Hypoxia refers to deficiency in amount of oxygen reaching the body tissue ; it differs from hypoxemia which pertains to inadequate amount of oxygen traveling in blood. Hypoxemia can contribute to hypoxia in the sense that, when there is an inadequate amount of oxygen in blood, it can lead to insufficient oxygen reaching the tissues. When there is complete lack of oxygen in tissues, this is termed as ‘anoxia’ or oxygen starvation.
When hypoxia occurs, it can affect the whole body a situation known as ‘generalized hypoxia’.However, if it affects a specific organ or part of the body, it is called tissue hypoxia. In addition, the condition can be termed as acute or chronic in which acute means a rapid onset. Chronic means that the condition occurs over time and slowly. When variations in oxygen concentration within the arteries occurs, it can cause deprivation of sufficient adequate oxygen supply in tissues or the whole body such as witnessed during a physical exercise.
Moreover, a mismatch between the demand of oxygen and its supply at the cells or cellular levels may as well lead to hypoxia. Often, confusion occurs in use of the terms hypoxia and hypoxemia since they are both related to oxygen levels but hypoxemia involves abnormally low concentrations of oxygen within the arterial blood.
What are the different types of hypoxia?
There are different types of hypoxia and they include hypoxic hypoxia, hypemic hypoxia, histotoxic hypoxia, and ischemic hypoxia. To elaborate these terms, hypoxic hypoxia simply refers to generalized insufficient oxygen supply in the whole body. In hypoxic hypoxia, the tissue does not receive sufficient oxygen since there is inadequate amount or concentration of oxygen in blood that flows to the tissues.
High altitude can trigger episodes of hypoxic hypoxia because of the low partial pressure of the atmospheric oxygen. When the atmospheric oxygen pressure is modified in an environment such as a sewer line, it may create the condition. Other causes of hypoxic hypoxia are such as a low partial pressure in oxygen created in lungs as a person switches to atmospheric air from an inhaled anesthesia. This is termed as diffusion hypoxia or the Fink effect.
Another cause of hypoxic hypoxia is a reduced oxygen saturation that is caused by hypopnea or sleep apnea. Chronic obstructive pulmonary disease- COPD, may cause inadequate pulmonary ventilation, which leads to hypoxic hypoxia. In hypemic hypoxia, the total oxygen content in blood reduces though the arterial oxygen pressure remains normal.
Histotoxic hypoxia occurs when there is adequate concentration of oxygen from the lungs that is delivered to tissues but the cells are not able to make use of it. Although oxygen is supplied sufficiently, the cells are unable to utilize it in their metabolic activities due to disabled oxidative phosphorylation enzymes and this situation is commonly witnessed when a person drinks alcoholic beverages.
Stagnant or ischemic hypoxia occurs due to inadequate blood flow. There is local restriction in the circulation of otherwise sufficiently oxygenated blood. This may be caused by ischemic heart disease, and cerebral ischemia.
Causes of hypoxia differ in one way or another and while the condition may be caused by lung disease, environmental conditions may also contribute to the condition. High altitude creates difference in atmospheric oxygen pressure creating partial oxygen pressure, which can cause insufficient amount of oxygen in body tissue.
When the lungs are affected by health conditions like asthma, COPD, pneumonia, lung cancer, pulmonary hypertension, and rheumatoid lung disease, these conditions can create hypoxia. Not breathing enough or hypoventilation situation can cause the reduced amount of oxygen in body tissue. Hypoventilation may be central where the brain does not stimulate the lungs to breathe as witnessed in anesthesia use, effects of stroke, or trauma caused by a head injury.
Side effects of certain medications such as those used to treat pain may cause hypoventilation. Illegal drugs can also cause changes in the function of brain in stimulating the lungs to breath. Peripheral hypoventilation may occur when there is obstruction of airways, which interrupts breathing for example, choking caused by large foreign objects that lodges to the trachea. Drowning, cardiac arrest, and suffocation may also result to hypoventilation.
A patient with anemic hypoxia may also have problem of insufficient oxygen in tissues. When poisoning occurs from carbon monoxide, the hemoglobin is not able to bind oxygen molecules properly causing lack of utilization of oxygen. Moreover, if there is obstruction of the vessel carrying oxygenated blood to tissue by a clot, as may happen in a heart attack, such a condition may cause ischemic hypoxia. This prevents the tissues from receiving oxygen.
There are different symptoms and signs experienced by people who suffer from hypoxia and they include dizziness and fainting, dyspnea or shortness of breath, headache, lethargy, confusion and lack of judgment. A rapid heart rate may be witnessed as well as elevated blood pressure or hypertension.
A tingling warming sensation, loss of coordination, tunnel vision, increased levels of red blood cells count in chronic hypoxia are other symptoms experienced by a person. The extremities and lips may suffer from bluish tinge or discoloration of skin, a condition known as cyanosis. Hypoxia affects organs like the liver, brain, and heart. With severe hypoxia, it can cause irreversible damage within a short time after its onset. Seizures, coma, and death could also occur. Chronic but milder hypoxia may also result to damage in organs of the body with time.
The treatment of hypoxia largely depends on the causal factor. When you are short of breathe, oxygen therapy may be recommended while the real cause of the condition is determined for more specific and appropriate treatment. In case of effects of high altitude sickness or condition, oxygen enrichment may help counteract hypoxia. This may include increasing the concentration of oxygen in air by use of oxygen concentrators. Mechanical ventilation may be applied if symptoms of hypoxia are severe with use of a ventilator. If hypoxia is caused by blockage of blood vessel leading to the brain, then the clot or hardened vessel is treated. Similarly, if the hypoxia is caused by tumor in lungs, then the removal of the tumor can help relieve the condition.