Hypoxemia Vs. Hypoxia

The terms 'hypoxia' or 'hypoxemia' may sound quite similar, but they are two different conditions. Hypoxia is the medical condition characterized by the shortage of oxygen in the body or a particular region of the body, while hypoxemia refers to decreased partial pressure of oxygen in blood. Hypoxemia or low partial pressure of oxygen in blood can however, lead to hypoxia. Hypoxia caused by hypoxemia is known as hypoxemic hypoxia, and it is more commonly experienced by people during high altitude ascension and inadequate pulmonary ventilation.

Comparison Between Hypoxemia and Hypoxia

Causes
As has been mentioned above, hypoxemia refers to low partial pressure of oxygen in blood, and it can be caused by factors like, low inspired partial pressure of oxygen. The partial pressure of oxygen in the inspired gas can be low due to low barometric pressure. This is the reason why people experience hypoxemia while ascending mountains or during high altitude ascension. Some other important hypoxemia causes are, alveolar hypoventilation, right to left shunt or shunting of blood from right to left side of circulation and diffusion impairment across the blood gas membrane of the lung.

On the other hand, hypoxia can be caused by a large number of factors. It can result from a fall in partial pressure of oxygen in arterial blood, which is known as hypoxemic hypoxia. Hypoxemic hypoxia can be caused by factors like, high altitude ascension, insufficient pulmonary ventilation, sleep apnea and heart mechanism failure. Conditions like, chronic obstructive pulmonary disease, cyanide toxicity, carbon monoxide poisoning, ischemic heart disease, choking, suffocation, very low blood pressure, asphyxiation caused by the inhalation of smoke, stroke and accumulation of abnormal hemoglobin in blood can also be associated with hypoxia.

Symptoms
The symptoms of these two conditions basically depend on their severity. In general, the most common hypoxemia symptoms are, shortness of breath, restlessness, anxiety and headaches. Severe cases of hypoxemia can cause tachycardia, and an increase in blood pressure. In the extreme cases, hypoxemia may lead to coma as well. The symptoms of hypoxia on the other hand, depend on the severity of oxygen deprivation, as well as the specific type. The more commonly observed symptoms of hypoxia are, severe headaches, shortness of breath, nausea and fatigue. Shortage of oxygen in brain due to hypoxia can cause changes in consciousness and uncoordinated movements. Sometimes, it can lead to coma as well. Some other hypoxia symptoms are, rapid breathing, poor judgment, poor reflexes, breathing difficulty, cyanosis or bluish discoloration of the skin, mental fatigue, vision impairment, dizziness and seizures. In extreme cases, hypoxia can lead to death as well.

Hypoxia can lead to a life-threatening condition, if the supply of oxygen to a vital organ like, the brain gets impaired significantly. Therefore, hypoxia is treated promptly by putting the patient on mechanical ventilation. In other words, supplemental oxygen or oxygen therapy is required for the treatment of hypoxia. For resolving the mild cases of hypoxemia, physicians usually advise the patient to lie down. This can help to increase the supply of oxygen. Mechanical ventilation is usually required only in the case of severe hypoxemia.