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Encyclopedia > Hypoxia (medical)

Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. Hypoxia in which there is complete deprivation of oxygen supply is referred to as anoxia. Pathology (from Greek pathos, feeling, pain, suffering; and logos, study of; see also -ology) is the study of the processes underlying disease and other forms of illness, harmful abnormality, or dysfunction. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ...


Hypoxia is distinguished from apoxemia. Apoxemia is an abnormally low partial pressure of oxygen (PO2) in arterial blood [1]. A frequent error is to use the term hypoxemia to mean low oxygen content in arterial blood. It is possible to have a low oxygen content (eg due to anemia) but a high PO2 also incorrect use can lead to confusion. // Hypoxemia (or hypoxaemia) is an abnormally low partial pressure of oxygen (PO2) in arterial blood (West J. Pulmonary Pathophysiology: The Essentials p22). ...


Generalised hypoxia occurs in healthy people when they ascend to high altitude, where it causes altitude sickness, and the potentially fatal complications of altitude sickness, high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Hypoxia also occurs in healthy individuals when breathing mixtures of gases with a low oxygen content, for example while diving underwater, especially with closed-circuit rebreather systems that control the amount of oxygen in the air breathed in. Altitude training uses mild hypoxia to increase the concentration of red blood cells in the body for increased athletic performance. High altitude are regions on the Earths surface (or in its atmosphere) that are high above mean sea level. ... Altitude sickness, also known as acute mountain sickness (AMS) or altitude illness is a pathological condition that is caused by acute exposure to high altitudes. ... High altitude pulmonary edema (HAPE) is a life threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy mountaineers at altitudes above 2500m. ... High altitude pulmonary edema (HAPE) is a life threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy mountaineers at altitudes above 2500m. ... High altitude cerebral edema (or HACE) is a severe (frequently fatal) form of altitude sickness. ... Cerebral edema is swelling of the brain which can occur as the result of a head injury, cardiac arrest or from the lack of proper altitude acclimatization. ... A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycles exhaled gas. ... Altitude training (or an altitude camp) is where endurance athletes train at high altitude, usually over 2,500 m (8,000 ft) above sea level, for several weeks. ...

Contents

Symptoms

Symptoms of generalized hypoxia depend on its severity and speed of onset. In the case of altitude sickness, where hypoxia develops gradually, the symptoms include headaches, fatigue, shortness of breath, a feeling of euphoria and nausea. In severe hypoxia, or hypoxia of very rapid onset, changes in levels of consciousness, seizures, coma and death occur. Severe hypoxia induces a blue discolouration of the skin, called cyanosis (haemoglobin is blue when it is not bound to oxygen (deoxyhaemoglobin), as opposed to the rich red colour that it has when bound to oxygen (oxyhaemoglobin)). In cases where the oxygen is displaced by another molecule, such as carbon monoxide, the skin may be 'cherry red' instead of cyanotic. Altitude sickness, also known as acute mountain sickness (AMS) or altitude illness is a pathological condition that is caused by acute exposure to high altitudes. ... A headache (cephalalgia in medical terminology) is a condition of pain in the head; sometimes neck or upper back pain may also be interpreted as a headache. ... For the Beck song, see Nausea (song). ... This article is about the medical term, epileptic seizure, as distinct from a non-epileptic seizure. ... In medicine, a coma (from the Greek koma, meaning deep sleep) is a profound state of unconsciousness. ... Cyanosis refers to the bluish coloration of the skin due to the presence of deoxygenated hemoglobin in blood vessels near the skin surface. ... 3-dimensional structure of hemoglobin Hemoglobin or haemoglobin is the iron-containing oxygen-transport metalloprotein in the red cells of the blood in mammals and other animals. ... 3-dimensional structure of hemoglobin. ...


Types of hypoxia

  • Hypoxic hypoxia is a generalized hypoxia, an inadequate supply of oxygen to the body as a whole. The term "hypoxic hypoxia" refers to the fact that hypoxia occurs as a consequence of low partial pressure of oxygen in arterial blood, in contrast to the other causes of hypoxia that follow, in which the partial pressure of oxygen in arterial blood is normal. Hypoxic hypoxia may be due to:
    • Low partial pressure of atmospheric oxygen such as found at high altitude [2] or by replacement of oxygen in the breathing mix either accidentally as in the modified atmosphere of a sewer or intentionally as in the recreational use of nitrous oxide.
    • Either Sleep apnea or Hypopnea causing a decrease in oxygen saturation of the blood.
    • Inadequate pulmonary ventilation (e.g. in chronic obstructive pulmonary disease or respiratory arrest).
    • Shunts in the pulmonary circulation or a right-to-left shunt in the heart. Shunts can be caused by collapsed alveoli that are still perfused or a block in ventilation to an area of the lung. Whatever the mechanism, blood meant for the pulmonary system is not ventilated and so no gas exchange occurs (the ventilation/perfusion ratio is zero). Normal anatomical shunt occurs in everyone, because of the Thebesian vessels which empty into the left ventricle and the bronchial circulation which supplies the bronchi with oxygen.
  • Anemic hypoxia in which arterial oxygen pressure is normal, but total oxygen content of the blood is reduced.[3]
  • Hypemic hypoxia when there is an inability of the blood to deliver oxygen to target tissues.
  • Histotoxic hypoxia in which quantity of oxygen reaching the cells is normal, but the cells are unable to effectively use the oxygen due to disabled oxidative phosphorylation enzymes.
  • Ischemic, or stagnant hypoxia in which there is a local restriction in the flow of otherwise well-oxygenated blood. The oxygen supplied to the region of the body is then insufficient for its needs. Examples are cerebral ischemia, ischemic heart disease and Intrauterine hypoxia, which is an unchallenged cause of perinatal death.

Hypoxic hypoxia is hypoxia resulting from a defective mechanism of oxygenation in the lungs; may be caused by a low tension of oxygen, abnormal pulmonary function or respiratory obstruction, or a right-to-left shunt in the heart. ... 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. ... 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. ... View of Jupiters active atmosphere, including the Great Red Spot. ... R-phrases S-phrases Supplementary data page Structure and properties n, εr, etc. ... Sleep apnea or sleep apnoea is a sleep disorder characterized by pauses in breathing during sleep. ... Hypopnœa is a medical term for abnormally shallow breathing or slow respiratory rate. ... Oxygen saturation is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. ... Chronic obstructive pulmonary disease (COPD) is an umbrella term for a group of respiratory tract diseases that are characterized by airflow obstruction or limitation. ... Respiratory failure is a medical term for inadequate gas exchange by the respiratory system. ... In medicine, a shunt is a device designed to drain excess cerebrospinal fluid from the brain and carry it to other parts of the body. ... The alveoli (singular:alveolus), tiny hollow sacs which are continuous with the airways, are the sites of gas exchange with the blood. ... In the heart, a ventricle is a heart chamber which collects blood from an atrium (another heart chamber that is smaller than a ventricle) and pumps it out of the heart. ... A bronchus (plural bronchi, adjective bronchial) is a caliber of airways in the the respiratory tract that conducts air into the lungs. ... This article discusses the medical condition. ... Hyperaemia (AmE hyperemia) is the medical condition in which blood congests in a part of the body. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... 3-dimensional structure of hemoglobin Hemoglobin or haemoglobin is the iron-containing oxygen-transport metalloprotein in the red cells of the blood in mammals and other animals. ... In medicine, ischemia (Greek ισχαιμία, isch- is restriction, hema or haema is blood) is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. ... Cerebral ischemia is an ischemic condition where the brain or parts of the brain do not receive enough blood flow to maintain normal neurological function. ... Ischaemic heart disease is a disease characterized by reduced blood supply to the heart. ... Perinatal mortality (PNM), also perinatal death, refers to the death of a fetus or neonate and is the basis to calculate the perinatal mortality rate. ...

Pathophysiology

After mixing with water vapour and expired CO2 in the lungs, oxygen diffuses down a pressure gradient to enter arterial blood around where its partial pressure is 100mmHg (13.3kPa).[2] Arterial blood flow delivers oxygen to the peripheral tissues, where it again diffuses down a pressure gradient into the cells and into their mitochondria. These bacteria-like cytoplasmic structures strip hydrogen from fuels (glucose, fats and some amino acids) to burn with oxygen to form water. Released energy (originally from the sun and photosynthesis) is stored as ATP, to be later used for energy requiring metabolism. The fuel's carbon is oxidized to CO2, which diffuses down its partial pressure gradient out of the cells into venous blood to finally be exhaled by the lungs. Experimentally, oxygen diffusion becomes rate limiting (and lethal) when arterial oxygen partial pressure falls to 40mmHg or below. In order to meet Wikipedias quality standards, this article requires cleanup. ... Section of an artery For other uses, see Artery (disambiguation). ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... It has been suggested that Cytoplast be merged into this article or section. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... Phenylalanine is one of the standard amino acids. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... The Sun (Latin: Sol) is the star at the center of the Solar System. ... This article needs additional references or sources for verification. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ...


If oxygen delivery to cells is insufficient for the demand (hypoxia), hydrogen will be shifted to pyruvic acid converting it to lactic acid. This temporary measure (anaerobic metabolism) allows small amounts of energy to be produced. Lactic acid build up in tissues and blood is a sign of inadequate mitochondrial oxygenation, which may be due to hypoxemia, poor blood flow (e.g. shock) or a combination of both.[4] If severe or prolonged it could lead to cell death. Pyruvic acid (CH3COCO2H) is an alpha-keto acid which plays an important role in biochemical processes. ... For the production of milk by mammals, see Lactation. ...


Vasoconstriction and vasodilation

In most tissues of the body, the response to hypoxia is vasodilation. By widening the blood vessels, the tissue allows greater perfusion. The blood vessels are part of the circulatory system and function to transport blood throughout the body. ...


By contrast, in the lungs, the response to hypoxia is vasoconstriction. This is known as "Hypoxic pulmonary vasoconstriction", or "HPV". 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. ... The blood vessels are part of the circulatory system and function to transport blood throughout the body. ...


See also

Suffocation redirects here, for the band, see Suffocation (band). ... Cerebral hypoxia (the pathological condition is called hypoxic encephalopathy) is to a hypoxic condition in which there is a decrease of oxygen supply to the brain or parts of the brain despite adequate blood flow (compare with cerebral ischemia). ... A hypoxic tumor is a tumor whose cells have been deprived of oxygen. ... Wikipedia does not have an article with this exact name. ... From Wikipedia, the free encyclopedia Revision as of 06:34, 3 January 2007 by SnowFire (Talk | contribs) (diff) ← Older revision | Current revision (diff) | Newer revision → (diff) Jump to: navigation, search Time of useful consciousness (TUC) is defined as the amount of time an individual is able to perform flying duties... 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... Altitude training (or an altitude camp) is where endurance athletes train at high altitude, usually over 2,500 m (8,000 ft) above sea level, for several weeks. ... The 1999 South Dakota Learjet crash involved a chartered Learjet 35 flying between Orlando to Dallas, Texas. ... Helios Airways Flight 522 (HCY 522 or ZU522) was a Helios Airways Boeing 737-31S flight that crashed on August 14, 2005 at 12:04 EEST into a mountain north of Marathon and Varnavas, Greece. ...

Footnotes

  1. ^ West J. "Pulmonary Pathophysiology: The Essentials" 1977 Williams & Wilkins p22
  2. ^ a b Kenneth Baillie and Alistair Simpson. Altitude oxygen calculator. Apex (Altitude Physiology Expeditions). Retrieved on 2006-08-10. - Online interactive oxygen delivery calculator
  3. ^ Kenneth Baillie and Alistair Simpson. Oxygen content calculator. Apex (Altitude Physiology Expeditions). Retrieved on 2006-08-10. - A demonstration of the effect of anaemia on oxygen content
  4. ^ Hobler KE, Carey LC (1973). "Effect of acute progressive hypoxemia on cardiac output and plasma excess lactate" (scanned copy). Ann Surg 177 (2): 199-202. PMID 4572785. 

Year 2006 (MMVI) was a common year starting on Sunday (link displays full 2006 calendar) of the Gregorian calendar. ... is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday (link displays full 2006 calendar) of the Gregorian calendar. ... is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...

Bibliography

  • Hypoxia - An invisible enemy, Fast, Airbus technical magazine, #38 : presentation for non specialists of hypoxia and related safety procedures in civil airplanes

  Results from FactBites:
 
Hypoxia (medical) . Enpsychlopedia (876 words)
Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply.
Hypoxia also occurs in healthy individuals when breathing mixtures of gases with a low oxygen content, for example while diving underwater, especially with closed-circuit rebreather systems that control the amount of oxygen in the air breathed in.
Severe hypoxia induces a blue discolouration of the skin, called cyanosis (haemoglobin is blue when it is not bound to oxygen (deoxyhaemoglobin), as opposed to the rich red colour that it has when bound to oxygen (oxyhaemoglobin)).
Hypoxia (medical) - Wikipedia, the free encyclopedia (811 words)
Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply.
Hypoxia also occurs in healthy individuals when breathing mixtures of gases with a low oxygen content, for example while diving underwater, especially with closed-circuit rebreather systems that control the amount of oxygen in the air breathed in.
Severe hypoxia induces a blue discolouration of the skin, called cyanosis (haemoglobin is blue when it is not bound to oxygen (deoxyhaemoglobin), as opposed to the rich red colour that it has when bound to oxygen (oxyhaemoglobin)).
  More results at FactBites »

 
 

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