Oxygen is essential for life. In order for humans to function properly, oxygen must be present in adequate amounts throughout the body. A person's oxygen saturation level measures the amount of oxygen carried in the blood. A number that falls too low can signal catastrophic consequences. That's why hospitals monitor oxygen saturation alongside pulse rate and blood pressure when determining a patient's condition.
Facts
Blood transports oxygen throughout the body thanks to hemoglobin, an iron-containing protein in red blood cells. Hemoglobin molecules can carry up to four oxygen molecules. The percentage of oxygen carried in the blood provides the saturation level.
For instance, if one hemoglobin molecule is carrying three oxygen molecules, the hemoglobin is carrying only 75 percent of its total capacity. In a larger blood sample, 1,000 hemoglobin molecules could carry up to 4,000 oxygen molecules. If only 3,920 oxygen molecules are transported, that equals 98 percent of total capacity. That means the blood's oxygen saturation level is 98 percent.
Significance
If a person's oxygen saturation level is too low, it means inadequate amounts of oxygen are reaching vital organs and body cells. This can lead to respiratory failure and possiblly death.
While ideal levels may vary depending upon the individual, the oxygen saturation level for a young, healthy adult tends to fall between 95 and 100 percent. Respiratory failure actually can set in when the oxygen saturation level drops to 90 percent. That doesn't leave much deviation between normal and possibly fatal, so it's critical for doctors and nurses to monitor a patient's oxygen saturation at all times.
Testing
An accurate, easy way to measure oxygen saturation levels is through pulse oximetry. A pulse oximeter is a small clip that attaches to a patient's finger. The oximeter shines two bright lights, one red and one infrared, through the finger to measure the blood oxygen levels. It does this by analyzing the color of the arterial blood. Oxygen-rich blood is bright red. In order to tell the arterial blood apart from the surrounding tissue, the oximeter measures the change in the overall color in coordination with the beating pulse.
Considerations
Pulse oximeters require a strong regular pulse to register an accurate oxygen saturation reading. People with cold hands and feet can sometimes have weak pulses in their extremities, leading to inaccurate readings.
Misconceptions
Despite some erroneous reports, the accuracy of pulse oximeters isn't affected when patients have anemia, sickle cell disease or bilirubin in the blood.
Tags: oxygen saturation, saturation level, oxygen saturation level, oxygen molecules, oxygen saturation, arterial blood, blood oxygen