Chronic Hypoxia

Chronic hypoxia can result either from a number of medical conditions such as any disease associated with chronic blood loss, cardiac disorders, pulmonary edema, or from adjustment to high altitudes after moving from the sea level.

Conditions promoting chronic hypoxia gradually induce degradation in tissue oxygenation levels leading to a physiological stresses that influence multiple body systems. 

JBS Haldane is said to have remarked that a lack of oxygen not only stops the machine but also wrecks the machinery. ²⁶⁰ In the 1960s it was shown that a PaO₂ of at least 18 mm Hg is necessary to sustain mitochondrial function, and to generate adenosine triphosphate, which is essential for all major cellular biochemical functions. ²⁶⁰ Learn more about Aerobic Cellular Respiration...

Cellular hypoxia may be defined as a state in which convective or diffusive oxygen transport fails to meet the tissue demand for oxygen and when the rate of adenosine triphosphate synthesis becomes limited by the oxygen supply. ²⁶⁰

Decreases in oxygen supply set in motion adaptive mechanisms designed to maintain cellular activity at a minimum acceptable level; the failure of these mechanisms during hypoxia results in cellular dysfunction and can lead to irreversible cell damage. ²⁶⁰

In patients with chronic lung diseases chronic hypoxia can induce a decreased arterial vessel density due to the fibrosis or destruction often associated with development of the disease. Some negative mechanical reactions such as an increased wall stress and pressure caused by hypoxic pulmonary vasoconstriction are also well known outputs of chronic hypoxia initiating a cascade of changes at a cellular level.

One example of a chronic disease associated with developing chronic hypoxia and Pulmonary Edema is Chronic Obstructive Pulmonary Disease (COPD). COPD is well explaind in the following video...

Chronic Hypoxia Symptoms

Patients affected by Chronic Hypoxia, whether due to disease or environmental conditions such as high altitude, experience sluggish mental responses, persistent mental and physical fatigue, loss of ability to perform many physical tasks. Unless treated, the condition may increase pulmonary hypertension, enhanced right-heart load and lead to a spectrum of serious disabilities, increasing the risk of mortality.

Therefore it is especially important to estimate the pathophysiological and functional outcome that may be derived from the chronic hypoxia-induced sympathetic developments.

If you prefer to learn more about Hypoxia by reading a textbook, we recommend a selection of books here.... Providing a detail overview of hypoxia, hypoxia symptoms and types, the recommended books address the distinctive problems that hypoxia presents to vulnerable organs such as the kidney, liver, heart and brain.

Chronic Hypoxia and High Altitude Sickness

Many otherwise healthy individuals experience high altitude sickness within a day or two after ascent to altitudes above 8,000 feet, particularly if they arrived by air from sea level. Symptoms include headache, lethargy, insomnia, anorexia, and in some cases nausea and vomiting. Believed to be due to mild cerebral edema, acute mountain sickness typically resolves over several days even if the individual remains at altitude.

High altitude cerebral edema and high altitude pulmonary edema are more serious, sometimes fatal maladaptations of previously healthy individuals who ascend rapidly above lO,OOO-12,000 feet, which typically occur several days after arrival. Chronic altitude sickness occurs in some individuals after months or years of residence at high altitude. Read more about Altitude Sickness...

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Hyperbaric oxygen (HBO₂) significantly increases the oxygen diffusion driving force, thus increasing oxygen availability to tissues. This helps to correct negative effects of hypoxia and restore normal tissue oxygenation.