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 an excellent way of screening sick people from really sick people, a more accurate measurement is obtained by measuring oxygen directly from arterial blood. This is important in places like intensive care units or when a patient is under anesthesia having an operation.
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.
One of the circumstances where pulse oximetry is employed is during sleep studies. These investigations require an overnight stay in the hospital and are done for the purpose of finding out if someone has a condition called sleep apnea. This is when a person periodically stops breathing during the night. At best, they wake up drowsy and fuzzy-headed. At worst, it is a risk factor for life-threatening conditions like heart attack and stroke.
There are two categories of sleep apnea, neurological and obstructive. Obstructive sleep apnea (OSA) is more common than neurological sleep apnea, but no less dangerous. Treatments may include a device that is prescribed by a dentist to keep the mouth partially open at night, continuous positive airway pressure (CPAP) or, in extreme cases, surgery to correct an anatomic deformity that makes the airway unable to 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.
Anybody can be diagnosed with either form of sleep apnea. The principal risk factors are age over 40, obesity and being male. This is a particularly heart-breaking condition in young babies, who can sometimes stop breathing for periods as long as 20s. This is frightening for new parents. Fortunately, alarms are available that can sound an alert when the baby has an apnea episode. CMS pulse oximeters may also be purchased for use at home for both adult and child use.
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 an excellent way of screening sick people from really sick people, a more accurate measurement is obtained by measuring oxygen directly from arterial blood. This is important in places like intensive care units or when a patient is under anesthesia having an operation.
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.
One of the circumstances where pulse oximetry is employed is during sleep studies. These investigations require an overnight stay in the hospital and are done for the purpose of finding out if someone has a condition called sleep apnea. This is when a person periodically stops breathing during the night. At best, they wake up drowsy and fuzzy-headed. At worst, it is a risk factor for life-threatening conditions like heart attack and stroke.
There are two categories of sleep apnea, neurological and obstructive. Obstructive sleep apnea (OSA) is more common than neurological sleep apnea, but no less dangerous. Treatments may include a device that is prescribed by a dentist to keep the mouth partially open at night, continuous positive airway pressure (CPAP) or, in extreme cases, surgery to correct an anatomic deformity that makes the airway unable to 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.
Anybody can be diagnosed with either form of sleep apnea. The principal risk factors are age over 40, obesity and being male. This is a particularly heart-breaking condition in young babies, who can sometimes stop breathing for periods as long as 20s. This is frightening for new parents. Fortunately, alarms are available that can sound an alert when the baby has an apnea episode. CMS pulse oximeters may also be purchased for use at home for both adult and child use.