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

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.

New transcutaneous jaundice device with two optical paths.

OBJECTIVES: To confirm the accuracy and precision of transcutaneous bilirubin (TcB) values measured by a new device with two optical paths (JM-103) and the value of total serum bilirubin (TSB) level in clinical units of measurement. METHODS: For comparison of the levels of accuracy and precision of JM-103 and the old device (JM-102), serum samples were collected from 77 Japanese infants in three different hospitals including 24 preterm infants and 53 term infants. Measurement of TcB by JM-103 and JM-102 were performed on the forehead of each infant within 30 min before or after blood sampling. RESULTS: The range of TSB was limited to 19.6 mg/dL and to 17 mg/dL for preterm infants. The correlation coefficients for all subjects (r = 0.94) and for term and preterm subjects between TcB measured by JM-103 and TSB was higher than that between TcB measured by JM-102 and TSB. The regression line in term infants between TcB measured by JM-103 and TcB was similar to that in preterm infants. The error distribution of TcB measured by JM-102 and TSB for all subjects (0.00 +/- 2.21) and for term and preterm subjects was larger than that of TcB measured by JM-103 and TSB (all subjects, 0.30 +/- 1.55).