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Tribute to Dr. Takuo Aoyagi, inventor of pulse oximetry - PubMed

Tribute to Dr. Takuo Aoyagi, inventor of pulse oximetry

Katsuyuki Miyasaka et al. J Anesth. 2021 Oct.

Abstract

Introduction: Dr. Takuo Aoyagi invented pulse oximetry in 1974. Pulse oximeters are widely used worldwide, most recently making headlines during the COVID-19 pandemic. Dr. Aoyagi passed away on April 18, 2020, aware of the significance of his invention, but still actively searching for the theory that would take his invention to new heights.

Method: Many people who knew Dr. Aoyagi, or knew of him and his invention, agreed to participate in this tribute to his work. The authors, from Japan and around the world, represent all aspects of the development of medical devices, including scientists and engineers, clinicians, academics, business people, and clinical practitioners.

Results: While the idea of pulse oximetry originated in Japan, device development lagged in Japan due to a lack of business, clinical, and academic interest. Awareness of the importance of anesthesia safety in the US, due to academic foresight and media attention, in combination with excellence in technological innovation, led to widespread use of pulse oximetry around the world.

Conclusion: Dr. Aoyagi's final wish was to find a theory of pulse oximetry. We hope this tribute to him and his invention will inspire a new generation of scientists, clinicians, and related organizations to secure the foundation of the theory.

Keywords: Anesthesia safety; History; Patient monitoring; Pulse oximetry.

© 2021. The Author(s).

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Figures

Fig. 1
Fig. 1

Models of principles of pulse oximetry. a Two-wavelength model. Only arterial blood pulsates, while the tissue does not move. b Three-wavelength model. The tissue is pushed by the pulsation of arterial blood

Fig. 2
Fig. 2

Simulations considering the effects of tissues. Changes in the attenuation ratio when tissue pulsation is absent and only oxygen saturation changes. Changes in the attenuation ratio when oxygen saturation is constant and the tissue thickness changes

Fig. 3
Fig. 3

In vitro experimental models. a Single-layer model (only arteries change). Changes in the blood layer reduces the thickness of the open air layer. b Two-layer model (the effects of tissues were simulated). Changes in the blood layer reduces the thickness of the layer of cow’s milk (tissues). The thickness of the blood layer is changed periodically by changing the pressure of blood using a transparent elastic plate on one side of the blood layer.

Fig. 4
Fig. 4

Comparison of measured values between the in vitro models and humans [13]. The measurement results in the two-layer model tended to be more closely similar to those in humans than those in the single-layer model.

Fig. 5
Fig. 5

Comparison between the two- and five-wavelength systems

Fig. 6
Fig. 6

OXIMET Met 1471. The light emitted by a light emission diode travels to the finger probe and the transmitted light is analyzed by a silicon photodiode mounted in the chassis. The incident and transmitted light travels to and from the chassis through the fiberoptics, respectively

Fig. 7
Fig. 7

A pulse-generating apparatus for the in vitro pulse oximetry devised by Hamaguri. A rotary pump generates pulse waves in an artificial cell with a pair of translucent glass windows on both sides of the cell. Light emitted by a halogen lamp travels across the windows. The transmitted light is spectrophotometrically analyzed for oxygen saturation by using the pulse oximetry principle. By changing the hematocrit of the sample blood pumped in the cell one can estimate the effect of scattering of light by blood corpuscles. Namely, the oxygen saturation by the in vitro pulse oximetry and that measured by a Radiometer (OSM-2) are compared with different hematocrit of the sample blood

Fig. 8
Fig. 8

N-100 Pulse Oximeter (1983, Nellcor)

Fig. 9
Fig. 9

Nellcor Pulse Oximeter Prototype as delivered to us in 1982. Note the absence of the "N-100" designation, this was added at a later date as N-100A. The first commercial model was called N-100B.

Fig. 10
Fig. 10

A souvenir photo from the 2015 IEEE Honors Ceremony

Fig. 11
Fig. 11

The world’s first pulse oximeter (ear oximeter OLV-5100)

Fig. 12
Fig. 12

Mainstream CO2 sensor cap-ONE (TG-980P)

Fig. 13
Fig. 13

MRI-compatible CO2 sensor module (TG-MR9T)

Fig. 14
Fig. 14

A photo at the Lifetime Achievement recognition during the Innovations and Applications of Monitoring Perfusion, Oxygenation and Ventilation (IAMPOV, 2012) symposium on the campus of Yale University

Fig. 15
Fig. 15

Memorial photo in 2015 Tokyo IAMPOV Symposium (at auditorium in St. Luke’s International University)

Fig. 16
Fig. 16

Memorial photo at the 3rd IAMPOV Symposium Award Ceremony, 2012

Fig. 17
Fig. 17

HP Company ad for an ear oximeter (1973). Eight wavelengths (650-1,050 nm), heated ear probe to obtain arterialization. It was accurate, but large and hard to operate. It was not a monitor.

Fig. 18
Fig. 18

Dr. Aoyagi showing his work to Dr. Byron Aoki of the University of Hawaii (at the author's office at NCCHD, 2002)

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