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.

Historical vignette: Dr Charles Robson; pioneer Canadian pediatric anesthetist.

Charles Robson (Figure 1) was born in New Westminster, British Columbia (now a suburb of Vancouver), in 1884 and graduated in medicine from McGill University in Montreal in 1913. Having interned and with some anesthesia training at the Royal Victoria Hospital in Montreal, he was sent overseas to work in a Canadian Army Hospital where he founded a school to train military anesthetists. Returning to Canada in 1919, he joined the staff of the Hospital for Sick Children in Toronto as chief anesthetist, a position he held until 1951 (1). During most of this time, he was the sole full-time anesthetist at the hospital; administration of anesthesia at this hospital was not limited to staff anesthetists until 1950 (1).

Neuropsychopathology in the SIV/macaque model of AIDS.

Of the 40 million people living with HIV/AIDS worldwide in 2003, only 7% received highly active antiretroviral treatment (HAART). Without treatment, approximately half of AIDS patients will suffer from NeuroAIDS including neurological dysfunction, peripheral neuropathies, motor impairment, cognitive difficulties and frank dementia. HAART has reduced mortality from AIDS in the developed world, but CNS/neurological complications continue to be a leading cause of death or disability in AIDS patients on HAART. Despite years of use in developed countries, it is still not clear what the long-term impact of HAART will be on NeuroAIDS. The mechanisms of AIDS-related CNS pathology, in the presence or absence of HAART, are not completely understood. Infection with simian immunodeficiency virus (SIV) in macaques provides an excellent research model of AIDS, including AIDS-related CNS pathology and cognitive/behavioral impairments. A major goal of research with the SIV/macaque model has been to characterize behavioral and cognitive impairments in NeuroAIDS and elucidate the CNS pathology behind these impairments. Review of the studies assessing cognitive impairment in SIV infected macaques demonstrates the high concordance between neuropsychological impairment in human and simian AIDS. Consistent with results in human AIDS patients, SIV-infected monkeys tend to be impaired most often on tasks dependent upon intact frontal cortical and/or subcortical functioning. Building on the strengths of the SIV/macaque model of AIDS, directions for future research are discussed including further mechanistic studies of the neuropathology leading to cognitive impairment as well as assessment of the impact of antiretroviral therapy or drugs of abuse on NeuroAIDS.