further exacerbates the problem.

The respiratory alkalosis leads to changes in the way the nervous system fires and leads to the paresthesia, dizziness, and perceptual changes that often accompany this condition. Other mechanisms may also be at work, and some people are physiologically more susceptible to this phenomenon than others.

Hypocapnia

Hypocapnia or hypocapnea (from the Greek words υπό meaning below normal and καπνός kapnós meaning smoke), also known as hypocarbia, sometimes incorrectly called acapnia, is a state of reduced carbon dioxide in the blood. Hypocapnia usually results from deep or rapid breathing, known as hyperventilation.

Hypocapnia is the opposite of hypercapnia.

Hypophosphatemia

Hypophosphatemia is an electrolyte disorder in which there is a low level of phosphate in the blood. Symptoms may include weakness, trouble breathing, and loss of appetite. Complications may include seizures, coma, rhabdomyolysis, or softening of the bones.Causes include alcoholism, refeeding in those with malnutrition, diabetic ketoacidosis, burns, hyperventilation, and certain medications. It may also occur in the setting of hyperparathyroidism, hypothyroidism, and Cushing syndrome. It is diagnosed based on a blood phosphate concentration of less than 0.81 mmol/L (2.5 mg/dL). When levels are below 0.32 mmol/L (1.0 mg/dL) it is deemed to be severe.Treatment depends on the underlying cause. Phosphate may be given by mouth or by injection into a vein. Hypophosphatemia occurs in about 2% of people within hospital and 70% of people in the intensive care unit (ICU).

Hypoventilation

Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (hypo meaning "below") to perform needed gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapnia) and respiratory acidosis. Hypoventilation is not synonymous with respiratory arrest, in which breathing ceases entirely and death occurs within minutes due to hypoxia and leads rapidly into complete anoxia, although both are medical emergencies. Hypoventilation can be considered a precursor to hypoxia and its lethality is attributed to hypoxia with carbon dioxide toxicity.

Intracranial pressure

Intracranial pressure (ICP) is the pressure inside the skull and thus in the brain tissue and cerebrospinal fluid (CSF). ICP is measured in millimeters of mercury (mmHg) and, at rest, is normally 7–15 mmHg for a supine adult. The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF. Changes in ICP are attributed to volume changes in one or more of the constituents contained in the cranium. CSF pressure has been shown to be influenced by abrupt changes in intrathoracic pressure during coughing (intra-abdominal pressure), valsalva maneuver, and communication with the vasculature (venous and arterial systems).

Intracranial hypertension, commonly abbreviated IH, IICP or raised ICP, is elevation of the pressure in the cranium. ICP is normally 7–15 mm Hg; at 20–25 mm Hg, the upper limit of normal, treatment to reduce ICP may be needed.

Kussmaul breathing

Kussmaul breathing is a deep and labored breathing pattern often associated with severe metabolic acidosis, particularly diabetic ketoacidosis (DKA) but also kidney failure. It is a form of hyperventilation, which is any breathing pattern that reduces carbon dioxide in the blood due to increased rate or depth of respiration.

In metabolic acidosis, breathing is first rapid and shallow but as acidosis worsens, breathing gradually becomes deep, labored and gasping. It is this latter type of breathing pattern that is referred to as Kussmaul breathing.

Panic attack

Panic attacks are sudden periods of intense fear that may include palpitations, sweating, shaking, shortness of breath, numbness, or a feeling that something bad is going to happen. The maximum degree of symptoms occurs within minutes. Typically they last for about 30 minutes but the duration can vary from seconds to hours. There may be a fear of losing control or chest pain. Panic attacks themselves are not typically dangerous physically.Panic attacks can occur due to a number of disorders including panic disorder, social anxiety disorder, post traumatic stress disorder, drug use disorder, depression, and medical problems. They can either be triggered or occur unexpectedly. Smoking, caffeine, and psychological stress increase the risk of having a panic attack. Before diagnosis, conditions that produce similar symptoms should be ruled out, such as hyperthyroidism, hyperparathyroidism, heart disease, lung disease, and drug use.Treatment of panic attacks should be directed at the underlying cause. In those with frequent attacks, counselling or medications may be used. Breathing training and muscle relaxation techniques may also help. Those affected are at a higher risk of suicide.In Europe about 3% of the population has a panic attack in a given year while in the United States they affect about 11%. They are more common in females than males. They often begin during puberty or early adulthood. Children and older people are less commonly affected.

Pitt–Hopkins syndrome

Pitt–Hopkins syndrome is a rare genetic disorder characterized by developmental delay, epilepsy, distinctive facial features, and possible intermittent hyperventilation followed by apnea. As more is learned about Pitt Hopkins, the developmental spectrum of the disorder is widening, and can also include difficulties with anxiety and ADHD, and sensory disorders. It is associated with an abnormality within chromosome 18; specifically, it is caused by an insufficient expression of the TCF4 gene.PTHS has traditionally been associated with severe cognitive impairment, however true intelligence is difficult to measure given motor and speech difficulties. Thanks to augmentative communication and more progressive therapies, many individuals can achieve much more than initially thought. It has become clearer that there is a wider range of cognitive abilities in Pitt Hopkins than reported in much of the scientific literature.

Respiratory alkalosis

Respiratory alkalosis is a medical condition in which increased respiration elevates the blood pH beyond the normal range (7.35–7.45) with a concurrent reduction in arterial levels of carbon dioxide. This condition is one of the four basic categories of disruption of acid–base homeostasis.

Tachypnea

Tachypnea is abnormally rapid breathing.

In adult humans at rest, any respiratory rate between 12 and 20 breaths per minute is normal and tachypnea is indicated by a rate greater than 20 breaths per minute. Children have significantly higher resting ventilatory rates, which decline rapidly during the first three years of life and then steadily until around 18 years. Tachypnea can be an early medical sign of pneumonia in children.

Symptoms and signs relating to the respiratory system (R04–R07, 786)
Auscultation
Breathing
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