hypoxia

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hypoxia

 [hi-pok´se-ah]
diminished availability of oxygen to the body tissues; its causes are many and varied and includes a deficiency of oxygen in the atmosphere, as in altitude sickness; pulmonary disorders that interfere with adequate ventilation of the lungs; anemia or circulatory deficiencies, leading to inadequate transport and delivery of oxygen to the tissues; and finally, edema or other abnormal conditions of the tissues themselves that impair the exchange of oxygen and carbon dioxide between capillaries and tissues. adj., adj hypox´ic.  

Signs and symptoms vary according to the cause. Generally they include dyspnea, rapid pulse, syncope, and mental disturbances such as delirium or euphoria. cyanosis is not always present and in some cases is not evident until the hypoxia is far advanced. The localized pain of angina pectoris due to hypoxia occurs because of impaired oxygenation of the myocardium. Discoloration of the skin and eventual ulceration that sometimes accompany varicose veins are a result of hypoxia of the involved tissues.

The treatment of hypoxia depends on the primary cause but usually includes administration of oxygen by inhalation (see oxygen therapy). In some vascular diseases, administration of vasodilators may help increase circulation, hence oxygen supply, to the tissues.
affinity hypoxia hypoxia resulting from failure of the hemoglobin to release oxygen to the tissues, as may occur with a left-shifted oxyhemoglobin dissociation curve.
anemic hypoxia hypoxia due to reduction of the oxygen-carrying capacity of the blood as a result of a decrease in the total hemoglobin or an alteration of the hemoglobin constituents.
circulatory hypoxia stagnant hypoxia.
histotoxic hypoxia that due to impaired utilization of oxygen by tissues, as in cyanide poisoning.
hypoxemic hypoxia (hypoxic hypoxia) that due to insufficient oxygen reaching the blood, as at the decreased barometric pressures of high altitudes.
stagnant hypoxia that due to failure to transport sufficient oxygen because of inadequate blood flow, as in heart failure.

hy·pox·i·a

(hī-pok'sē-ă),
Decrease below normal levels of oxygen in inspired gases, arterial blood, or tissue, without reaching anoxia.
[hypo- + oxygen]

hypoxia

(hī-pŏk′sē-ə, hĭ-)
n.
1. Deficiency in the amount of oxygen reaching body tissues.
2. Depletion of dissolved oxygen in aquatic environments to levels that are detrimental or fatal to aerobic organisms, often caused by eutrophication.

hy·pox′ic adj.

hypoxia

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

hy·pox·i·a

(hī-pok'sē-ă)
Lower than normal levels of oxygen in inspired gases, arterial blood, or tissue, short of anoxia.

hypoxia

Deficiency of oxygen in the tissues. Local hypoxia can lead to GANGRENE; general hypoxia to the death of the individual. Hypoxia occurs mainly as a result of obstructive artery disease, especially ATHEROSCLEROSIS. It may also occur from respiratory disease that prevents access of oxygen to the blood, ANAEMIA, certain forms of poisoning and suffocation.

hypoxia

the reduction of oxygen levels.

Hypoxia

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

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.

hy·pox·i·a

(hī-pok'sē-ă)
Decreased below normal levels of oxygen in inspired gases, arterial blood, or tissue, without reaching anoxia.
[hypo- + oxygen]
References in periodicals archive ?
Senger, "Moderate GSK3beta inhibition improves neovascular architecture, reduces vascular leakage, and reduces retinal hypoxia in a model of ischemic retinopathy," Angiogenesis, vol.
[6,7] Retinal hypoxia causes increased vascular endothelial growth factor(VEGF) which stimulates the neovascularization of iris and angle of anterior chamber.
Higher concentrations of vitreous EPO in BRVO are exclusively caused by the retinal hypoxia and are related to CME [46].
Hatchell, "Vitrectomy prevents retinal hypoxia in branch retinal vein occlusion," Investigative Ophthalmology & Visual Science, vol.
(2) The pathophysiology of anemic retinopathy seems to be related to retinal hypoxia, venous stasis, angiospasm and increased capillary permeability.
Pimonidazole (Hypoxyprobe) has been extensively applied as a marker to detect the hypoxia of cancer both in vitro and in vivo, which was applied in our study to assess the retinal hypoxia [21].
As shown in Table 1, retinal capillary microaneurysms are not specific to diabetes, having been demonstrated in a number of nondiabetic clinical disorders that, however, are all associated with some type of retinal hypoxia.