An oximeter, or a pulse oximeter, is a medical device that measures the amount of oxygen in the blood. A pulse oximeter has become an important monitoring tool in modern medicine. The oximeter is attached to a monitor so as to enable a direct reading of the patient’s oxygenation at all times. This is because timely recognition of low saturation conditions and emergency correction measures can prevent potentially devastating complications. Before the oximeter was invented, a series of complicated blood tests were needed. Oximeter manufacturers have been rising to the occasion by continually improving on their products to reduce the margin of error and provide safer tools. Clinicians are thus provided with the most technologically advanced systems. Oximeters now come in a variety of shapes and sizes, and they serve a variety of uses, but the main aim of all oximeters is to monitor oxygen saturation readings. Clinical motion by the patient and corresponding errors in reading accurate saturation levels pose a major challenge to manufacturers. Clinical motion may cause volatility, dashing of display, inaccuracy, and freezing of saturation readings. Studies reveal that among adults extending, rubbing, clenching and flexing are the most common motions. In infants, kicking, clenching and flexing are the most common motions. Clinical motions are irregular and are generally very short in duration. Oximeters traditionally calculate saturation by measuring the difference in trough and peak of each plethysmographic waveform. Advanced digital signaling allows the modern hi-tech meters to make accurate readings that were otherwise impossible. An oximeter usually measures the percent of normal. Normal ranges usually vary from 95 to 100 percent. The blood vessels expand and contract with the heartbeat, so the monitored signals bounce in time with the heartbeat. Modern oximeters can also clip onto the finger of a patient and determine the amounts of chemicals by using optical properties of light. The way in which pulse oximetry works is interesting. Well oxygenated blood is bright red in color, while poorly oxygenated blood is darker, almost purple in tinge. Bright red blood will absorb more light. Oximeters can also distinguish between venous and arterial bloods. Oximeters or blood-oxygen monitors are critical in emergency medicine and can be crucial for patients with cardiac or respiratory problems. Another interesting use of the meter is in non-pressurized airplanes where pilots operate above 10,000 feet, thus needing supplemental oxygen. Oximeters are routinely used in operating rooms and intensive care units as a part of their vital-sign monitoring. They are also used in sleep labs and with overnight oximetry tests to determine nocturnal hypoxemia (drop in oxygen levels). Patients who need supplemental oxygen aids or any other type of non-invasive breathing aids are thus helped greatly. Other than hospitals and labs, people who are dependent on supplemental oxygen find it useful to own an oximeter. Such people feel comfort and security in being able to monitor their own oxygen needs. When such people become extremely short of breath, they are able to understand processes that take place within them, and thus feel empowered. People use oximeters while exercising or exerting themselves, so they can monitor their oxygen levels continually. Oxygen is a form of medication, and oxygen levels should not be adjusted without consulting a doctor first. It is good for patients to be proactive with their own health care, but one should not get obsessed with the readings and get over alarmed.