Pulse oximetry is a non-invasive method allowing the monitoring of the oxygenation of a patient's blood. The term non-invasive in medicine has two meanings: A medical procedure which does not penetrate or break the skin or a body cavity, i. ... Oxygenation refers to the amount of oxygen in a medium. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ...

A sensor is placed on a thin part of the patient's anatomy, usually a fingertip or earlobe, or in the case of a neonate, across a foot, and a light containing both red and infrared wavelengths is passed from one side to the other. Changing absorbance of each of the two wavelengths is measured, allowing determination of the absorbances due to the pulsing arterial blood alone, excluding venous blood, skin, bone, muscle, fat, and (in most cases) fingernail polish. Based upon the ratio of changing absorbance of the red and infrared light caused by the difference in color between oxygen-bound (bright red) and oxygen unbound (dark red or blue, in severe cases) blood hemoglobin, a measure of oxygenation (the per cent of hemoglobin molecules bound with oxygen molecules) can be made. Human heart and lungs, from an older edition of Grays Anatomy. ... For the network protocol, see finger protocol. ... On the ear of humans and many other animals, the earlobe (lobulus auriculæ, sometimes simply lobe or lobule) is the soft lower part of the external ear or pinna. ... For other uses, see Red (disambiguation). ... For other uses, see Infrared (disambiguation). ... For other uses, see Wavelength (disambiguation). ... Electromagnetic radiation may be characterised by its wavelength. ... In spectroscopy, the absorbance A is defined as , where I is the intensity of light at a specified wavelength λ that has passed through a sample (transmitted light intensity) and is the intensity of the light before it enters the sample (or incident light intensity). ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Structure of hemoglobin. ... Oxygenation refers to the amount of oxygen in a medium. ... Structure of hemoglobin. ...

Indication

This is useful in any setting where a patient's oxygenation is unstable, including intensive care, operating, recovery, emergency and hospital ward settings, pilots in unpressurized aircraft, for assessment of any patient's oxygenation, and determining the effectiveness of or need for supplemental oxygen. Assessing a patient's need for oxygen is the most essential element to life; no human life thrives in the absence of oxygen (cellular or gross). Although pulse oximetry is used to monitor oxygenation, it cannot determine the metabolism of oxygen, or the amount of oxygen being used by a patient. For this purpose, it is necessary to also measure carbon dioxide (CO₂) levels. It is possible that it can also be used to detect abnormalities in ventilation. However, the use of pulse oximetry to detect hypoventilation is impaired with the use of supplemental oxygen, as it is only when patients breathe room air that abnormalities in respiratory function can be detected reliably with its use. Therefore, the routine administration of supplemental oxygen may be unwarranted if the patient is able to maintain adequate oxygenation in room air, since it can result in hypoventilation going undetected. Oxygenation refers to the amount of oxygen in a medium. ... Intensive care medicine or critical care medicine is concerned with providing greater than ordinary medical care and observation to people in a critical or unstable condition. ... Aviators are people who fly aircraft either for pleasure or for a job. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) pale blue (liquid) Standard atomic weight 15. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... In medicine, hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (hypo means below) to perform needed gas exchange. ...

History

In 1935 Matthes developed the first 2-wavelength ear O₂ saturation meter with red and green filters, later switched to red and infrared filters. This was the first device to measure O₂ saturation. 1935 (MCMXXXV) was a common year starting on Tuesday (link will display full calendar). ...

In 1949 Wood added a pressure capsule to squeeze blood out of ear to obtain zero setting in an effort to obtain absolute O₂ saturation value when blood was readmitted. The concept is similar to today's conventional pulse oximetry but suffered due to unstable photocells and light sources. This method is not used clinically. In 1964 Shaw assembled the first absolute reading ear oximeter by using eight wavelengths of light. Commercialized by Hewlett Packard, its use was limited to pulmonary functions and sleep laboratories due to cost and size. Year 1949 (MCMXLIX) was a common year starting on Saturday (link will display the full calendar) of the Gregorian calendar. ... A photoresistor is an electronic component whose resistance decreases with increasing incident light intensity. ... Also Nintendo emulator: 1964 (emulator). ...

Pulse oximetry was developed in 1972, by Aoyagi at Nihon Kohden using the ratio of red to infrared light absorption of pulsating components at the measuring site. It was commercialized by BIOX/Ohmeda in 1981 and Nellcor in 1983. Nellcor Incorporated in 1982, and introduced it into the US operating room market in 1983. Prior to its introduction, a patient's oxygenation was determined by a painful arterial blood gas, a single point measure which typically took a minimum of 20-30 minutes processing by a laboratory. (In the absence of oxygenation, damage to the brain starts in 5 minutes with brain death in another 10-15 minutes). In the US alone, approximately $2 billion was spent annually on this measurement. With the introduction of pulse oximetry, a non-invasive, continuous measure of patient's oxygenation was possible, revolutionizing the practice of anesthesia and greatly improving patient safety. Prior to its introduction, studies in anesthesia journals estimated US patient mortality as a consequence of undetected hypoxemia at 2,000 to 10,000 deaths per year, with no known estimate of patient morbidity. Year 1972 (MCMLXXII) was a leap year starting on Saturday (link will display full calendar) of the Gregorian calendar. ... Year 1981 (MCMLXXXI) was a common year starting on Thursday (link displays the 1981 Gregorian calendar). ... Year 1983 (MCMLXXXIII) was a common year starting on Saturday (link displays the 1983 Gregorian calendar). ... The creation of Dr. William NEw, Jack LLoyd and Jim CORenman, NELLCOR introduced the first clinically and commercially viable pulse oximeter in 1983, the now famous N-100, based on a technology originally developed in 1972, by Aoyagi at Nihon Kohden using the ratio of red to infrared light absorption... Year 1982 (MCMLXXXII) was a common year starting on Friday (link displays the 1982 Gregorian calendar). ... Year 1983 (MCMLXXXIII) was a common year starting on Saturday (link displays the 1983 Gregorian calendar). ... Arterial blood gas measurement is a blood test that is performed to determine the concentration of oxygen, carbon dioxide and bicarbonate, as well as the pH, in the blood. ... Brain damage or brain injury is the destruction or degeneration of brain cells. ... Brain death is defined as a complete and irreversible cessation of brain activity. ... Anesthesia or anaesthesia (see spelling differences) has traditionally meant the condition of having the perception of pain and other sensations blocked. ... // Hypoxemia (or hypoxaemia) is an abnormally low partial pressure of oxygen (PO2) in arterial blood (West J. Pulmonary Pathophysiology: The Essentials p22). ...

By 1987, the standard of care for the administration of a general anesthetic in the US included pulse oximetry. From the operating room, the use of pulse oximetry rapidly spread throughout the hospital, first in the recovery room, and then into the various intensive care units. Pulse oximetry was of particular value in the neonatal unit where the patients do not thrive with inadequate oxygenation, but also can be blinded with too much oxygen. Furthermore, obtaining an arterial blood gas from a neonatal patient is extremely difficult. ICU room An Intensive Care Unit (ICU) or Critical Care Unit (CCU) is a specialised department in a hospital that provides intensive care medicine. ...

In 1989, Diab and Kiani at Masimo Corporation invent Signal Extraction Pulse Oximetry (Masimo SET) using many proprietary breakthrough technologies and algorithms to separate the arterial signal from the non-arterial noise (e.g. venous blood movement during motion). The result was the first pulse oximetry technology scientifically and clinically proven to be accurate during conditions of patient motion and low perfusionThe technology was launched commercially in 1995.

With SET technology as the foundation, Masimo introduced a new oximetry technology in 2005 called pulse co-oximetry that allows clinicians to go beyond oxygen saturation to continuously and non-invasively measure carboxyhemoglobin, methemoglobin, pulse rate pleth variability index, and perfusion index. Called Rainbow SET technology, it uses multiple (7+) wavelengths of light and sophisticated signal processing including parallel engines and adaptive filters to calculate dyshemoglobin saturation values, allowing clinicians to detect and treat potentially life threatening conditions earlier than ever before.

Limitations

This is a measure solely of oxygenation, not of ventilation, and is not a substitute for blood gases checked in a laboratory as it gives no indication of carbon dioxide levels, blood pH, or sodium bicarbonate levels. The metabolism of oxygen can be readily measured by monitoring expired CO₂. Saturation figures also give no information about blood oxygen content, as a patient can be severely anemic but still fully saturated. In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. ... Arterial blood gas measurement is a blood test that is performed to determine the concentration of oxygen, carbon dioxide and bicarbonate, as well as the pH, in the blood. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... For other uses, see PH (disambiguation). ... Flash point Non-flammable. ...

Falsely low readings may be caused by hypoperfusion of the extremity being used for monitoring (often due to the part being cold or from vasoconstriction secondary to the use of vasopressor agents); incorrect sensor application; highly calloused skin; and movement (such as shivering), especially during hypoperfusion. To ensure accuracy, the sensor should return a steady pulse and/or pulse waveform. Falsely high or falsely low readings will occur when hemoglobin is bound to something other than oxygen. In cases of carbon monoxide poisoning, the falsely high reading may delay the recognition of hypoxemia (low blood oxygen level). Methemoglobinemia characteristically causes pulse oximetry readings in the mid-80s. Cyanide poisoning can also give a high reading because it reduces oxygen extraction from arterial blood (the reading is not false, as arterial blood oxygen is indeed high in early cyanide poisoning). In medicine, shock (hypoperfusion) is a life-threatening medical emergency characterized by inability of the body to supply enough oxygen to meet tissue requirements. ... The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... In medicine, shock (hypoperfusion) is a life-threatening medical emergency characterized by inability of the body to supply enough oxygen to meet tissue requirements. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ... This article is about the chemical compound. ...

It should be noted that pulse oximetry only reads the percentage of bound hemoglobin. It can be bound to other gasses such as carbon monoxide and still read high even though the patient is hypoxic. The only noninvasive methodology that allows for the continuous and noninvasive measurement of the dyshemoglobins carboxyhemoglobin and methemoglobin is a pulse co-oximeter. A CO-oximeter is a device for of detecting hypoxia, a medical condition relating to oxygen deficiency at tissue level. ...

See also

• Oxygen sensor
• Oxygen saturation
• Pulse oximeter
• Capnography, measuring of carbon dioxide (CO2) in the respiratory gases

// An oxygen sensor is an electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed. ... Oxygen saturation is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. ... A portable saturometer (for emergencies) Measure by optic properties through the nail A pulse oximeter is a medical device that indirectly measures the amount of oxygen in a patients blood. ... Capnography is the indirect monitoring of carbon dioxide (CO2) concentrations in a patients blood. ...

External links

• Masimo Corporation
• Nonin Medical
• Nellcor Incorporated
• Learn how an oximeter works by building an optical heart rate monitor
• Do I need pulse oximeter?
• Practical applications of Pulse Oximeter
• A Brief History of Pulse Oximetry