Milestones:Pulse Oximetry, 1972
Title
Pulse Oximetry, 1972
Citation
Pulse oximetry, a non-invasive technique to measure blood oxygen saturation continuously and immediately without a blood sample, was introduced in 1972 by Takuo Aoyagi of Nihon Kohden Corporation. The company launched its OLV-5100 as the first ear pulse oximeter in 1975. Subsequent developments by others made pulse oximeters a reliable and affordable standard of care in hospitals, clinics, and homes.
Street address(es) and GPS coordinates of the Milestone Plaque Sites
Advanced Technology Center, Nihon Kohden Corporation. Address:1-1-6 Kusunokidai, Tokorozawa City, Saitama 359-0037, Japan, GPS coordinates: N 35.78718, E 139.47514, Advanced Technology Center, Nihon Kohden Corporation. Address:1-1-6 Kusunokidai, Tokorozawa City, Saitama 359-0037, Japan, GPS coordinates: N 35.78718, E 139.47514
Details of the physical location of the plaque
The plaque will be displayed at the entrance hall of Advanced Technology Center, Nihon Kohden Corporation.
How the plaque site is protected/secured
The plaque will be displayed in a showcase placed at the entrance hall of Advanced technology Center, Nihon Kohden Corporation, which can be accessible to the public with permission.
Historical significance of the work
0. Reason for the person's name on the plaque.
The discovery of the principle and the first pulse oximeter by Dr. Aoyagi are the cornerstones of this case. Dr. Aoyagi is widely known as the inventor of the pulse oximeter, and his work is highly regarded both in the field of electrical and electronics and in the field of medical biology. Thanks to Dr. Takuo Aoyagi's great achievement of developing the first 'pulse oximeter', he was honored with 'IEEE Medal for Innovations in Healthcare Technology' in 2015 for the first time in Japan [5]. He also received the American Society of Anesthesiologists "Honorary Member Award" in 2021, and his name is widely known in the medical field [6]. Dr. Aoyagi was nominated as a candidate for the Nobel Prize by his nominators [3] [5].
The major historical significance of developing 'pulse oximeters’ is summarized as follows.
1. Historical Background of Developing 'Pulse Oximeters'
Supplementary oxygen is indispensable to patients with respiratory or cardiac problems, pilots operating in unpressurized aircraft, mountain climbers at high altitudes, athletes exercising, etc. Pulse oximetry is based on a unique concept to compute a person's arterial oxygen saturation without the need for calibration, using the pulsatile variations in the optical density of tissues in the red and infrared wavelengths. Thus, pulse oximetry is particularly convenient for noninvasive continuous measurement of blood oxygen saturation [1,2].
Pulse oximetry, the principle of the pulse oximeter, was discovered in 1972 [1] by Dr. Takuo Aoyagi at a Japanese medical electronic equipment manufacturer, Nihon Kohden Corporation. The first product OLV-5100 Ear Oximeter was launched in 1975 [7]. Pulse oximeters have since been used as a medical device that noninvasively monitors the oxygen saturation of a patient’s blood and changes in the blood volume in the skin [1-5]. Now, a typical 'pulse oximeter' uses an electronic processor and a pair of small LEDs (light-emitting diodes) facing a photodiode through a translucent part of the patient’s body, usually a fingertip or an earlobe, as can be seen from Fig. 1 [2]. One LED is red with a wavelength of 660 nm, and the other is infrared with a wavelength of 940 nm. Media:(Pulse.pdf)
2. Historical Achievements of Commercializing Pulse Oximeters
Pulse oximetry is a noninvasive method for monitoring a person’s oxygen saturation. In what follows, how this method has been commercialized is itemized.
(1) Pulse oximetry is found not only to be conducive to noninvasive measurement of a patient's blood oxygen saturation, but also to be useful in any setting where a patient’s oxygenation is unstable, including intensive care, operating, emergency and hospital ward settings, pilots in unpressurized aircraft, etc., for the assessment of any patient's oxygenation, and determining the effectiveness of or the need for supplemental oxygen. Thus, the ‘pulse oximeter’ proves to be utilized for monitoring noninvasively a patient’s blood oxygen saturation [2].
(2) Due to their simplicity of use and the ability to provide continuous and immediate oxygen saturation values, ‘pulse oximeters’ are of critical importance in emergency medicine and for the practical use for patients with respiratory or cardiac problems, especially COPD, as well as for the diagnosis of sleep disorders such as apnea and hypopnea [2].
(3) Portable battery-operated ‘pulse oximeters’ are indispensable not only to pilots operating in unpressurized aircraft above 5,000 m where supplemental oxygen is a vital necessity but also to mountain climbers and athletes whose oxygen levels decrease drastically at ultra-high peaks and with demanding exercise, respectively [2].
(4) Connectivity advancements have made it possible for patients to have their blood oxygen saturation continuously monitored without a cabled connection to a hospital monitor, not sacrificing the flow of patient data back to bedside monitors or centralized patient surveillance systems [2].
(5) For patients with COVID-19, pulse oximetry helps with the early detection of silent hypoxia, in which the patients still look and feel comfortable, but their SpO2 (peripheral oxygen saturation) is perilously low. In addition, such low SpO2 may indicate severe COVID-19-related pneumonia, requiring a ventilator [2].
３． Pulse Oximeters - Social Impact and influence on later systems
(1) It is significant that the development of the world's first product “Ear Oximeter” enabled noninvasive measurement of blood oxygen saturation, which had been impossible until then, and that was put to practical use not at the laboratory level but as a medical device. Although this product had various engineering limitations and limited clinical use, the products that followed the "Ear Oximeter" improved upon the design and exploded in popularity, protecting the health of many people globally. "Ear Oximeter" was the cornerstone.
(2) After Dr.Aoyagi’s idea of a pulse oximeter and the launch of the first product “Ear Oximeter”, it was further developed by Minolta, Ohmeda, and Nellcor, paving the way to the commercialization of a device that revolutionized clinical monitoring for decades to come. It has been the standard for intraoperative monitoring since the late 1980s. After that, the usage expanded from just the operating room into intensive care units and recovery rooms. However, the technology shortcomings with frequent false alarms during patient motion and low perfusion became apparent.
(3) Masimo commercialized a new technology of pulse oximeter using adaptive filters in 1995 that substantially eliminated the problems of motion artifact, low peripheral perfusion, and many low signal-to-noise situations. This greatly extended the utility of SpO2 in high-motion, low-signal and noise-intensive environments. The new generation of pulse oximeters after Masimo have proven to be more accurate and robust in critical patients and neonates.
Obstacles (technical, political, geographic) that needed to be overcome
Although the idea of pulse oximetry originated in Japan, the device development lagged due to a lack of business, clinical, and academic interest. On the other hand, in the U.S., the awareness of the importance of anesthesia safety led to the widespread use of pulse oximetry around the world, due to academic foresight and media attention in combination with excellence in technological innovation [3]. The following describes a number of obstacles that still needed to be overcome for the progress of pulse oximetry:
(1) Pulse oximetry solely measures hemoglobin saturation, but it is not a complete measure of respiratory sufficiency, nor a substitute for blood gases checked in a laboratory, since it gives no indication of base deficit, carbon dioxide levels, blood pH, or bicarbonate concentration [2].
(2) Since pulse oximeter devices are calibrated in healthy subjects, the accuracy is poor in some cases for critically ill patients and preterm newborns [2]. The new “generation” of pulse oximeters has proven to be more accurate and robust in critical patients and neonates.
(3) Obesity, hypotension, and some hemoglobin variants can reduce the accuracy of the results. Some home pulse oximeters have low sampling rates which can significantly underestimate dips in blood oxygen levels. The accuracy of pulse oximetry deteriorates considerably for readings below 80% [2].
(4) Since pulse oximetry measures only the percentage of bound hemoglobin, a falsely high or falsely low reading will occur when hemoglobin binds to something other than oxygen, as pointed out below [2]: - Hemoglobin has a higher affinity to carbon monoxide than it does to oxygen, and a high reading may occur despite the patient’s actually being hypoxemic. In the case of carbon monoxide poisoning, this inaccuracy may delay the recognition of hypoxia. - Cyanide poisoning gives a high reading because it reduces oxygen extraction from arterial blood. In this case, the reading is not false, since arterial blood oxygen is indeed high in early cyanide poisoning. - COPD, especially chronic bronchitis, may cause false readings.
Features that set this work apart from similar achievements
Although some oximeters were put on the market in the 1940s through the 1960s, and technology to realize today’s pulse oximetry was extremely difficult because of poor photocell and light sources. In addition, the first absolute reading ear oximeter was assembled in 1964, but it used eight wavelengths of light, rather than the two used today [2].
On the contrary, a great number of 'pulse oximeters' developed since 1972 have realized the following distinctive features:
(1) The 'pulse oximeter' is usable as a medical device that noninvasively monitors the oxygen saturation of a patient’s blood and changes in blood volume in the skin [1-5].
(2) Owing to the ability to provide continuous and immediate oxygen saturation values, 'pulse oximeters' are very useful for patients with respiratory or cardiac problems as well as for diagnosis of sleep disorders such as apnea and hypopnea [2].
(3) Portable battery-operated pulse oximeters offer health benefits to a variety of people, such as pilots, mountain climbers, athletes, etc. Some portable pulse oximeters employ software that charts a person's blood oxygen and pulse, serving as a reminder to check blood oxygen levels [1-3].
(4) With the use of connectivity advancements of pulse oximeters, patients can have their blood oxygen saturation continuously monitored without a cabled connection to a hospital monitor, not sacrificing the flow of patient data back to bedside monitors or centralized patient surveillance systems [2].
(5) A typical 'pulse oximeter' uses an electronic processor and a pair of small LEDs facing a photodiode through a translucent part of the patient’s body, usually a fingertip or an earlobe. One LED is red with a wavelength of 660 nm, and the other is infrared with a wavelength of 940 nm [2].
Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English or accompanied by an English translation.
Significant references
[1] J. W. Severinghaus and Y. Honda, “History of blood gas analysis. VII. Pulse oximetry”, J. Clinical Monitoring, vol. 3, pp. 135-138, 1987.
[2] "Pulse oximetry": https://en.wikipedia.org/wiki/Pulse_oximetry, 11 March 2023.
[3] K. Miyasaka, et al., “Tribute to Dr. Takuo Aoyagi, inventor of pulse oximetry”, J. Anesthesia, vol. 35, pp. 671-709, 2021.
[4] T. Aoyagi and M. Kishi, “Optical device for measuring arterial oxygen saturation”, Japan Patent, 53-26437, 1978. (in Japanese).
[5] "Mr. Takuo Aoyagi and the pulse oximeter": http://www.nihonkohden.co.jp/information/aoyagi/. (in Japanese).
[6] Alexander A Hannenberg . “Takuo Aoyagi, Ph.D., American Society of Anesthesiologists Honorary Member”, Anesthesiology, 135(4):591-596. 2021.
[7] Nihon Kohden Corp. OLV-5100 Ear Oximeter Brochure, 1975. (Original Japanese Brochure and a corresponding English translation)
Appendices:
References [4] and [5] were written in Japanese, for which English abstracts are provided as follows.
① Reference [4]: This article describes the patent gazette of Japan Patent 53-26437 on the 'Pulse Oximeter' invented by Takuo Aoyagi and Michio Kishi at Nihon Kohden Corporation (Tokyo. Japan), which was applied on March 29, 1974, and obtained on October 9, 1975. This patent gazette claims the extent and distinctive features of invented technologies.
② Reference [5]: This article outlines Dr. Aoyagi's achievements of developing the fist pulse oximeter, featuring (i) the principle of pulse oximeter, (ii) Dr. Aoyagi's discovery of the method of developing pulse oximetry, (iii) the first product 'Ear Oximeter OLV-5100' put on sale in 1975 by Nihon Kohden Corporation, (iv) the diffusion process of pulse oximeters, (v) Dr. Aoyagi's short history, and (vi) the list of patents by Dr. Aoyagi.
Supporting materials
See references
