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Encyclopedia > Apnea
Name of Symptom/Sign:
Apnea
Classifications and external resources
ICD-10
ICD-9 786.03

Apnea, apnoea, or apnœa (Greek απνοια, from α-, privative, πνεειν, to breathe) is a technical term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged. Depending on the patency (openness) of the airways 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. Apnea can be voluntarily achieved (i.e., "holding one's breath"), drug-induced (e.g., opiate toxicity), mechanically induced (e.g., strangulation), or it can occur as a consequence of neurological disease or trauma. The term symptom (from the Greek meaning chance, mishap or casualty, itself derived from συμπιπτω meaning to fall upon or to happen to) has two similar meanings in the context of physical and mental health: Strictly, a symptom is a sensation or change in health function experienced by a patient. ... In medicine, a sign is a feature of disease as detected by the doctor during physical examination of a patient. ... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) is a coding of diseases and signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as classified by the World Health Organization (WHO). ... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... In animal physiology, respiration is the transport of oxygen from the ambient air to the tissue cells and the transport of carbon dioxide in the opposite direction. ... A top-down view of skeletal muscle Muscle (from Latin musculus little mouse [1]) is contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. ... Human respiratory system The lungs flank the heart and great vessels in the chest cavity. ... Gas can also refer to gasoline and natural gas and also hydrogen. ... The heart and lungs (from an older edition of Grays Anatomy) The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... Gas exchange or respiration takes place at a respiratory surface - a boundary between the external environment and the interior of the body. ... Cellular respiration was discovered by mad scientist Mr. ... This article does not cite its references or sources. ... Scoring the poppy pod. ... In medicine, a trauma patient has suffered serious and life-threatening physical injury resulting in secondary complications such as shock, respiratory failure and death. ...

Contents

Mechanism

Under normal conditions, humans cannot store much oxygen in the body. Apnea of more than approximately one minute's duration therefore leads to severe lack of oxygen in the blood circulation. Permanent brain damage can occur after as little as three minutes and death will inevitably ensue after a few more minutes unless ventilation is restored. However, under special circumstances such as hypothermia, hyperbaric oxygenation, apneic oxygenation (see below), or extracorporeal membrane oxygenation, much longer periods of apnea may be tolerated without severe consequences. This article is about modern humans. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) pale blue (liquid) Standard atomic weight 15. ... For transport in plants, see Vascular tissue. ... Brain damage or brain injury is the destruction or degeneration of brain cells. ... For other uses, see Death (disambiguation), Dead (disambiguation), Death (band) or Deceased (band). ... Hypothermia is a condition in which an organisms temperature drops below that Required fOr normal metabolism and Bodily functionS. In warm-blooded animals, core [[body Temperature]] is maintained nEar a constant leVel through biologic [[homEostasis]]. But wheN the body iS exposed to cold Its internal mechanismS may be unable... Hyperbaric oxygen therapy (HBOT) is the medical use of oxygen at a higher than atmospheric pressure. ... In intensive care medicine, extracorporeal membrane oxygenation (ECMO) is a technique of providing both cardiac and respiratory supportoxygen to patients whose heart and lungs are so severely diseased that they can no longer serve their function. ...


Untrained humans cannot sustain voluntary apnea for more than one or two minutes. The reason for this is that the rate of breathing and the volume of each breath are tightly regulated to maintain constant values of CO2 tension and pH of the blood. In apnea, CO2 is not removed through the lungs and accumulates in the blood. The consequent rise in CO2 tension and drop in pH result in stimulation of the respiratory centre in the brain which eventually cannot be overcome voluntarily. Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... For other uses, see PH (disambiguation). ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ...


When a person is immersed in water, physiological changes due to the mammalian diving reflex enable somewhat longer tolerance of apnea even in untrained persons. Tolerance can in addition be trained. The ancient technique of free-diving requires breath-holding, and world-class free-divers can indeed hold their breath underwater up to depths of 223 metres and for more than eight minutes. An apneist, in this context, is someone who can hold their breath for a long time. Submerging the face into water causes the mammalian diving reflex, which is found in all mammals (including humans, although it is less pronounced), but especially in marine mammals (as, for example, whales and seals. ... Freedive photographer Free-diving is an aquatic sport, considered an extreme sport, in which divers attempt to reach great depths unassisted by breathing apparatus. ...


Hyperventilation

Many people have discovered, on their own, that voluntary hyperventilation before beginning voluntary apnea allows them to hold their breath for a longer time. Some of these people incorrectly attribute this effect to increased oxygen in the blood, not realizing that it is actually due to a decrease in CO2 in the blood and lungs. Blood leaving the lungs is normally fully saturated with oxygen, so hyperventilation of normal air cannot increase the amount of oxygen available. Lowering the CO2 concentration increases the time before the respiratory center becomes stimulated, as described above. In medicine, hyperventilation (or hyperpnea) is the state of breathing faster or deeper (hyper) than necessary, and thereby reducing the carbon dioxide concentration of the blood below normal. ...


This error has led some people to use hyperventilation as a means to increase their diving time, not realizing that there is a danger that their body may exhaust its oxygen while underwater, before they feel any urge to breathe, and that they can suddenly lose consciousness — a shallow water blackout — as a result. If a person loses consciousness underwater, especially in fresh water, there is a considerable danger that they will drown. An alert diving partner would be in the best position to rescue such a person. A shallow water blackout is a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive in water typically shallower than five metres (16 feet), when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that...


Apneic oxygenation

Because the exchange of gases between the blood and airspace of the lungs is independent of the movement of gas to and from the lungs, enough oxygen can be delivered to the circulation even if a person is apneic. This phenomenon (apneic oxygenation) is explained as follows:


With the onset of apnea, an underpressure develops in the airspace of the lungs, because more oxygen is absorbed than CO2 is released. With the airways closed or obstructed, this will lead to a gradual collapse of the lungs. However, if the airways are patent (open), any gas supplied to the upper airways will follow the pressure gradient and flow into the lungs to replace the oxygen consumed. If pure oxygen is supplied, this process will serve to replenish the oxygen stores in the lungs. The uptake of oxygen into the blood will then remain at the usual level and the normal functioning of the organs will not be affected.


However, no CO2 is removed during apnea. The partial pressure of CO2 in the airspace of the lungs will quickly equilibrate with that of the blood. As the blood is loaded with CO2 from the metabolism, more and more CO2 will accumulate and eventually displace oxygen and other gases from the airspace. CO2 will also accumulate in the tissues of the body, resulting in respiratory acidosis. In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. ... Respiratory acidosis is acidosis (abnormal acidity of the blood) due to decreased ventilation of the pulmonary alveoli, leading to elevated arterial carbon dioxide concentration. ...


Under ideal conditions (i.e., if pure oxygen is breathed before onset of apnea to remove all nitrogen from the lungs, and pure oxygen is insufflated), apneic oxygenation could theoretically be sufficient to provide enough oxygen for survival of more than one hour's duration in a healthy adult. However, accumulation of carbon dioxide (described above) would remain the limiting factor. General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ...


Apneic oxygenation is more than a physiologic curiosity. It can be employed to provide a sufficient amount of oxygen in thoracic surgery when apnea cannot be avoided, and during manipulations of the airways such as bronchoscopy, intubation, and surgery of the upper airways. However, because of the limitations described above, apneic oxygenation is inferior to extracorporal circulation using a heart-lung machine and is therefore used only in emergencies and for short procedures. In medicine, the field of (cardio)thoracic surgery is involved in the surgical treatment of diseases affecting the heart (cardiovascular disease) and lungs (lung disease). ... This drawing shows a bronchoscope inserted through the mouth, trachea, and bronchus into the lung; lymph nodes along trachea and bronchi; and cancer in one lung. ... This article or section needs copy editing for grammar, style, cohesion, tone and/or spelling. ... A heart-lung machine (upper right) in a coronary artery bypass surgery. ...


References

  • J.F.Nunn; Applied Respiratory Physiology; Butterworth-Heinemann Ltd; ISBN 0-7506-1336-X (4th edition, 1993)
  • This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.

Encyclopædia Britannica, the eleventh edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...

See also

Hypopnœa is a medical term for abnormally shallow breathing or slow respiratory rate. ... Sleep apnea, sleep apnoea or sleep apnœa is a sleep disorder characterized by pauses in breathing during sleep. ... mechanical or forced ventilation is the use of powered equipment, e. ... Freedive photographer Free-diving is an aquatic sport, considered an extreme sport, in which divers attempt to reach great depths unassisted by breathing apparatus. ... A shallow water blackout is a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive in water typically shallower than five metres (16 feet), when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that... Latent hypoxia hits on ascent A deep water blackout is a loss of consciousness caused by cerebral hypoxia on ascending from a deep freedive or breath-hold dive, typically of ten metres or more when the swimmer does not necessarily experience an urgent need to breathe and has no other...

External links

Look up Apnea in
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  Results from FactBites:
 
Dr. Koop - Sleep Apnea- Health Encyclopedia and Reference (1018 words)
Apnea is defined as a cessation of oronasal airflow of at least 10 seconds in duration.
In a third type of apnea, mixed apnea, a brief period of central apnea is followed by a longer period of obstructive apnea.
Polysomnography, a technique used to diagnose obstructive sleep apnea, records the number and duration of apnetic episodes, determines the stage of sleep and oxygen saturation and observes when the patient awakens.
Apnea - Wikipedia, the free encyclopedia (913 words)
Apnea (British spelling - apnoea) (Greek απνοια, from α-, privative, πνεειν, to breathe) is a technical term for suspension of external breathing.
During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged.
Apnea can be voluntarily achieved (i.e., "holding one's breath"), drug-induced (e.g., opiate toxicity), mechanically induced (e.g., strangulation), or it can occur as a consequence of neurological disease or trauma.
  More results at FactBites »

 
 

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