hypoxia

hypoxia /hy·pox·ia/ (hi-pok´se-ah) reduction of oxygen supply to a tissue below physiological levels despite adequate perfusion of the tissue by blood.hypox´ic

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anemic hypoxia  that due to reduction of the oxygen-carrying capacity of the blood owing to decreased total hemoglobin or altered hemoglobin constituents.

histotoxic hypoxia  that due to impaired use of oxygen by tissues.

hypoxic hypoxia  that due to insufficient oxygen reaching the blood.

stagnant hypoxia  that due to failure to transport sufficient oxygen because of inadequate blood flow.

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hy·pox·i·a (h-pks-, h-)

n.

Insufficient levels of oxygen in blood or tissue.

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hy·poxic adj.

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Hypoxia

Hypoxia, or altitude sickness, reduces the amount of oxygen in the brain causing such symptoms as dizziness, shortness of breath, and mental confusion.

Mentioned in: Altitude Sickness, Anesthesia, General, Aviation Medicine, Electronic Fetal Monitoring, Inhalation Therapies, Ventricular Fibrillation

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hypoxia

[hīpok′sē·ə]

Etymology: Gk, hypo + oxys, sharp, genein, to produce

inadequate oxygen tension at the cellular level, characterized by tachycardia, hypertension, peripheral vasoconstriction, dizziness, and mental confusion. Mild hypoxia stimulates peripheral chemoreceptors to increase heart and respiration rates. The central mechanisms that regulate breathing fail in severe hypoxia, leading to irregular respiration, Cheyne-Stokes respiration, apnea, and respiratory and cardiac failure. Increased sensitivity to the depressant effect of opiates on the respiratory system is common in chronic hypoxia, causing severe depression of respiration or apnea from relatively small doses. If the availability of oxygen is inadequate for aerobic cellular metabolism, energy is provided by less efficient anaerobic pathways that produce metabolites other than carbon dioxide and water. The tissues most sensitive to hypoxia are the brain, heart, pulmonary vessels, and liver. Treatment may include cardiotonic and respiratory stimulant drugs, oxygen therapy, mechanical ventilation, and frequent analysis of blood gases. Compare hypoxemia. See also acute hypoxia, anoxia, chemoreceptor, chronic hypoxia, hyperventilation, respiratory center. hypoxic, adj.

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hypoxia (hī·pkˑ·sē·),

n insufficient oxygen supply to tissues in the body; symptoms include hypertension, dizziness, peripheral vasoconstriction, tachycardia, mental confusion, and other manifestations.

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hypoxia (hīpok´sē),

n low oxygen content or tension.

hypoxia, anemic,

n a type brought about by a reduction of the oxygen-carrying capacity of the blood because of a decrease in the complete blood counts or an alteration of the hemoglobin constituents.

hypoxia, anoxic,

n a type resulting from inadequate oxygen in inspired air or interference with gaseous exchange in the lungs.

hypoxia, histotoxic,

n a type resulting from the inability of the tissue cells to use the oxygen that may be present in normal amount and tension.

hypoxia, metabolic,

n a type resulting from an increased tissue demand for oxygen.

hypoxia, stagnant,

n a type resulting from decreased circulation in an area.

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hypoxia

a broad term meaning diminished availability of oxygen to the body tissues.

Its causes are many and varied. There may be a deficiency of oxygen in the atmosphere, as in altitude sickness, or a pulmonary disorder that interferes with adequate ventilation of the lungs. Anemia or circulatory deficiencies can lead to inadequate transport and delivery of oxygen to the tissues. Finally, edema or other abnormal conditions of the tissues themselves may impair the exchange of oxygen and carbon dioxide between the capillaries and the tissues. The effect of hypoxia is to reduce the functional activity of tissues. The initial response may be one of temporarily increased activity. Terminally the tissue may be irreparably damaged.

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anemic hypoxia

due to inadequate supply of hemoglobin in the blood.

cerebral hypoxia

may be acute or chronic causing either a tremor-convulsion syndrome or one of longer term weakness, ataxia, apparent blindness and lethargy.

fetal hypoxia

occurs as a result of deprivation of the fetus of oxygen during parturition, because it is delayed or the umbilical cord pinched off. Clinically there is weakness, imbecility, disinclination to suck, possibly hypothermia. Foals experience a much more violent, convulsive or dummy syndrome. See also neonatal maladjustment syndrome. Called also intrapartum hypoxia.

intrapartum hypoxia

see fetal hypoxia (above).

ischemic hypoxia

insufficient oxygen in tissues because of an inadequate blood supply.

stagnant hypoxia

inadequate supply of oxygen to tissues because of slow rate of passage of the blood through the tissues.

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hypoxia

An inadequate supply of oxygen to tissues. It may occur in some pathological conditions. Examples: in long-standing cases of diabetes there is corneal hypoxia (with consequent high epithelial fragility and some neovascularization) and retinal hypoxia (with consequent neovascularization). Corneal hypoxia (with consequent oedema, loss of sensitivity, etc.) may also occur in contact lens wear. See anoxia; epithelial microcysts; mitosis; oedema; critical oxygen requirement; proliferative retinopathy; corneal exhaustion syndrome; overwear syndrome; tear pumping.

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hypoxia

Cardiology A low O₂ concentration in arterial blood. See Cerebral hypoxia.