Photo/Illutration A pulse oximeter (Asahi Shimbun file photo)

A pulse oximeter resembles an oversized plastic clothes pin at first glance.

Brought into the limelight by the novel coronavirus pandemic, the device is clipped onto the tip of a patient's index finger to instantly display the oxygen saturation of the blood.

I learned only recently that research by Japanese engineer Takuo Aoyagi led to the invention of the modern pulse oximeter.

Born in Niigata in 1936, Aoyagi aspired to be an inventor and studied engineering at university. After a stint at Shimadzu Corp., he joined Nihon Kohden Corp. in 1971, a leading manufacturer of medical electronics equipment, where he was told by his superior to "develop something unique."

A conversation with an anesthesiologist inspired Aoyagi to devote his research to the development of an easy-to-use device for determining the oxygen level in arterial blood.

Since oximeters back then could not read oxygen levels without drawing a blood sample, health care providers had to make a guess based on the complexion of individual patients.

Aoyagi focused on the pulse and succeeded in isolating signals from arterial blood, which made continuous monitoring possible.

That was a veritable coup. But it took a while before his invention was fully appreciated by the medical community.

The usefulness of his device was fully recognized only in the 1980s, when medical crises caused by oxygen deficiency under anesthesia made news headlines in the United States. This resulted in a number of companies rushing to commercialize pulse oximeters, which came to be marketed globally and saved countless lives.

Aoyagi late in his life was still working to improve his device.

When he died in April last year at the age of 84, a U.S. daily ran a lengthy obituary.

Naoki Kobayashi, 62, a special researcher at Nihon Kohden, recalled, "He was a dyed-in-the-wool engineer who wanted to make useful things rather than author academic papers."

A mourning Yale emeritus professor revealed that he had personally recommended Aoyagi for the 2013 Nobel Prize in Physiology or Medicine.

With more than 100,000 COVID-19 patients around the nation today forced to "help themselves" by recuperating at home, the pulse oximeter has become something of a national lifeline.

It is an invention that definitely deserves greater re-evaluation in Japan.

--The Asahi Shimbun, Aug. 28

* * *

Vox Populi, Vox Dei is a popular daily column that takes up a wide range of topics, including culture, arts and social trends and developments. Written by veteran Asahi Shimbun writers, the column provides useful perspectives on and insights into contemporary Japan and its culture.

Related News