When doctors, nurses or paramedics need a quick estimate of a patient's oxygen levels, they use technology called CMS pulse oximeters. These little gadgets can be easily clipped onto a finger or an earlobe and indirectly measure oxygen levels by determining the percentage of hemoglobin, a respiratory pigment, that is saturated with the life-giving gas. Normal values in most people are 95 percent or more.
The physical principles of how a pulse oximeter works are beyond the scope of this article. It is based on the absorbance of light. By shining light of two different wavelengths into the skin, the instrument can calculate the light absorbance, and hence the concentration of O2 in blood that is circulating in the arteries.
While this is a decent method of measuring oxygen saturation, it gives no information about the actual level of oxygen in the blood. More accurate measurements of blood oxygen levels may be obtained by measuring arterial blood flow. The best method of doing this is by sticking a needle directly into an accessible artery.
Jamming a needle into an artery, which are by design very thick, is very painful for the patient. Because of this, it is not routinely done unless it is really necessary. The feeling of having a needle pierce into an artery has been compared to having a sharp implement poking directly into a bone.
A pulse oximeter may also be used for research purposes, for example, during sleeping studies. These investigations are performed when a patient is suspected to have a condition called sleep apnea. People with this type of disorder are unable to breathe, sometimes for dangerously long periods, while they are sleeping. This can result in stroke, heart attack or even death. At best, it can leave people foggy headed and tired the next day.
There are two main types of sleep apnea, obstructive and neurological. Obstructive sleep apnea (OSA) is the more common of the two and is also the easiest to treat. Therapies include surgery, continuous positive airway pressure (CPAP) or prescribing a device that the patient puts in their mouth when they go to bed that helps them to keep their airway open.
Central, or neurological sleep apnea, is less common and harder to treat than OSA. Instead of stopping the breathing process, the brain doesn't attempt it. There is often a serious condition underlying neurological OSA that affects the brain stem. This is the brain area that is responsible for breathing and heart rate. Neurological sleep apnea can happen by itself or in combination with OSA.
The biggest risk factors for sleep apnea are being overweight, male gender or being over the age of 40. However, sleep apnea can happen to anybody. Some small babies can stop breathing for as long as 20 seconds, which is very disturbing for already anxious new parents. If a baby is discovered to be at risk for this condition, the parents can obtain an alarm that will alert them if and when this happens. CMS pulse oximeters are also available for use at home.
The physical principles of how a pulse oximeter works are beyond the scope of this article. It is based on the absorbance of light. By shining light of two different wavelengths into the skin, the instrument can calculate the light absorbance, and hence the concentration of O2 in blood that is circulating in the arteries.
While this is a decent method of measuring oxygen saturation, it gives no information about the actual level of oxygen in the blood. More accurate measurements of blood oxygen levels may be obtained by measuring arterial blood flow. The best method of doing this is by sticking a needle directly into an accessible artery.
Jamming a needle into an artery, which are by design very thick, is very painful for the patient. Because of this, it is not routinely done unless it is really necessary. The feeling of having a needle pierce into an artery has been compared to having a sharp implement poking directly into a bone.
A pulse oximeter may also be used for research purposes, for example, during sleeping studies. These investigations are performed when a patient is suspected to have a condition called sleep apnea. People with this type of disorder are unable to breathe, sometimes for dangerously long periods, while they are sleeping. This can result in stroke, heart attack or even death. At best, it can leave people foggy headed and tired the next day.
There are two main types of sleep apnea, obstructive and neurological. Obstructive sleep apnea (OSA) is the more common of the two and is also the easiest to treat. Therapies include surgery, continuous positive airway pressure (CPAP) or prescribing a device that the patient puts in their mouth when they go to bed that helps them to keep their airway open.
Central, or neurological sleep apnea, is less common and harder to treat than OSA. Instead of stopping the breathing process, the brain doesn't attempt it. There is often a serious condition underlying neurological OSA that affects the brain stem. This is the brain area that is responsible for breathing and heart rate. Neurological sleep apnea can happen by itself or in combination with OSA.
The biggest risk factors for sleep apnea are being overweight, male gender or being over the age of 40. However, sleep apnea can happen to anybody. Some small babies can stop breathing for as long as 20 seconds, which is very disturbing for already anxious new parents. If a baby is discovered to be at risk for this condition, the parents can obtain an alarm that will alert them if and when this happens. CMS pulse oximeters are also available for use at home.
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