Pulse oximeters are medical devices used to measure the oxygen level (or oxygen saturation) in the blood. Pulse oximeters are considered to be a noninvasive, painless, general indicator of oxygen delivery to the tissues (e.g., finger, earlobe, or nose).
Pulse oximeter technology utilizes the light absorptive characteristics of hemoglobin and the pulsating nature of blood flow in the arteries to aid in determining the oxygenation status in the body. First, there is a color difference between arterial hemoglobin saturated with oxygen, which is bright red, and venous hemoglobin without oxygen, which is darker.
Second, with each pulse or heartbeat there is a slight increase in the volume of blood flowing through the arteries. Because of the increase of blood volume, albeit small, there is an associated increase in oxygen-rich hemoglobin. This represents the maximum amount of oxygen-rich hemoglobin pulsating through the blood vessels.
A clip-like device called a probe is placed on a body part, such as a finger or ear lobe, to measure the blood that is still carrying or is saturated with oxygen. The probe houses a light source, a light detector, and a microprocessor, which compares and calculates the differences in the oxygen-rich versus oxygen-poor hemoglobin. One side of the probe has a light source with two different types of light, infrared and red, which are transmitted through the finger to the light detector side of the probe. SPO Medical pulse oximeters use reflectance technology to measure oxygen saturation. The oxygen-rich hemoglobin absorbs more of the infrared light and the hemoglobin without oxygen absorbs more of the red light. The microprocessor calculates the differences and converts the information to a digital readout. This information helps the physician assess the amount of oxygen being carried in the blood and evaluate the need for supplemental oxygen.
Anatomy of the respiratory system:
The respiratory system is made up of the organs involved in the interchanges of gases, and consists of the:
The upper respiratory tract includes the:
- nasal cavity
- ethmoidal air cells
- frontal sinuses
- maxillary sinus
The lower respiratory tract includes the lungs, bronchi, and alveoli.
What are the functions of the lungs?
The lungs take in oxygen, which cells need to live and carry out their normal functions. The lungs also get rid of carbon dioxide, a waste product of the body's cells.
The lungs are a pair of cone-shaped organs made up of spongy, pinkish-gray tissue. They take up most of the space in the chest, or the thorax (the part of the body between the base of the neck and diaphragm).
The lungs are enveloped in a membrane called the pleura.
The lungs are separated from each other by the mediastinum, an area that contains the following:
The right lung has three sections, called lobes. The left lung has two lobes. When you breathe, the air enters the body through the nose or the mouth. It then travels down the throat through the larynx (voice box) and trachea (windpipe) and goes into the lungs through tubes called main-stem bronchi.
One main-stem bronchus leads to the right lung and one to the left lung. In the lungs, the main-stem bronchi divide into smaller bronchi and then into even smaller tubes called bronchioles. Bronchioles end in tiny air sacs called alveoli.
Reasons to use Pulse Oximeters
Pulse oximeters may be used to assess the adequacy of oxygen levels (or oxygen saturation) in the blood in a variety of circumstances such as surgery, other procedures involving sedation (e.g., bronchoscopy), adjustment of supplemental oxygen as needed, effectiveness of lung medications, and patient tolerance to increased activity levels. Other reasons may include, but are not limited to, the following:
mechanical ventilation - use of a ventilator to support breathing
sleep apnea - periods of cessation of breathing during sleep
medical conditions, such as heart attack, congestive heart failure, anemia, lung cancer, asthma, or pneumonia
Risks of using a Pulse Oximeter
Pulse oximetry is a quick, noninvasive method of measuring oxygen saturation in the blood. Risks associated with using a pulse oximeter are minimal and rare.
Prolonged application of the probe may cause tissue breakdown at the application site. Skin irritation may result from the adhesive used in adhesive-containing probes.
Use of pulse oximeters in cases of smoke or carbon monoxide inhalation is contraindicated, because oximetry cannot distinguish between normal oxygen saturation in the hemoglobin and the carboxyhemoglobin saturation of hemoglobin that occurs with inhalation of smoke or carbon dioxide.
There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.
Certain factors or conditions may interfere with the results of the test. These include, but are not limited to, the following:
decreased blood flow to the peripheral vessels
light shining directly on the oximetry probe
movement of the area to which the probe is attached
severe anemia (decreased red blood cells)
extreme warmth or coolness of the area to which the probe is attached
recent injection of contrast dye