What is hypoxia?

Quick Answer
An inadequate supply of oxygen to tissues caused by either oxygen delivery not being sufficient for tissue requirements or utilization of oxygen being ineffective
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Causes and Symptoms

Various diseases or conditions of the lungs can cause mechanical problems with air exchange. These problems generally cause a diminished supply of oxygen and an excess of carbon dioxide in the blood. Hypoxia is present in any condition that causes inadequate amounts of oxygen to be delivered to body cells. Various types of hypoxia have been identified, including hypoxemic, anemic, and stagnant. Hypoxemic hypoxia is related to inadequate oxygen in inhaled air or respiratory problems that prevent adequate oxygen from reaching lung capillaries. Anemic hypoxia is related to any condition that causes a reduction in hemoglobin. Although adequate oxygen may reach the blood, it is not adequately transported to tissues. Stagnant hypoxia is related to reduced blood flow to capillaries and may be caused by conditions such as heart failure or obstruction of a blood vessel.

Treatment and Therapy

The treatment of hypoxia depends on its cause. Although oxygen therapy (administration of inhaled oxygen) seems a logical therapeutic measure, it may be helpful in some types of hypoxia but of little value in others. Oxygen therapy is clearly indicated when hypoxia is due to lack of oxygen in environmental air, to hypoventilation, or to problems that interfere with pulmonary diffusion. Oxygen therapy is moderately helpful in hypoxia from anemia and carbon monoxide poisoning. When hypoxia is caused by failure of the circulatory system, oxygen therapy may be slightly beneficial. It is of almost no value when hypoxia is caused by the inability of cells to use oxygen. In addition to oxygen delivered by face mask or cannula, in emergency situations a cricothyroidotomy and tracheostomy may be performed. Mechanical ventilation may also be necessary.

Adequate tissue oxygenation is evaluated by the following: Does the atmospheric air contain enough oxygen and humidification? Is the airway clear, or does it seem to contain excess secretions? Is the client able to ventilate without pain or discomfort? Do both sides of the thorax rise and fall equally with inhalation? Does breathing sound noisy? Are the rate, rhythm, and depth of respiration within normal limitations? Is cough and sputum production present? Is chronic lung disease present? Are blood gases within normal limits? Is the complete blood count within normal limits? Is the radial/apical pulse rate, rhythm, and volume within normal limits? Is blood pressure within normal limits? Is mental confusion, disorientation, or memory loss present?

Bibliography

Des Jardins, Terry. Clinical Manifestations and Assessment of Respiratory Disease. New York: Elsevier Science, 2005.

Lei Xi, and Tatiana V. Serebrovskaya, eds. Intermittent Hypoxia: From Molecular Mechanisms to Clinical Applications. Hauppauge, N.Y.: Nova Science, 2013.

"NINDS Cerebral Hypoxia Information Page." National Institute of Neurological Disorders and Stroke. October 2010.

Roach, Robert C., Peter D. Wagner, eds. Hypoxia Into the Next Millennium. New York: Springer Science + Business, 2013.

Vordermark, Dirk. Hypoxia: Causes, Types and Treatment. Hauppauge, N.Y.: Nova Science, 2012.

Wilkins, Robert L. Egan’s Fundamentals of Respiratory Care. New York: Elsevier Health Sciences, 2008.

Wilkins, Robert L. Respiratory Disease: Case Study Approach to Patient Care. New York: F. A. Davis, 2006.